Aortic Valve Regurgitation

Aortic valve regurgitation (AR) is defined as blood flow from the aorta to the left ventricle in diastole because of an incompetent aortic valve (Fig. 27-17). Aortic valve insufficiency is

generally acquired through valve infection, dilation and dissection of the aortic root, trauma, or long-term degenerative change of the valve, particularly in the setting of hypertension. Patients with a history of prosthetic valves can also have aortic valve insufficiency (Fig. 27-18). Aortic insufficiency can also be caused by a congenital bicuspid aortic valve.

Aortic regurgitation leads to volume overload of the left ventricle and an increase in left ventricular end-diastolic pressure (LVEDP). In chronic AR, symptoms might not appear before LV cavity dilation and reduced LV function develop. In acute AR, a sudden rise of LVEDP occurs because of the inability of the left ventricle to dilate acutely in response to a sudden volume overload. Patients are generally acutely symptomatic with CHF. Patients with severe AR will eventually become symptomatic, displaying symptoms of dyspnea and CHF. Angina is less common but can result from a reduction in coronary perfusion pressure. Physical signs of severe AR include a rapid, quick arterial pulse (Corrigan's pulse), a wide pulse pressure, an early high-pitched, blowing diastolic murmur heard best over the left sternal border, an S3 gallop, and a low-pitched diastolic murmur at the apex (Austin-Flint murmur).

The ECG shows LVH and possibly conduction abnormalities. Echocardiography can help make the diagnosis accurately and also provides information about LV function and cavity size. Other associated valvular abnormalities can also be assessed by the echocardiogram. Aortic root and left atrial sizes can be measured (Zoghbi et al., 2003). Stress testing can provide information about functional capacity and hemodynamic response to exercise. Diagnostic angiography allows the verification of the severity of the AR and helps in the assessment of the aortic root size, cavity size, and the presence or absence of CAD.

The surgical treatment of AR is indicated in symptomatic patients with dyspnea, angina, or CHF (Bonow, 2000). Asymptomatic patients should undergo surgery if LVEF is 55% or less, or left ventricular end-systolic dimension approaches 5.5 cm. Patients with moderate to severe AR should avoid competitive sports, heavy workloads, and weightlifting. Patients with severe AR may benefit from long-acting vasodilators such as nifedipine XL. This treatment before aortic valve replacement may improve postoperative ejection fractions and improve long-term outcomes (Scog-namiglio et al., 2005). Following valve replacement for AR, the use of beta blockers may improve cardiac performance (Matsuyama et al., 2000).

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