73 Dict. Encyc. des Sci. méd., Paris, 1876.
III. Ancient Clots.—There are several varieties which differ considerably in their outward conformation and appearances, and are formed at a period more or less removed from the time of death: (a) Stratified coagula, which are attached intimately to the cardiac walls, and present frequently an aspect which has been confounded with that of true vascularization. So intimate is their adherence at times that to effect their separation the scalpel has to be used, and in the attempt the endocardium is detached. This membrane is frequently affected at the level of their attachments with an alteration of atheromatous nature. The volume of these coagula differs considerably. According to the old writers, they may have become large enough to fill the cavities entirely of one side of the heart and weigh at least a pound.74 This is evidently an exaggeration, and coagula of this size could only be formed after death. Still, very large clots, formed some time previous to death, have been carefully described by Bouillaud.75 These should be considered very exceptional cases, and according to Raynaud76 such masses would inevitably cause immediate death. Notwithstanding this affirmation, an ancient clot so voluminous as to fill an entire cavity has occasionally been found. Such an instance is the one referred to by Parrot,77 where the left auricle was found distended by a stratified coagulum, whilst the other cavities were relatively empty. Generally, the volume of these clots varies from that of a walnut to that of a grain of millet. Sometimes they are flattened out, cover a large surface, and extend from one cavity into another. It is extremely infrequent to encounter a coagulum which fills more than the one-third or one-half of the cavity which contains it. These coagula have different shapes. They are ovoid, globular, sessile, pedunculated. Their number is usually in inverse proportion with their volume. When they have a certain mass and occupy the cardiac cavities they are often unique.
74 Cited by Bucquoy, Des Concrétions sanguines, Paris, 1863, p. 62.
75 Traité des Maladies du Coeur.
76 Dict. de Médecine et de Chirurgie, vol. viii. p. 565.
77 Dict. Encyc. des Sci. méd., 1 Série, vol. xviii. p. 481.
(b) Warty excrescences, which deposit generally upon the surfaces or margins of the aortic or mitral valves, although they may be found adherent to other portions of the endocardium. These warty growths or vegetations are only so in appearance, for their real structure is mainly that of fibrin. Rarely do we find them in the right heart. They have a jagged mulberry or cauliflower aspect, and adhere to an otherwise healthy endocardial lining or to points where an alteration or fissure already exists. Sometimes they are in the form of rounded pedunculated masses, as described by Laennec,78 and have given rise to no obvious symptoms during life. These deposits of fibrin should be distinguished from morbid growths and exuded lymph. The latter may be augmented in size by layers of fibrin, and may require close inspection to clearly differentiate them. The two preceding varieties of clot are often apparently due to some constitutional dyscrasia.
78 "Végétations globuleuses," Traité d'Auscultation médiate, t. ii. p. 630.
(c) Globular concretions or fibrinous cysts, the latter term being adopted on account of the well-known contents, which have a grumous or purulent appearance79 and are of fluid consistence. They are limited by a cyst-wall, and are firmly attached to the walls of the heart either by a single pedicle or by a series of roots intertwined with the columnæ carneæ or musculi pectinati. Usually they occupy situations in the cardiac cavities somewhat removed from the direct current of the blood. The favorite situations for them are at the apex of the left ventricle or in the appendix of the right auricle. According to Rokitansky,80 they almost invariably occupy the left ventricle, but the observations of later writers show conclusively that this is an error (Bristowe). Thus, Hayden states that in his belief the right chambers are much more frequently the seat of thrombosis than the left chambers. This difference is explained by the greater tendency to stasis in the right heart, where also there is less considerable muscular development. Of 44 fatal cases of valvular lesion, he cites 24 instances of cardiac thrombosis on the right side of the heart, and 12 instances on the left side. No case is reported by him in which the coagulum existed solely on the left side.81 They have been found inserting upon the cardiac valves, and in this situation, owing to their pedunculated formation and varying position, have sometimes occasioned curious physical phenomena. A rare instance of this kind is cited by Walshe,82 where, the mitral valve being perforated, the concretion caused at one time a systolic, at another a diastolic, murmur. They vary in size from a pullet's egg to that of a hazelnut, and exist singly in a cardiac cavity or are in considerable numbers. When we attempt to detach them from the cardiac parietes, we frequently tear through some of their roots and leave small masses behind. When quite numerous they are also small in size, and may then be wholly lodged in the interspaces between the fleshy columns. Under these circumstances they are usually continuous with one another and extend their processes underneath the muscular bands, which are only attached by their extremities to the walls of the heart.83 These clots have been found in the heart free of all attachments. In one such instance reported by Pitres84 they were very numerous and were contained in all the cavities of the heart. This was a rare example. Their surface is usually smooth and the cyst-wall occasionally very thin. The cyst itself may be unilocular or divided into a number of smaller intercommunicating cavities. Occasionally, through rupture of the sac-wall, the contents have been emptied into the cardiac cavity outside. The color of these globular or ovoid concretions is buff or brick-red, and corresponds very nearly with the fluid contained in their interior. The different coloration of the contents is due mainly to the larger or smaller proportion of the coloring matter of the blood mingled with them. Sometimes these ancient concretions are covered by coagula of later formation, and it is only after close inspection that we can determine their real character. The endocardium is usually intact at their level, and rarely shows signs even of irritative inflammation. Hence we conclude that in an analogous manner with preceding forms of coagula they owe their existence to a constitutional alteration of the blood. Whilst the rule is that on section these globular concretions offer an interior consistence which is more or less softened, yet occasionally we encounter one in which the structure is homogeneous throughout, and presents very closely the appearance everywhere revealed by its external aspect. The elements, under these circumstances, of the sac-wall and the interior part of the concretion are almost identical. Under the microscope these are recognized as being mainly compound granular bodies, oil-globules, some imperfect cells, or altered blood-corpuscles surrounded by a network of fibrin. After a brief period, and in consequence of disintegration, the contents of these cysts may resemble pus and show certain differences in their constituents according to their appearance. "When white or buff-colored they consist almost solely, if not solely, of molecular matter, oil, and broken-down corpuscles, with which are frequently mixed compound granular cells and colorless acicular crystals. When presenting a brick-red or chocolate hue they exhibit, in addition to the elements just mentioned, numerous blood-corpuscles more or less altered, and consequently more or less indistinct, and occasionally also ruby-colored, rhomboidal, hæmatoid crystals."85
79 Pathol. Society's Trans., vol. xiv. p. 65 et seq.