Valves changed by chronic endocardi tis are more or less opaque, thickened, and cicatricial or calcified. They may be contracted, deformed, curled up, and adherent by their edges to one another. The chord tendinece may be involved in the process and thereby deformed, or fastened one to another, or greatly tracted so that the distorted valve is apposed to the muscular The apices of the papillm themselves may be more or less fibrotic. rcetal endocarditis is usually of this chronic form.
Valvular Lesions.
Whether the abnormal state of the affected valve causes incompetence or obstruction, there results in either ease an unnatural demand upon the muscular power of the heart. Thus, stenosis leads to an increased effort during systole of that cavity which is obliged to force blood through the narrow outlet, and a leaking valve permits blood to flow back ward into the cavity which it has just left, and thus obliges it to do part of its work a second time. In either case, the af fected cavity is made to contain a larger amount of blood than normal.
In case either auriculo-ventricular valve leaks, the corresponding ventricle receives, during diastole, a larger amount of blood than normal from the overdis tended auricle.
The heart possesses reserve forces, and, while the immediate effect of a valvular lesion is dilatation of the chamber af fected, the secondary result is hyper trophy of the muscular walls, and a more or less complete fulfillment of the new demands. Unfortunately, however, there is for several reasons a tendency to retro gression. In the first place, the valvular endocarditis may grow worse by slow change or because of a recurrent acute inflammation. Secondly, the myocar dium is apt to deteriorate so that the muscular power of the heart diminishes. Thirdly, in some forms of valvular dis ease, particularly aortic, the coronary arteries from which the heart derives its nourishment are apt to be involved. The period during which the heart, having hypertrophied, remains equal to the de mands made upon it is called the period of "compensation." Sudden exertion, great mental excitement, or the stress of intercurrent disease may cause a tem porary "disturbance" of this compensa tion. Finally, extreme degrees of val vular deformity and myocardial degen eration bring about "ruptured compensa tion," from which there is little hope of recovery.
Mitral Regurgitation.
Definition.—Insufficiency of the mitral valves, permitting blood to leak into the left auricle during systole.
Symptoms.—The subjective symptoms of mitral regurgitation depend upon the degree of compensation present in the in dividual case. Thus, if the condition is a favorable one, the patient may be un conscious of any unnatural state what ever, having no dyspncea except on con siderable physical exertion. On the other hand, if the circulation is beginning to be embarrassed, we may observe palpita tion, shortness of breath on exertion or excitement, cyanosis, cedema of the de pendent parts, and so on, as described in a previous volume under DILATATION OF TIIE HEART. On physical examination the heart is found to be enlarged mainly in its transverse diameter, the apex being pushed toward the left, and the limit of dullness extending further toward the right than in health. The cardiac im pulse may be more diffuse than in health, and visible in the epigastrium as well as in the normal position. In young sub jects the pnecordia may be somewhat bulged. On palpation, a systolic thrill may sometimes be distinguished; this is not, by any means, the rule, however. On auscultation, we hear at the apex of the heart a murmur systolic in time and transmitted outward toward the axilla. This murmur is also audible inside the lower angle of the scapula. At the base the pulmonie second sound is accented and often reduplicated. The pulse in well-compensated cases may be nearly normal. In later stages it is rather small, frequent, of low tension, and irreg ular in force and rhythm.
Diagnosis.—The important factors in diagnosis are, first, the systolic murmur, which is usually heard loudest at the apex and transmitted outward, and which, in some instances, may be heard over a much more extensive area; in fact, al most all over the chest. Again, the murmur may be audible merely along the left edge of the sternum. The sound is of a blowing character, sometimes musical, especially toward its termina tion, and it replaces the first sound of the heart to a greater or less extent.