ESSAY II.
Morbid Anatomy of the Internal Lining Membrane of the Heart.
The membrane which lines the cavities of the heart is very liable to disease, but not equally so in every part. Where it is thin and transparent, and admits the colour and character of the muscular structure upon which it is spread to be seen through it, it is seldom found diseased; but where it is of a denser texture, either in itself or from an admixture of other structures, whether cellular or fibrous, with its own, it is frequently, and often exclusively diseased. This latter character of a denser texture belongs to it where it forms the tough white circles which surround the apertures of communication between the auricles and ventricles; also where it is reflected upon itself, and forms the loose duplicatures of membrane, which are given off, as it were, from the internal surface of the heart, either at the fibrous circles intermediate between the auricles and ventricles, constituting the tricuspid and the mitral valves, or at the commencement of the pulmonary artery and aorta, constituting the semilunar valves.
It is remarkable how curiously disease is apt to limit itself to the spaces just pointed out. Of the fibrous circle between the auricle and ventricle, of the valves which originate from it, and of the tendinous cords which connect the valves with the carneæ columnæ, there will not be the smallest space free from disease; but the disease will abruptly stop where the tendinous cords cease and the carneæ columnæ begin[1].
The membrane, however, where it covers the fleshy columns of the heart, is not exempt from the possibility of disease: but when disease actually affects it, it has seldom originated there, but has generally spread from other parts of the same membrane, although (as we have just remarked) it is apt to stop short before it reaches this.
Of the two sides of the heart, the membrane which lines the left is unquestionably the more liable to disease. But my own observation would never have led me to conclude that the membrane of the right side was so far exempt as it is commonly thought to be. Speaking from the best recollection I have of the specimens which have fallen under my examination, I should say that, in one-third of the cases where disease has been found on the left side, it has existed on the right side also, and been essentially of the same character. But there has been a remarkable difference in the extent to which it has proceeded on each side respectively: while on the left it has gone so far as to be the undoubted cause of death, on the right, although essentially of the same character, it has been only just beginning.
It very seldom happens that disease appertains to the lining of the right cavities of the heart exclusively; and, where it affects both, the disease in the right cavities is very seldom found in advance of that in the left.
It should seem, indeed, according to the ordinary course of things, that disease does not begin in the lining of the right cavities of the heart, until it has already advanced to an extreme degree in the left.
The internal lining of the heart, as well as of the arteries, is often found to have become of a red colour. This redness, so well known to all who are accustomed to examine dead bodies, used to be regarded as a mere stain imparted to it by the colouring matter of the blood after death. Yet a due consideration of various circumstances connected with it will hardly warrant this conclusion.
It has been found whether the heart or artery be full or empty of blood; and if blood be present it has been found, whether it is liquid or clotted; and if it be clotted, whether it does or does not retain its colouring matter. External temperature, and length of time between the death of the patient and the dissection of his body, have not made any difference in the frequency with which this peculiar appearance occurs. Lastly, no artificial methods, such as washing of any kind, can get rid of it; nor will inclosing blood within an artery for any period produce it[2]. This simple redness is sometimes seen universally in both sides of the heart and throughout the whole arterial system, and sometimes in patches only, of greater or less extent, whether in the arteries or in the heart.
Now, when all these circumstances are considered, although in some instances it may be a mere stain imparted by the colouring matter of the blood after death, it is plainly impossible that it should be of that nature in any large proportion of the numerous instances in which it is found.
But if the appearance in question implies (as I believe it generally does) a morbid condition, of what kind is that condition? There are the same objections to considering mere redness as equivalent to inflammation here as in the pericardium, or in any other part of the body: here, as elsewhere, in one case it may be the condition out of which inflammation is to spring; while in another it may not be destined to give origin to any change in the structure of the part beyond itself, and may itself constitute the whole disease.
It appears to me, that this mere redness of the internal lining of the heart and arteries has become a matter of undue perplexity to pathologists, because they have laboured to infer from it more than the simple fact itself will authorize. All I wish to establish concerning it is, first, that it is not always (probably very seldom) a mere stain imparted by the colouring matter of the blood after death; secondly, that it alone does not constitute inflammation.
