A system of practical medicine. By American authors. Vol. 3

by Unknown

CYANOSIS AND CONGENITAL ANOMALIES OF THE HEART AND GREAT VESSELS.

BY MORRIS LONGSTRETH, M.D.

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The questions involved in the subject of the congenital defects of the heart and its great vessels and their causes are not easy of settlement. In the first place, the seat, the extent, and the consequences of the deficiency or defect are not regular or constant. Secondly, the causes and the mode and date of their origin are involved in great obscurity. Their classification either on a purely topographical or on a purely etiological basis is almost impossible on the one hand, because the changes are so irregular and varying, and, on the other hand, because our knowledge of the primary cause or causes of the alterations is quite defective. The views which at the present time find most favor arrange the various malformations into classes according to the period of development of the foetus at which the arrest or change of tissue occurred—as it were, a chronological classification. The ideas in respect to the pathology or the pathological causes of malformed hearts have undergone great changes—changing in some degree pari passu with the mode of classification, and in great degree inducing and compelling such changes.

In early times deformed hearts were looked upon as monsters, curiosities, lusus naturæ. When a knowledge of foetal development and circulation was acquired the deformed heart was compared with the heart-formation in classes of a lower grade than mammals. Such were the beliefs of comparative anatomy and physiology that it was held that the human foetus was matured by stages from the forms found in the lowest invertebrates through the various ascending scales of the animal kingdom. This classification was, on the basis of comparative anatomy, purely anatomical. The underlying thought of such pathological teaching was that in the original ovum something was left out—an actual deficiency of parts which, when developed in the natural manner, made man different from the lower animals; or else, supposing these parts to have been originally present, there was a defect of plasticity, causing a failure of the proper adhesion of symmetrical portions. Excessive development was looked upon as a surplus of parts in the ovum, and by their growth certain of the openings of the heart were prematurely closed. In this view of the pathological alterations no expression of opinion was made how the excess or deficiency of structure was occasioned: the malformation was merely a failure of the parts to rise and pass through the various grades of development—a too rapid or a too slow growth of one or more of the various parts of the foetal heart. There was no reason assigned why the human ovum had in it deficiencies or excesses of material, and thus came to resemble in one of its parts the conditions found in lower animals.

About 1850, Dittrich of Erlangen, by his studies of inflammation of the heart during intra-uterine life, quite diverted public opinion from the older views of the subject. Peacock's earlier studies preceded this work by a few years, and a few years later came Meyer,¹ who greatly extended the scope and influence of the inflammatory theory of Dittrich. Ten years later commenced the clinical recognition of congenital heart defects, and especially the anatomical changes in congenital narrowing of the pulmonary artery, by Von Dusch and by Mannkopff,² and by Stoelker.³ Friedberg had, however, as early as 1844, published his studies of the stages of development of the circulatory organs in the human embryo, and had in accordance therewith divided the malformation of the heart into three groups, corresponding to the three periods of the heart's growth. This was the classification adopted quite independently by Peacock of London in his first publication in 1857. It was not until after Dittrich's studies⁴ and Meyer's that any distinctive cause was assigned for the failure to develop.

¹ Virch. Arch., Bd. xii., 1857.

² Ann. des Charité-Krankenh. zu Berl., 1863.

³ Diss., Bern, 1865.

⁴ See Dorsch's (his student) dissertation, Die Herzmuskelentzundung als Ursache angeborner Herzcyanose, Erlangen, 1855.

Carl Heine,⁵ and also Halbertsma, proposed a classification based on the quantitative and qualitative differences. Under the first division the former placed such changes as absence of the heart, deficiency of individual parts, abnormal smallness, atresia, and fissures; and, in the other direction, duplication of the heart as a whole or in its individual parts, and abnormal largeness. The qualitative differences were deviations of form, of position, and of the arrangement of the great vessels.

⁵ Angeborene Atresie d. Ostium arteriosum dextrum, Beitrag z. Lehre v. d. angeborenen Herzanomalium, Tübingen, 1861.

Peacock's classification in his earlier edition (1858) was partly on the basis of the time at which arrest of development occurs, and partly on the degree of impediment to the circulation and the functions of the heart. In his second edition he adheres to the same classes, with slight modifications, thus: 1. Arrest of development early in foetal life (fourth to sixth week; heart with two or three cavities; single or imperfectly divided arterial trunk); 2. Arrests at a later period (sixth to twelfth week; imperfect auricular or ventricular septa; imperfect or misplaced vessels); 3. Those after the third foetal month (closure and patency of foetal passages; irregularities of valves, cavities, etc.).

Kussmaul (1865) published a very important work on malformations due to defects of the pulmonary artery,⁶ and these malformations he considers under two general groups—viz. those having their origin before the ventricular septum closes, and those occurring after this period. His most valuable contribution to the subject is the importance which attaches to the distinction between primary and secondary defects or arrests of development—i.e. between an original alteration of growth or morbid condition, and those which follow from it as a necessary consequence. Of his classification, and of the importance of pulmonary artery malformations, a further description will be given.

⁶ Ueber angeborene Enge und Verschluss der Lungenarterienbahn, Freiburg, i. B.

For study, one would wish to arrange the malformations in classes convenient for clinical purposes. For example, separate them into groups of the defects compatible with extra-uterine existence and those incompatible with adult life. Unfortunately, this division is not possible. We find many cases of defects involving originally the same seat: in one the individual lives many years, in another the obstruction immediately induces symptoms, and death soon comes. A classification according to the seat of the disease alone, if it could be made, would give the subject a simplicity equal to that of valvular heart disease in the adult. Here, however, we find such variations in the details of the alteration that if this principle of classification alone is employed the confusion becomes very great. It would seem, therefore, that the principle first made use of by Kussmaul, of classifying the defects by distinguishing the primary malformations from their secondary effects, renders the subject the most simple, and at the same time affords the advantage of more readily understanding the mechanism of their production.

It will be useful to pass over seriatim, following the course of the foetal circulation, the various valves, orifices, and foetal openings to be able to comprehend which are most liable to defects or to see which defects most frequently occur, and also to find which alterations produce the greatest disturbance of the circulation.

1. The Foramen Ovale and Septum of the Auricles.—In markedly deformed hearts the entire septum may be in greater or less degree wanting, as seen in cases of the bilocular or trilocular organ. This defect is comparatively rare, and the foetus has but a short extra-uterine life. In other cases the septum is complete, but the foramen may be unusually large, and remain unclosed wholly or in part; perforations may be present, or the valve may merely fail to adhere. Of the latter cases, the patent foramen is found in conjunction with defects at other parts, while small sieve-like perforations or the mere non-adherence of the membrane—both of very common occurrence—may be owing to a temporary obstruction during the early hours of life or to any unknown cause, or may possibly be due to a reopening of the foramen from an acquired disturbance of the circulation. Opinions vary as to the mechanism of the closure of the foramen. Some consider it a passive process due to increased blood-pressure in the left auricle, coming from the entrance of the current of aërated blood from the lungs; others speak of it as an active process resulting from the excitation to contraction of the muscular fibres in the membranous valve. Whatever may be the mechanism, patency of the foramen ovale of undoubted foetal origin (excepting the minute perforations and oblique slits) must be looked upon in nearly every case as a secondary defect—secondary to an obstruction to the outflow of blood from the ventricles through the great arterial trunks, or it may be from the auricle itself through defect of the auriculo-ventricular orifice. In a vastly preponderating number of cases it results from pulmonary artery obstruction. The foramen may close, however, in such a case if an outlet is provided by the aorta through an open septum ventriculorum, or when this vessel arises from both ventricles. Narrowing or closure of the right auriculo-ventricular orifice, as a primary cause, can prevent the closure of the foramen ovale; primary narrowing of the tricuspid orifice is very rare, single or combined with other defects. In these cases the direction of the blood is from the right auricle to the left. There are, however, cases on record of patency of the foramen ovale in which the blood-current is from the left to right side, the reverse of the foetal course. Here the cause to be looked to is a congenital deficiency of the mitral orifice, or a narrowing, closure, or malposition of the aorta.

2. The Right Auriculo-ventricular Orifice and Tricuspid Valve.—A primary deficiency of this orifice and the valve guarding it very rarely occurs as a primary defect and uncombined with malformation of other parts of the pulmonary circulation. It does come in certain cases in conjunction with great narrowing of the pulmonary orifice or artery, but by no means commonly. If the pulmonary outlet is normal and in the usual position, the right auriculo-ventricular orifice is never found closed, although the leaflets have been seen defective, permitting regurgitation. In certain other cases the orifice and valve, as well as entire right ventricle, show a failure to develop, and all these parts appear shrivelled. This condition is a secondary result, due to a great deficiency of the pulmonary artery and narrowing of the pulmonary conus. The malformation of the pulmonary artery in such cases results from an unequal division of the truncus communis—the narrowing of the conus generally from endo-myocarditis. The aorta is unusually large in diameter. The blood from the right auricle passes through the foramen ovale to the left side of the heart; the ductus arteriosus Botalli remains open, or in very rare cases the mixed venous blood reaches the lung through collateral channels. In rare cases the blood, in addition to the open foramen ovale, has a direct passage from the right auricle into the left ventricle.

3. The Pulmonary Artery and the Right Conus Arteriosus.—This situation presents by far the largest number of cases of congenital heart malformation of primary occurrence. The defects at this part require different interpretations according as they are found within the right ventricle or in the pulmonary artery itself. So frequent are the defects at these seats that Kussmaul bases his classification, for a large proportion of cases, on the malformation of the pulmonary artery track, and describes them as combined with defects secondarily resulting in other parts.

The narrowing or closure may exist either at the limit between the sinus and the conus of the right ventricle, the conus arteriosus may be uniformly narrowed, or the defective development may involve the orifice only or the whole length of the pulmonary artery. Many of these defects, resulting in closure or narrowing, are due, as Rokitansky was the first to show, to inflammatory changes. It is Kussmaul's great merit to have pointed to the fact that a very large proportion of all malformations owe their origin primarily to diseased conditions originating at this seat. The varieties of these defects and their secondary consequents will be described later.

4. Patency of the Septum Ventriculorum.—The degree of deficiency of the septum varies greatly. The entire partition between the ventricles may be wanting or exist in merely a rudimentary condition. Ordinarily, there is found a triangular, rounded, or oval opening in the septum close to the base of the heart, at the portion which in the normal heart consists of only a membrane (pars membranacea). Besides this usual opening, one, or even two, others may present themselves at other points of the septum, thus forming multiple communications between the cavities. In narrowing or closure of the pulmonary passage the septum is more or less deflected toward the left ventricle to allow a freer passage of blood from the right side of the heart through the open septum into the aorta. In other cases the passage of blood may be from the left ventricle into the right—the reverse of the usual direction. The defects of the septum are usually of a secondary character, dependent on primary malformation of other parts, and, as already said, chiefly those of the pulmonary track. They are of congenital origin, commencing early in foetal life, before the third month, when normally the septum closes. Hence patency of this septum furnishes in many cases a valuable means of determining the date of the primary defects with which it is found combined. This malformation, however, does very rarely stand as an isolated defect, and still more rarely it is believed to have been acquired through an ulcerative destruction (myocarditis) of a portion of the septum, either during foetal or extra-uterine life; wasting or atrophy of the membranous part is sometimes thought to have occurred. In these latter cases a misdirection of the blood-current of a marked sort rarely occurs unless the inflammatory or other changes affect the main arterial orifices.

5. The aortic and mitral orifices are very much less frequently found narrowed or obstructed as the result of congenital primary defects than the orifices and their valvular apparatus of the right heart; and, also following the rule which obtains on the right side, the mitral is less frequently affected than the aortic orifice.

