Recovery and viability of an acute myocardial infarct after transmyocardial laser revascularization

Abstract

Objectives. The short- and long-term effectiveness of transmyocardial laser revascularization was evaluated in the setting of an acute myocardial infarction.Background. Theoretically, transmyocardial laser revascularization allows direct perfusion of the ischemic area as ventricular blood flows through the channels to the myocardium.Methods. Infarcts were created by coronary occlusion in 30 sheep. Eighteen of these sheep were studied to assess short-term efficacy. The infarct was reperfused after 1 h by either removing the occlusion or by laser drilling using a high power carbon dioxide laser. The occlusions were left in place for the control group. To monitor regional recovery, percent systolic shortening was measured. To evaluate long-term effectiveness, 12 additional sheep underwent creation of an infarct. Six were treated with the laser, and six were untreated. The animals were restudied 30 days later.Results. In the short-term experiment, the control and reperfusion groups exhibited no recovery of regional contractility. The laser group demonstrated improvement throughout the recovery period. There was a significant difference in the area of necrosis within the same area at risk (reperfusion group 44 ± 6% and control group 39 ± 5% vs. laser group 6 ± 2%). After 30 days, none of the control animals showed evidence of contraction in the infarct, whereas the laser-treated animals did. Histologic analysis of the laser-treated infarcts revealed patent channels surrounded by viable myocardium. The control-group infarcts were necrotic and scarred.Conclusions. On the basis of both short- and long-term improved contractility, as well as diminished necrosis in the area at risk, these results indicate that transmyocardial laser revascularization may be an alternative method of treating ischemic heart disease.