Effects of Aortic Regurgitation on Left Ventricular Performance

Abstract

The volume of regurgitant blood flow and its effects on the performance of the left ventricle were assessed at operation in 14 patients with varying degrees of aortic regurgitation. Instantaneous forward and regurgitant flows in the ascending aorta were measured with a sine-wave electromagnetic flowmeter simultaneously with left ventricular and aortic pressures. In eight patients who had aortic regurgitation without associated stenosis, 63 to 75% of the total forward stroke volume regurgitated during the succeeding diastole. The calculated regurgitant orifice areas ranged from 0.13 to 0.44 cm 2 /m 2 . After replacement of the aortic valve with a Starr-Edwards prosthesis, the absence of regurgitant flow was proved in every patient, and the records of aortic blood flow closely resembled those seen in patients with normal aortic valves. Net forward blood flow increased by an average of 60%, total left ventricular stroke volume fell 42%, and the mean aortic pressure rose 29%. The pressure work of the left ventricle was elevated preoperatively in five of the eight patients (average 89 g-m/stroke/m 2 ) and fell significantly to an average of 34 g-m/stroke/m 2 after valve replacement. Kinetic ventricular work was high in seven of the eight patients and comprised 10% of total work before replacement but only 4.8% afterward. Similar observations were made in five patients with aortic stenosis and associated aortic regurgitation, ranging in severity from 24 to 72% of total forward stroke volume. In four patients in whom the valve was replaced, no residual regurgitation was present afterward, and net forward flow rose an average of 49%. Kinetic left ventricular work was extremely high in every patient and averaged 26% of total work preoperatively and 13% after valve replacement. In this group, pressure work was variable both before and after operation. The studies described provide definitive information concerning the effects of aortic valve disease on left ventricular performance in man and document the favorable changes in flow, pressure, and left ventricular work which immediately follow aortic valve replacement.