Résumé
We studied 7 patients before and after mitral valve replacement (MVR) for chronic mitral regurgitation (MR) and 5 control subjects by echocardiography and right heart catheterization to assess left ventricular function, hemodynamics and plasma catecholamine concentrations during supine bicycle exercise. Left ventricular (LV) end-systolic dimension decreased and LV systolic function increased significantly during exercise in patients and control subjects. LV systolic function (fractional shortening and mean velocity of circumferential fiber shortening) was significantly lower in patients after MVR than before MVR (p < 0.05). Cardiac index at peak exercise was significantly higher in patients after MVR than before MVR (p < 0.05). Significantly greater augmentation in plasma norepinephrine (NE) levels were observed during exercise in patients both before and after MVR than in control subjects (p < 0.05). No significant differences in mean pulmonary artery pressure (PAP) and pulmonary capillary wedge pressure (PCWP) were observed between the patients before and after MVR. Thus, it is concluded that LV systolic and pump function (CI) during exercise were augmented by a compensatory activation of sympathetic nervous system in patients both before and after MVR for chronic MR.