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Human coronary microvessels in diabetes and ischaemia. Morphometric study of autopsy material
R Yarom1, H Zirkin, G Stämmler
1Department of Anatomical Pathology, Groote Schuur Hospital, South Africa.
Insights
Diabetic patients with heart attacks show reduced capillary density, suggesting inadequate blood vessel growth contributes to heart disease severity in diabetes. This may increase vulnerability to further heart injury.
Area of Science:
- Cardiovascular Science
- Diabetology
- Pathology
Background:
- Ischaemic heart disease (IHD) is a significant complication in diabetic patients.
- The severity of IHD in diabetics is often greater than in non-diabetics.
- Capillary inadequacy has been hypothesized as a contributing factor.
Purpose of the Study:
- To investigate the hypothesis that capillary inadequacy contributes to the excessive severity of IHD in diabetic patients.
- To compare microvascular characteristics in the hearts of diabetic and non-diabetic individuals, with and without myocardial infarction.
Main Methods:
- Morphometric analysis of intramural microvessels in autopsied heart sections from four groups: diabetics with myocardial infarction (MI), diabetics without MI, non-diabetics with MI, and normoglycaemic individuals without heart disease.
- Quantification of capillary numerical density, capillary to myofibre ratios, and myofibre diameters.
- Statistical comparison of averages across groups.
Main Results:
- Normoglycaemic patients with MI exhibited increased morphometric values compared to controls.
- Diabetic patients with MI demonstrated significantly lower capillary densities than all other groups.
- Capillary to myofibre ratios and myofibre diameters showed variations across groups, with diabetics with MI often showing altered dimensions.
Conclusions:
- Diabetes is associated with reduced capillary density in the context of myocardial infarction.
- An inadequate ischaemia-induced, reactive angiogenesis may occur in diabetic hearts.
- This microvascular dysfunction could contribute to increased myocardial vulnerability to ischaemic injury and potentially diabetic cardiomyopathy.
Abstract:
The objective of this study was to test the hypothesis that excessive severity of ischaemic heart disease in diabetics is due, in part, to capillary inadequacy. Sections from autopsied hearts of diabetic patients with and without myocardial infarction as well as from those of patients with infarcts and no diabetes were used for morphometric studies of intramural microvessels in areas without infarction. Normoglycaemic patients with normal hearts were also examined. Two to five transverse sections from each of 44 hearts (stained with methenamine silver) were examined for capillary numerical density, capillary to myofibre ratios, and myofibre diameters. Averages for each case and totals for each group were calculated and compared. Normoglycaemic patients with infarcts had increased morphometric values. Diabetics with infarcts had significantly lower capillary densities than the other groups. In conclusion, it is suggested that in diabetes there is an inadequate ischaemia-induced, reactive angiogenesis. This may contribute towards increased myocardial vulnerability in further ischaemic injury and perhaps to diabetic cardiomyopathy.