7 Gazette médicale de Strasbourg, 1857.
ETIOLOGY.—So soon as the blood is withdrawn from the influence of life it no longer remains fluid, but rapidly coagulates. Thus it is we find frequently after death coagula filling the cavities of the heart and extending in long ribbon-like bands into the larger vessels, more particularly in the veins. What occurs here is very similar to what we notice in a bowl which receives the blood of a venesection. Here the blood thickens rapidly, the clot forms, leaves the sides of the bowl, assumes the appearance of jelly more or less colored owing to the corpuscles enclosed in the meshes of fibrin, and is bathed in a quantity of ambient serum. A similar change takes place in the heart: the serum is imbibed by the tissues and the clot remains in its cavities.
Coagulation of the blood is a very complex problem. Many theories seek to explain it. On the one hand, it has been said the fibrin pre-exists in the blood, and by the fact of the slowing of the circulation, the reduction of the temperature, etc. the fibrin separates from the blood and coagulates. Again, it is admitted that the fibrin does not exist formed in the blood, but that a fibrinogenous material is present which is acted upon by the hæmoglobin or globulin contained in the red globules, the leucocytes, and the corpuscles of connective tissue, and sometimes is, sometimes is not, caused to precipitate as fibrin (Virchow). The exact conditions which occasion the activity of the globulin are unknown. The reaction which takes place has been said to resemble that which takes place between amygdalin and emulsin when prussic acid is formed, or between myrosin and myronic acid when the volatile oil of mustard is produced. Further, it is stated, in accordance with accurate chemical investigations, that the plasma of the blood contains a substance called plasmin, which separates itself into fibrin which coagulates and into fibrin which remains dissolved in the blood (metalbumen, Robin). These fibrins are evidently of two kinds. The plasmin divides itself under the influence of slowing of the circulation, the action of acids, of foreign bodies, of oxygen in excess, etc.; it remains intact in a fluid condition when the vascular walls and globules are healthy, the blood circulating with normal rapidity, and in presence of alkaline principles.8 According to Foster,9 "Coagulation is the result of the interaction of two bodies, paraglobulin and fibrinogen, brought about by the agency of a third body, fibrin ferment." Schmidt concludes that when blood is shed a number of white and intermediate corpuscles fall to pieces, by which act a quantity of fibrin ferment and of paraglobulin is discharged into the plasma. These meeting there with the already present fibrogen give rise to fibrin, and coagulation results.
8 Dict. de Méd. et de Chirurgie pratique, vol. viii. p. 569.
9 A Textbook of Physiology, p. 22, New York, 1880.
As regards the formation of clots within the body, it is supposed that injured or diseased spots or foreign bodies first attract, and then, as it were, by irritation cause the death of, a certain number of corpuscles.10 The views of Schmidt of the fibrino-plastic function of paraglobulin are not accepted by all investigators; and some authors believe that the fibrinogen as well as the fibrin ferment arises from the white corpuscles.11
10 Pflüger's Archiv, vi. (1872), p. 413; xi. (1875), pp. 291 and 515; xiii. (1876), pp. 93 and 146; quoted by Foster.
11 Frédericq, L., Recherches sur la Coagulation du Sang, Bruxelles, 1877, quoted by Foster.
According to Bristowe,12 the frequency of sanguineous concretions does not depend upon sex, but is in a certain relation with age. He has remarked, for example, that they are proportionately more often met with at the extremes of life than toward middle age. This might be explained satisfactorily, perhaps, on the supposition that at these periods the circulation is at times very feeble, owing either to congenital feebleness on the one hand or chronic organic affections on the other. At all events, when we seek for the causes which have most influence in determining the formation of cardiac concretions previous to death, we find—I. the mechanical, or those which act specially in slowing the current of blood through the heart. These causes may exist within the heart or may be removed from it. II. The vital or pathological. These causes are of somewhat difficult determination at times, and pertain usually to affections in which there is notable blood-change, in which the quantity of the fibrin has been augmented absolutely or relatively, or to those of infectious type—viz. diphtheria; or to those constitutional in nature—phthisis, cancer, etc. III. The inflammation of the endocardium or endocarditis. This is admitted by Andral, in a note upon the etiology of cardiac concretions in the work of Laennec, as having special importance. Bouillaud also attributed their formation in certain cases to the chemical action of pus which was present in the economy.
12 Pathol. Society's Trans., vol. xiv. p. 71, quoted by Bartholow.