Pulmonary versus systemic hemodynamics in determining exercise capacity of patients with chronic left ventricular failure

Abstract

Right, but not left ventricular ejection fraction correlates with exercise capacity in patients with left ventricular failure, suggesting an important role of the pulmonary circulation. Hemodynamics were measured at rest and during bicycle exercise to symptomatic maximum in 41 patients with chronic left ventricular failure. Maximal oxygen consumption averaged only 12.8 +/- 5.2 ml/min/kg. Pulmonary wedge pressure rose from 21.9 +/- 8.2 to 35.9 +/- 9.3 mm Hg during exercise, while pulmonary arterial mean pressure rose from 31.8 +/- 10.9 to 50.4 +/- 12.9 mm Hg (both p less than 0.0001). Resting cardiac index and resting systemic arterial mean pressure did not correlate with maximal oxygen consumption (r = 0.23 and 0.20, respectively), which, however, did correlate with pulmonary wedge pressure (r = -0.54, p less than 0.001), pulmonary arterial mean pressure (r = -0.49, p less than 0.01), and total pulmonary resistance (r = -0.43, p less than 0.01). Maximal oxygen consumption did not correlate with resting systemic vascular resistance (r = -0.20) or resting pulmonary vascular resistance (r = -0.26). During exercise, total pulmonary resistance remained unchanged at 6.5 +/- 3.8 U while systemic vascular resistance fell significantly. The relation between total pulmonary resistance and exercise capacity and the failure of total pulmonary resistance to fall during exercise suggest that afterload on the right ventricle may be an important determinant of exercise capacity in patients with chronic left ventricular failure.