Morphology of Poorly Contracting Ventricle in Patients with Coronary Artery Disease

Summary

Light and electron microscopic morphometry was carried out on myocardial tissue samples of 79 patients with coronary artery disease. Transmural biopsies of the myocardium perfused by the left anterior descending branch (LAD) were obtained during coronary bypass operation or aneurysmectomy. LAD-stenosis was measured and regional LAD wallmotion was defined by hemiaxis shortening from preoperative angiogram. Patients without collaterals to the LAD on arteriogram (subset A) were compared to patients with collaterals (subset B). Patients in subset A were grouped according to degree of stenosis into groups A (62% stenosis), B (86% stenosis), C (97% stenosis) and D (100% stenosis). Patients in subset B had 100% occlusion (group E). In subset A LAD wall-motion fell and myocardial fibrosis increased when stenosis progressed without collaterals. No change of intracellular compartments (contractile material, mitochondria, sarcoplasm) occurred with the progression of stenosis. In group E LAD wall-motion was augmented and fibrosis was reduced when compared to occlusion without collaterals of group D. Subendocardial fibrosis was higher than subepicardial when data were pooled (27 versus 20%, p < 0.05, n = 39).

We conclude: fibrous replacement of the myocardium occurs with progression of stenosis, (2) in coronary occlusion, collaterals reduce the degree of fibrous replacement and augment regional function, (3) intracellular content of contractile elements, mitochondria and sarcoplasm of the surviving myocardium is unaffected by the amount of fibrous replacement. (4) This fact documents viability of residual myocardium, and indicates bypass surgery.

Key words

Coronary artery disease - Collateral circulation - L.V. wall-motion - Myocardial ultrastructure