It may not be improper to mention the circumstances under which it has occurred to myself to find it. I have met with it most frequently, and to the largest extent, in subjects whose previous disease has produced a constant and habitual impediment to the transmission of blood through the heart and through the lungs, and that impediment has gone on increasing to the hour of their death; also in those, whatever might have been the nature of their disease, whose dissolution (I mean the actual process of dying) has been tardy and agonizing, and marked by great labour of respiration; in the apoplectic, for example, in whom, after sense and consciousness were extinct, life had been protracted, with stertorous breathing, for many days.
In such subjects the countenance, the lips, and the whole skin, give evidence during life of blood pushed beyond the natural sphere of the circulation, and detained in the extreme blood-vessels. Hence it is obvious that the causes which have loaded and distended the capillaries in every part of the body have had a like influence upon the vasa vasorum.
I do not mean to say that I never met with this peculiar condition of the heart and arteries under other circumstances, or that other causes may not produce it; but that I am not acquainted with it under any other with which, from frequent coincidence, it has seemed to have a natural connexion, or which have afforded a reasonable explanation of the phenomenon.
This condition of the heart and arteries, considered as inflammation, has been assigned by some as the cause of fevers of the more malignant kind. The frequency with which it has been found in some particular epidemic, must have led to the conclusion. But, however this may be, from my own observation, not restricting myself to the fever of any particular season, but taking into account all complaints called febrile, and belonging to all seasons, also from the result of inquiry among medical men who have had large acquaintance with morbid dissections, and from the experience of those who have made this particular point a subject of investigation (Laënnec and Andral) I venture to conclude that it has no essential connexion with fevers of any kind, either as cause or as effect.
On some occasions the internal membrane of the heart and arteries, wherever it exhibits the appearance described, will allow itself to be peeled off from the subjacent structure with the least possible force; this facility of separation ceasing entirely beyond the boundary of the red tinge.
Here unquestionably is further evidence of a diseased condition: but of what nature? Most pathologists would consider this to be of the nature of inflammation—and I believe justly.
There is indeed much difficulty in pronouncing upon the nature of minuter changes of structure detected in the internal parts of the body after death. We are obliged to arrive at conclusions by help of analogies drawn from morbid processes, which we have watched in their progress during life, upon the external surfaces; for during life we have the functions and sensibilities of the part to aid us in forming a right judgment concerning its disease. When, during life, one tissue is separated from another, as the periosteum from the bone, or the cuticle from the skin, or the mutual cohesion between different tissues is sensibly weakened, we find it to be owing to the intervention of serous fluid which does not belong to their healthy state; and this, together with increased vascularity, or redness and heat, and pain, is enough to bespeak the presence of inflammation. All these conditions cannot remain after death. Hence, if we desire to form positive opinions concerning much which is unfolded by dissection, we must supply the defect by analogy. Thus, whenever, in any part of the heart or arteries, the cohesion between the internal membrane and the subjacent structure is manifestly lessened, and the membrane is unusually red at that part, we may regard these appearances as the vestiges of inflammation, without thinking that we go too far in so regarding them.
The internal lining of the heart and arteries is often found red solely in the neighbourhood of ulcerated spaces, when there can be no doubt concerning the existence of inflammatory action.
But the internal lining of the heart and arteries gives the most unequivocal evidence of its inflammation when it is found of a deep red colour, with coagulable lymph adhering to its surface. This condition is represented, as it was found in the aorta, in one of the beautiful plates, illustrative of the diseases of arteries, by Mr. Hodgson[3]. And the same condition, in the heart, I have seen in a preparation of Dr. Farre's, where lymph is deposited, upon the circular zone, which forms the aperture of communication between the left auricle and ventricle. These appearances denote the most acute inflammation: they are, I suspect, very rarely met with. In the few instances in which I have heard of them, they have been found where death has taken place after short and severe suffering, and with symptoms which characterize inflammation.
But the specimens of disease most frequently met with in the internal lining of the heart, consist in an entire change of its natural structure, and in the formation of new products upon it or within it. Many of these, from the analogy of morbid actions in other parts of the body, must be considered to result from chronic inflammation.
In any of those situations which have been stated as especially liable to disease, the membrane will become thick, tough, inelastic, puckered and shrivelled; and cartilage or gristle, and bone, will enter into its structure; excrescences will sprout out from it, resembling warts and fungus; and it will become ruptured and ulcerated.
