a u s c u l t a t i o n    t u t o r
Aortic Regurgitation

An early diastolic murmur (lower pitched and shorter than in chronic
aortic regurgitation) may be present. An Austin-Flint murmur, which is
caused by the regurgitant flow causing vibration of the mitral
apparatus, is lower pitched and short in duration. The decrescendo
diastolic murmur is heard best with the patient leaning forward in full
expiration in a quiet room. It is the cardiac murmur most commonly
missed.

Aortic regurgitation is diagnosed by Doppler - most efficiently by Color
Doppler Imaging. The regurgitant jet occurs during diastole toward the
left ventricular cavity. From the 4 chamber or apical views, the color
signal is primarily displayed as red-yellow, since its direction is toward
the transducer and the jet can be distinguished from the mitral
diastolic inflow.

The long axis view can show the difference between mild
regurgitation, which has a narrow base and short jet, compared to
severe with broad base and long jet extent. The force in the latter may
show presystolic closure on M-mode tracing.

Incompetent closure of the aortic valve can result from intrinsic
disease of the cusp, diseases of the aorta, or trauma. Aortic
regurgitation may be a chronic disease process or it may occur
acutely, presenting as heart failure. The most common cause of
chronic aortic regurgitation used to be rheumatic heart disease, but
presently it is most commonly bacterial endocarditis. In developed
countries, it is caused by dilatation of the ascending aorta (eg, aortic
root disease, aortoannular ectasia).

Diastolic reflux through the aortic valve can lead to left ventricular
volume overload. The severity of the aortic regurgitation is dependent
on the diastolic valve area, the diastolic pressure gradient between the
aorta and left ventricle, and the duration of diastole. An increase in
systolic stroke volume and low diastolic aortic pressure produces an
increased pulse pressure.
t h e     h e a r t
Normal Cardiac Cycle
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