[Myocardial structure and left ventricular function in aortic valvular diseases].

In this study 13 patients with aortic stenosis (AS) and 19 patients with aortic regurgitation (AR) were analyzed to investigate the correlation between myocardial structure and left ventricular (LV) function. LV end-diastolic dimension (Dd), LV end-systolic dimension (Ds), LV Mass Index (LVMI), FS, mVcf and the normalized rate of change of LV dimensions during systole and diastole (-V/Dd, +V/Dd) were assessed using M-mode echocardiography before and after aortic valve replacement. The myocardial structures were investigated from the biopsied specimen in the operation using both light and electron microscopes. Then muscle fiber diameter (Diameter), the degree of interstitial fibrosis (%Fibrosis) and the myocyte volume fraction (%MF, %MT, %SA) were quantitatively evaluated by using a computerized system. And semi-quantitative analysis was made with electron microscopic score (EM-score). The results were as follows. 1. AS group: Left ventricular myocardial degeneration was mild. Significant positive correlationships were found between preoperative LVMI and Diameter (p < 0.01), and between the former and the volume fraction of the myofibrils (%MF) (p < 0.05). And significant positive correlationship was seen between Diameter and %MF (p < 0.05). However, no significant correlationship was seen between preoperative LVMI and %Fibrosis. Both LV systolic and diastolic function (-V/Dd, +V/Dd) showed significantly negative correlationship to LVMI preoperatively (p < 0.01, p < 0.05) and postoperatively (p < 0.05, p < 0.05). And in the patients with preoperative LVMI larger than 300 g/m2 and Diameter larger than 30 microns, +V/Dd was irreversible postoperatively. 2. AR group: EM-score in AR was significantly higher than that in AS (p < 0.05). Preoperative LVMI showed significantly positive correlationship to %Fibrosis (p < 0.01). And postoperative LVMI showed significantly positive correlationship to fibrous content (p < 0.01). Both LV systolic and diastolic function -V/Dd, +V/Dd) showed significantly negative correlationship to LVMI preoperatively (p < 0.05, p < 0.01) and postoperatively (p < 0.01, p < 0.01). And in the patients with preoperative LVMI larger than 300 g/m2 and %Fibrosis larger than 16%, both -V/Dd and +V/Dd were irreversible postoperatively. The above mentioned results indicated that preoperative LVMI and the morphologic parameters were useful to predict the reversibility of the postoperative LV function in both AS and AR.