Growth Factors and Transmyocardial Laser Revascularization as Promoters for Angiogenesis in Patients suffering from Coronary Artery Disease

Coronary Artery Disease (angina pectoris or as extreme myocardial infarction) is caused by different pathogenetic factors within the coronary arteries. All these factors lead to occlusion of the vessel and blood flow is decreased. The treatment of this severe disease is currently done through medication, angioplasty (PTCA) coronary artery bypass grafting (CABG) and recently as a kind of ultima ratio through Transmyocardial Laser Revascularization (TMR). Patients who have undergone aortocoronary bypass grafting may have reoccurence of symptoms after a few years. Some of these patients cannot undergo another bypass operation because of the poor morphology of their native coronary arteries. And therefore Transmyocardial Laser Revascularization is in some centers the method of choice for these patients. During the TMR-procedure 20 to 35 channels are burned into the ischemic left ventricular myocardial wall using a flexible laser probe. This operation is done without cardiopulmonary bypass on the beating heart and has been performed so far in 30 patients at our department in Vienna. Postoperative clinical studies of TMR have consistently shown a significant reduction in angina and after 2 months an increase of the heart`s function could be seen. Histologic and blood flow studies in animal models have shown that Transmyocardial Laser Revascularization dearly enhances development and growth of new blood vessels (angiogenesis) in the heart. The underlying mechanisms by which TMR enhances angiogenesis have not been identified in detail, it has been hypothesized that the inflammatory response incited by the laser injury results in liberation of angiogenic cytokines and growth factors. Angiogenic growth factors have also been shown to induce angiogenesis in experimental models of ischemia when administered into the myocardium or when injected into the coronary arteries. During my intended stay at Columbia University, New York, it is planned to do basic research on Transmyocardial Laser Revascularization (molecularbiology, histologic and immunohistochemic studies) and to step forward in this new technique. Second, to make advances in the field of angiogenic growth factors, to establish a new method of treatment of coronary artery disease in the near future. Last winter, a first pilot study was done in New York which I financed privately. The results were so promising, that the studies should be continued as soon as possible.