Recognition and Treatment of Acute Aortic Regurgitation

Abstract

Acute aortic regurgitation usually results from infective endocarditis, but is also caused by aortic dissection and trauma to the heart. Most of the left ventricular stroke volume is regurgitated back into the left ventricle; thus, the forward stroke volume to the body and the cardiac output may be severely compromised. An acute increase in left ventricular end-diastolic volume results in a marked increase in left ventricular end-diastolic pressure, and the mitral valve usually closes prematurely. Compensatory tachycardia is the rule and helps to shorten diastole; thus, the time available for aortic regurgitation to occur is reduced, and the cardiac output is often maintained. On physical examination, there is tachycardia; the peripheral arterial pulse shows a rapid rise, but the systolic pressure is normal; the diastolic pressure is normal or even reduced; and the pulse pressure is often normal. The electrocardiogram (ECG) may be normal except for sinus tachycardia and often for nonspecific ST-T changes. The chest roentgenogram usually shows signs of pulmonary venous hypertension or even pulmonary edema. Echocardiography may show vegetations on the aortic valve, prolapse of an aortic leaflet into the left ventricle, and premature mitral valve closure. Doppler echocardiography is useful in detecting the presence of aortic regurgitation. In cases of infective endocarditis, the appropriate antibiotic therapy must be given. Aortic regurgitation due to dissection of the aorta is usually an indication for surgery. In patients with severe aortic regurgitation, available medical therapy includes digitalis, diuretics, and vasodilators. When patients respond dramatically to the use of digitalis, diuretics, and arterial dilators, surgical therapy can be delayed until heart failure and infection are controlled and the patient is more stable. If the patient does not respond immediately and dramatically to therapy, then valve replacement should not be delayed, even if the infection is uncontrolled or the patient has had little antibiotic therapy.