MYOCARDIAL CAPILLARIES AND AUTONOMIC NERVES IN DIABETES - MORPHOMETRIC STUDY OF AURICLES FROM BYPASS-SURGERY BIOPSIES

Patients with diabetes mellitus are excessively vulnerable to myocardi al ischemia and often suffer from autonomic cardiac dysfunction. They are also known to have specific capillary pathology and abnormalities of substances essential for the neoangiogenic cascade. These backgroun d data led us to the hypothesis that the severity of ischemic heart di sease in diabetes is attributable (at least in part) to microcirculato ry and autonomic inadequacy caused by microangiopathy and failure of p ostischemic adaptive neoangiogenesis. To test this hypothesis we compa red myocardial capillaries, autonomic nerve endings of 19 diabetics, 3 0 normoglycemics with ischemic heart disease, and 9 valve replacements serving as nonischemic controls. Right atrial appendages obtained dur ing coronary bypass surgery were utilized for light, fluorescent, and electron microscopic morphometry. Although in this series there were n o significant differences in the clinical and laboratory hemodynamic v alues between the ischemic normoglycemic and diabetic patients, the la tter showed marked capillary and nerve terminal pathology, and their c apillary density as well as capillary to myofiber ratios were signific antly lower. In addition, the mean capillary area, volume fraction, an d intercapillary distance were higher in diabetics. The mean area of t he nerve varicosities was also smaller, and this was correlated with c apillary density. We concluded that the findings support the hypothesi s that cardiac vulnerability in diabetes is connected with inadequate adaptive neoangiogenesis and that this seems to be associated with atr ophic changes in the nerve terminals.