Diseases of the heart and arterial system : designed to be a practical presentation of the subject for the use of students and practitioners of medicine . closure of thevalves. In those cases of stenosis of sclerotic origin in which thecusps are not adherent but interfere with the blood-flow on ac-count of stiffness which prevents their swinging back in the normalway, regurgitation is usually so freely permitted that the case isclassed as one of insufficiency. In the second class, vegetations on the aortic valve may assumesuch proportions as to induce narrowing of the orifice. These oc-cur mos
Diseases of the heart and arterial system : designed to be a practical presentation of the subject for the use of students and practitioners of medicine . closure of thevalves. In those cases of stenosis of sclerotic origin in which thecusps are not adherent but interfere with the blood-flow on ac-count of stiffness which prevents their swinging back in the normalway, regurgitation is usually so freely permitted that the case isclassed as one of insufficiency. In the second class, vegetations on the aortic valve may assumesuch proportions as to induce narrowing of the orifice. These oc-cur most usually on the ventricular surface of the valve segments,and in that situation of course interfere also with the closure ofthe valve, producing leakage. The narrowing is usually the pre-dominant effect, however, of a large vegetation in this interesting type of stenosis, shown well in Fig. 64, is that inwhich vegetations develop in one or more of the sinuses of Yal- 319 320 DISEASES OF THE HEART salva. Calcified thrombi in this location almost completely pre-vent the opening of the valve, and may produce an extreme gradeof Fig. 63.—Heart of Aortic Stenosis, with Adherent Aortic Cusps, and alsoAcute Endocarditis. Aortic stenosis is not always located in the valve, however, forthe aortic ring, and sometimes the whole trunk of the vessel, maybe narrowed. This is probably most often a congenital of the heart, or more properly of the conus arteriosus ofthe left ventricle, may also produce the secondary effects of ste-nosis of the orifice. It goes without saying that aortic stenosis, according to its de-gree, presents more or less resistance to the outflow of blood from AORTIC STKNOSIS 321 the ventricle. I -der, therefore, to discharge a normal volume of blood through the diminished opening, the ventricle is obliged tocontract more powerfully and more slowly. This increased workresults in the development of hypertrophy. Fraentxel is of the
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