6. Of the Malformations of the Great Vessels.—Such changes may come alone, though usually they are combined with simultaneous or consecutive defects in other parts of the central circulatory apparatus. Of the sorts of defects or malformation which these two vessels suffer, there are two chief forms to be described: 1, such as result from an unequal division of the vessels in their formation from the truncus communis; 2, those which result in more or less complete transposition of their origins. Of the transpositions we may find two sorts: in one the vessels maintain nearly their normal relative positions to each other, but each communicates with the improper ventricle; in the other they are transposed relatively to each other and also to the respective ventricles. In the first of these classes, unequal division, one variety may be ascribed to a defective or irregular development of the septum by which the vessels are formed of unequal sizes; the other, originating later in foetal life—i.e. after the third month (for the septum between the vessels is completed nearly simultaneously to the ventricular septum)—results from inflammatory or other morbid change in or about the orifice and trunk of one or other vessel, causing a narrowing or closure, the other vessel showing compensatory enlargement. This form is not a true unequal division of vessels. The apparent origin of one or both vessels from the same ventricle in these cases is not a true example of transposition of the vessel, but is due to a deviation of the septum ventriculorum toward one side or the other from increased blood in the ventricle from which the outflow is more or less completely obstructed. True transpositions of the vessels, both relatively to each other as well as to the ventricles, originate very early in foetal life, and these as well as the unequally-divided vessels are primary defects, and are usually accompanied by many secondary changes. Another malformation occasionally found, involving the beginning portion of the great vessels, is a failure of complete division: the septum truncus communis remains rudimentary, and the blood of the aorta is free to mingle with that in the pulmonary artery. This defect may be accompanied with a rudimentary septum ventriculorum.

7. Ductus Arteriosus Botalli.—This foetal orifice varies greatly in the conditions which are presented; sometimes it is entirely wanting, in others patulous and even in a state of dilatation; in others, again, a short portion is patent (this state is probably comparable to failure to adhere seen in the valve of the foramen ovale or the sieve-like opening in the fossa ovalis; unlike the valve of the foramen, the ductus probably never reopens), or in yet others the ductus is closed in some cases of malformation, and in others of very similar character it remains open. It becomes difficult to explain the varied states of the duct, so dissimilar are they to other defects of development present. In none of the conditions which are presented can the malformations be regarded as of a primary character. Our surprise at certain of its conditions probably must depend on a failure to justly appreciate the primary malformation present, or else on changes in the heart and the circulation coming at a period subsequent to the date of origin of the malformation of the duct itself. When the duct is open at one end and closed at the other, the open part communicates usually with the pulmonary artery, since the closing process commences normally at the aortic extremity: the closure beginning at the pulmonic extremity is occasionally seen in malformations of heart where the blood-current has had a reverse direction through the duct.

The premature closure of the ductus arteriosus Botalli, which is spoken of by some authors, seems to be a rather unfair designation to apply to the condition. In most cases it is in reality an absence of the duct dependent on the defective development of certain of the branchial arches. In other cases the apparent premature closure is due to general uniform narrowing, almost closure, of the pulmonary orifice and vessels; in such cases the lungs are supplied by the enlarged bronchial arteries or other collateral branches. The ductus arteriosus Botalli remains patulous when the pulmonary artery is narrowed or closed; in these cases the blood from the right side of the heart to reach the lungs must pass either through an opening in the septum ventriculorum or through the patent foramen ovale. The duct is generally open in cases of transposition of the main arteries, or even in cases of obstruction of the aortic orifice, or of uniform narrowing of the descending aorta or its main branches. Its usual length and its point of origin from the pulmonary artery or its branches, as well as its junction with the aorta, may vary. Two ducts have been found—one from each pulmonary branch, one of them joining the aorta as usual, the other seeking one of its branches. A distinct duct has been found arising directly from the right ventricle. None of these defects are to be considered as primary malformation, but as the secondary results from alterations of the circulation occasioned by other malformations of the heart or of its great vascular trunks.

Fully bearing in mind the distinction which must be made between primary and secondary defects, and the fact that congenital lesions of the orifices and valves are mostly located on the right side of the heart, let us look at various causes which are capable of producing malformations. In many cases, from the condition of the parts, it is possible to say positively that the alterations are dependent on an inflammatory process commencing in the endo-myocardium at an early period of foetal existence; this is true even after excluding cases in which the inflammatory products present may fairly be considered to be the result of defective development and not its cause. Inflammation was, as has already been shown, long ago pointed out as the cause of these obstructive malformations. Rokitansky (1844) was followed in his views by many, who asserted, probably wrongly, that this condition was the sole cause of the misdirection of development. It was considered that while in very many cases the evidences of the inflammation remained indubitable, in others, through a greater lapse of time, the inflammatory products became less distinct or were wholly removed. Thus, all defects of development may be traced as the results of some obstruction of the pathways of the foetal blood, which, on the one hand, effects the closure of certain vessels or orifices, or on the other hand maintains patent others which normally should be obliterated. It is much easier to trace these causes when they operate during the later periods of development, after the heart and great vessels have assumed the general shape they maintain, than those which operate at the earlier periods of transition. It is plain to us that an obstruction of the pulmonary artery or its branches coming before the end of the third foetal month must, by preventing the flow of blood through it from the right ventricle, maintain an opening of greater or less size in the incomplete septum ventriculorum. It is much less easy—or, in fact, impossible—to be positive about an obstruction or other change which causes the transposition or an unequal division of the great vessels, or which prevents entirely the development of either septum. Nevertheless, we can believe that some obstruction of the foetal circulation causes the former defect as well as the latter, if we may judge of so dark a question by the analogies. In fact, what would present itself as a trifling obstacle in the third or fourth month of foetal life would in the sixth week be an impassable obstruction.

It has been urged against the view that some inflammatory process is the invariable cause of the obstacle, by those who support the development theory, that, as the heart remains in a rudimentary condition, the defects result from a want of formative or plastive activity of the parts. It seems, however, as difficult to account for the want of formative activity which prevents the development of the septum or causes an unequal division of great arterial trunks as to find the traces of an obstruction. Maternal impressions or shocks have doubtless caused many headless foetuses or otherwise misshapen the product of conception during the early months of development. The effect on the foetus from such shocks cannot of course be a direct nervous impression, such as those seen producing local disturbances of nutrition or of formative activity in the adult's own organism, but it is due to disturbances of the placental circulation, by which the blood-current is delayed in the foetal circuit. Such delay may result in a temporary obstruction of the blood in certain foetal vessels. A delay of the blood-current during a few hours in the early period of development of the foetus, when formation is excessively rapid, may result in changes which become permanent. The evidences of such obstruction may fade completely. Osler⁷ has recently urged that it is difficult to suppose an endocarditis limited to the pulmonary valves in an embryo not more than an inch in length, and whose heart could not be above a few millimeters in size. But is it not possible to suppose an endocardial inflammation which affects at the same time, for example, the vascular orifices and the line of the rudimentary septum? The septum may thus be prevented from further development, and the orifice suffer malformation by subsequent contraction. The evidences of the inflammation would greatly lessen as the size of the heart expanded. Cannot inflammation, syphilis, or other communicable disease, from which we know the foetus suffers, be substituted for the unknown "want of formative activity"? In respect to the extent of surface involved in the foetal heart in inflammatory or other morbid processes, can we not suppose that the area exhibiting evidences of disease in the minute heart would be as restricted as in the adult heart? In rheumatic endocarditis of the adult the cause which leads to the inflammation is a general one; the evidences we find of the morbid process, however, are confined to very narrow limits. The reasons for this restriction may be the same.

⁷ Montreal Gen. Hos. Reps., vol. ii.

The simple narrowing of a blood-track where direct evidence is wanting may be explained by the occurrence of a specific morbid process as satisfactorily as by an appeal to lack or excess of formative power. The real difficulty arises in the explanation of cases of transposition of the great vessels. The problem is in every way a most difficult one for solution under any supposition. If it were true that the formation of the pulmonary artery and the aorta was from the start by separate blood-channels, and these distinct vessels suffered a genuine transplantation and became attached to the wrong ventricle, the aorta to the right and the pulmonary to the left ventricle, then undoubtedly we should be compelled to accept the developmental theory as usually expressed. But it is not the case that these vessels are developed in distinct trunks: their development results from the division of a common trunk through an infolding of the walls or the gradual formation of a septum proceeding contemporaneously with the septum of the ventricles, the vessels at the same time making a half turn on their axis. A delay in the formation of either septum may result in the malapposition of the vessels to the ventricles. The septum which is probably delayed in formation is the vascular septum, since it is apparently the growth of this septum that applies the force which results in the axis rotation of the vessels. Are we again to explain the abortive formation of the vascular septum or any portion of the branchial arches by the unknown want of formative power? The want of formative power must have a cause; it does not come spontaneously. Are not inflammatory endarteritis and syphilitic lesions of the blood-channels probable causes of the contraction or obliteration of portions of the branchial arches?

Another question, dark and obscure, requires a short comment. It is commonly accepted, if an abnormal communication (speaking of small openings) exists between the two ventricles, that the septum has been prevented from closing by the blood-current being diverted from its usual course through narrowing of an arterial ostium, and compelled to flow into one or the other ventricle. The patency or the closure of the ventricular septum is held as a criterion of the date of origin of the primary malformation. We know that certain ulcerations of the endo-myocardium may result in forming openings between the two ventricles, but is it not possible that a perforation may be made in the ventricular septum after it has closed by a lesion originating at an arterial ostium of the same character as one that prevented the septum from closing? The muscular tissue of the heart from the third to the sixth foetal month, and even later, is of very soft character. A rapidly-coming closure, or even temporary obstruction, of one or the other great arterial trunks would greatly increase the blood-pressure within the corresponding ventricular cavity. The ventricular septum would become stretched and thin, and might readily be perforated, so delicate is the muscular tissue.

If such a possibility is consummated, it must alter the value which has hitherto been placed on the opening in the ventricular septum as a criterion of the date of origin of the primary lesions of the great vessels which ordinarily are the cause of the patent condition of this partition.

It is to be seen from a review of the recorded cases of malformation of the heart that defects of the arterial outlet of the right ventricle are the primary cause of the largest number of cases. It is impossible to state the proportion of these to those at other orifices or the great vessels, so incomplete are the records and so unlike are the opinions of the reporters. It is but natural that this the more active ventricle of foetal life should exhibit more frequently defects of development, since the left ventricle in adults suffers more commonly in its valvular apparatus during its more active period.

The position at which the defects resulting in obstruction of the blood-current through the pulmonary artery may occur have been mentioned. The degree of the narrowing is of much importance—much more than the seat of the obstruction; but of still greater consequence is the date of origin of the defect of development, since on its occurrence early or late in foetal life depend the condition of the septum ventriculorum and the perfection of secondary compensatory alterations which render the heart capable or incapable of a prolonged extra-uterine life.

Narrowing or closure of the course of the blood passing through the pulmonary artery may be divided into two classes: 1, those cases in which the septum ventriculorum is imperfect to a greater or less degree; and 2, those in which it is fully formed, the separation between the ventricles being complete. The date of their origin corresponds to different periods of the development of the foetus. The earlier the obstruction comes in the normal outlet of the ventricle, the more rudimentary is the ventricular septum. The size of the opening of the septum depends on the degree of narrowing of the pulmonary outlet as well as on the date of origin of the obstruction. If the arteries are transposed in relation to the ventricles, and one of them becomes obstructed, the effect on the septum is the same, although the direction of the current through the opening is reversed. Kussmaul and others have pointed to certain exceptions which may lead to errors. In a congenital opening of the ventricular septum, isolated from other defects, an endocarditis involving the pulmonary orifice may occur subsequent to the time of the usual closure of the septum, or even after birth. It would be difficult to distinguish such a case from one of pulmonary narrowing occurring before the third foetal month. The character of the inflammatory changes and the size of the pulmonary artery beyond the point of narrowing would assist in marking the distinction. It must be remembered, however, that the pulmonary artery is recorded as possessing a large size beyond the seat of narrowing in cases of undoubted congenital origin.

