EXTRACARDIAC ADJUSTMENT OF MITRAL CHORDAE REPLACEMENT

This study was designed to determine the feasibility of completing mit ral chord repair externally when the heart was weaned from bypass. Ten anesthetized dogs (22.9 +/- 4.6 kg) were placed on cardiopulmonary by pass through a left thoracotomy. The left atrium was opened and one or two marginal chords of the anterior mitral leaflet mere divided. A do uble-armed 2-O polypropylene suture was placed in the margin of the mi tral leaflet, and both suture ends were brought outside of the ventric le through the anterior papillary muscle, but were not anchored. Produ ction of mitral incompetence was verified when the animals were weaned from bypass. Mean left atrial pressure (LAPm), the v wave of the left atrial pressure (LAPv), systolic billowing of the anterior leaflet in to the left atrium above the mitral closure line (two-dimensional echo cardiography, long axis), and function curves (left atrial-aortic syst olic pressure, LAP(v)-AoSP) were used to determine valve competence an d functionality of the repair. All values are expressed as means +/- S E, Acute mitral incompetence in this model was associated with severe left atrial bulging left atrial billowing of the anterior leaflet (7-1 2 mm, 9.6 +/- 1.6 mm), significantly increased left atrial pressure [L AP(v), 30.5 +/- 5.8; LAPm, 23.6 +/- 4.3 mm Hg; both P < 0.01 vs contro l (10.5 +/- 2.5 and 7.5 +/- 2.7 mm Hg, respectively)], and decreased s ystemic pressure development (AoSP, 84 +/- 8.8 vs 108 +/- 12.3 mm Hg; P < 0.01). The slope of the atrial-systemic pressure curve was decreas ed significantly, shifted to the right and reduced by more than half ( 2.1069 vs 0.9190; P < 0.05). External adjustment of the pledgeted sutu re ends returned all values to within control limits (LAPV, 12.7 +/- 4 .1; LAPm, 9.8 +/- 4.3; AoSP, 104 +/- 10.5; LAP-AoSP slope, 2.0909; all P = n,s.), atrial bulging was not evident, and atrial displacement of the valve leaflet could no longer be visualized. These data suggest t hat mitral chord repair is feasible through a thoracotomy and, more im portantly, final adjustments to obtain optimal chord length can be com pleted externally, guided by changes in dynamic, physiologic parameter s. (C) 1996 Academic Press, Inc.