The first effect of this narrowing is to cause hypertrophy of the left ventricle, and as long as this ventricle is able to force the blood through the narrowed opening at the aortic valve, the general circulation is perfect. Nature again steps in to cause such a heart to heat deliberately, allowing time for the contracting ventricle to force the blood through the narrowed orifice. The blood pressure may be sufficient, or even increased if arteriosclerosis is present, although the rise of the sphygmograph tracing is not so high as normal. If the pressure in the aorta is sufficient from the amount of blood forced into it, the coronary arteries receive enough blood to keep up the nutrition of the heart muscle. Sooner or later, however, the left ventricle will become weakened, especially when there is arteriosclerosis or other hypertension, and chronic endocarditis and fatty degeneration result. If the left ventricle becomes sufficiently weakened or dilated, the same damming back of the blood through the lungs and right heart occurs, and more or less serious signs of broken compensation develop. The main danger, however, with a heart with this lesion, occurring coincidently with arteriosclerosis, is a progressive chronic myocarditis. OTHER LESIONS Tricuspid insufficiency, except as rarely found in the fetus, is generally due to a relative insufficiency rather than to an actual disease of the tricuspid valve. In other words, if the right ventricle dilates the valve may be insufficient. Tricuspid stenosis, pulmonary stenosis and pulmonary insufficiency are rare, and are probably nearly always congenital. The diagnosis as to whether the murmurs heard in the heart are hemic, functional, accidental, or indicative of valvular lesions would be without the scope of this book. It is always presumed that a correct diagnosis has been made, or at least a presumptively correct diagnosis. Frequently more than one murmur and more than one lesion in a heart are present. Often one murmur denotes a permanent lesion, and another may be one that will become corrected when compensation is improved. SYMPTOMATOLOGY AND TREATMENT OF CHRONIC VALVULAR LESIONS Before discussing the treatment of broken compensation in general, it may be well to describe briefly the differences in the symptoms and treatment of the various valvular lesions. MITRAL STENOSIS: MITRAL NARROWING This particular valvular defect occurs more frequently in women than in men, and between the ages of 10 and 30, and is generally the result of rheumatic endocarditis or chorea, perhaps 60 percent of mitral stenosis having this origin. Other causes are various infections or chronic disease, such as nephritis. Of course, like any valvular lesion, it may be associated with other lesions, and sooner or later in many instances, when the left ventricle becomes dilated or weakened, mitral insufficiency also occurs.