Hemodynamic and Ventilatory Effects of Exercise in the Upright Position in Patients with Left-to-Right Shunts

Abstract

Nine patients having ventricular septal defect or patent ductus arteriosus performed bicycle exercise of moderate intensity in the upright position while oxygen consumption and pulmonary and systemic blood flows and pressures were being measured. Resting pulmonary vascular resistance (PVR) was normal in five patients and elevated in four. Right-to-left shunt became apparent or increased during exercise in patients with elevated PVR. The rise of pulmonary "wedge" pressure and of right atrial pressure during exercise was not related to the resting PVR. Both ventilation and pulmonary artery pressure increased more rapidly during exercise in patients with high PVR than in the normal PVR group. Left atrial blood remained fully saturated during exertion in three patients with high PVR and arterial oxygen unsaturation.