The alteration in the form and size of the right ventricle varies greatly according to the time at which the pulmonary obstruction originates. The ventricle seems to maintain its size, and even to become hypertrophied and dilated, when the pulmonary obstruction occurs before the closure of the septum: if the pulmonary artery is obliterated or exceedingly narrowed at a later period, the ventricle shrivels, because no blood is able to pass, and gradually more and more of the foetal current passes through the foramen ovale to the left side; if, however, the pulmonary defect is but slight, the right ventricle continues its function, becomes hypertrophied, and may dilate. In pulmonary obstruction the right ventricle changes its form somewhat in accordance with the seat of obstruction. Thus the primary obstruction may be in the pulmonary artery or its branches; or in other cases the malformation is found within the cavity of the right ventricle. The last group is spoken of as conus stenosis.

The malformations of the conus of the right ventricle may present themselves under three forms: they all act as constrictions, but alter the shape of the ventricle very variously; their effect on the circulation is practically the same, varying only with the closeness of the constriction. If an inflammatory process occur at the seat of the normal muscular constriction between the sinus and the conus, it may result in fibrous thickening and contraction; thus the normal division of the sinus from the conus becomes exaggerated and permanent. The narrowed portion may continue to exhibit evidences of endocarditis, or these may fade away, leaving a smooth surface. These narrowed parts seem to be especially liable to inflammation at a subsequent period as the bulk of the blood and the force of the circulation increase. Peacock describes a condition of narrowing due to muscular hypertrophy alone. It would seem in these cases that the hypertrophy was, in not a few of the instances, an acquired condition, and not congenital.

These cases present a heart having, as it were, a double or subdivided ventricle, comparable to that of the turtle. The condition has been described by some writers as a supernumerary ventricle. The form and size of the communication between the two portions of the ventricles vary very greatly: in some of the cases due to inflammation the passage merely admits of a large probe, and consists of a firm fibrous ring, or there may be two or more such openings. In constriction by muscular bands the opening is usually a large oval with smooth walls. In these cases the size and the condition of the walls of the so-called supernumerary ventricle present different appearances according to the degree of constriction and the size of the pulmonary opening; it is probable also that the condition of the ventricular septum influences the consecutive alteration in the parts. When the constriction is close and but little blood enters the conus, its walls are thin and flaccid, while in cases of less marked narrowing, provided the pulmonary artery remains nearly normal, the walls of the conus become hypertrophied, in conjunction with a similar development of the other parts of the right ventricle.

In other cases the entire conus may be uniformly narrowed: this change is due almost invariably to inflammatory lesions, and in many instances it is difficult to determine whether the condition is of foetal origin or whether it arose during the early months of extra-uterine life or even at a later period. Its occurrence in conjunction with other malformations would point to its origination during the developmental period. The conus may also present a constriction directly at or just beneath the valvular orifice of the pulmonary artery. This condition is almost invariably combined with some narrowing of the artery itself, and there is so constantly present evidence of inflammation of recent date that it is almost impossible to say whether the defect is not due to a myocarditis originating after the developmental period. With this condition the entire conus usually presents more or less shrinkage or collapse, becoming greater as the constriction at the orifice is more marked. This collapse of the conus is to be looked upon as secondary to the primary defect at the orifice.

Closure or narrowing of the pulmonary artery trunk may be traced to many conditions acting at several different points of the course of the blood. Nearly all these conditions are caused by inflammatory lesions which result in contractions of the arterial walls. In fact, pulmonary artery defects not dependent on inflammatory changes are very obscure and difficult of explanation. In adult life we know of only two conditions which lead to obliterations of vessels; first, inflammation of the lining membrane (endarteritis); and second, stoppage of the blood-current, usually through pressure directly applied to the vascular trunk. The clots of blood which occupy the vessels form both in advance and beyond the point of pressure; hence we can look for obstruction, causing closure of the pulmonary artery, at either extremity of the blood-course. Thus, we may think of a primary conus obstruction which may secondarily have the effect of reducing the size of the pulmonary artery, but it is never obliterated through this means; nearly always some blood passes in this direction, and blood also enters the pulmonary artery from the ductus arteriosus Botalli: both conditions necessarily tend to keep the artery from complete collapse; moreover, the artery, even in cases of very narrow conus, may remain of its usual size. The same effect may be produced by narrowing of the tricuspid orifice. This condition is a very rare one, and never could lead to complete closure of the pulmonary artery unless this orifice were entirely obliterated and the septum of the ventricles remained closed. Peacock speaks of premature occlusion of the ductus arteriosus Botalli as one of the causes of narrowing of the pulmonary artery. The obliteration of this portion of the branchial arches, by preventing the blood flowing in its usual course to the descending aorta, he thinks results in narrowing the calibre of the pulmonary artery. May not the condition be equally well interpreted in a different manner? May not it be that the obstruction of the artery was the cause of collapse of the ductus? One would think it possible, if an obstruction arose in the ductus arteriosus Botalli, for the blood-current in the pulmonary artery to maintain another branchial arch patulous for its accommodation, or, failing this, to dilate the pulmonary branches and thence return to the left side of the heart. In rare cases the pulmonary artery has been found deficient in size when the lungs are malformed, either by reduction in their size as a whole or by the absence of one or more lobes. Such a cause has very little opportunity of acting with much force on the pulmonary artery during foetal life. This cause and all the others in this group are to be looked upon as secondary in their effects.

In primary defects of the pulmonary artery trunk the vast majority afford indubitable evidences of an original inflammatory causation; others are due just as positively to a defective evolution of this vessel from the common arterial trunk. Instances are on record of the complete closure of the pulmonary artery and its conversion into a ligamentous cord: these cases are very rare. In a somewhat larger number a pretty uniform narrowing, sometimes to an extreme degree, and often exhibiting thickened walls, is found. It is much more frequent to see the obstruction of the artery, due to inflammatory changes, at its valvular orifice.

Peacock describes the narrowing at the pulmonary orifice in many cases to be due to disease of the pulmonary valves, whereby the number of cusps are reduced in number, or to a membrane stretched across with small openings in its central portion; or the obstruction may consist of a duplicature of the lining of the vessels, or even to bands of muscular fibres surrounding the orifice. Two valves of unequal size may be found at the orifice, giving evidence that the larger one has been formed by the adhesion of two of the normal cusps; the membranous obstruction is probably due to the union more or less complete of the three cusps. The curtains thus formed protrude into the course of the artery and form a deep circular sinus between the valves and the walls of the vessel. The opening between these adherent valves varies from a transverse slit to a tubular or barrel-shaped orifice—a tube within a tube. These diseased valves are thickened, very firm, fibrous, or even calcified. In other cases the obstruction consists of abundant warty elevations, so numerous that they are equally effective in preventing the passage of blood as the united valves. The size of the opening is sometimes extremely reduced, measuring only five millimeters in diameter. The pulmonary artery is most generally less in size than normal, but never becomes reduced to the same extent as its orifice, unless it has likewise suffered from inflammatory disease; otherwise its walls remain thin, resembling the venæ cavæ.

In addition to disease within the calibre of the vessel, Meyer, who strongly advocated the inflammatory cause for all these defects, pointed to pericarditis, occurring at the origin of the pulmonary artery and compressing the vessel, as a rare method of causation.

In a very large majority of the cases of pulmonary narrowing on record the septum ventriculorum is found to be more or less defective. In accordance with the usual principles, this defect of the septum, in conjunction with narrowing of the pulmonary artery, is held to indicate that the obstruction of the artery dates from a period of development anterior to the closure of the septum. This view was advanced by Hunter in 1783. But Peacock gives an account of many cases of pulmonary narrowing, combined with open septum ventriculorum, in which the obstruction was caused by adhesion of the pulmonary valves. It is, however, a fact that the development of the valvular apparatus is not effected until after the septum of the ventricles is completed. How, then, can we suppose valves to adhere so as to obstruct the pulmonary artery and prevent the closure of the septum when in reality the valves themselves have not developed? Does it not seem possible that in some rare cases the opening found in the septum ventriculorum is in reality a reopening? Another case is on record of open septum ventriculorum and narrowing of the pulmonary orifice in a child born of a mother who suffered a prolonged fright during the fifth month of utero-gestation. Strong mental impressions are accounted causes of malformation of the foetus, and in this case the fright, if it was the origin of the defective development of the septum, came more than two months too late.

In cases of pulmonary narrowing with open septum the aorta communicates freely with the right ventricle, or appears to arise from both ventricles, or more rarely from the right cavity alone (the deficient pulmonary artery remaining in its usual position). Many opinions have been held as to which one of the three defects is primary. Hunter's conclusion has most generally prevailed. The obstruction of the course of the pulmonary artery is looked upon as the primary defect. From the obstruction the right ventricle becomes distended, and the opening of the septum is due to the blood-pressure, which prevents the final closure. The blood-pressure also alters the direction of the septum and pushes it farther to the right. Thus the septum comes to stand directly under the aortic orifice, or by a further deviation to the left side brings that orifice wholly within the right cavity. In these simple cases the origin of the aorta from the right ventricle is not a real but merely an apparent transposition or transplantation of this vessel; the aorta has not been moved, but only the septum has been moved under its orifice, and the right ventricle has consequently become more extensive. In other cases the aorta seems to move more toward the right side, usually coming also more to the front, and in other cases there is an actual transposition of these vessels. The method of this transposition will be further described.

Meckel's original theory for open septum and narrowed pulmonary artery was that the defect was primarily in the septum of the ventricles, due to a want of formative energy, and the pulmonary artery closed itself, as do other arteries, from want of use. Meyer showed that a defect of the septum was incapable of causing narrowing of the pulmonary artery, since the exit of blood is easier through the artery, from the form of the right ventricle, than through the open septum; the passage of the blood from right to left is opposed by the blood-mass in the left cavity. Heine also thought the pulmonary-artery narrowing was a secondary defect, but did not think the opening of the septum caused the narrowing. He considered the primary malformation to be a deviation of the septum to the left. The deviation of the partition before its closure brought the aorta within the left cavity, and furnished a free exit for the blood from this chamber shorter and more convenient than through the pulmonary and the ductus arteriosus Botalli to the descending aorta; the pulmonary artery collapsed for want of use, similarly to other foetal blood-courses. Hence, Heine considered that in all cases of open septum and apparent transposition of the aorta which exhibited no evidences of inflammation as a conjectural cause of narrowing or closure of the pulmonary artery the explanation was to be found in a primary deviation of the septum ventriculorum.

The difficulty in Heine's theory lies in showing the mechanism of a deviation of the septum without a primary obstruction of the flow of blood through the pulmonary artery. The hypertrophy of the right ventricle which Heine proposed as an explanation is almost certainly a secondary effect of the obstruction, and therefore cannot be supposed to originate a deviation of the septum; it is doubtful if hypertrophy can be considered as a cause of increased blood-pressure within the cavity of a ventricle under any circumstances, and certainly not as exercising pressure in a direction to cause the supposed deviation of the septum. An open septum without obstruction of the pulmonary orifice, which rarely occurs, does not produce hypertrophy of the right chamber.

The explanation of cases of open septum with obstruction of the pulmonary artery seems entirely satisfactory by Hunter's theory, or by what Kussmaul has named the engorgement theory. But when there is a real transposition of the arteries, the pulmonary placed farther to the left and behind and coming from the left cavity, the aorta in front and to the right and arising from the right or pulmonary chamber, thus changing their relative positions and their orifices exchanging ventricles, the difficulty of explanation becomes great, and the cause of the abnormal relations of the vessels cannot be traced to a simple deviation of the septum ventriculorum.

