Left Ventricular Performance Following Correction of Free Aortic Regurgitation

Abstract

Left ventricular (LV) myocardial contractility, or inotropic state, was characterized in terms of the instantaneous relations between velocity of circumferential fiber shortening (V CF ), determined cineangiographically, and LV wall tension (hoop stress), calculated from LV dimensions and pressure, in five patients before and 7 to 10 mo after aortic valve replacement for free aortic regurgitation. Preoperatively the cardiac index was reduced or the LV end-diastolic pressure was markedly increased (or both occurred) in four patients, in each of whom depression of inotropic state was documented by a reduced V CF at maximum wall tension, ranging from 0.13 to 1.07 circumferences (circ)/sec (normal, > 1.40 circ/sec) at wall tensions of 318 to 464 g/cm 2 (normal, 178 to 417 g/cm 2 ). In one patient in whom LV end-diastolic pressure and cardiac index were normal preoperatively, V CF was 1.66 circ/sec at a maximum tension of 440 g/cm 2 . Following operation, LV end-diastolic pressure fell in the four patients with depressed inotropic state (average decrease, 23 mm Hg) and cardiac index increased (average increase, 0.93 L/min/m 2 ). However, no change in the tension-velocity relation was observed postoperatively, V CF ranging from 0.27 to 1.14 circ/sec in these patients, indicating that no change had occurred in the inotropic state. In addition, a fixed abnormality in diastolic LV pressure-volume characteristics, determined from preoperative and postoperative measurements of pressure and radius during diastole, had occurred in patients with depressed myocardial function. In contrast, in the patient with normal myocardial function, LV end-diastolic radius was reduced by 33% postoperatively while end-diastolic pressure was unchanged, suggesting reversal of stress relaxation, or creep, following relief of volume overload.