Cardiopulmonary Dynamics in Patients with Anastomosis of the Superior Vena Cava to the Right Pulmonary Artery

The cardiopulmonary dynamics of the circulation through the right lung were studied in six patients with severe cyanotic congenital heart disease who had undergone surgery with anastomosis of the superior vena cava to the right pulmonary artery. Pressure gradients across the right lung varied with respiratory changes in a way opposite from normal in that increasing intrathoracic pressure was associated with increased pressure gradients across the right lung. Radiocardiographic and cinefluorographic studies indicated that periods of changing intrathoracic pressure (spontaneous breathing and intermittent positive-pressure respiration) augmented flow, whereas absence of respiratory motion or sustained increased intrathoracic pressure (Valsalva maneuver) impeded flow through the right lung. The diminution of flow through the right lung during periods of sustained increased intrathoracic pressure occurred in the presence of an increased pressure gradient between the right pulmonary artery and left atrium.