For the explanation of these cases of complete transposition of the vessels, as well as their transplantation relatively to the ventricles, Rokitansky has traced respectively the development of the two arterial trunks from the common trunk and of the septum ventriculorum. He considers that the partitioning of the arterial trunks is the governing factor in their formation, and that the ventricular septum is arranged in conformity with the septum of arterial trunks. In tracing the development of the circulatory apparatus in man there seems to be no doubt that the heart develops exactly like that of other vertebrates.

The very first rudiment of the heart is a spindle-shaped thickening of the intestinal fibrous layer of the fore part of the alimentary canal. This spindle-shaped formation then becomes a hollow pouch, and separates from the intestinal layer and lies free in the cardiac cavity. The earliest condition yet seen in the human being is that from an embryo of about two weeks (Coste), in which the viscus appeared as a simple tube in the shape of a letter S—the hollow rounded pouch having slightly elongated and bent to this form, and simultaneously turned spirally on an imaginary axis, so that the posterior part of the tube rested on the dorsal surface of the anterior part. The yelk-veins connect at its posterior part, while the arteries form a continuation of its anterior extremity. The spiral turning and curving increase, and simultaneously two shallow indentations appear in the twisted pouch, transversely to its long axis, looking like kinks in a flexible tube. These indentations mark the outline of the three primitive portions of the central organ—viz. the first, with which the veins communicate, represents the future auricles; the next, the ventricles; the third portion, the common arterial trunk (aortic bulb or truncus arteriosus communis). Early in development the first section is the largest, but by the time the S is formed the middle or ventricular portion exceeds in size the auricles and their appendages. So far, the central organ remains a continuous tube, indented transversely in its course at the points which mark its future division; the blood moves through it as through a coiled tube, entering by the veins and passing out by the aortic bulb to the vascular or branchial arches; the venous entrance is posterior, the arterial exit is anterior and is directed toward the future aortic arch. This is the condition at the end of the second week. The future auricles and ventricles now form a common cavity; the indentation between them, called the auricular canal, represents the future auriculo-ventricular orifice. The future fibrous ring forming this orifice is the first to be developed of all the permanent structures of the heart; its infolding to form the two auriculo-ventricular orifices comes early, but at a later date than here spoken of. Its exact method of development is not clearly described.

Between the second and fourth weeks is exhibited an indication of the future most important step in development; this process does not really step forth until the fourth week, although superficial traces of a furrow antedate this time. This step is the division of three sections of the tube into opposite halves, a right or venous, a left or arterial half. This division results in the formation of the future septa between the auricles and between the ventricles, and separates the common arterial trunk (aortic bulb) into the future aorta and pulmonary artery. This partition is spoken of as longitudinal; but it will be seen, if the real lines of growth of the future auricular and ventricular septa are carefully regarded, that the indentations which mark their site are also transverse, as were the primitive ones for division of the auricles from the ventricles. The proximal end of the tube comes in contact with the distal portion by a further bending movement, so that these two ends go to make the left half of the heart; and the middle portion of tube, composed partly of auricle and partly of ventricle, forms the right half of the heart. This secondary indentation, commonly spoken of as longitudinal, is in reality transverse, although, from the more markedly bent condition of the tube which has come about, it does not advance in the same plane as the primitive indentation of the tube. The mechanism of the division of the aortic bulb will be described later.

This secondary indentation, which finally results in the formation of the auricular and ventricular septa, appears earlier in the ventricular cavity, about the fourth week, and later in the auricles, about the eighth week. By about the twelfth week the process of formation for the muscular partitions is completed; the septum ventriculorum normally is gradually built up, and by this time has joined itself, at the base of the heart, to the septum forming itself in the arterial bulb; thus the right and left ventricles are finally separated. The septum in the auricles is also finished in its muscular part, mostly built up from the base and posteriorly toward the roof of the cavity, leaving, however, the foramen to be closed by the membrane some days after birth.

The foetal heart from the fourth week onward becomes more and more rounded in outline, and finally more or less rectangular. The auricular appendages become conspicuous and overhang the ventricles. The future left ventricle appears larger than the right, and the former projects notably leftward and downward. The aortic bulb or common trunk appears to arise wholly from the right ventricle, although the vessel communicates with both cavities, since at this period the cavities are undivided. The furrow which marks the line of the future septum ventriculorum runs to the left of the root of the common trunk; and until at least as late as the sixth week this trunk appears from the exterior to be in connection only with the future right ventricle.

As early as the sixth week, possibly earlier, a distinct furrow is seen on both sides of the common trunk running longitudinally from its root at the ventricle to its first branch (branchial arch). This indentation does not traverse directly to the ventricular furrow; in fact, at this period the ventricular furrow is not conspicuous at the origin of the trunk toward the base of the heart, the septum within not having risen as yet to the base of the ventricles. During the formation of this furrow the common trunk continues its slow partial rotation on its axis; the rotation of the other parts of the cardiac tube has ceased; the segments of the tube have come to a standstill—become, as it were, fixed and adherent to each other, the proximal to the distal end, the anterior surface to the posterior, through the previous bending of the tube on itself.

Within the common trunk Rokitansky has described the changes, as seen in cross-sections, which result in its division into a permanent aorta and pulmonary artery, and also the adaptation of the septum arteriosus trunci to the septum ventriculorum. He says that at an earlier period than here described for the external furrow appearing, on the inner surface of the truncus arteriosus communis (aortic bulb), to its left side and somewhat posteriorly, above the starting-point of the anterior limb of the septum ventriculorum, a little swelling appears, which grows toward the right and slightly forward, so that the common trunk is divided into an anterior rather left-hand, and a posterior right portion, respectively the pulmonary artery and aorta. The growth does not pass in a straight line through the lumen of the common trunk, but so that the forming septum makes a concavity posteriorly toward the aorta, and a convexity anteriorly toward the pulmonary; thus, on cross-section the aorta has the outline of the gibbous moon—the pulmonary, fitting into it, separated by the septum, of a new moon. The septum ventriculorum, as seen starting at the base of the ventricles from the fibrous ring of the auriculo-ventricular orifice (having already been built upward from the future apex of the heart), originates at a point on the posterior wall of the common ventricular cavity in exact correspondence with the starting-point of the little swelling on the inner surface of the common arterial trunk. The two septa are thus formed in apposition. The septum ventriculorum, in advancing forward to meet the other limb of the septum forming on the opposite wall of the ventricular cavity, follows the septum trunci arteriosus communis, surrounds the posterior vessel (the aorta) to its front, then passes around it to its right; the pulmonary is on the other side of the septum; the portion of the septum ventriculorum between the orifices of the vessels is the pars membranacea of the septum. The anterior portion of the septum ventriculorum forms one wall of the arterial conus of the right ventricle. Thus it happens that by the eighth week the common trunk is divided into aorta and pulmonary artery; the structure of the septum ventriculorum is so far advanced that these vascular trunks are connected with the proper ventricles, but the septum ventriculorum does not close completely until about the twelfth week.

In explaining the occurrence of a transposition of the arterial trunks in accordance with the facts of their normal development, Rokitansky says, if the septum trunci, starting from the usual point of the little swelling on the inner surface of the common trunk, turns abnormally with its concavity forward (instead of backward as normally), and thus passes through the trunk, there will be established an anterior left aorta and a posterior right pulmonary, because the septum ventriculorum in its growth conforms to the direction of the septum trunci. Thus, another than the usual portion of the common trunk is partitioned off and placed in communication with the respective ventricles. This furnishes us with examples of transposition of the arterial trunks relatively to each other, but not transposed in relation to the ventricle into which they are implanted. The great majority of specimens of this sort with which we are acquainted—and Rokitansky knew no others—show an open septum. They are usually spoken of, therefore, as instances of "both vessels arising from the same ventricle (the right usually)," or of "aorta communicating with both ventricles, the pulmonary artery normally placed." Rokitansky assigns no reason for this deviation in the line of growth of the septum trunci across the lumen of the common trunk; in fact, he never examined a malformed heart during this stage of development. The deviation of the septum trunci, the primitive factor in this malformation—since to it the septum ventriculorum conforms its development—he accounts for by chance (deviation of formative energy). It seems much more probable, as it is always the pulmonary artery which must be reduced in size when the concavity of the septum trunci presents anteriorly (the aorta occupies the smaller area when the concavity of the septum is posterior), that the deviation of the septum trunci is due to some one of the many conditions (endo-myocarditis) which have already been pointed out as the cause of pulmonary-artery narrowing or closure; hence, another malformation of the heart can be thus traced to pulmonary obstruction, the evident cause of so many other defects.

For examples of transposition of the vessels, both relatively to each other and to the ventricles, with complete closure of the septum ventriculorum, Rokitansky also gives a satisfactory explanation. It is important to note the distinction between cases of closed and open septum. Transposition of the vessels with open septum are, as already shown, doubtful instances of transposition from one ventricle to the other, although the vessels may be transposed in relation to each other; furthermore, the mechanism which explains relative transposition of the vessels does not explain the implantation of the vessels into the improper ventricle. His explanation is that the starting-point of the little swelling from which the septum trunci forms is shifted to a point farther forward on the inner circumference of the common trunk, and at the same time has its concavity anteriorly, and as in the previous case decreasing also the area of the pulmonary artery; and thus the aorta comes more forward and to the right, and the pulmonary artery passes more to the left and backward. The septum ventriculorum, in conforming itself to the abnormal starting-point and direction of the septum trunci, must consequently pass across the common ventricular cavity in such direction that the aorta comes in connection with the pulmonary side of the heart, and the pulmonary artery with the systemic heart. Consequently, Rokitansky traces both the relative and the actual transposition of the arterial trunks to the deviation either of the direction or of the starting-point of the septum trunci. The deviation of the position of the little swelling on the inner surface of the common trunk, which Rokitansky supposes, is probably not an actual transference or misplacement of this point of formative energy, but in reality a failure of the common trunk (aortic bulb) to continue its axis-rotation, as it normally does, after the other portions have become fixed. This premature cessation of the rotation of the common trunk would leave the starting-point of the septum trunci in a more anterior position than normal, since the trunk rotates normally in a direction to bring its left side, on which the starting-point of the septum trunci is situated, more posteriorly. A pericardial inflammatory adhesion, such as Meyer pointed out for certain cases of pulmonary artery obstruction, would fix the common trunk, prevent its proper rotation, and at the same time narrow the pulmonary orifice in certain instances. In other cases, in which the pulmonary artery is found of normal size, the septum trunci may be supposed to divide the vessel in the usual direction (concavity posteriorly as normal), whilst the septum trunci commenced to grow from an abnormal position, more anteriorly and to the left than normal (through failure of rotation); hence, as the septum ventriculorum conforms to its growth, the vessels become connected with the improper ventricle; the pulmonary, however, is not found permanently narrowed, and the septum ventriculorum is completely closed. Here the cause is a failure of the common trunk to rotate on its axis, probably from an external adhesion of its periphery.

Malformations affecting primarily the Right Side of the Heart.

In classifying defects in the course of the pulmonary artery we come to—

1. Closure or narrowing of the artery, with perfect ventricular septum.

Congenital obstruction of the pulmonary artery, with closed septum, although more rare than with open septum, is nevertheless a frequent defect. Unfortunately, it is very often impossible to distinguish with certainty whether the stenosis is essentially congenital or is acquired after birth. Complete closure is the least difficult to distinguish, because this defect very soon causes death; the prognosis in a merely narrowed orifice is much more favorable. The duration of life in complete closure never extends beyond a full year, while in undoubted congenital narrowing the age of sixty-five years has been attained.

