Regional pulmonary function in supine patients with mitral valve disease.

Supine tidal volume regional ventilation and perfusion images obtained in the posterior and lateral projections demonstrated several alterations in patients with mitral valve disease. Reversal of the gravitational perfusion gradient correlated with pulmonary venous and arterial hypertension; the supine studies reliably distinguished normal subjects from mitral patients. The reversed gradient was from posterior-base to anterior-apex. Focal defects were common and contributed to the reversed gradient in 50% of patients. Perfusion defects larger than those of ventilation, simulating emboli, occurred in 32%, particularly in the middle lobe and superior segment areas. Relative hypoventilation of the left lung was seen in 44% of these patients.