17 Tuckwell, St. Bartholomew's Hosp. Reports, vol. x., 1874.
I. Amongst the medical causes which frequently occasion pulmonary embolism we should mention diseases of the heart,18 of the lungs, the stomach, the kidneys, and the uterus. Mitral affections which have reached their ultimate period are a fruitful source of pulmonary embolism on account of the effect produced on the right heart. The slowing of the circulation in this condition by digitalis has been wrongly accused by some writers of favoring the production of emboli. Evidently, digitalis does not promote this formation when given with circumspection, as it increases the force of the heart-beats. Sometimes constitutional disease precedes the formation of emboli. This is particularly true of leucocythæmia, which is an efficient cause of it, at times, when sudden death has followed plugging of the trunk and both branches of the pulmonary artery.19 In the convalescence of typhoid fever pulmonary embolism is quite frequent, and follows upon the formation of thrombi in the veins. Such a specimen was presented by Fagge at the meeting of the London Pathological Society on Nov. 16, 1876. The patient died suddenly in the fourth week of an attack of typhoid fever following an attempt to get out of bed. The marked symptom of the case was intense dyspnoea.20 It would appear that emboli are more apt to take place in acute than chronic disorders, because in the former they grow more rapidly, are less intimately attached to the vascular walls, and in consequence are prone to become detached and carried in the current of the circulation.21 Chlorosis has been invoked as a cause of venous thrombosis of the lower extremities,22 but rarely under these circumstances has pulmonary embolism been due to its existence. Hayden23 reports a case of similar formation in advanced pulmonary phthisis. In this instance death occurred, but no symptoms of pulmonary embolism were at any time present. At the autopsy a firm, decolorized clot was discovered in either femoral vein. Although phthisis is a frequent cause of phlegmasia alba dolens, owing to the compression of enlarged lymphatic ganglia or the blood-dyscrasia, it is not often the source of pulmonary embolism (9 cases out of 160 of all kinds, according to Luzzato). A probable explanation of this fact is that the fibrinous coagulum does not form in the veins until a late period of the disease, and death results before it has had time to soften and disintegrate.24
18 Am. Journ. Med. Sci., Oct., 1876.
19 Hayden, Case 124, p. 1030.
20 Lancet, Nov. 24, 1876.
21 At times septic material is introduced into the blood and absorbed from disintegration of a clot. Hence arise typhoid or pyæmic symptoms.
22 Reports of Pathol. Soc. of London, vol. xvi.
23 Op. cit., p. 1024.
24 Dict. de Méd. et de Chirurgie, vol. xxix. pp. 336, 337.
II. Surgical affections are frequently the efficient cause of pulmonary embolism. Thus, out of 160 cases of the latter disease collated by Luzzato, 66 owed their origin to conditions embraced in this division. Wounds, contusions, compressions, diseases of, and all surgical operations upon, the veins are specially liable to be followed by pulmonary embolism. Sometimes the thrombus formed originally in the implicated vein takes place there spontaneously; sometimes it is the direct consequence of a localized phlebitis. Several times the injection of tincture of iron into varicose veins of the inferior extremity25 or into a nævus26 has been the occasion of symptoms indicating sudden obstruction of the pulmonary artery; again, it is an accident, more frequent than is generally admitted, of the operation of transfusion (Vulpian). According to Le Dentu,27 the varicose veins tend to cause stasis of the blood, and thus to favor coagulation. They are, therefore, a predisposing cause of the formation of thrombi, and hence of pulmonary embolism. Extensive burns and frostbite are also efficient causes of venous thrombus, and after this manner predispose to pulmonary embolism. The separation of the placenta after delivery leaves an open condition of the uterine sinuses which is a real traumatism, and which occasions the formation of sanguineous coagula. The irritation of the sinuses may extend to the large extra-uterine veins (iliacs), and lead to further deposits of fibrin which may give rise to pulmonary embolism. In these latter cases the inflammation of the veins, if it occurs, is apt to follow the formation of the coagulum. Cases of pulmonary embolism have sometimes been occasioned by the compression of the lower extremities with Esmarch's elastic bandage.28 Massari indeed cautions his readers against the use of elastic bandages for varicose subjects. Even if their use be deemed advisable, never should the limbs be permitted to remain bandaged during several consecutive hours, for fear lest fibrinous clots be formed. Azam cites a case of cyst into which an injection of iodine was made, and quickly followed by obliteration of the pulmonary artery. Hélie (1837), Gütterbock, and Marjolin (1837) have each related a case of pulmonary embolism following a sprain. The most frequent cause, in this division, of pulmonary embolism is without question fractures. The first case reported is probably one by Virchow in 1846 of an extra-capsular fracture of the thigh which led to a fatal termination by a pulmonary embolism.29 Sixteen years later (1862) a second fact of pulmonary embolism following upon a fracture was communicated to the Institute by Velpeau.30 In 1864, Azam31 read two memoirs—the first before the French Academy of Medicine, the second before the Congress of Bordeaux—in which not only the relation of fractures, but all kinds of traumatisms, to pulmonary embolism was fully considered. In these two articles several illustrative cases were recorded as being seen by Gosselin, Richet, and Labat. In the following years several articles of value appeared on the subject of emboli and of their relations with contusions and fractures. Among authors we should cite the names of Bertin (1868), Durodié (1874), and Besson (1878) as workers in this direction. It has been noted not only that the fractures amongst traumatisms cause a large proportion of cases of pulmonary embolism (16 times in 30 cases), but also that the number of instances of fracture of the leg largely predominate (11 cases).32 The explanation given to the latter circumstance is in part the near proximity of the bones with large veins (Verneuil), and second the dilatation of the veins themselves (Le Dentu). Occasionally the embolism of the pulmonary artery has consisted mainly of fat: in one instance there was fracture of the thigh consequent upon a fall;33 in the other the patient was suffering from a gunshot wound of the left knee.34 In both specimens examined after death under the microscope fatty matter was found in the capillaries and pulmonary arteries. It was probable that the fat had been transported by the veins—in part from the lacerated marrow, in part from the subcutaneous adipose tissue.