Cartilaginous depositions are often found beneath the membrane where it is single; or between its folds where it is double, in the situation of the valves; and thus they seem rather to belong to some structure contiguous to the membrane than to the membrane itself. Such depositions will proceed to a considerable extent, while the membrane still remains free from disease. From a valve, which has been thick, opaque, and cartilaginous, I have seen the membrane separated on both sides, and transparent; the opaque and cartilaginous matter being left behind. Where, in cartilaginous depositions, the lining of the heart has become puckered and uneven on its surface, and the valves shortened and altered in their shape, the membrane itself participates in the disease, and is generally incapable of being separated from the subjacent structure. But great thickening may take place in the situation of the valves, from deposition of cartilage, without any unevenness of their surface or alteration of their shape; and under these circumstances the membrane itself you may expect to find hitherto exempt from disease[4].
Osseous depositions are always, I believe, originally formed beneath, or exterior to, the membrane, both in the heart and in the arteries. There are two circumstances especially worthy of remark in this process of ossification: sometimes it is a pure and unmixed process: bone is formed, and nothing else. It is deposited in minute granules, or little brittle scales, or in plates of a larger size; and the intermediate spaces, whether in the heart or arteries, preserve their natural and healthy appearance. At first, these granules or scales, or plates of pure bone, are covered by a delicate pellicle, which is in fact the internal membrane of the heart or artery, separating them from the immediate contact of the circulating blood. But in process of time, as they increase in size, and become rough and unequal on their surface, they cause a rupture of the internal membrane, and have now nothing to separate them from the immediate contact of the blood[5].
Sometimes ossification is a mixed process, or rather, I suspect, the result of another morbid process preceding it. With the cartilaginous depositions already described there is an admixture of bone. The quantity of bone generally bears a very small proportion to the cartilage when they both occur together, as if the bone proceeded from the cartilage, and not the cartilage from the bone. It is sometimes seen growing from the surface of the cartilage, and is sometimes deposited in its substance, and only detected by the knife.
Simple ossification, as it occurs in the heart and arteries, has been classed among the natural changes which the parts in question are liable to undergo after a certain period of life. Of persons above the age of sixty years the proportion is that of seven in ten according to Bichât, in which ossification is discovered in some part of the arterial system. It very rarely happens that simple ossification is found before the period of old age: still it is difficult not to regard it as a morbid process.
But ossification, when it is a mixed process, is unquestionably the result of disease. It is met with at all periods of life; and probably constitutes one of the terminations of inflammation. The kind of morbid structures with which the bone is united leads to this belief.
Fungous, and wart-like excrescences, are found in all those parts of the internal lining of the heart, which have been already mentioned as most subject to disease. They seem to be the result of a new morbid action set up in parts already disorganized; for I have not met with them where the membrane has been otherwise healthy, but only where it has been thickened or cartilaginous, or ossified, ruptured, or ulcerated. They grow either from the surface of the membrane, or from its ruptured or ulcerated edges, and are always in immediate contact with the circulating blood[6].
According to my observation, when a fungous or warty excrescence has grown from the ruptured edges of the membrane, it has been from them exclusively, and from no other part of the lining of the same heart. And as rupture of the membrane seldom occurs in more than one situation at a time, the heart of the same individual seldom presents more than one excrescence of this kind: and as the aortic valves are the parts most liable to rupture, it is there that this single excrescence is most frequently found; not that rupture may not take place elsewhere. I once saw a single chorda tendinea ruptured; and a single fungous excrescence of considerable size hanging from it into the cavity of the left ventricle.
Now, this morbid growth is evidently connected with the lacerated state of the membrane in the conditions of its production, whereby it is limited to a small space.
It is probable that the membrane is first ruptured; that its lacerated edges inflame, and then throw out unhealthy lymph, or unhealthy granulations, in the shape of these fungous or wart-like excrescences. When they have sprung from a ruptured membrane, they have, in the specimens which I have examined, been larger than when they have arisen under other conditions.
But when such excrescences grow from the surface of the membrane which is thickened and cartilaginous only, but not lacerated, they are more apt to occur in many parts of it at the same time. I have seen the valvular apparatus between the auricles and ventricles on both sides, as well as the aortic valves of the same heart, studded with them. They were all about the size of hemp seeds: they adhered to the membrane with different degrees of tenacity, and wherever they were capable of being detached, they left a rough surface. The lining of the arteries has been known to give origin to morbid growths of the same kind, which have obstructed the passage of blood, and given occasion to the formation of a coagulum, which has obliterated the pulse.
