Effect of isometric exercise on cardiac performance and mitral regurgitation in patients with severe congestive heart failure

Left ventricular performance was studied during isometric exercise in 17 patients with severe congestive heart failure, combining invasive hemodynamic and echo-Doppler techniques. Isometric exercise at 30% of maximum resulted in a decrease in stroke volume index (27.4 ± 7.1 to 22.7 ± 7.4 ml/m²), with a significant increase in heart rate from 81 ± 10 to 92 ± 14 beats/min and in systemic vascular resistance from 1827 ± 527 to 2372 ± 737 dyne · sec · cm^-5. A significant rise in pulmonary capillary wedge pressure (18 ± 9 to 31 ± 10 mm Hg) was associated with a marked increase in mitral regurgitant volume (14 ± 11 to 27 ± 15 ml), calculated as the difference between total stroke volume obtained by two-dimensional echocardiography and forward stroke volume measured by pulsed Doppler at the aortic anulus. During isometric exercise, left ventricular end-diastolic and end-systolic volumes did not change markedly, but the total stroke volume tended to increase from 62 ± 13 to 67 ± 13 ml. The increase in mitral regurgitant volume induced by isometric exercise was correlated with the fall in forward stroke volume (r = 0.7, p < 0.01). Thus a rise in systemic arterial pressure induced by isometric exercise is associated with a decrease in cardiac performance attributable to redistribution of total left ventricular output with an increase in mitral regurgitation and a simultaneous decrease in forward cardiac output.