ARTERIOSCLEROSIS.
Arteriosclerosis is a term generally applied to a combination of these degenerations, with thickening and diminution of caliber. The changes combined are comprehended in the term atheroma, which is seen as a localized lesion in nodules or plaques in the aorta and larger vessels and in diffuse form in the smaller. Atheroma, as a complex degeneration, constitutes an interesting study, as it leads to well-marked changes in the vessel walls, which are softened at points by fatty changes, the little mass of debris resulting being called an atheromatous abscess (an unfortunate name), which may empty into the vessel, leaving a small cavity and opening known as the atheromatous ulcer. Around this occur usually the calcific changes above described. The disturbance and the roughening thus produced lead to the formation of fibrinous thrombi, which attach themselves firmly at these points. When to such a weakening of the vessel wall as is thus produced are added the elements of compensatory cardiac hypertrophy, and the sudden changes of blood pressure produced by certain occupations and alcoholic and other excesses, it will be seen how atheromatous patches constitute points of least resistance, where blood pressure may cause a vessel wall at least to bulge and thus to afford the beginnings of an aneurysm; while, by combination of various processes, final rupture may result.
The conditions are not so very different in the more diffuse forms, especially in patients who have not only a tendency to vascular disease but to increase it by the added toxemias of gout and syphilis, of various excesses and bad habits, in which not only do arterial coats suffer, but the heart muscle and lining as well. The relations then of systematic toxemias to arterial disease and finally to surgical conditions are not so circuitous as may at first appear.
ANEURYSM.
An aneurysm is a tumor communicating with an artery and containing circulating or coagulated blood, or both. It may be formed entirely from the wall of the vessel, or some portion of it may be formed by surrounding tissue. Several varieties of aneurysm are indicated by descriptive adjectives. They are divided, first, into true and false, the former being composed of all the vascular coats and being small and infrequent; the false aneurysms imply those in which the entire arterial wall does not participate. Aneurysms inside the body cavities are called internal, and those involving the limbs external. The terms spontaneous and traumatic apply here as elsewhere. Fusiform aneurysm implies a spindle-like dilatation of the vessel in somewhat regular form. The sacculated aneurysm is essentially a pouch protruding from one side of the vessel with which it communicates. When the sac ruptures the aneurysm becomes diffuse. If the outer coat gives way and the inner protrudes there is a hernial aneurysm. The dissecting aneurysm is one formed by separation between the arterial coats, so that blood coagulates or flows between them. Such an aneurysm tends to assume a sacculate form and to rupture. A varicose aneurysm is a sac through which an artery and adjoining vein communicate. A cirsoid aneurysm corresponds to a varix on the venous side of the circulation, and implies dilatation of an artery and its branches. (See [Figs. 140] to [145].)
Fig. 140
Fig. 141
Fig. 142