Hemodynamic evaluation of the Ionescu-Shiley pericardial xenograft in the mitral position.

Hemodynamic studies were performed in 27 patients at a mean interval of 40.3 (range 24 to 59) months following mitral valve replacement with pericardial xenografts. Six patients had sequential studies, one before operation and two separate investigations at mean intervals of 11.2 and 42.8 months following valve replacement. The results showed significant increase in cardiac index, reduction in mean pulmonary artery and wedge pressures, and decrease in pulmonary vascular resistance both at rest and during exercise, when compared with the preoperative values. The mean diastolic gradient across the pericardial xenografts was 6.4 mm. Hg at rest and 15.3 mm. Hg during exercise. The calculated xenograft surface area was 2.0 and 2.3 cm.2, respectively. The sequential studies established that the maximum hemodynamic improvement was achieved within the first year following valve replacement and that the functional performance of the xenografts was maintained, unaltered, with the passage of time.