The course of suppurative myocarditis is always unfavorable, but the fatal termination of the case is usually dependent on concomitant causes. The possibility of recovery in some instances of abscess of the heart is suggested by the occurrence of caseous and cretaceous masses, probably the remnants of collections of pus.
The chief danger in interstitial myocarditis is heart paralysis and sudden death, as occur in diphtheria and occasionally in rheumatism. From mild grades of the disease recovery may take place, and even when general and severe it has often been some indiscretion which has induced the collapse, as sudden sitting up in bed or getting out to attend to the calls of nature. Possibly the slight intramuscular scars and spots of atrophy furnish evidence of past acute myocarditis.
When suspected, the TREATMENT should consist of absolute rest, muscular and mental, with careful feeding and stimulation. If a rheumatic case upon the alkaline or salicylate treatment, the remedies should be stopped. I saw sudden death from heart failure in a case of acute rheumatism in which during four days the full alkaline treatment of Fuller was followed, and in which, by mistake, a much larger quantity of the bicarbonate of soda was given each day than had been intended. Strychnia and small doses of quinine may be given. Shall digitalis be employed in acute myocarditis? Upon this point authorities differ. If we regard it as simply increasing the force of the muscular contractions, we can understand the fear of straining a weakened heart; but digitalis has important trophic influences, and, while it stimulates the vigor of the contraction, improves the nutrition of the heart-muscle and renders it better able to contract. After all, the question amounts to the giving of digitalis in dilatation, and with a weak first sound and feeble action the careful administration, in conjunction with stimulants, will be found beneficial. Peter13 speaks highly of the application of a blister in the region of the heart.
13 Loc. cit.
Chronic Myocarditis (Fibroid Heart).
A condition characterized by the substitution in areas of variable extent of a fibrous connective tissue for the muscular substance. It is an interstitial growth, comparable to the cirrhosis of other organs, and the muscle-elements in the affected regions are wasted or entirely destroyed. The process may occur in a mild grade throughout the organ, but it is more common to find it distributed in certain parts which seem specially prone to this form of degeneration.
The conditions under which it is most likely to occur are those which we find in connection with arterio-sclerosis. It is an affection of adult and advanced life, and is met with most frequently associated with disease of the coronary arteries. In chronic valvular affections it is very common, and may be part of the so-called cyanotic induration or an extension from the thickened endocardium. Sometimes it seems a part of a general arterio-capillary fibrosis. In a few cases there is direct extension from the pericardium. Rheumatism is in this way indirectly responsible; possibly some of the cases are directly traceable to acute interstitial myocarditis occurring in this disease. Chronic alcoholism, syphilis, and gout are prominent factors in the etiology. Some of the most marked cases give no clue in the history or habits of any conditions which we could reasonably connect with the disease. Males are more often affected than females. The tendency to arterio-sclerosis seems to run in some families. Mental anxiety is not without influence, and when the disease is established seems very liable to bring on the anginoid attacks. The situation and extent of the fibrosis are very variable. The papillary muscles and the columnæ carneæ of the left ventricle are most frequently affected, less often the corresponding structures on the right side. The middle portion of the muscular bundles and the apices of the papillæ are first involved. In the latter the process may extend almost to their bases, but on section it will be found that it is more advanced in the superficial than the deep parts. This change is very common in cases of valvular disease with hypertrophy, especially mitral stenosis, but it often occurs in elderly persons who have had no special heart symptoms.
Beneath patches of pearly-white thickened endocardium local fibrosis may occur, often seen at the upper part of the septum in left ventricle, and in the dilated and thickened left auricle of mitral stenosis, and occasionally in other parts. This is usually regarded as an extension from a chronic endocarditis. More rarely the fibrosis extends from a thickened pericardium, but cases are on record of the conversion of the outer layers of the muscular fibres into a firm, hard tissue. We frequently meet with scattered areas of fibrosis in septum and ventricular walls without any implication of peri- or endocardium. During foetal life an endo-myocarditis may occur in the conus of the right ventricle, less frequently in the left, and produce very great narrowing by the gradual contraction of the newly-formed tissue. But the condition to which the term fibroid heart can be most properly given is an extensive affection of the left ventricle, involving most commonly the anterior wall near and at the apex and the lower part of the septum. In these cases there may be marked bulging at the apex, and on section the wall cuts with great resistance, and a dense fibrous tissue of a grayish-white appearance occupies the position of the myocardium. In extreme cases a large part of the septum and anterior wall is in this state, and may present only traces of muscular tissue. There is usually thinning, sometimes thickening, of the affected portions, and the septum bulges toward the right ventricle. The endocardium is opaque, often much thickened, and directly continuous with the fibrous tissue. The columnæ carneæ may be narrow and flattened, and the lacunæ between them very small. The chamber is usually dilated. The upper third of the septum and the base and posterior wall of the ventricle in such cases present a marked contrast to the affected parts, and may look natural, but more commonly are hypertrophied. The other chambers may not show any special change or there may be scattered areas of fibrosis. The thinning and dilatation at the apex and septum are the conditions which precede and lead to the formation of cardiac aneurism. The valves may be normal, but in many cases there is sclerotic endocarditis and retraction. The histological appearance varies much with the stage of the process. When early or where advancing, the muscle-bundles are seen separated by round and elongated cells. The process is usually more marked about groups of fibres, which gradually become isolated by the increase of the growth, and in this way one often sees streaks or patches of muscle-tissue surrounded by the fibrous elements. The destruction of the muscle-cells is apparently by pressure; they gradually waste and present the condition of brown atrophy, the pigment of which remains and indicates the position of the fibres. The intimate pathology of the process is of great interest. Doubtless in some instances we may attribute the fibrosis to an extension of an indurative process from the endo- or pericardium, but the researches of Tautain,14 Martin,15 Huber (Karl),16 and others have thrown a new light on the subject, and it seems probable that in most instances the fibroid degeneration is associated with changes in the coronary arteries. The former describes an endarteritis and a periarteritis of the small vessels, leading to disturbance of nutrition and increase of the connective tissue (sclérose dystrophique). Huber in a considerable number of cases has traced the connection between the arterio-sclerosis, chiefly of the smaller twigs, and the indurative process. The region supplied by the obliterated arteriole is in the condition of an infarct and undergoes an anæmic necrosis, and subsequently by a proliferating myocarditis is transformed into a fibroid area. The condition is well described and figured by Ziegler.17 Why this obliterating endarteritis should be so limited in the majority of cases to the vessels of the left ventricle is not very clear. The parts most distant from the aorta seem most liable to the process, as the apex and the tips of the papillæ; and it is interesting in this connection to note that the left coronary artery is more frequently diseased than the right.
14 Thèse de Paris, 1878.