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

by Unknown

Mitral obstruction may be mistaken for the murmur of aortic regurgitation (see [page 657]), for a pericardial friction located over the apex, for a prolonged systolic murmur replacing the first sound at the apex, and for a prediastolic basic murmur transmitted to the apex.

1. To diagnosticate between local pericarditis and mitral stenosis, the same methods are employed and the same rules are to be observed as were mentioned in the diagnosis between aortic reflux and local pericarditis ([p. 664]).

2. A prolonged systolic apexial murmur, enduring as it does for the period of the first sound, that of the short pause, and reaching the second sound, is often accompanied by a muffled second sound readily mistaken for the first. The diagnosis of this murmur rests upon its soft and blowing character, the synchronism of the murmur with the systolic impulse and carotid pulsation, and the fact that there is no murmur with the second sound at the base.

FIG. 45.

Mitral and Aortic Obstruction and Regurgitation (from a Patient in Bellevue Hospital).

A prediastolic murmur is distinguished from a mitral stenotic murmur by its progressively diminishing intensity from the base to the apex, by its being accompanied by hypertrophy of the left ventricle, and by a jerking, irregular pulse. The preceding tracings explain themselves.

Mitral Regurgitation.

Regurgitation at the mitral orifice is due to a condition of the mitral valves which allows the blood to flow back from the left ventricle into the left auricle. The backward effects of mitral reflux are more varied than those of any other valvular lesion.

It is a common form of valvular disease, and in the majority of cases is the result of acute exudative or interstitial endocarditis.

MORBID ANATOMY.—The most common lesions which give rise to mitral regurgitation are thickening, induration, and shortening of the mitral valves. In rare instances it may occur independent of valvular disease from displacement of one or more of the segments of the valve, the result of changes in the papillary muscles, chordæ tendineæ, or the ventricular walls. It may also occur in extreme anæmia, or from relaxation of the papillary muscles and dilatation of the left ventricle, without a corresponding elongation of the papillary muscles, and from rupture of the chordæ tendineæ. In most instances, however, the valves are shortened, thickened, and indurated.