Physics Of Mitral Stenosis

Categories: Uncategorized
Sources: Disturbances Of The Heart

Mitral stenosis, though less common than mitral regurgitation, is a

frequent form of disease of the valves, especially in women. Often

this condition is associated with regurgitation; but in a simple

mitral stenosis the greatest hypertrophy is of necessity in the

right ventricle. The left auricle finds it difficult to empty all of

its blood into the left ventricle during the ordinary diastole of

the heart. This auricle then somewhat hypertrophies, but is unable

to prevent more or less damming back of the blood into the lungs

through the pulmonary veins. This causes passive congestion of the

lungs, and the right ventricle finds that it must labor to overcome

the increased resistance in the pulmonary artery, and hypertrophies

to overcome this increased amount of work. When this condition has

become perfected, compensation is established and the circulation is

apparently normal. Nature causes these hearts, when they are

disturbed or excited, to pulsate slowly, causing the diastole to be

longer than in a heart with mitral regurgitation. This allows more

blood to enter the left ventricle, and the left ventricle, acting

perfectly on the blood which it receives, causes a good systolic

pressure in the aorta and the systemic arteries. The left ventricle

in this condition does not become hypertrophied. If the heart does

act rapidly and the left ventricle contracts on an insufficient

amount of blood, the peripheral pulse is necessarily small and the

arterial tension is diminished. Very constant in this condition, and

of course noticeable whenever there is pulmonary congestion, is the

sharp, accentuated closure of the pulmonary valve. The lungs on the

least exertion are always a little overfilled with blood. The

pulmonary circulation is always working at a little disadvantage.

The first symptoms of lack of compensation with the lesion of mitral

stenosis are lung symptoms--dyspnea, cough, bronchitis, slight

cyanosis, sometimes blood streaks in the expectorated mucus and

froth, and, if the congestion is considerable, some edema of the

posterior part of the lungs, if the patient is in bed. Sooner or

later during this failing compensation the right ventricle becomes

dilated, and the symptoms of cardiac insufficiency and venous

congestion occur, as described above with mitral insufficiency.

Again, as in mitral insufficiency, if compensation is restored in

mitral stenosis, these symptoms are improved. These patients,

however, are never quite free from dyspnea on exertion. Any

inflammation of the lungs, even a severe bronchitis, is more or less

serious for the patients and their hearts. The mucous membrane of

their bronchial tubes and air vesicles is always hyperemic, and it

takes little more congestion to all but close up some of the

passages. and dyspnea or asthma, or suffocating, difficult cough is

the consequence.