Effects of multiple ischaemic events on human myocardium--an ultrastructural study.

Chronically ischaemic myocardium from patients with coronary heart disease was investigated by light and electron microscopy using tissue biopsies taken during cardiac surgery. Light microscopy showed a significantly increased amount of fibrotic material, cell size was variable. By electron microscopy, the most obvious alterations were abnormalities of nuclei, mitochondria, and a reduction of contractile material. This was confirmed by ultrastructural morphometry. The subendocardium was more severely altered than the subepicardium. It is concluded that repeated episodes of reversible ischaemic injury produce cellular degeneration and significant loss of myofibrils. Even though these patients do not exhibit gross histologic evidence of myocardial infarction, the cardiac tissues slowly deteriorates with loss of myocytes and an increased amount of fibrosis. These findings are interpreted as the morphologic correlate of functional disturbances, especially of hypokinesia of the affected area.