Functional Importance of Left Ventricular Long Axis Movement in Mitral Valvular Heart Disease

ABSTRACT

BACKGROUND: The effective ventricular function during ejection and filling is likely to depend on the coordinated action of the longitudinally and circumferentially orientated myocardial fibers and the function of these longitudinal fibers has not been extensively studied. METHODS: The role of longitudinally and circumferentially orientated fibers in left ventricular wall motion was evaluated by M-mode echocardiograms of the mitral ring(whose motion reflect long axis change) and the standard minor axis(left ventricular posterior wall), simultaneous recordings of phonocardiograms and electrocardiograms on the paper (speed 100mm/sec), in 24 healty individuals, 17 patients with mitral stenosis, 11 patients with open mitral commissurotomy and 17 mitral valve replaced patients. RESULTS: In the controls long axis shortening significantly preceded minor axis shortening (phase difference between two axes : 20+/-3 msec, mean+/-SEM) during early systole, indicating left ventricle become more spherical. This phase difference was also observed in the patients with mitral stenosis and in those with open mitral commissurotomy. In patients with mitral valve replacement(MVR) whose papillary muscles had been sectioned, the onset of long axis shortening was more delayed during early systole than that of short axis(-33+/-6msec) and the end of shortening was also prolonged to early diastole more than that of normal controls (54+/-3 msec vs 90+/-8 msec, mean+/-SEM, p<0.01 by t-test). CONCLUSION: We observed the time relations between long and short axis motion in normal controls. It can be concluded that the reversed time relation in patients with MVR is one of the important factors which may effect negatively on ventricular function and long-term prognosis, thus the surgical procedures to preserve papillary annular continuity should be considered in patients with mitral valvular disease. And the controlled, prospective, clinical trials with homogenous groups of patients are needed to evaluate the potential benefits of papillary annular continuity in preserving atrio-ventricular interaction in patients undergoing mitral valvular surgery.