Q. What is Acute Aortic Regurgitation?
Infective endocarditis, aortic dissection and trauma often produce severe AR. Acute increase in left ventricular end diastolic volume especially in a small pressure loaded hypertrophied heart increases left ventricular diastolic pressure and causes pulmonary edema. In the absence of compensatory mechanisms forward stroke volume is markedly decreased and patient develops cardiogenic shock. Tachycardia ensues and pulse pressure is low due to low cardiac output. In such a sick patient physical findings are difficult to appreciate. First sound is muffled. Early diastolic murmur is short and soft. Apical diastolic rumble may be present. There are no peripheral signs of chronic severe AR. Physical examination and Chest X-ray do not show any cardiomegaly.
Echocardiogram clinches the diagnosis. Severity and mechanism of AR and associated lesions will be known. Typically acute Severe AR causes short pressure half time of aortic regurgitant jet < 300 m sec., short deceleration time of early mitral filling wave < 150 m sec. and premature closure of mitral valve.
Acute severe AR is a surgical emergency. Pre-operatively patient may be stabilized with inotropes and vasodilatation like nitroprusside. IABP and beta blockers are contraindicated. Disease as well as treatment is associated with high mortality.