From this atresia the most striking consequence is a reduction of size of the right ventricle, increasing almost to closure. This result is so common that Peacock thought it was the law that in atresia the right ventricle reduced itself to closure, while in stenosis it dilated and became hypertrophied. This is not the law, but only a rule of very common occurrence. Instances of eccentric and concentric hypertrophy are found among the records of these cases. Great reduction of the right ventricle results probably only when the obstruction comes very soon after the completion of the septum ventriculorum—thus at a time when the ventricle is yet very small. The wasting of the right ventricle can reach a very high degree, and when it becomes very great the tricuspid orifice is also defective. The foramen ovale and the ductus arteriosus Botalli are, in complete closure, usually found open. The obstruction may come in the conus or at the valvular orifice, or the artery is found converted into a cord.

In seven cases the duration of life varied from four days to nine months.

When the stenosis does not reach a high grade, positive clinical signs are often wanting for the determination of its existence, and the difficulty becomes greater as the age of the person advances.

Clinically, we find congenital blueness with palpitation, dyspnoea, together with the physical signs of pulmonary stenosis; these symptoms, however, may make their first appearance only on the advent of some acute disease. Sometimes they come in the first month or the first year of life, or even much later. If abundant congenital compensatory changes are present, the symptoms may be postponed until further compensatory alterations become impossible; or at the narrowed orifice the development of a fresh endocarditis may determine the occurrence of symptoms. The mere increase of the body and of the mass of the blood may alter the relations of the circulation, and this disproportion may show itself with suddenness. Febrile conditions may also suddenly disorder the circulation.

The compensatory alterations which commonly are held to indicate a congenital origin of stenosis of the pulmonary artery are patulousness of the auricular septum and of the ductus arteriosus Botalli. When both of these remain open there cannot be much doubt that the date of origin is from the foetal state or in the first weeks of life. If only one of the foetal passages remains open, the ductus gives a greater surety of a foetal date than the foramen ovale. The closure of both foetal passages does not exclude a congenital origin if the obstruction of the pulmonary orifice is moderate. The patulousness of both foetal passages indicates that the defect arose at least shortly after birth, because these openings close within four or five weeks of this event. The foramen ovale alone open indicates very little with certainty, as it is so often found with one or more small openings without any probable cause. Bézot found it partially unprotected in 44 cases out of 155; Klob, 224 in 500; Wallmann, 130 in 300. Rokitansky has indicated that a strong blood-pressure not unfrequently may press the fibrous valve of the foramen strongly toward one auricle or the other, and thus lead to its atrophy in part, forming larger or smaller openings of communication between the two cavities. In doubtful cases of stenosis of the pulmonary artery such small openings are not signs of much value in determining the congenital origin of the stenosis. Unless there is a marked defect in the septum atriorum, the congenital origin of the pulmonary atresia or stenosis cannot be predicated on this ground.

Patency of the ductus arteriosus Botalli has been very rarely observed as a primary malformation. A coincidence of this as primary defect with post-natal stenosis of the pulmonary artery must necessarily be extremely rare. In persistence of the ductus art. Botalli the current passes from the aorta toward the pulmonary artery; the obstruction of the pulmonary artery conditions a dilatation with hypertrophy of the right ventricle. Reopening of the closed ductus is impossible.

The condition of the pulmonary valves as well as the diameter of the pulmonary artery itself and its branches often afford valuable points for the determination of the congenital origin of stenosis of this orifice. The greater the narrowing, or the more extreme the thinning of the wall, the earlier the coming of the obstruction.

Morgagni reported the first case of stenosis of the pulmonary orifice—in fact, the first case of congenital malformation of the heart—in a girl aged sixteen. He recognized the relationship of the open foramen ovale and the dilatation of the right ventricle as mechanical effects of the pulmonary stenosis.

2. Obstruction of the conus arteriosus dexter, with open ventricular septum.

A. The separation of the conus in the form of a so-called supernumerary third ventricle has been reported by Peacock in ten cases, and ten others have been added by Kussmaul from various sources. The degree of separation varies very greatly in individual cases: in some it is so slight that the designation becomes doubtful, while in others it is so great that the word stricture might with propriety be employed. In two cases a goosequill-sized opening existed between the sinus of the right ventricle and the conus; in others the communication between the two was multiple. The size of the supernumerary ventricle varies greatly; in one case of a girl of twelve years it would only contain a hazelnut.

In most of the cases the partitioning probably commences by hypertrophy of the muscular bands which are more or less marked in normal hearts in this situation: to this, as the result of endo-myocarditis, is added cicatricial contraction of the inflammatory products, whereby the original partitioning becomes greatly increased. The preponderating frequency of the seat of the stenosis directly at the transition of the conus to the sinus increases the likelihood of this explanation of its causation.

Alteration of the valves of the pulmonary artery, probably of foetal inflammatory origin, is of very frequent occurrence with supernumerary ventricle and conus stenosis; sometimes only two cusps are found, though four cusps have been noted; they may be absent or be replaced by a ring mass formed from their union. Normal valves have been observed unaltered by inflammatory changes. The conus appears always to suffer diminution, and the pulmonary artery is found more or less narrowed according to the degree of obstruction. The sinus of the ventricle is dilated and its walls hypertrophied. The aorta, mostly widened, springs in all cases from both the ventricles, unless wholly from the right one. The foramen ovale is generally more or less widely open, although it has been found closed; the ductus art. Botalli is mostly closed. The duration of life may be long; Kussmaul reports the oldest case at thirty-eight years.

B. Of primary uniform narrowing or shrinkage of the right conus art. dext. Kussmaul reports eight cases from various sources. The conus was shortened, and formed a ring-shaped fissure, gradually reduced in size toward the orifice of the pulmonary artery. The pulmonary valves were variously changed, mostly by union of one or more of the cusps, though sometimes remaining normal in shape, though very delicate. The pulmonary artery was generally narrowed to about the width of the calibre of the conus itself, unless further change came to it from its special involvement by endarteritis.

In all cases the aorta arose from both ventricles. The right side of heart was dilated, and the right ventricular wall hypertrophied. The foramen ovale remained open. The ductus arteriosus Botalli has been found absent or closed, and the collateral circulation effected by anomalous communications, oftentimes duplicate or manifold; in most cases the ductus remains open. The oldest patient in which this form of heart has been found was twenty-five years.

C. Ring-formed narrowing of the conus, due to a muscular band. Peacock reports this defect from a girl æt. nineteen, cyanotic from birth; the constriction was situated at the bases of the valves, and was formed by a muscular band covered by fibrous tissue, and the edges of the opening were studded with warty vegetations. The pulmonary valves were two in number, probably resulting from fusion of two of the cusps; were thickened and opaque, but smooth. The index finger could be passed between the valves. The artery was of small size, but much wider than the constriction. The aorta was dilated, and arose from both ventricles through a perforation of the septum ventriculorum. The foramen ovale was closed. The ductus art. Botalli gave free passage to a crowquill. The right side of heart showed dilatation and hypertrophy of both its cavities, and the tricuspid valve was thickened and had vegetations on its auricular aspect.

3. Simple stenosis and atresia of the pulmonary artery, with open septum ventriculorum.

This class includes malformations, with stenosis or atresia of the pulmonary artery, in which the defects occur before the completion of the ventricular septum, as the result of engorgement already described, but in which no other primary congenital defect exists; thus the separation of the pulmonary artery from the truncus arteriosus communis is completed; the auricles and ventricles are marked out by their septa, though not completely divided; the position of the aorta in relation to the pulmonary artery is either normal or more to its right; and there are no primary defects of any consequence in the other orifices of the heart. The simple stenosis or atresia of the pulmonary artery as thus defined is by far the most frequent malformation of the heart. Kussmaul has found about 90 described; among these are 26 cases of atresia.

As a rule, in partial obstruction the entire length of the artery, as far as the bifurcation, shows narrowing, but the greatest narrowing exists at the orifice of the pulmonary artery; only rarely are the orifice and the tube equally narrowed. Exceptionally, the tube has been found narrower just without the orifice, and later resumed its normal circumference. The walls are very often thin, like those of veins, and at times the vessel is shrunken. The valves are variously altered, often to a greater or less degree united, thickened, and opaque.

In complete closure two different conditions are seen; in some the artery itself to its bifurcation changes to a firm cord or thread; in others the tube is more or less narrowed and the orifice alone is closed.

As a rule, in stenosis and atresia of the pulmonary artery the conus is only moderately narrowed and its walls hypertrophied, while the sinus of the right ventricle is dilated and hypertrophied. The right auricle is dilated and hypertrophied. The tricuspid leaflets are clouded and thickened. The left ventricle is commonly small, and the wall not thicker than the dilated right ventricle. Sometimes the aortic and mitral valves suffer alterations of an inflammatory sort, probably of foetal origin. The shape and position of the heart are changed, but the size, as a whole, may not be much altered. The aorta may be widened, often to double the normal size. As to the origin of the aorta, it is often difficult to speak with certainty; its relative position to the pulmonary artery and to the body and axis of the heart is, as a rule, unchanged. Whether it is to be described as arising from one or both ventricles, or from the right one alone, depends on the posture which the septum ventriculorum assumes beneath its orifice. As a matter of fact, this relationship makes little difference to the flow of blood from the right ventricle, whose normal orifice is obstructed; provided the septal opening is sufficient, the flow of blood is secured and the hindrance to the circulation precluded. The opening in the septum ventriculorum may be only at the membranous portion, or it may also involve the adjacent muscular septum; the defect may be round or triangular, with its apex above and with smooth margins.

The foramen ovale has been found open in 39 cases out of 53. Its condition in this respect shows very great proportional variation in the different collections of cases. The open or closed condition of the foramen does not seem to depend on the degree of stenosis of the pulmonary artery itself. It depends, probably, more on the freedom of escape for the blood from both the ventricles through the aorta—probably also on the condition of the ductus arteriosus Botalli. The foramen ovale and ductus art. Bot. have been found closed much more frequently in stenosis than in atresia of the pulmonary artery, and the ductus is deficient or absent oftener in stenosis than in atresia. This absence of the ductus occurs in 13 per cent. of the cases, and tends to support Peacock's theory that narrowing of the pulmonary artery is the consequence of the defective development of that branchial arch out of which the ductus art. Botalli is formed.

It is of great interest to note the collateral circulation by which blood reaches the lungs when the pulmonary artery is closed. When the ductus arteriosus is open, the blood passes from the aorta into the ductus and the branches of the pulmonary artery become branches from it. When the ductus arteriosus is closed or very narrow, the bronchial arteries become the means of supply for the lungs, and through them the blood passes to be aërated. Branches from the coronary arteries have been found supplying a partial channel for the blood to the lungs, as well as the oesophageal, pericardial, internal mammary, and intercostal arteries.

The duration of life is often very considerable. Thirty-seven years have been attained.

4. Combined Stenosis and Atresia of the Pulmonary Artery.—Under this division are arranged other primary defects of the heart, which are found combined with stenosis and atresia of the pulmonary artery. It is very striking how frequently this artery is narrowed or closed in defects of the heart which date from the early period of foetal life, before the division of the truncus art. comm. and of the ventricles has occurred. It is only very rarely that defects from this early period show a normal width in this vessel; in the great majority it is narrowed or closed. The aorta is rarely affected in this manner. Changes in the aorta may come also, but a complete failure or great narrowness of this circulation is so difficult to overcome by a collateral circulation—more difficult than the pulmonary circulation—that life must cease in the foetus, or at least the conditions are incompatible with extra-uterine existence.

