A comparison of ultrastructural changes on endomyocardial biopsy specimens obtained from patients with diabetes mellitus with and without hypertension

Abstract

The pathogenesis of diabetic cardiomyopathy is unknown. The synergistic, or enhanced, effect of hypertension on pathological changes in the heart of diabetic patients has been highly suspected. The purpose of this study was to evaluate the myocardial changes related to diabetes mellitus with and without hypertension, using biopsy specimens. We examined the ultrastructural changes in biopsy specimens of the endomyocardium obtained from 25 patients. They were divided into four groups: controls without hypertension or diabetes mellitus (n = 6), and patient with hypertension (n = 3), diabetes mellitus (n = 8), and diabetes with hypertension (n = 8). The diabetic patients showed nearly normal or mildly depressed systolic left ventricular function. Ultrastructural pictures were analyzed for thickening of the capillary basement membrane, presence of toluidine blue-positive materials (i.e., materials showing metachromasia) in the myocytes, size of myocytes, and interstitial fibrosis. The thickening of the capillary basement membrane, the accumulation of toluidine blue-positive materials, and interstitial fibrosis were all significantly greater in the patients with diabetes mellitus compared to the control subjects. The myocytes tended to be small (cell atrophy) in the diabetes group. Although these pathological changes in the heart were characteristic of diabetic patients, irrespective of the presence or absence of hypertension, the presence of hypertension increased the pathological changes of myocardial cells as well as abnormality in the capillary vessels in patients with diabetes mellitus. Alterations in the myocardial cells and capillaries, caused by diabetes mellitus, may lead to myocardial cell injury and interstitial fibrosis and, ultimately, to ventricular systolic and diastolic dysfunction, especially when the diabetes is accompanied by hypertension.

Alteration in haemodynamics and pathological changes in the cardiovascular system during the development of Type 2 diabetes mellitus in OLETF rats

“…Although the cause of relaxation abnormality is not clarified by this study, it is suggested that depressed myofibrillar Ca 2+ -stimulated ATPase, de- The capillary vessels in the heart changed spirally (arrow) in OLETF rats (×200). Lower panel: Electron micrograph showing capillary basement membrane in the heart was thickened in OLETF rats at 62 weeks creased sarcoplasmic reticulum Ca 2+ -pump activities, and abnormal sympathetic innervation of the heart might be partly responsible for impaired relaxation of the diabetic heart [8,31]. Moreover, changes in the afterload resistance might partially relate to lower maximal -dP/dt at 62 weeks in OLETF rats, although afterload resistance was not measured in this study.…”

Longitudinal Changes in Left Ventricular Diastolic Function in a General Population

“…20 Microvascular damage may lead to myocardial cell injury and reactive fibrosis/hypertrophy. 21 Our study has to be interpreted within the context of its potential limitations and strengths. First, the Doppler blood flow measurements and the TDI velocities are prone to measurement error.…”

Diabetes Complications

“…The increase in basement membrane matrix and fibrosis that leads to diabetic glomerulosclerosis occurs in all vascular beds. Endomyocardial biopsy of persons with diabetes shows increased fibrosis, particularly with concomitant hypertension (44). There is also evidence of disordering of extracellular matrix in diabetic cardiomyopathy.…”