Hemodynamic Response to Discoid Mitral Valve Replacement

Hemodynamic studies were performed before and daily for 7 to 10 days after mitral valve replacement with a discoid prosthesis in 15 patients. Left atrial mean pressure fell from a mean of 27.5 mm Hg before surgery to normal levels (mean 11 mm Hg) within 24 hours of surgery. Cardiac index reached normal levels (mean 2.97 L/min/m 2 ) within 48 hours of valve replacement, and remained in the normal range throughout the early postoperative period in 12 of the 15 patients. The association of normal left atrial pressure and cardiac output in response to the increased metabolic demands of the postoperative period has not been reported with caged-ball mitral valve replacement. Pulmonary artery mean pressure and pulmonary vascular resistance showed a sharp decrease toward normal in the early postoperative period. In seven patients with systemic pulmonary hypertension, pulmonary artery mean pressure decreased from 72 mm Hg before surgery to 38 mm Hg at 7 to 10 days. The observed hemodynamic findings in these patients are consistent with experimental evidence that discoid mitral prostheses offer less resistance to blood flow than caged-ball mitral prostheses.