A. Combination with partial persistence of the truncus arteriosus communis. The defects coming under this head show usually very great deficiency of the organ and its great vessels, although the heart itself in rare instances shows the proper arrangement of the cavities and their valves. The persistence of the truncus art. comm. may be complete or partial; the defect consists in the total absence or arrest of growth of the septum of the truncus, which partitions it into two portions. Normally, the two septa grow simultaneously and meet at the base of the heart. In cases of persistence of the truncus art. comm. the upper septum fails to develop. In incomplete division of the truncus the pulmonary artery suffers more than the aorta, and the former is always narrower than its fellow-vessel. This difference varies greatly. The valves of the pulmonary artery often fail entirely, and the ductus art. Botalli is many times absent.

B. Combination with cor biloculare.—Here we have a heart consisting of two cavities—one auricle and one ventricle—where no partitioning has taken effect. The defect results from the failure of the septum ventriculorum to grow; and with this, as in the former division, comes also a more or less complete failure of the septum trunci art. comm.

C. Combination with single ventricle and divided auricles (cor triloculare biatriatum).—In the cases of single ventricle with more or less complete division of the auricles the pulmonary artery generally shows narrowing to a greater or less degree; it may still be pervious, although its orifice is closed, or it may be throughout entirely obliterated. The valves may be entirely wanting. The duration of life is very short, though in a very few with effective compensatory changes it may be prolonged very considerably.

D. Combination with divided ventricle and a single auricle (cor triloculare biventriculare).—In strictness, this defect is nothing more than an open foramen ovale with some deficiency of the pulmonary artery; but, in reality, the heart is much more malformed. The whole septum atriorum is wanting; the superior or descending vena cava is doubled—one entering the left part of the common auricle, the other opening more to the right. The ventricular septum shows a greater or less defection, the pulmonary artery is narrowed, and the aorta arises from both ventricles or wholly from the right one.

E. Combination with special anomalies in the position of both the great arterial trunks.—Here come a variety of anomalies in the arrangement of the aorta and the pulmonary artery in relation to their respective ventricles and to themselves.

a. In transposition of the great arteries, the aorta arising from the right ventricle and the pulmonary artery from the left cavity, either there comes a general transposition of all the viscera or the heart alone is reversed. Very rarely in transposition of the vessels the septum ventriculorum is closed, commonly open, and although the size of the vessels may be normal, usually their relation and position continue reversed throughout their course. In cases where the pulmonary artery is narrowed the duration of life is short. b. The pulmonary artery may arise from the left ventricle and the aorta from both ventricles; or, c, the aorta may come wholly from the right ventricle, and the pulmonary artery from both cavities; the latter vessel may be narrowed or show its normal width or even be considerably dilated. d. Both the great vessels may arise from the left ventricle, very much dilated, with the aorta in front of the pulmonary artery and the latter narrowed. e. The relation of the great arteries may be found reversed—i.e. the aorta in front and the pulmonary artery behind, and the aorta spring from both ventricles and the pulmonary from the right alone.

F. Combination with primary defects of other valvular orifices of the heart.

a. The tricuspid valve may be quite rudimentary, producing by the regurgitation thus allowed, especially when combined with pulmonary stenosis, great dilatation of the right auricle. When the pulmonary artery is narrowed the septum ventriculorum remains open; the aorta carries the blood, distributing it to the lungs by an open ductus arteriosus Botalli or a collateral circulation. The collateral circulation is less developed the greater the width of the pulmonary artery. The foramen ovale may close in such a case, but when it remains open the relief to the over-distended right auricle is very great.

b. Many cases of congenital stenosis and atresia of the right auriculo-ventricular orifice are reported in which the condition of the pulmonary artery is not described. In fact, it is a difficult matter to determine if the auriculo-ventricular narrowing is a primary one. Its defective size may be merely, as it were, a rudimentary condition, a failure to enlarge through disuse. When the pulmonary orifice is closed and the right ventricular cavity remains small, the tricuspid orifice is naturally small in size. There are, however, undoubted cases of tricuspid narrowing with or without stenosis of the pulmonary artery; the defect consists in a primary contraction of the fibrous ring or in the union by partial adhesions of the leaflets.

Malformations affecting primarily the Left Side of the Heart.

Primary defects of the systemic side of the heart are, for the reasons already given, very much more rarely seen than those of the pulmonary heart. In such cases the aortic conus and its orifice are found more frequently affected than the mitral orifice; both of these orifices, however, may be congenitally altered without foetal malformations at other parts of the heart being present; such cases are on record, though only sparsely scattered through the literature of cardiac diseases. Dilg⁸ has recently made an important addition to this subject. He proposes a classification on a new basis for all forms of cardiac malformation; to these classes he makes conform the malformations of the left side of the heart. In the first class he places all cases dependent on an inflammatory process occurring in the foetal heart after its normal development is completed; in the second, those cases of malformation in which the deviation from the normal consists in defects of formation; in the third, those which present a combination of endo-myocarditis with defective development.

⁸ Virch. Arch., Bd. xci., S. 193–259, 1883: "Ein Beitrag zur Kenntniss seltener Herzanomalien in Anschluss an einem Fall von angeborner linksseitiger Conusstenose."

Among the many cases of malformation of the heart which he presents there are reports of 15 cases of stenosis of the conus, which are to be divided into two categories, in accordance with his classification. In the first group, in 7 cases the stenosis is due to an inflammatory process, and is conditioned by the results of the endo-myocarditis localized in the aortic conus. These cases must have originated at a late period of foetal life, and they correspond closely to the conditions arising in the adult organs from similar processes. In all the specimens the mitral orifice was involved, and contributed a share in the production of the conus stenosis; in all the cases the aortic valves also had suffered inflammatory changes. Here Dilg also speaks of a band-like hypertrophy of muscular fibres, marking the outlines of the aortic conus, similar to the condition described by Peacock in the right ventricle; in this condition there was no evidence of endocarditis, and the condition may have been due to cadaveric rigidity. The left ventricle presented varying conditions according to the state of the aortic and mitral valves; in some cases there was concentric hypertrophy, or, more strictly speaking, narrowing or shrivelling of the cavity with hypertrophied walls; in others dilatation existed. The other cavities of the heart were influenced by the competency of the mitral orifice, but almost always showed considerable hypertrophy and dilatation. The valvular apparatus of the right heart was not free from evidences of old inflammation, but this condition was not very marked. The ages of the reported cases reached from thirty to seventy-five years.

In the second group there are eight cases in which the defective condition of the aortic conus caused malformation of other parts of the heart. Here the conus stenosis occurred at an early period of foetal development, before the permanent structures of the heart were fully formed. The conus stenosis is to be considered as primary, the other defects as secondary. As we have already seen, the left side of the heart is much less liable to deforming causes, and when such do occur the secondary defects are less conspicuous. Thus, in only four of these cases were there such malformations of other parts of the heart as openings in the septa of the ventricles or auricles, patency of the ductus arteriosus Botalli. The defects consist more usually in what were formerly called excesses of development, such as the formation of bands below the aortic orifice; or of deficiencies of development, such as only two aortic valves. These conditions are very doubtfully due to formative excesses or deficiencies, but rather to intense inflammatory processes or other morbid conditions which have resulted in the formation of excessive cicatrices or the removal of normal parts.

Another division of cases shows narrowing of the aortic trunk itself. This condition is probably always a true defect of development; so far as these cases, collected by Dilg, show, it is unquestionably so. In narrowing or closure of the pulmonary artery trunk it is found that in some instances this condition was dependent on an endarteritis resulting in a partial occlusion of the lumen of the vessel; here, however, the aortic trunk furnishes no evidences of such a process. It must therefore be due to an unequal division of the truncus arteriosus communis. The cause and the mechanism of this unequal division of the common trunk, resulting in a reduction of the size of the aorta, are probably similar to what Rokitansky indicated for the reduction in the size of the pulmonary artery trunk.

In the specimens of aortic narrowing (no cases of complete closure are reported) from this cause and mechanism the pulmonary artery has been found unusually wide, but this condition of the pulmonary trunk is not very conspicuous, and does not necessarily result from the narrowed state of the aorta. The compensatory or secondary defect of open septum ventriculorum, or even of the auricular septum, is, in these cases, neither invariable nor necessary to a proper maintenance of the foetal or adult circulation. In fact, the open ventricular septum is rare; the condition of the auricular septum is, in the reports, often not stated. The left ventricular walls commonly show a preponderance of hypertrophy over dilatation of this cavity, but in some cases the distension of the cavity is marked.

SYMPTOMS.—The most striking symptom which occurs in malformation of the heart is the cyanosis, but the appearance of this peculiar symptom may be postponed until some time, even a long period, after birth. In the newly-born infant presenting a blue color the diagnosis rests between the not infrequent temporary failure of respiration from many causes and a defective development of the circulatory organs. In most cases the doubt is promptly solved by the voluntary or artificial efforts of breathing, whereby the cyanosis disappears. If the dark hue persists after the respiratory movements have been developed, the cyanosis may be found to depend either on cardiac malformation or an imperfect expansion of the lungs (atelectasis). The distinction between these two conditions can usually be made by a study of the respiratory movements, by the state of the heart's action and of the pulse, aided sometimes by an inspection of the outlines of the chest. In cardiac malformation respiration seems to be well performed and full, though often hurried or labored; in atelectasis this function is often found characteristically altered by being short, high, and imperfect, with imperfect distension; the ribs, instead of moving upward and outward, fall toward the median line, and the chest fails to expand transversely. In malformation the heart's action and the pulse are rapid, and a murmur can often be heard. The thoracic outline may deviate from the usual antero-posterior flattening by the sternum being prominent in cases where the heart, instead of its usual position to the left, is placed more centrally, as comes in certain defects of development. Both of these conditions may be present, and then the symptoms are mixed in character.

Cases of atelectasis, sufficiently marked to give rise to persistent cyanosis, if not relieved too frequently show a pretty rapid increase of color, becoming deeply livid, with convulsive movement, ending shortly in death. The diagnosis in such cases between a cardiac malformation and a non-expanded lung is almost impossible unless the respiration shows characteristic features. It is probable that the treatment proper for the latter would aggravate the condition of the circulation in malformation. In a majority of cases a post-mortem examination is necessary to determine whether the cyanosis is of cardiac or of pulmonary origin. In the atelectatic condition, if death comes within a few days of birth, the ductus arteriosus Botalli and the foramen ovale may both be found open, especially the latter, their time of normal closure not having arrived; in cases dying at a later period, if the foetal openings are still found patulous, the open state must be considered as dependent on the condition of the lung-tissue, since in malformation of the heart the patulous state of these foetal openings is, as has already been shown, rare as a primary defect, and, except in connection with defects of development resulting in obstruction, which operate at other points of the foetal circulation, is almost never found. In other words, an open foramen or ductus is a secondary defect, dependent, on the one hand, on a primary obstruction of the cardiac ostia, or, on the other hand, it may be on a primary atelectasis or malformation of the lungs.

If the child passes beyond the first weeks of life without exhibiting cyanosis, the subsequent occurrence of the condition becomes almost a pathognomonic symptom of cardiac or vascular malformation, unless it can be shown that the coloration is dependent on some acute disease, especially acquired valvular disease: in this connection collapse of the lung (post-natal atelectasis), too, must be remembered.

It is during the first week of life that cyanosis makes its appearance in the great majority of cases of malformation of the heart, in the proportion of more than two to one of the cases. The coloration, once developed, may remain permanent and of equal intensity until death, but as less than 8 per cent. of infants with malformation die within the first week, and only 36 per cent. within the first year, this symptom usually remits. It may wholly disappear, to return on very slight provocation, such as excitement, or on exertion, on the advent of acute disease, or without apparent cause. Probably about one-fourth of those who die in infancy perish in paroxysms of dyspnoea, another quarter of acute disease, and the remaining half of convulsions; and toward death the cyanosis generally becomes very intense.