The internal lining of the heart is liable to ulceration, not as a common consequence of simple inflammation, but as an occasional consequence of some of those diseased conditions which have been described.
It is most commonly found around scales and spiculæ of bone, and under such circumstances as to leave no doubt that the bone itself has furnished the source of irritation from which it springs. The ulceration commences from the very border of the bony scale, as if it was a process of nature for detaching it, and to a considerable distance around the ulceration the membrane is reddened, and easily detached from the subjacent structure. Where there are several distinct scales of bone, it is not uncommon to find a circle of ulceration around each of them.
Ulceration is also met with where there is a thickened and cartilaginous state of the membrane without ossification. Under these circumstances, as far as I know, it affects no definite form. It is often a very destructive process of disease, obliterating large portions of the valvular structure, and penetrating deep into the muscular substance of the heart.
Rupture of the internal lining of the heart is not easily distinguished from ulceration. In collections of morbid anatomy, many unquestionable specimens of ulceration are described as specimens of rupture. Rupture must always be looked for in the valvular apparatus of the heart, i. e. in the valves themselves, or in the chordæ tendineæ which are their appendages. It is probably incapable of taking place elsewhere, except as a part of a rupture, which involves the whole organ.
That solution of continuity which is evidently without loss of substance; that of which the separated edges when they are brought together are completely adapted to each other; also that which is unaccompanied by any thickening or other morbid condition of the valve; the solution of continuity which is found under these circumstances, may safely be considered to proceed from rupture, and not from ulceration[7].
But it is probable that these characteristic conditions do not long remain after the occurrence of the rupture. Complete specimens of them are very rare; but specimens are numerous where the solution of continuity, by its form and direction, bespeaks rupture, while its rounded edges and the general thickening of the valve denote ulceration. These, it may be fairly conjectured, do in fact exhibit a compound of both. The membrane was originally ruptured, but disease has subsequently arisen and obscured the character of the mechanical injury.
The greater number of those concretions, which were regarded by the older anatomists as polypi of the heart, were unquestionably portions of mere blood, which had undergone coagulation after death. The blood remaining in the heart after death discharges itself of its colouring matter as it coagulates, and, giving off processes between the muscular fasciculi, assumes a shape which has suggested the name of polypus[8].
I have often found (I presume, therefore, that it is not an uncommon occurrence) coagula of an irregularly laminated texture having their colouring matter not entirely discharged, but unequally distributed through them, which have been most intimately adherent to some part of the lining of the heart. Of these some have admitted of separation, while the surface of the membrane and the surface of the clot were left rough at the place of contact, and others were incapable of being detached without the membrane being detached along with them. The appendix of the left auricle is a situation in which they are apt to occur, and they are generally accompanied by an extensively diseased condition of the lining membrane. These coagula, from their laminated texture, and from the intimacy of their union with the internal lining, seem to be essentially different from polypi of the heart. They appear to be connected with a process of disease in the membrane, and to have obtained their union with it long before the death of the patient.
I once saw two separate tumors, entirely resembling what are called polypi, between the carneæ columnæ of the left ventricle, and firmly adherent to the heart; and in the centre of each a distinct formation of pus. The heart was otherwise healthy[9].
There are three preparations in the museum of the College of Surgeons, put up by Mr. Hunter himself, and noted by him as exhibiting "Tumors on the inner surface of the right ventricle, seemingly composed of layers of coagulable lymph one upon another, the central part having the appearance of glary mucus." This last appearance (the mucus) no longer remains in any of the three, but in its stead there is a cavity. The tumors which I have mentioned as originally containing in their centre a distinct formation of pus, also now present in its stead a cavity. The preparation preserved at St. Bartholomew's, and those at the College of Surgeons, are probably specimens of the same disease.
Here what in the recent parts seemed to be pus or glary mucus, and the cavities still remaining in the preparations, must suggest the suspicion, that these tumors, whether they grew from the surface or were deposited from the blood, had become organized, and afterwards inflamed; and that the inflammation had terminated in the formation of an abscess.