Regional differences in pulmonary vascular resistance in the same patient. A study of partial anomalous pulmonary venous return, intact atrial septum, and mitral stenosis before and after surgical correction.

Using hemodynamic and radionuclide perfusion data, we measured regional pulmonary vascular resistances in a patient with mitral stenosis and anomalous pulmonary venous drainage with intact atrial septum before and after surgical correction. Pulmonary vascular resistance in the right upper lung region that had anomalous drainage to a normal-pressure right atrium was compared to resistance of a region in the left upper lung similar in size that had normal drainage to a high-pressure left atrium. Preoperatively, pulmonary vascular resistance in both regions was elevated but was considerably higher in the left upper lung region. Postoperatively, pulmonary vascular resistance fell substantially in the left upper lung with the fall in left atrial pressure, whereas it changed minimally in the right upper lung after elimination of the left-to right shunt. These findings are related to vascular abnormalities on biopsies obtained from both regions.