A system of practical medicine. By American authors. Vol. 3

by Unknown

DISEASES OF THE CORONARY ARTERY.

Chronic Endarteritis (Arterio-sclerosis; Atheroma).

This is the most important inflammatory disease of the coronary artery which has been observed. It resembles chronic endarteritis elsewhere, and frequently accompanies the same affection of the aorta, though it may occur alone. The disease may be general, affecting both coronary arteries equally, or one may be more involved than the other, or the disease may be confined to one vessel or to even a small branch.

ETIOLOGY.—Chronic endarteritis of the coronary arteries is especially a disease of middle and advanced life. It occurs most frequently in the male sex. The coronary artery stands fifth in the order of frequency in which the vessels are attacked. The disease is attributed to the misuse of alcoholic drinks, syphilis, chronic lead-poisoning, gout, and chronic kidney disease, by encouraging an early senescence of the tissues, and hence favoring the occurrence of the arterial change.

SYMPTOMS.—There are no symptoms which are peculiar to the disease, those which exist being due to the consecutive changes in the substance of the heart. We may divide cases for convenience of description into those with an acute course and rapid death; those pursuing a subacute course; and, finally, those having a chronic one. In the first instance, sudden death either occurs in a person apparently in perfect health after the manner of a syncope, as in one getting out of bed or standing on the street, while straining at stool, or under sudden emotional excitement. Death may not follow on the instant, but occurs in the course of a longer or shorter time. The attack begins with pressure in the cardiac region, anxiety, restlessness, streaming pain. The complaints and anxiety increase; the breath becomes short and troublesome, the pulse small, frequent, and intermittent; finally, collapse occurs, with oedema of the lung. Death takes place with either a clear mind or slight delirium. Such a fatal ending may cover a day or two or only a few hours. Almost always careful subsequent inquiry elicits the fact that for some time past respiratory or cardiac difficulties have existed, which appeared and disappeared and were not regarded as serious or suspicious. Sudden death may also occur in cases of protracted chronic heart disease following arterio-sclerosis, with an old history of the symptoms of angina pectoris, under the appearance of a fainting fit or of a severe attack of angina or oedema of the lung lasting several days. In such a case rupture of the heart may be found, with bloody infiltration of the cardiac muscle and effusion of blood into the pericardium. In other cases there may be small hemorrhages, often with pronounced infarct formation and softening. In still other cases neither hemorrhage nor infarction is found, but fatty degeneration of the muscle or beginning softening. The sclerosis in such cases is usually very distinct, and affects the trunk and anterior descending branches of the left coronary artery. Sometimes it is hard to find the diseased spot, as it may be circumscribed or on a side branch. In the last-mentioned cases, where sudden death occurs in a chronic process, no post-mortem signs of acute disease are usually found. A chronic fibroid process, with atrophy, exists, which has run a tolerably latent course and leads to death under the appearance of sudden cardiac weakness.

PATHOLOGY.—There are two stages of chronic endarteritis: 1. The stage of simple thickening of the intima; 2. The stage of ulceration and the accompanying further changes.

At first, the normal smooth, shining inner surface of the intima is interrupted here and there or in long stretches by flat rounded elevations, which gradually merge into the healthy surrounding tissues, and are characterized by a paler, more transparent character, and at the same time softer but elastic consistence. The surface of these thickenings, which are frequently located at the point where branches are given off, is either perfectly smooth or slightly wrinkled. Besides these translucent spots there are similar ones which are opaque, whitish or yellowish in color, and have a somewhat rougher surface. Lastly, there are very pronounced thickenings with a yellow color. In the slighter degrees these spots occur singly. In the more pronounced cases they may take up the greater part of the surface; the wall of the vessel is thickened, the inner surface is uneven, and the vessel itself more or less dilated. In the beginning the intima retains its shining surface: after the disease has lasted a long time this is changed, and the second stage appears. Roughnesses, erosions, and ulcerations appear, or more commonly calcification of the wall. This latter appears at first as little thin layers, and finally in large shield-like plates of lime salts, which may occupy the whole circumference of the artery and change it into a stiff, bony tube. It is found where ulceration has occurred, and often without the appearance of the latter. Together with the rigidity of the wall there occurs a slight tortuousness of the vessel. At first the superficial layers of the intima are soft; next they become more sclerosed, and their tissue denser and finally striated; or disintegration, commencing deep in, may reach as far as the surface and lead to an atheromatous ulcer. A more or less abundant deposit of lime salts follows in the sclerosed layers of the intima, leading to the formation of homogeneous plates as hard as bone.

The result of the process at first is diminution of the calibre of the vessel, next diminution of the elasticity and contractility of the artery: it loses its resistance and suffers dilatation in consequence of the blood-pressure, and may attain aneurism. Or if calcification occurs early the diminution of the lumen remains, or perhaps even increases, and may reach an almost complete occlusion of the vessel.

The effects on the heart which follow this form of disease of the coronary artery, though described in another place, had best be enumerated here: 1. The flow of blood not being sufficiently interfered with to cause disease, the heart may remain unchanged. 2. Hemorrhagic infarction may result, accompanied by simple fatty degeneration or softening, which is the most frequent cause of rupture of the heart. 3. Fibrous degeneration or myocarditis may occur, leading perhaps to aneurism of the heart. 4. There may be a combination of these two—a greater or less marked fibrous degeneration, to which a fresh hemorrhagic softening is added.

DIAGNOSIS.—There are no pathognomonic symptoms of this disease, and it is doubtful if a diagnosis can be arrived at. When the conditions spoken of under Etiology pertain, and certain of the symptoms mentioned in connection with the disease are present, a suspicion of chronic endarteritis of the coronary artery may be entertained with some degree of probability.