Acute Aortic Regurgitation

Sudden development of retrograde blood flow through an incompetent aortic valve into the left ventricle during ventricular diastole.

Trauma, infective endocarditis, or aortic dissection may cause acute aortic regurgitation.

Symptoms and Signs

Frequently, patients present with acute severe pulmonary edema and tachycardia; often, hypotension also occurs. Heart failure is precipitated by abrupt ventricular volume overload within a noncompliant left ventricle and pericardial sac; compensatory hypertrophy or dilation does not have time to occur. Because myocardial oxygen demand increases and subendocardial coronary blood flow decreases, myocardial ischemia and its complications, including sudden death, may occur early in the course of the disorder.

The carotid pulse has a collapsing quality, like that of the left ventricle pressure curve, because of rapid runoff back into the left ventricle. In acute aortic regurgitation compared with the chronic form, the collapsing quality is less pronounced, aortic diastolic pressure cannot decrease as low (because of the rapid elevation of left ventricular filling pressure), and systolic pressure does not increase as much (because of the smaller stroke volume). Therefore, pulse pressure is not as wide, and many of the peripheral signs of severe chronic aortic regurgitation are absent.

The rapid increase in left ventricular filling pressure causes the mitral valve to close late in diastole, making the first heart sound soft. Because pressure in the aorta and left ventricle equilibrates early in diastole, the diastolic murmur along the left sternal border can be harsh and short. In patients with tachycardia and a short diastole, the diastolic murmur can be so short that it is difficult to hear, or it may be absent.

Diagnosis and Treatment

Acute aortic regurgitation should be considered in patients with acute heart failure or pulmonary edema. Echocardiography helps confirm the diagnosis. The ECG may be normal initially. Echocardiography often shows early mitral valve closure.

Acute aortic regurgitation must be differentiated from other causes of acute severe heart failure (eg, myocardial infarction with papillary muscle, chordal, or septal rupture). Pulmonary edema may be erroneously attributed to myocardial infarction because the heart is not enlarged, the wide pulse pressure may be absent, and the murmur may not be detected. Doppler echocardiography and ECG are the most helpful procedures in differential diagnosis.

If the cause is aortic dissection involving the ascending aorta, urgent aortic valve replacement or resuspension of the valve is indicated. For all patients who have signs of acute aortic regurgitation due to other etiologies, even those who do not have obvious pulmonary edema, urgent aortic valve replacement should be performed because clinical deterioration of these patients is rapid and sudden death is possible. If the cause is infective endocarditis, appropriate antibiotics should be given for 12 to 24 hours before aortic valve replacement.