MIXED AORTIC VALVE LESION

SALIENT FEATURES

· Pulse may be bisferious, small volume or large volume, depending on the dominant lesion.

· Displaced apex beat (remember, a small left ventricle is inconsistent with chronic severe AR).

· Early diastolic murmur of aortic regurgitation.

· Ejection systolic murmur of aortic stenosis.

Proceed as follows:

Tell the examiner that you would like to check the blood pressure, in particular to determine the pulse

pressure (systolic minus diastolic pressure).

DIAGNOSIS

This patient has mixed aortic stenosis with aortic regurgitation (lesion) due to rheumatic heart disease

(aetiology). He has a dominant stenosis and is in cardiac failure (functional status).

Note

In dominant aortic stenosis:

· Pulse volume is small.

. Blood pressure is normal and pulse pressure is narrow.

In dominant aortic regurgitation:

· Pulse is collapsing.

· Pulse pressure is wide.

QUESTIONS

What are common causes of mixed aortic lesions?

· Rheumatic heart disease.

· Bicuspid aortic valve.

What is the pathophysiology of mixed aortic valve disease?

· In mixed aortic valve disease, one lesion usually predominates over the other and the

pathophysiology resembles that of the pure dominant lesion. When aortic stenosis predominates, the

pathophysiology and, therefore, the management resembles that of pure aortic stenosis (J Am Coil

Cardiol 1998; 32: 1486-588). TheLV in these patients develops concentric hypertrophy rather than

dilatation. The timing of aortic valve replacement (as in pure aortic stenosis) depends on symptoms

(Circulation 1998; 98: 1949-84).

· When AR is more than mild and the AS is predominant, the concentrically hypertrophied and

non-compliant left ventricle is on the steeper portion of the diastolic pressure-volume curve, resulting in

pulmonary congestion. Theretore, although neither lesion by itself is sufficiently severe to merit surgery,

both together produce substantial haemodynamic compromise and require surgery (Circulation 1998; 98:

1949-84).

· When the AR is severe and the AS is mild, the high total stroke volume from extensive regurgitation

may produce a substantial transvalvular gradient. Because the transvalvular gradient varies with the

square of the transvalvular flow (Am Heart J 1951; 41: 1-29), a high gradient in predominant regurgitation

may be predicted primarily on excess transvalvular flow rather than on a severely com-promised orifice

area (Circulation 1998; 98: 1949-84).

In mixed aortic valve disease is cardiac catheterization more accurate than Doppler

echocardiography to measure valve area?

Aortic valve area will be measured inaccurately at the time of cardiac catheteriz-ation in mixed aortic

valve lesions if the cardiac output is measured either by the Fick or the thermodilution method as both

these methods usually underestimate total valve flow. The valve area can be measured more accurately

using Doppler echocardiography (by continuity equation) in mixed aortic stenosis and aortic regurgitation.

However, the confusing nature of mixed valve disease makes cardiac catheterization necessary to obtain

additional haemodynamic information in most patients (including coronary anatomy) (Circulation 1998;

98:1949 84).

How would you manage such a patient?

· Surgical correction of disease that produces more than mild symptoms.

· When the AS is dominant: operate in the presence of even mild symptoms.

· When the AR is dominant: surgery can be delayed until symptoms develop or asymptomatic

LVdysfunction becomes apparent on echocardiography.