1. Deficient And Excessive Formation

We have already considered this subject at p. 117, where we treated of the most important anomalies.

2. Anomalies Of Size - Hypertrophy And Atrophy Of The Valves

Anomalies of size in the valves, that is to say, their superficial enlargement or diminution, usually correspond to an altered thickness of the valves, the former being commonly associated with attenuation, and the latter with thickening of the valves. Exceptions do, however, occasionally present themselves.

Hypertrophy of the valves is found to be almost constantly associated with dilatation of the ostia of the heart, and here we see a healing tendency in nature which endeavors to maintain the valves in a state of sufficiency. We observe this in the auriculo-ventricular, as well as the arterial valves, and more especially in those upon the left side of the heart, which, as is well known, is more frequently affected with dilatation of the cavities and ostia. The valves, as we have already remarked, are in these cases usually thin, delicate, and transparent, and so attenuated as occasionally to exhibit actual perforations (atrophy); in like manner the papillary tendons are found to be thinner and more slender in proportion to the extent of the dilatation, while there is a striking thinness and transparency of the whole of the inner lining of the heart. - Exceptions are, however, occasionally observed; the enlarged valve appearing tolerably thick in comparison with the degree of its hypertrophy, which shows that the fibrous tissue of which it is composed must have increased in bulk. This is especially shown in hyper-trophied aortic valves by the corresponding enlargement in size and thickness of their nodules, and the fibres passing from them.

If we except the shrivelling of the valves induced by the inflammatory process and its products, atrophy of the valves is of rare occurrence, although it may, indeed, very frequently be overlooked. It occurs in diminution (concentric atrophy) of the heart, and is manifested in the form of a shrivelling of the valves, more especially at their free margin, whence the whole valve, including the margin, is found to be thicker and less transparent. - Kingston has observed a case of shortening of the auriculo-ventricular valves, with unaltered thickness, flexibility, and transparency, and with normal width of the ostium, and has described it as a form of atrophy of the valves. Shortening may affect one, or more, or all the apices of the valves, and its immediate consequence is insufficiency. It has hitherto only been observed in the auri-culo-ventricular valves.

Hypertrophy of the valves affects either their fibrous texture or their investment of endocardium. We have already observed that hypertrophy of the fibrous basis of the valves is occasionally associated with their general hypertrophied condition. We, moreover, frequently notice in the auriculo-ventricular valves, and especially the mitral, both in individuals of advanced life and in young persons, a pale white, yellowish-white bulging, or thickening of the valve towards its free edge, or a series of bulgings at the insertions of the papillary tendons, which, however, do not interfere with the function of the valve. No osseous concretions are ever developed in this hypertrophied tissue of the valves. In young persons, we occasionally meet with a condition of this portion of the valvular structure, which very probably indicates incipient hypertrophy of the fibrous texture, the free edge appearing swollen, more especially at the insertions of the papillary tendons. This bulging is produced by a pale red, translucent, more or less gelatinous substance, effused into the texture of the valves, from which, as from a blastema, the fibrous tissue is developed. This substance is very commonly found to consist of a translucent, partly homogeneous, and partly indistinctly fibrous mass, in which are imbedded numerous cell-nuclei, and the so-called nucleated fibres. It may be observed in reference to the arterial valves, that hypertrophy of the aortic valves, more especially of their nodules, is not of very rare occurrence. This last-named condition is, however, less frequently observed.

Hypertrophy of the Endocardium is, on the other hand, both more frequent and more intense in the arterial valves, where it more especially affects the aortic valves, as might be expected, from the greater tendency of the left side of the heart and of the trunk of the aorta, to a similar condition of excess of growth in the endocardium and the lining arterial membrane. The valves become thicker in consequence of the deposition of new layers, and the aortic valves more especially at their nodules and free margin present an appearance of bulging; the protuberance being roundish or cylindrical in form, uneven and nodular, and having occasionally a somewhat prismatic or facetted character from the pressure which they mutually exert on one another. The valves thus coalesce with one another, and with the walls of the arteries, by means of prolonged depositions from their lateral insertions. This increase of bulk, which is intrinsically important, is rendered more so in consequence of its secondary effects. A shrivelling process, similar to that by which the arteries are analogously diseased, now affects the valves, which become thicker, full and rigid, and degenerate into a cylindrically formed swelling, and by this means on the one hand contract the ostium, and on the other become insufficient. A bony substance may also be developed in the deposited strata in the form of nodular, round, or band-like ossifications, equally important with those affecting the arteries; or, lastly, this deposit may exhibit (as when it affects the arteries) an atheromatous disintegration and loss of substance resembling an ulcerous process, which, in the same manner as the ossifications, may produce fibrous coagula in the form of granular, villous vegetations.

This form of hypertrophy of the valves and its so-called consecutive phenomena, occur only in their greatest intensity in the aortic valves, for the disease invariably exhibits an inferior degree of intensity when it affects the auriculo-ventricular valve on the left side of the heart. This disease is always associated with hypertrophy of the endocardium, and more especially with the deposition of new arterial membrane in the aorta. Although it is most common in advanced life, it does occasionally occur at the age of thirty, or even earlier, and gives rise to the insufficiency of the aortic valves, which is very often gradually and almost imperceptibly developed in persons of advanced life. It is not of endo-carditic origin, although it is very often erroneously regarded as a consequence and residuum of endocarditis.1