[Transmyocardial laser revascularization. Histopathology of laser channels in 10 postoperatively deceased patients 1 to 18 days after treatment with a CO2 laser].

TMLR (Transmyocardial laser revascularization) is a disputed cardiosurgical technique available in Europe since 1994 that aims to deliver additional blood flow to ischemic myocardium from the left heart chamber. Goal of our study is morphological examination of laser channels in human hearts to answer the questions: Are there patent laser channels with communication to the left chamber and to intramural vessels? We examined hearts of 10 patients who died during the first 18 days after TMLR. Channels were examined in histological serial sections under the light microscope. Laser channels in the first days postoperatively have a lumen diameter of about 1 mm and are surrounded by coagulation necrosis about 500 microns thick. Despite phagocytic removal of necrotic tissue the lumen diameter decreases during the following two weeks. Open intramyocardial channels can be shown in all patients. These channels communicate with intramural vessels, but in no instance with chamber lumen. Our results suggest that clinical benefits are based on improved distribution of coronary blood. Additional blood is not delivered from left chamber lumen to the myocardium. However, our patients represent the small subgroup of the decreased. If similar observations can be made in the majority of patients living symptom free after TMLR remains open.