Myocardial scarring after transmyocardial laser revascularization: A potential mechanism of clinical improvement?

Background and Objective The morphological evolution of transmyocardial laser channels was analyzed in a pig model. Materials and Methods Five channels were created in the lateral wall of the left ventricle of 12 animals, using a Ho:YAG laser. In half of the animals, an additional infarction was induced in the same area. Animals were sacrificed at one-week intervals until week 5 and the critical regions of the left ventricular wall were subjected to microscopic computed morphometrical analysis. Results There was no clearly patent lumen at any stage. Cross-sectional area of the channels fell from 8.5 ± 1.2 mm2 at day 0 to 2.1 ± 0.1 mm2 at day 35. From day 7 onward, the channel area was gradually replaced by granulation tissue and the proportion of the channel occupied by granulation scar tissue increased from 37 ± 2% at day 7 to 100% at day 28. In the subgroup with concomitant infarction, granulation tissue of both channel and infarction became indistinguishable from day 14 onward. Conclusions These results suggest strongly that channel patency is not the mechanism of angina relief after transmyocardial laser revascularization with Ho:YAG laser. Lasers Surg. Med. 25:79–87, 1999. © 1999 Wiley-Liss, Inc.