A morphological quantitative study of small vessels in diabetic cardiomyopathy.

In 25 adult diabetic patients, tissue fragments from myocardium were removed at necropsy and processed routinely. The morphometrical analysis was made using eye-piece ocular micrometer on a definite microscopic area. The arteriolar wall thickness increased from 5.10 mu +/- 1.71 in control group to 7.37 mu +/- 1.98 in the diabetic heart. The arterioles number decreased from 5.82/mm2 +/- 0.54 in the nondiabetics to 2.51/mm2 +/- 0.65 in the diabetic heart. The mean arteriolar diameter increased from 24.61 mu +/- 7.7 in the control group to 29.45 mu +/- 8.25 in the diabetic myocardium. The mean capillary diameter increased from 4.09 mu +/- 0.63 to 5.69 mu +/- 1.34 in diabetics. The capillaries number/mm2 decreased from 6.98 +/- 1.55 in the nondiabetics to 4.39 +/- 1.54 in diabetic patients. All differences, less the mean arteriolar diameter, are statistically significant. The following microscopical aspects were found in the small intramural coronary arteries: proliferation of endothelial cells with focal protuberances leading to partial narrowing of the lumen; increased thickness of the arteriolar wall due to fibrosis and accumulation of neutral mucopolysaccharides; alterations of elastic fibers. Frequently small areas of perivascular fibrosis and isolated foci of myocytolysis were found as well. These results suggest that the arteriolar impairment, especially the thickening of the arteriolar wall, could play a role in the pathogenesis of diabetic cardiomyopathy.