Adverse influence of baroreceptor dysfunction on upright exercise in congestive heart failure.

To test the hypothesis that baroreceptor autoregulation is an important determinant of exercise performance, the hemodynamic responses to the gravitational stress of head-up tilt and upright exercise were assessed in 41 patients with severe chronic congestive heart failure. Three patterns of autonomic dysfunction during head-up tilt were identified. Group A patients had near-normal circulatory reflexes whereas Group B patients experienced orthostatic hypotension and Group C patients lacked the afferent stimulus of venous pooling. Group A patients had a significantly longer exercise duration than both Groups B and C (607 +/- 104 versus 330 +/- 86 and 365 +/- 53 seconds, respectively, p less than 0.05) and a significantly higher double product at peak exercise (17,779 +/- 956 versus 12,235 +/- 869 and 13,760 +/- 998, respectively, p less than 0.05). Thus, baroreceptor abnormalities in the autoregulatory response to postural change are important determinants of the cardiovascular responses required during exercise and influence exercise performance. These abnormalities may help clarify the discrepancies between supine and upright exercise performance and may influence the long-term efficacy of vasodilator therapy in chronic congestive heart failure.