Acute effect of transmyocardial revascularization (TMR) on ischemic myocardium

The contribution of TMR to restoring blood flow to ischemic myocardium remains controversial. We therefore examined the effect of TMR on ischemic myocardium, concentrating on the acute change of regional perfusion and myocardial metabolism through TMR channels. Five anesthetized dogs underwent temporal (2 min) coronary ligation of left anterior descending artery (LAD) twice: 10 min before and 10 min after TMR using CO₂ laser. Transmural blood flow was measured under temporal LAD ligation before and after TMR using heavy element loaded microspheres into left atrium. Metabolic influence was evaluated by NADH fluorescence on rapidly excised frozen myocardial sections. The microsphere activity revealed no significant differences between pre- and post TMR. Dense and diffuse NADH fluorescence was documented all over the ischemic region and did not show particular change around the TMR channels. We concluded that in the acute phase TMR channels did not act as the direct blood pathway from ventricle to the ischemic myocardium, and did not improve the metabolic function immediately.