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[Ultrastructural study of left ventricular myocardium in mitral regurgitation--correlations with postoperative
Abstract:
Light and electron microscopic examination was carried out in tissue samples which were obtained from the left ventricular free wall in 21 patients with mitral regurgitation during open-heart surgery. Their correlations with postoperative cardiac functions were also studied. The area of the interstitial fibrosis (%fib) was calculated from the light microscopic examination of the tissue samples, and changes of intracellular structures were expressed in scores by means of electron microscopy (EM-SCORE). Postoperative hemodynamics were studied with echocardiography before and after exercise. The hemodynamic parameters consisted of SVI, CI, EF, FS, mVcf and percent changes of these parameters before and after exercise. 1. EM-scores correlated with EF, FS and mVcf at rest with correlation coefficient of -0.653, -0.629 and -0.712 respectively and their significant levels were all less than 0.005. They also correlated with EF, FS and mVcf after exercise with correlation coefficient of -0.665 and -0.708 respectively and their significant levels were all less than 0.005. They also correlated with %delta EF, %delta FS and %delta Vcf with correlation coefficient of -0.79, -0.76 and -0.811 respectively and their significant levels were all less than 0.005. 2. Percent fibrosis did not correlated with the hemodynamics at rest. But they correlated with EF, FS after exercise with correlation coefficient of -0.577 and -0.599 respectively and their significant level reached less than 0.01. They also correlated with %delta EF, %delta FS and %delta mVcf with correlation coefficient of -0.584, -0.599 and -0.571 respectively and their significant levels were all less than 0.01. 3. There were no correlations between EM-score and %fib. 4. There were significant correlations between left ventricular function and myocardial morphology, in patients with mitral regurgitation. The patients with EM-score over 7 and %fib. over 14% showed poor left ventricular function and poor cardiac reserve postoperatively.