Pathology of Transmyocardial Angiogenesis and Arteriogenesis.

Abstract

Transmyocardial laser revascularization (TMLR) is increasingly used for improving myocardial perfusion in patients with diffuse coronary artery disease and refractory ischemia. The efficacy of TMLR, however, is in doubt because no definite increase in blood flow or longevity has been demonstrated. Although histologic results after TMLR show some neocapillary formation, the relative amount of angiogenesis is similar to what occurs naturally after myocardial infarction. Hence, it is suspected that these few capillaries would be sufficient to maintain a viable myocardium. Alternatively, the creation of collateral vessel "arteriogenesis" rather than capillary formation alone may improve the clinical outcome. Comprehensive experimental studies seem to indicate the feasibility of producing new collaterals. This method of vascularization is dependent upon specific cytokines or enzymes that induce proliferation of native arterial endothelial cells and smooth muscle cells. It is critical that we develop a better understanding of which factors regulate arteriogenesis, and concentrate on methods to document its existence in the clinical and experimental setting.