If the malformation is not of character or degree to develop cyanosis early in life, the child grows and passes through the usual stage of development, usually, however, feeble, poorly nourished, incapable of common exertion, but often without any special phenomena to attract attention, and the vice of formation is undetected unless by a special examination. There are several other symptoms frequently present in connection with malformation, but not of a pathognomonic character. Dyspnoea, though rarely occurring without cyanosis, may attract attention, and, if frequently brought on by active exercise, increases in violence, to be later accompanied with the cyanosis originally absent. Palpitation is not uncommon, especially in cases of great hypertrophy with dilatation, in hearts struggling to overcome an obstruction; in other cases it is absent or only occurs on exertion in connection with dyspnoea and cyanosis. The degree of animal heat varies greatly, judging by the various opinions expressed by writers. The sensation of patients able to express their feeling is often that of chilliness, and in some cases the surfaces of the body feel cold, although the indications of the thermometer show no great variation from the normal temperature. It is obvious that no very great variation from this standard is compatible with the long duration of life, although a depression may exist during or immediately after paroxysms of dyspnoea or cyanosis. Cough is also frequent, but is probably always due to some acquired pulmonary disease.

The physical signs offer increased facilities for the recognition of defects of development. In the early reported cases there are of course no records of these conditions, and there is therefore a lessened number of instances from which to collate the physical signs. In the early days of life it has been shown wherein the presence of a cardiac murmur may lead to the distinction between malformation and atelectasis. In later periods of life the physical signs cannot be regarded as characteristic. There are no signs by which a malformation can be distinguished accurately from an acquired cardiac disease, so that without the clinical history and a grouping of symptoms the diagnosis cannot be made from the physical examination.

Inspection and palpation of the chest often show the heart to be in an unusual position, placed more centrally under the sternum. It must be remembered that transposition of the heart to the right side is not unfrequently unaccompanied with any malformation of its ostia giving rise to symptoms; and this organ may be even more markedly displaced without being malformed, although under both these conditions irregularities of the principal trunks are usually found.

Percussion frequently shows enlargement of the area of cardiac dulness, but, on the other hand, at the post-mortem examination the heart is often found markedly defective without externally showing variation of its size or shape, or of its position within the thorax; hence in such cases no deviation from the normal will be revealed on percussion or inspection of the chest. It is probable that cardiac murmurs are not always to be detected in cases of even marked defects of development, but when present it is recorded most frequently that a single murmur is heard over the base of the heart, blowing in character and systolic in time. Such a sound is probably produced by the passage of the blood through an abnormal opening between the ventricles or through the foramen ovale. Other murmurs may also be present; if the arterial ostia are defective from narrowing, roughness, or insufficiency of their valvular apparatus, abnormal sounds of different characters, diastolic or systolic in time, may be heard. Too few observations as yet exist for a general diagnostic scheme to be formulated. Auscultation of the intra-uterine heart may in the future become sufficiently accurate to enable us to prognosticate a congenital cardiac malformation or disease; there is one case on record in which a correct diagnosis was made in this way.

The ends of the fingers and toes are frequently described as bulbous. This rounding and retraction of the nails, frequently spoken of as clubbing, does undoubtedly exist in many cases, but the condition cannot be regarded as characteristic of malformation of the heart, since it comes with even more frequency in tubercular disease of the lungs, in chronic pleurisy, and in other chronic pulmonary maladies.

Lebert has recently insisted on the connection between stenosis of the pulmonary artery and tuberculosis, not merely as a coincidence, but as the cause of the development of the tubercles in the lungs. Many others have spoken of this connection, and very many are the cases recorded—perhaps nearly one-quarter of the whole number. In some cases large or small single cheesy masses exist; in others cavities form, and in rare cases a miliary tuberculosis exists, still more rarely affecting other organs than the lungs. In view of the recent dogmas of tuberculosis it is doubtful if many of these authors would at present insist on the connection between malformation of the heart and tuberculosis being other than a coincidence, since it is not apparent why such patients are more likely to be invaded by a bacillus of tuberculosis than other persons, and this organism is known to grow so readily wherever the spores chance to fall.

DURATION OF LIFE.—In connection with certain malformations some indications have already been given in respect to the duration of life in such defects. It is, however, apparent that the degree of the obstruction to an orifice or vessel, and still more the completeness of the secondary compensatory alterations, exert a greater influence than the seat of the malformation on the continuance of life. The occasional slight isolated malformations, such as open septa without obstruction of the orifices, in themselves often entail no symptoms, and, unless combined with acquired valvular disease, exercise no influence on the duration of life; here, however, the prognosis merges entirely into the acquired malady.

Of the other conditions of malformation, narrowing of the aorta and of the aortic conus seems to be, on the whole, compatible with a longer duration of life than any other condition, and these defects cause death in the early days or months in fewer cases than similar obstructions on the right side of the heart. This result apparently comes from the fact that the left ventricle seems to possess unlimited capacity for hypertrophy, and hence is able to overcome the obstruction; when the aortic valves allow of regurgitation the compensation fails and death comes sooner. When the main branches of the aorta are defective or when the descending aorta is derived from the pulmonary artery, the duration of life is much shortened.

In cases of pulmonary narrowing in general it may be stated that the greater the obstruction the shorter the life. This rule is subject to many exceptions; so frequent are the exceptions that the rule is almost valueless for determining the life in any given case. Complete closure of the pulmonary trunk has permitted of the continuance of life for sixteen years, and then ended from an intercurrent acute disease. When the septa are maintained open—when, therefore, the communications between the pulmonic and systemic sides of the heart are free—a greater age is attained than when these openings have become closed. This condition of the pulmonary artery in order to permit of a long duration of life must be coincident with a considerable development of the collateral circulation by which the blood freely enters the lungs for aëration; otherwise the compensation fails very soon.

In transposition of the main trunk relatively to the ventricles, with closure of the septum ventriculorum (very rare), life ends not many weeks after birth; if the septa remain open, which is not common, life may be prolonged for a year or two.

Cyanosis.

There are two views to be found, set in opposition to each other, to account for the peculiar blue coloration of the skin and mucous membranes in cases of malformation of the heart. The first explanation attributes the phenomenon to a general congestion of the venous system, due to the obstruction of the pulmonary artery. This view was proposed by Morgagni in connection with his, the first described, case of malformation of the heart. The other view considers that the intermingling of venous and arterial blood through any channel, but especially by means of abnormal openings in the septa, produces the blue coloration. Numerous writers have defended each of these theories of causation; from most of their observations darkness rather than light has resulted through the attempt to defend one or the other theory exclusively.

Gintrac defended the admixture theory for cyanosis, and his views became so well known that a large majority of persons conformed their belief to his teachings. This author distinguished four varieties of blue coloration: first, that due to some malformation of the heart or great vessels, by which the blood of the right side of the heart enters the systemic arterial circulation; second, likewise due to intermixture of the blood, but produced by conditions developed after birth through the re-establishment of the passages of communication or other changes in the circulation; third, where the coloration appears without direct admixture of the blood, but from organic disease of the heart; fourth, cases without malformation, from a suppression of the menses. Before the time of Gintrac, cyanosis had a very indefinite signification, and the condition was looked upon, and was classed by very many, as one of the cachexiæ, and was often spoken of as a form of icterus. He, however, held that the organic lesions of the heart and great vessels were the necessary conditions of its production, and that the mixture of the red and black blood, and the distribution of the mixed fluid by means of the arteries to all parts of the body, determined its essential character. He showed, too, that all communications between the right and left heart were not followed by cyanosis; the explanation of the absence of the blue color was that from the simultaneous contraction of the auricles and ventricles of the two sides of the heart an equilibrium was produced, and the blood did not deviate from its normal course. This result followed only when the normal exits of the blood were unobstructed. This supposition, as is apparent, is not in accord with the facts. During the filling of the ventricles, before the muscular contraction of the walls occurs, the blood has the opportunity of freely mingling if the opening between the cavities is sufficiently large: that the blood will not thus mingle when the muscular contraction acts remains to be proved. Cases of open septum ventriculorum, as an isolated defect, without obstruction of the great vascular trunks (a rare condition), are not attended with cyanosis: the absence of this symptom, as will be shown later, is readily to be explained on other grounds than those supposed by Gintrac. The normal outlets of the blood are, however, almost always obstructed to a greater or less degree; and here the explanation of the absence of the cyanosis fails. In the delayed appearance of cyanosis Gintrac considered the reason to be that the venous blood differed less from the arterial in the young subject than in those of more advanced age, because, on the one hand, the aëration was more active, and, on the other hand, the deterioration of arterial blood was less marked. In other cases he points to an increase of the obstruction, through inflammatory changes, as the probable reason for the delayed appearance of the blue color; in still other cases it was supposed to be due to a disturbance of the equilibrium of the pulmonary and systemic circulation from an increase in the blood-mass. In cases of unilocular and bilocular hearts, of which the author speaks, his explanation completely fails, for here the admixture of the blood within the heart is very marked; yet such cases have been reported without cyanosis. He further believed that openings in the ventricular septum, as well as between the auricles, were effected after birth as the results of acquired cardiac disease.

Gintrac, in speaking of the causes of cyanosis, says that the condition shows no hereditary tendency; that the pregnancy during which the defective infant is developed is without noticeable phenomena; and that the confinement is normal. It is on some of these points that we are in want of accurate information. It has been pointed out that many congenital defects of the heart result from morbid processes affecting the organ during its developmental stage. These lesions are the same in kind as those which produce cardiac and vascular disease in the adult, and are likewise of a sort capable of communication from the parent to the foetus. Such diseases are found acting oftentimes temporarily in the parent; and if they acted during pregnancy, or even if present only at the time of conception, their results would rationally be expected to be displayed in the foetus. Such diseases as rheumatism and syphilis, which may be regarded as temporarily-acting maladies, would come under this class, and doubtless many others might be added to the list. The work of collecting the histories of pregnancies or the condition of the parents at or before the time of conception would be painfully tedious: such records do not exist at present, and they could be made sufficiently full only in exceptional cases; but their value in determining the causes which operate in the production of defective development of the heart cannot be too highly estimated.

The conclusions stated by Moreton Stillé⁹ seem to be the first which justly cover the ground from a comparison of large numbers of cases of malformation of the heart. The first conclusion by him is that cyanosis may exist without admixture of the blood; by this was meant that no abnormal communication between the right and left sides of the heart, and no channels between the principal vascular trunks, are present. He mentions five cases of cyanosis occurring in which no means of admixture existed. The second conclusion is that there exists no proportion between cyanosis and the degree in which the blood is mixed; for this he cites four cases, some with the aorta arising from the right ventricle, others of hearts with only two cavities and the common trunk undivided, in which the cyanosis was only partial or transient. The third conclusion, the converse of the first, and reinforcing the preceding one, is that complete admixture of the blood may take place without cyanosis. The fourth, that the variation in the extent, depth, and duration of the discoloration is inexplicable by the doctrine of the mixture of the blood.

⁹ "Inaug. Thesis." Amer. Journ. Med. Sci., N. S., vol. viii., 1844.

Having shown that commingling of arterial and venous blood cannot be the cause in itself of cyanosis, Stillé proceeds to the study of the other theory—viz. that it is due to congestion of the general venous system resulting from some obstruction in the right side of the heart or in the pulmonary artery, impeding the passage of the blood through the heart. These structural lesions must fulfil the three following indications: 1st, that they shall be sufficient in degree to account for the symptom; 2d, that they be present in every case of cyanosis, or in their place some other cause acting on similar principles; 3d, that they shall never exist without cyanosis or without a satisfactory explanation of the exceptional occurrence. He holds that contraction of the pulmonary artery is to be taken as the type of all the lesions that may produce cyanosis, and that this type fulfils the indications given above.

