EFFECTS OF VALVE-REPLACEMENT ON VENTRICULAR MECHANICS IN MITRAL REGURGITATION AND AORTIC-STENOSIS

Background. This study in humans assessed changes in left ventricular function early and late after correction of mitral regurgitation (MR) (n = 9) or aortic stenosis (AS) (n = 10). Methods. Ventricular functio n was measured with radionuclide and micromanometer-derived pressure-v olume loops during preload manipulation, thermodilution cardiac output s, and echocardiograms. Late radionuclide and echocardiographic data w ere acquired at 24 hours and 20 months. Results. Perioperative left ve ntricular performance (stroke work-end-diastolic volume relationship) did not change for patients with MR or AS. Significant changes in afte rload occurred: ejection fraction (MR, 0.49 to 0.37; AS, 0.54 to 0.60; both, p = 0.013), mean left ventricular ejection pressure (MR, 73 to 91 mm Hg; AS, 138 to 93 mm Hg; both, p < 0.01), and end-systolic wall stress (MR, 26 to 42 x 10(3) dynes/cm(2); AS, 37 to 22 x 10(3) dynes/c m(2); both, p < 0.01). Ejection efficiency improved for MR patients (0 .69 +/- 0.26 to 1.0 +/- 0.15; p < 0.05). The 20-month data showed impr oved New York Heart Association functional class, normal resting eject ion fraction, and normal exercise response for both groups. Conclusion s. Early after operation, a significant change in left ventricular loa d was seen with correction of MR and AS. Data obtained late after oper ation showed improvement consistent with ventricular remodeling.