Percutaneous Transluminal Myocardial Revascularization : An Emerging

(TMR) is a form of revascularization technique in which small channels are created between the ischemic myocardium and the left ventricular cavity. The therapeutic value of this technique is derived from studies of reptilian hearts in which blood is delivered to heart muscle via a network of channels directly from the left ventricle. This is supported by findings of Wearn and colleagues. They described “arterio-sinusoidal” communications or vessels that seemed to connect a microcirculatory network from the coronary arteries directly with the left ventricular cavity. Based upon these findings, investigators tried to increase myocardial perfusion “directly” by augmenting blood flow into existing myocardial sinusoids or by creating new sinusoids. In 1935, Beck grafted vascularized mediastinal fat or parietal pericardium to the heart surface. I n the 1940s, Vineburg implanted the distal end of the internal mammary arteries directly into canine myocardium and demons tra ted a myocardial “blush” as well as collateralization to the epicardial coronary arteries. In 1954, Vineburg extended this approach by tunneling the internal mammary artery into the myocardium of patients. Both symptoms and survival improved with the implants, and their long-term patency and collateral supply function were documented. In 1965, Sen and colleagues used blunt instruments to create transmural channels (“transmyocardial acupuncture”) to deliver oxygenated blood directly from the ventricle into sinusoidal channels of the microcirculation or into other vessels perforated by the channels. Unfortunately, channels fibrosed and closed within a few weeks, offering no long-term benefit. Clinical trials of TMR (Table 1). With the rapid evolution of coronary artery bypass surgery and coronary angioplasty as methods to treat patients with ischemic heart disease, there was reduced interest in investigations designed to evaluate the adequacy of direct myocardial revascularization. A subgroup of patients has emerged who are not candidates for coronary bypass or coronary angioplasty. This group includes patients with severe diffuse coronary disease, small vessel disease, total coronary occlusions, and those who have had previous revascularization attempts with poor results. Incomplete revascularization in these patients has been associated with a greater likelihood of recurrent angina and subsequent cardiac events, including myocardial infarction and death. – 1 0 TMR using laser energy to revascularize the myocardium is being used as a potential alternative for augmenting Percutaneous Transluminal Myocardial Revascularization: An Emerging Te c h n o l o g y