Aortic Stenosis
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Disturbances Of The Heart
Aortic narrowing or stenosis is a frequent occurrence in the aged
and in arteriosclerosis when the aorta is involved. It is not a
frequent single lesion in the young. If it occurs in children or
young adults, it is likely to be combined with aortic regurgitation,
meaning that the valve hay been seriously injured by an
endocarditis.
The first effect of this narrowing is to cause hypertrophy of the
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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.