The following are conditions which render the prognosis in each valvular lesion more or less unfavorable:
In aortic stenosis the prognosis is less grave than in any other valvular lesion. Life may be prolonged and good health enjoyed for many years. Yet it must be remembered that extensive aortic stenosis rarely exists without attendant regurgitation.
So long as the hypertrophy of the left ventricle compensates for the obstruction, the prognosis is good; but when the hypertrophied walls fail to overcome the obstruction, dilatation begins, and the ventricular systole becomes feeble and intermitting, and the arterial supply to the brain is so much diminished as to lead to cerebral anæmia.
If after sudden exertion or violent muscular effort there is interruption or great irregularity in the heart's action, sudden death may occur from a complete arrest of the ventricular systole.
Evidences of excessive hypertrophy and dilatation, the occurrence of syncope, signs of cerebral anæmia, attacks of vertigo, great muscular prostration, continued and marked paleness of the face, and irregularity of the pulse, render the prognosis exceedingly unfavorable in aortic stenosis.
If the presence of vegetations can be determined, there is danger from cerebral embolism.
When there are no evidences of alterations in the ventricular walls after an aortic obstructive murmur has existed for some time, it may be assumed that no vegetations exist on the valves, and that the murmur is not due to extensive aortic stenosis, and consequently is not dangerous to life.
When the mitral valves become involved, the combined lesions render the prognosis unfavorable.
Death may result from cerebral complications, pulmonary oedema, or cardiac degeneration.
Aortic insufficiency is a much graver form of valvular disease than aortic stenosis. It is difficult to estimate the probable duration of life in aortic insufficiency, for it frequently gives rise to no symptom that would lead to its diagnosis until it is far advanced. Twenty-one days and five years are the extreme limits that have been recorded. It must always be borne in mind in estimating the factors for and against a good prognosis that in no other valvular lesion is sudden death so liable to occur. Yet the record of the cases which I have given ([page 680]) indicates that mitral stenosis is nearly, if not quite, as frequently a cause of sudden death.