Importance of the mitral complex in left ventricular contraction--an analysis of the results of mitral valve replacement with preservation of the posterior mitral complex.

The importance of the mitral complex in left ventricular contraction was studied in seventy-five patients who underwent mitral valve replacement (MVR) with preservation of the posterior mitral complex (modified MVR:mMVR), and in one hundred and twenty-two patients who had conventional mitral valve replacement (cMVR). Mechanical heart valves (Medtronic Hall or St. Jude Medical valves) were used in MVR. Patients after mMVR showed lower left atrial pressures, higher left ventricular stroke work indexes, and better left ventricular function curve using less catecholamines than those after cMVR during the initial 24 hours following cardiopulmonary bypass. M-mode echocardiographic analysis revealed that the sequential apex-to-base contraction of the ventricular wall was better preserved after mMVR than after cMVR. This tendency was more prominent in mitral regurgitation (MR) than in mitral stenosis (MS) patients. Echocardiographic analysis revealed that the posterior mid left ventricular segment began to contract and reached maximal contraction earlier than the basal segment in patients before and after mMVR. After cMVR, this tendency was less noticeable, and the contraction processed and peaked almost simultaneously in all segments. The mitral complex plays an important role in left ventricular contraction, and modified MVR can be said to be an excellent procedure for preserving left ventricular function.