Most writers since Stillé have coincided with him, or have regarded cyanosis as partly due to venous congestion and partly to commingling of arterial and venous blood. Some writers, however, have pointed to the abnormal communications between the right and left side of the heart, and asked why, if admixture of the venous and arterial blood is not the cause of cyanosis, should the admixture through such openings be found in such a large proportion of cases. Such writers have failed to distinguish between the primary and secondary defects of development. They have failed to see that the pulmonary obstruction which prevents the blood during extra-uterine life from passing to the lungs for aëration, and consequently produced the cyanosis, prevented the closure of the ventricular septum during intra-uterine life, or of the auricular septum within a few days of birth. In reply to the above question it may be pointed out, as Peacock has done, that such communications between the two sides of the heart are all important for the continuance of life, even for the shortest period, when the pulmonary artery is occluded.

It is evident, as Peacock has shown, that if Stillé's first and third conclusions are true, as the cases undoubtedly show, the theory of intermixture of the blood does not account for the condition of cyanosis. It is probable in many of these cases with abnormal openings in the septa that the intermixture of the blood is but slight, since if the pressure on the two sides of the heart is equal—and it may become equal through the establishment of a collateral circulation, although primarily it was unequal—no intermixture takes place through the defective septa. Neither does the admixture theory account for cases of intermittent or delayed cyanosis. Such cases can only be supposed to be due to a varying propulsive power or to a subsequent increase of the pulmonary obstruction. Neither does admixture account for localized cyanosis; for example, in the face or in one extremity: this condition, rare as it is, must be due to other causes. Peacock, while combating the admixture theory, considers that Stillé's conclusions in favor of the congestion theory as dependent on obstruction of the pulmonary artery are too exclusive. He discusses also the relationship of congenital cyanosis due to malformation, to cyanosis acquired through pulmonary and cardiac disease as seen in the adult, and shows why the latter condition is rarely ever as intense as the former, and also why acquired obstruction of the pulmonary artery is not necessarily productive of cyanosis. The reason of the difference he believes consists in the compensatory hypertrophy of the right ventricle, with perhaps a gradual diminution of the blood-mass, as seen in some cases.

On the whole, Peacock subscribes to the congestive theory, but thinks that the intensity of the cyanosis is modified by the capacity of the capillaries, by the period of development or duration of the obstruction, by the natural coloration of the skin, and by the color of the blood itself.

Under these two theories, and the arguments offered in support of them, there seems to be no other explanation possible of the condition of blueness, and yet the whole story of the mechanism of cyanosis does not seem clear. Partly, this is due to the incomplete knowledge of the physiology of the aëration of the blood which obtained during the most active period of the discussion of cyanosis and its causation. Let us consider briefly the simplest case of cyanosis. Every child born has in one sense a temporary malformation of the heart—an open foramen ovale which does not close for several days after birth. Every child is born partially cyanotic, owing to compression of the uterine sinuses or pressure on the umbilical cord; it is completely cyanotic if there occurs premature separation of the placenta. The cyanosis continues until the child breathes. The cause of this cyanosis must be looked for, not in the temporary malformation, but in the imperfect expansion of the lungs. As soon as the respiratory function is assumed—as soon as, in other words, the pulmonary-artery branches carry a full amount of blood which becomes aërated in the lungs—the cyanosis ceases, although the foramen ovale is not yet closed.

The closure of the foramen by a trapdoor valve is, as has already been pointed out, not in accordance with the anatomical facts: turning the newly-born infant on its right side does not favor, as it is commonly supposed, the closure by gravity of a preformed swinging lid, which when it has dropped down for ever partitions the right from the left auricle. The right-sided position may favor the expansion of lungs or in other ways promote the pulmonary circulation, but in itself it does not tend to close the foramen. In fact, cyanosis does not here depend on the defective development, but on want of aëration of the blood.

Again, looking to the skin or mucous membrane, what is the condition of the blood and of the circulation which renders the parts of a blue color, and in what do they differ from the normal? In the normal state of the blood and circulation the capillaries of a given area are filled, one half with arterial blood, and the other half with venous blood; that is to say, the capillaries at the point of their origin from the arterioles contain pure arterial blood: as the blood-current proceeds outward the blood becomes progressively less and less red and more and more blue or black; when the venous radicle is reached the blood-current is of as dark a hue as it ever becomes. In general terms, therefore, it may be said, taking the average, that in a given area half the blood is venous, half arterial. Here, then, we see, with an equal mixture of the red and blue blood, nothing resembling cyanosis. It is evident, therefore, that to produce a cyanotic hue the blood must be wholly venous; the intensity of the blueness will vary with the amount of non-aërated blood present in the capillaries. But let us suppose an equal admixture of right- and left-sided blood to take place—for example, when the aorta arises from both ventricles, the pulmonary artery obstructed. It cannot be supposed that the venous blood would retain its dark hue. The contact of the two bloods within the aorta on their way to the capillaries would result in arterializing the venous blood at least one-half, so that when it arrives at the capillary network the intensely blue color of a marked case of cyanosis would have disappeared.

Besides this, there are other considerations to be taken into account to show that neither of the two exclusive theories accounts for the state of the blood and of the circulation in cyanosis. If the condition of the cyanotic parts, due to acquired valvular heart disease or various morbid states of the pulmonary tissue of an acute character be compared with the same parts in cyanosis from malformation of the heart, striking differences are discernible. If the simple condition of cyanosis of the part due to localized pressure on the veins be examined, the differences are even more perceptible. In the malformation there is an admixture of blood; in the other condition there is no opportunity for the intermingling of the currents. In the latter the cyanotic area becomes swollen, and the intensity of the color may become lessened through the oedematous condition; in the former the skin of the cyanotic infant rarely if ever presents any swelling; the veins of the part show little, if any distension, as is so frequent in the latter; cases of malformation in which subsequent endocarditis with additional obstruction occurs may show oedema and swelling similar to cases of acquired valvular disease. In these cases of cyanosis the condition must be due to a want of aëration of the blood, since it never appears until such alterations of the pulmonary tissue and circulation are reached as to render it certain that the blue coloration is due to a want of aëration of the blood. Fulness of the veins and oedema may be present, but never general cyanosis.

Another important consideration in the production of cyanosis does not seem to have been fully appreciated. It is the fact that in all cases of obstruction of the pulmonary artery the collateral circulation, carried on by very varying channels, the bronchial arteries, the oesophageals, the coronaries in some cases, the internal mammaries and intercostal arteries in rare cases, or by the ductus arteriosus Botalli, which alone must be always inadequate in marked narrowing of the pulmonary trunk,—the collateral circulation must always remain insufficient for carrying sufficient blood to the lungs for aëration. Kussmaul was the first to call particular attention to this fact; and it is to this condition of insufficient channels for the blood reaching the lungs that certain cases of cyanosis must owe their causation.

Hence it must be that, in all the complex conditions found in cases of cyanosis from defective development of the heart, a want of due arterialization or aëration of the blood is at the foundation of the state as seen in the cyanotic area. Whether it results in a given case from excessive admixture of venous blood with the arterial when the current reaches the capillaries, or from venous stasis due to central obstruction, of which pulmonary-artery narrowing or closure is the type, or whether from a failure of sufficient blood to reach the lung, as where the collateral circulation remains imperfect, or as seen in certain cases of defective development of the lungs, is most difficult to ascertain. That sufficient consideration has not been given to the third possible factor in the causation of cyanosis—viz. failure of the blood to reach the lung, as distinguished from general venous congestion alone—is evident. That intermingling of the blood from the two sides of the heart must inevitably reduce the red color is certain—that in very many cases the reduction in color does not cause cyanosis can be readily understood from the consideration already offered. The cases of free admixture in which cyanosis does occur may coincide with a condition of very imperfect collateral circulation to the lungs, and hence with a low aëration of blood of the left ventricle, insufficient, therefore, to bring up the color of the blood from the right side of the heart above the cyanotic point.

Whether non-aëration of the blood from failure to reach the lungs, apart from general venous congestion, is a sufficient explanation of the cyanosis in a large majority of cases or in the whole number, is not apparent from the records of reported cases. Much more accurate post-mortem accounts, made with a view to determine the question, than at present exist will be required. In a number of well-reported cases of defective pulmonary artery with a free admixture of blood the pulmonary collateral circulation is found to be well developed, and no cyanosis had appeared, or had been but trifling and inconstant. In other cases of quite as marked pulmonary obstruction with but slight commingling of the blood through abnormal apertures and but slightly-developed collateral circulation, cyanosis has been found intense and constant. In the two conditions the possibilities for general venous congestion are about the same, though perhaps not equal, while the striking difference, apart from the admixture of the blood-current, consists in the conveniences for the aëration of the blood.

The only variety of malformation of the heart in which intense and constant cyanosis must inevitably be present is that very rare form of transposition of the great trunks, the aorta springing from the right ventricle, the pulmonary artery from the left, with closure of the septum ventriculorum; the pulmonary veins enter the left auricle bearing red blood, and the venæ cavæ the right auricle with blue blood; if the ventricular septum is closed, the aorta necessarily carries blue blood to the systemic circulation, and the pulmonary artery is filled with red, carrying it back to the lungs, whence the fluid has just come. In such relation of the principal trunks, even if the ductus arteriosus Botalli and the foramen ovale remain open, cyanosis is necessarily present. The bulk of the blood in the aorta is blue: the only points in which it comes in contact with red blood are, first, at the foramen ovale: here the intermingling is not sufficient to bring it above the cyanotic color; and, secondly, at the ductus arteriosus, and here the tube is not favorably directed for a copious intermingling of the two bloods, neither can it probably ever be sufficient in itself for this purpose. Hence the aortic blood is almost wholly venous. If these two foetal openings did not persist life could not continue beyond a few hours, or even a few minutes, after birth. In such a case the cyanosis does not depend on general venous congestion, and specimens are reported of this sort in which the great vascular trunks were without obstruction, life having been maintained for a few months; adult existence is probably impossible. If, however, with such transposition of the vessels to the improper ventricle, the septum ventriculorum remains widely open, cyanosis may be absent or inconstant, because, apparently, admixture of the blood and also aëration are sufficiently free. But in cases of transposition of the vessels, or even in the much more frequent specimens without transposition, when the track to the lungs is defective either from want of a collateral pulmonary circulation or directly from impervious pulmonary artery, cyanosis becomes more intense and more constant or comes in more frequent paroxysms, irrespective of the presence or absence of evidences of general venous congestion.

It would seem to result from this grouping of facts, and looking at them from a reverse bearing to Moreton Stillé's point of view, that distal rather than proximal obstruction of the pulmonary artery, taken as a type, was the cause of cyanosis. Admixture of arterial and venous blood must reduce the redness of the arterial stream, just as certainly as red paint mixed with black varnish will render the black less intense: whether admixture alone ever produces a deep cyanotic hue of the surfaces is probably more than doubtful; that admixture will prevent constant cyanosis seems certain, when cases of complete transposition of the vessels with open septum ventriculorum are compared with those with closed septum, the other conditions remaining the same. General venous congestion from pulmonary obstruction or other causes outside the pulmonary tissue produces cyanosis, but of a sort quite unlike the typical cyanotic condition of malformation of the heart. It may therefore be doubted if the cyanosis seen in obstruction of the pulmonary artery is due to general venous congestion; it may be wholly produced by conditions on the other side of the obstruction—viz. want of aëration of the blood, which must ever remain the essential feature of cyanosis. This supposition allows of an easy explanation of the difference between cases of apparently equal obstruction of the artery, in some of which cyanosis is present and in others absent; it also allows of the explanation of inconstant or paroxysmal cyanosis where the obstruction, and consequently the venous congestion, is uniform and permanent.