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

by Unknown

¹⁶ Bellingham Dis. of Heart, 1857, p. 152; also Trans. Path. Society, vol. iii., March, 1868, p. 3, article by Prof. Law.

Mitral Stenosis.

Stenosis, or obstruction of the auriculo-ventricular opening of the left heart, is due partially to constriction at the base of the mitral valves, and partially to adhesions of the valve-tips or chordæ tendineæ. It usually occurs as a consequence of rheumatic endocarditis, rarely of atheromatous degeneration, and is most likely to occur in endocarditis affecting young persons.

Mitral disease is present in one-half the cases of valvular diseases of the heart. Usually, insufficiency and stenosis of the mitral orifice occur together, and stenosis probably never occurs without some insufficiency.

MORBID ANATOMY.—As a result of acute exudative or interstitial endocarditis, the valves are rendered shorter and narrower, as well as thicker and more cartilaginous, than normal. These rigid valvular projections not only obstruct the flow of blood from the auricle to the ventricle, but allow of its regurgitation from the ventricle into the auricle. In mitral stenosis there is not only thickening and contraction of the valves, but the valve-tips or the chordæ tendineæ become adherent, and sometimes each papillary muscle gives rise to a corrugated, cylindrical mass pierced with one or more slits, indicating the chordæ of which it was originally made up. The wall of the valve, especially toward its free edge, is greatly thickened, and these thickened portions are so dense that they have a distinctly cartilaginous feel. On the valvular flaps that have undergone this sclerotic change calcareous masses are very frequently developed, and are especially liable to form when a gouty diathesis exists.

When the chordæ tendineæ and papillary muscles have become adherent, the edges of the valves are drawn down toward the apex of the heart; and since the flaps are adherent for a greater or less distance upward from their bases, the valve presents a funnel-shaped appearance with its base looking toward the auricle and its apex toward the ventricle, whose smaller opening, rarely circular, usually resembles a slit with its axis in the line which unites the original segments of the valve. This button-hole slit may scarcely admit the tip of the little finger, while the normal mitral orifice permits the easy introduction of three fingers.

Annular (ring-like) stenosis is far more common at the mitral than at the aortic orifice. Hard, wart-like vegetations frequently develop on the puckered and seamed flaps, which increase the already existing obstruction. Sometimes the funnel-shaped appearance is wanting, and the flaps are stretched horizontally across, with a small opening in the centre, like a diaphragm: looked at it from the auricle, this slit is often crescentic in shape.

In cases of long standing the vegetations may become calcified. If the new tissue in the diseased valves undergoes fatty change and softens, ulcerative processes are set up and the chordæ tendineæ may rupture. On the floor of such ulcers calcareous masses and débris are frequently found.

Hayden thinks that "all funnel-shaped mitral stenosis is the result of primary acute inflammation and thickening of the valve-segments, with cohesion of their adjacent edges." Out of 62 cases of mitral stenosis, 59 assumed the button-hole form, and 3 only the funnel-shape (Fagge and Hayden).

In rare instances the tendons will adhere to the wall of the heart as well as become matted together. Adjacent to the valves the endocardium will usually be found slightly thickened.