Difference between the response of the pulmonary and systemic circulation during exercise in congestive heart failure.

Thirty nine patients with cardiomyopathy were evaluated by a hemodynamic study at rest and during isotonic exercise. These patients were divided into two groups on the basis of their left ventricular ejection fraction (LVEF): A, control group (LVEF greater than 40%, N = 19); B, severe congestive heart failure group (LVEF less than or equal to 40%, N = 20). Patients in group A showed adequate cardiovascular responses to exercise, i.e. increased cardiac index (80%) and stroke volume index (17%), decreased systemic vascular resistance (36.8%) but no significant change in pulmonary arteriolar resistance values. In contrast, patients in group B showed a slight and heart rate-dependent increase in cardiac index (38.5%), no improvement of stroke volume index (-3.4%), decreased systemic vascular resistance (21.6%) and increased pulmonary arteriolar resistance (41.2%) with exercise. This group also showed a significant increase in right atrial pressure that might reflect a decrease in right ventricular performance secondary to an abnormal pulmonary vascular response during exercise.