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.