The relative high morbidity and mortality of mitral valve replacement (MVR) appears to be related to an impairment in left ventricular (LV) function. This two-part investigation was designed to assess the effect of MVR on global LV function in an isolated heart preparation and to evaluate whether a mitral prosthesis with a flexible annulus would be of benefit. In part I (14 pigs), the effects of each step in MVR were studied. Division of the chordae tendinae caused a severe deterioration in LV function (systolic pressure, 180 ± 13 versus 120 ± 10 mm Hg; p < 0.05; developed pressure, 167 ± 13 versus 108 ± 11 mm Hg; p < 0.05; first derivative of LV pressure [dP/dt], 2,630 ± 300 versus 1,610 ± 180 mm Hg/sec; p < 0.05; balloon volume, 30 ml). Fixation of the mitral annulus prior to division of the chordae tendineae resulted in a small decrease (no significant) in LV function but had no effect after the chordae tendineae were divided. In Part II (10 pigs), two mitral annular prostheses were studied: a standard rigid prosthesis and a prosthesis of identical size but with a flexible annulus. LV function was better with the flexible than the right prosthesis (systolic presure, 118 ± 10 versus 89 ± 5% control, p < 0.02; developed pressure, 120 ± 11 versus 87 ± 5% control; p < 0.02; dP/dt, 119 ± 10 versus 85 ± 4% control; p < 0.02; balloon volume, 30 ml). These results demonstrate that MVR causes a profound deterioration in LV function, a deterioration primarily due to division of the chordae tendineae. Fixation of the mitral annulus with a rigid prosthesis may also be an important cause of LV dysfunction.
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Cardiology and Cardiovascular Medicine