CHRONIC VALVULAR DISEASE.—Results of valve lesions. Narrowing of a valve causes increased difficulty in emptying the chamber of the heart behind it. Insufficiency of a valve allows the return of the blood through the valve during the dilation of a chamber, thus increasing the amount of blood entering the chamber beyond the normal. Either trouble causes dilation of the chamber and compensatory hypertrophy. Enlargement of its wall must take place in order to perform the extra work demanded constantly, for the normal reserve force of the heart muscles can accomplish the extra task only temporarily. This enlargement increases the working power of the heart to above normal, but the organ is relatively less efficient than the normal heart, as its reserve force is less and sudden or unusual exertion may cause disturbance or failure of the compensation acquired by the enlargement. If this loss of reserve force is temporary, compensation is restored by further enlargement and by diminution, by rest, of the work demanded of the heart. Any valvular lesion, whether a stenosis (narrowing) of the outlet or insufficiency from the moment of its origin, leads to certain alterations in the distribution of pressure upon each side of the affected valve. If the body of the heart itself did not possess a series of powerful compensatory aids, that is, the power of making good a defect or loss, or restoring a lost balance, to improve this relation of altered pressure, then every serious lesion at its very beginning would not only cause serious general disturbances of circulation, but very soon prove fatal. Without compensation of the power of making good the defect or loss, the blood in every valvular disease or lesion would be collected behind the diseased valve. The heart's reserve power prevents to a certain extent such a dangerous condition; the sections of the heart lying behind the diseased valve work harder, diminish the blood stoppage and furnish enough blood to the peripheral arteries. The reserve force is used in stenosis to overcome the obstacle, whereas in insufficiency it must force more blood forward during the succeeding phase through the diseased valve. To effect this increased work permanently, anatomic changes in the heart are bound to follow. The changes consist in hypertrophy (enlargement of the heart muscle) and dilatation of the different chambers. Under this head, compensation, is included the increased filling and increased work of certain heart chambers with their resulting dilatation and hypertrophy. But this compensation cannot last forever. It fails sometimes and certain symptoms follow as hereafter related. Therefore persons who have valvular disease and who have been informed that the heart has adapted itself to the condition by enlarging of its walls and chambers and thus forming the condition called compensation, should be very careful of their mode of living and not put any undue or sudden strain upon the heart that might destroy the conditions that make compensation continue. In the following pages symptoms are given showing what happens when compensation continues and when it fails.
[CIRCULATORY DISEASES 343]
AORTIC INSUFFICIENCY OR INCOMPETENCY.—The valves are not doing their work thoroughly.
Symptoms.—They are often long absent; headache, dizziness, faintness, flashes of light, difficult breathing, and palpitation on exertion, and pain in the heart region may occur early. The pain may be dull and localized, or sharp and radiating to the neck or left arm. When compensation fails, we have difficult breathing, which is worse at night, swelling of the eyes and feet, cough, anemia. Sudden death is more common in this than with any other valvular disease. You can hear a soft blowing sound by listening with your ear.
NARROWING (Aortic Stenosis).—Caused by chronic endocarditis, etc. Their valve segments are usually adherent to each other by their margins and are thickened and distorted.
Symptoms.—When compensation is gone, diminished blood in the brain causes dizziness and faintness.
MITRAL INSUFFICIENCY OR INCOMPETENCY.—This is the most common valvular disease. The segments of the valve may be shortened and deformed. There is often stenosis (narrowing) caused by this deformity. The effects are regurgitation, flowing back of blood from the left ventricle into the left auricle, which is also receiving blood from the lungs, causing dilatation of the auricle and its enlargement to expel the extra blood; dilatation and other enlargement of the left ventricle occurs on account of the large quantity of blood forced in by the auricle; obstruction to flow of blood from pulmonary veins due to extra blood in left auricle, hence dilatation and enlargement of right ventricle which forces blood through the lungs; dilatation and enlargement of right auricle.
Symptoms.—If compensation is slightly disturbed we have blueness (cyanosis), clubbing of the fingers, hard breathing on exertion, and attacks of bronchitis and bleeding from the lungs. If compensation is seriously disturbed we are likely to have the blueness (cyanosis) more marked, heart beat feeble and irregular, constant hard breathing, with cough and water or bloody sputum, dropsy in the feet first and going up and involving the abdomen and chest cavities.
MITRAL STENOSIS.—This is the narrowing of the valve opening. It is most common in young persons, chiefly females. The narrowing of the valve opening may be due to thickening or hardening of the valve segments, adhesion of their edges, thickening and contraction of the tendinous cords of the valve ring.
Symptoms.—Similar to mitral insufficiency, but they develop slower and those symptoms of venous congestion of the lungs, liver, etc., are more marked; bleeding from the lungs is more common.