We have completed the evaluation of a patient with acute mitral regurgitation. Before moving on to the laboratory findings and the hospital course of our patient, it is important to remember that the sudden onset of pulmonary edema also can be caused by another acute valve condition: acute aortic regurgitation.
Acute aortic regurgitation
Acute aortic regurgitation shares many similarities with acute mitral regurgitation. In both, there is a sudden onset of symptoms. In patients with acute AR, the normal size left ventricle is suddenly confronted with an overwhelming increase in blood volume during diastole. The sudden volume overload into a left ventricle that has not had time to dilate and alter its compliance characteristics, they result in a marked increase in left ventricular diastolic pressure and acute pulmonary edema. The early equalization of aortic and left ventricular diastolic pressures causes the diastolic murmur of acute AR to be short.
Acute AR pressure curves
These simultaneous left ventricular and aortic pressure curves illustrate the relationship of the hemodynamic events to the timing and contour of the diastolic murmur in acute and chronic aortic regurgitation. The configuration of the murmur in aortic regurgitation is the result of the compliance characteristics of the left ventricle. In acute aortic regurgitation, the left ventricle is near normal sized with relatively normal compliance. The regurgitant jet, therefore, causes left ventricular diastolic pressure to rise rapidly, quickly approaching the aortic root diastolic pressure. This limits the regurgitant volume. The decrescendo diastolic murmur, therefore, is relatively short in duration and often mid frequency. In chronic aortic regurgitation, the large left ventricle is more compliant. The regurgitation volume, therefore, is greater, but causes only a modest increase in left ventricular diastolic pressure. The high frequency murmur begins with aortic closure and continues throughout most of diastole, as the gradient between the aortic root and left ventricle remain high throughout this period.