Anomalous smallness of the heart appears under two essentially different forms, being either congenital and original, or the result of atrophy - atrophied. Abnormal smallness from either of these causes is of incomparably less frequent occurrence than excessive size.

The former of these conditions is occasionally associated with a foetal conformation of the heart, patency of the foramen ovale, and even with more considerable malformations; but many cases present exceptions to this rule. The degree of abnormal smallness varies, the heart of the adult being in some well-marked cases no larger than that of a child of six or seven years of age. This condition appears to be most common in the female sex, and is not unfrequently connected with retarded development of the sexual organs, especially where this arrested development affects the whole system. The opinion expressed by Laennec, that frequent syncope is dependent on a heart too small in relation to the body of the individual, is worthy of observation.

Atrophy of the heart accompanies, to a certain extent, all general wastings of the body, being commonly observed after typhus, and especially in marasmus, in consequence of tuberculous and cancerous secondary formations and their disintegration. An atrophied condition of the heart is also occasionally produced by pressure and want of space, as for instance by bulky secondary products in the mediastinum, and is, moreover, also the result of pericarditis, accumulations of fat on the heart, etc. Contractions of the openings of the coronary arteries is an important and influential cause.

The heart itself differs under these circumstances, the tissue being either tough, and in that case usually of a reddish-brown color, or relaxed, easily torn, of a rusty fawn-color, and a faded appearance. According to Bouillaud, three different forms may be established in reference to the cavities of the heart, viz.: a. Simple atrophy, wasting (attenuation) of the walls, with a normal condition of the capacity of the cavities.

b. Eccentric atrophy, attenuation of the walls with dilatation of the cavities.

c. Concentric atrophy, a normal or even an increased thickness of the walls, with contraction of the cavities; this is the most common form.

In the first form the volume of the heart is contracted; in the second it may be contracted, normal, or augmented; in the third it is constantly and generally strikingly contracted. This last form approaches most nearly to original smallness, with which it may even be confounded.

Besides the above named-characteristics of the muscular substance of the heart, other signs of atrophy may be mentioned, as, for instance, disappearance of the fat of the heart, serous infiltration of the adipose cellular tissue at the apex, the base, etc, in consequence of shrivelling of the opaque pericardium and of the milk-spots that may be present; and, lastly, an unusually winding course of the coronary artery.

Morbid attenuation, atrophy of the endocardium, and of the valves, will be considered in the sequel.