Diabetic cardiomyopathy. A morphological study of intramyocardial arteries.

The mechanism of heart failure in patients with diabetic cardiomyopathy is not clear. Previous studies suggested that vascular lesions specific for diabetes mellitus were present and that the lesions could be the basis for impaired cardiac function. We have investigated the histologic and histochemical characteristics of intramyocardial vessels (20 to 500 microns) in a group of diabetics using comparable groups of patients with hypertension, patients with hypertension and diabetes mellitus, and, as controls, patients with neither hypertension nor diabetes mellitus. Analysis of multiple blocks taken from the 42 study patients disclosed no lesions specific for diabetes mellitus or hypertension. The discrepancy between our findings and earlier reports is probably due to a lack of controls and the use of non-perfusion-fixed material in the earlier studies.

Staining in normal and ischemic human myocardium. A study of myoglobin, IgG, glycogen, and diastase-PAS.

Using the indirect immunofluorescence technique, we studied the distribution of myoglobin in normal and ischemic human myocardium obtained at autopsy and at surgery. Glycogen, diastase-PAS staining of the sarcoplasm, and IgG were also studied and compared with the structure of the lesions and the distribution of myoglobin. The surgical material we used was largely free of autolysis and was the most satisfactory. Prolonged fixation of tissues in formaldehyde solution or perfusion fixation of autopsy specimens both proved to be unsatisfactory as myoglobin was absent from the myocardium. This loss presumably represents diffusion of myoglobin due to autolysis and the method of fixation. Another group of autopsy specimens that was briefly fixed by immersion in formaldehyde solution prior to processing was more satisfactory. Although they showed some extracellular diffusion of myoglobin, the autolyzed normal areas could still be clearly differentiated from the autolyzed ischemic areas.