EXPLORING BETTER METHODS TO PRESERVE THE CHORDAE TENDINEAE DURING MITRAL-VALVE REPLACEMENT

Background. It is not known how best to resuspend the mitral chordae t endineae during mitral valve replacement to optimize postoperative lef t ventricular (LV) systolic and diastolic function. Methods. Six diffe rent techniques to preserve the chordae during mitral valve replacemen t were compared in 12 dogs using a nondistorting isovolumic technique: conventional, all chordae severed; anterior, all chordae preserved an teriorly; partial, anterior papillary muscle chordae preserved anterio rly; posterior, all chordae preserved posteriorly; oblique, anterior p apillary muscle chordae directed anteriorly and posterior papillary mu scle chordae posteriorly; and counter, opposite of oblique chordal dir ection. Control measurements (no chordal tension) were recorded betwee n each experimental condition. Results. The oblique method tended to h ave the best LV systolic function versus the conventional method (E(ma x) = 4.0 +/- 1.8 versus 3.3 +/- 1.2 mm Hg/mL [mean +/- standard deviat ion]; p = 0.08 by repeated-measures analysis of variance; physiologic intercept E(es100) = 20.3 +/- 8.6 mL [p < 0.05 versus control]), with no major change in LV diastolic stiffness. The posterior method had a lower E(max) (3.3 +/- 1.2 mm Hg/mL) than the oblique method, but a sim ilar E(es100) (20.8 +/- 8.1 mL; p < 0.05 versus control) and the best diastolic LV performance (LV diastolic stiffness = 0.46 +/- 0.23 mm Hg /mL). The counter method also had good systolic function (E(max) = 3.8 +/- 1.2 mm Hg/mL; E(es100) = 19.7 +/- 7.5 mL; p < 0.05 versus control ), but had less favorable diastolic properties (0.65 +/- 0.37 mm Hg/mL ; p < 0.05 by repeated-measures analysis of variance versus posterior) . Conclusions. In this isovolumic preparation in normal canine hearts, the oblique method of chordal resuspension was associated with the be st LV systolic function, whereas the counter technique impaired LV dia stolic function. These preliminary results warrant further study in ej ecting and failing hearts to determine conclusively which chordal orie ntation best preserves LV performance after mitral valve replacement.