Quantitative approach to the histopathology of the biopsied right ventricular myocardium in patients with diabetes mellitus.

For the purpose of studying the clinicopathology of the biopsied myocardium in patients with diabetes mellitus, the diameter of right ventricular myocardial cells and diffuse perimysial fibrosis of biopsied myocardium were measured quantitatively. Seven healthy controls and nine diabetic patients without hypertension or coronary arterial disease were subjected to this study. The degree of diabetic complications was mild to moderate. The diameter of myocardial cells was measured and the degree of diffuse perimysial fibrosis was assessed by the point-counting method using a square grid, in which the distance between the points was 10 micron. Over 2000 points which lay on the longitudinally cut myocardial cells and on the interstitial fibrosis stained by the Mallory-Azan method were measured. Percentage fibrosis was calculated according to the formula: percentage fibrosis = (points lying on the interstitial fibrosis)/[(points lying on the myocardial cell) + (points lying on the interstitial fibrosis)] X 100. The results were as follows. The mean diameter of right ventricular myocardial cells in patients with diabetes mellitus was significantly larger than that of controls (P less than 0.01). The percentage fibrosis of diabetic patients was significantly higher than that of controls (P less than 0.01). There was no significant correlation between the histopathological measurements and clinical features. It is concluded that hypertrophy of myocardial cells and interstitial fibrosis of the myocardium exist even in mild diabetes mellitus.