Digital Radiographic Quantification of Myocardial Blood Flow Around a Transmyocardial Laser Channel in Rabbit Hearts

Abstract

Background A mechanism underlying the benefits of transmyocardial laser revascularization (TMLR) has been presumed to be improvement in perfusion. We evaluated myocardial blood flow around a laser channel using digital radiography combined with a 3 H-labeled desmethylimipramine ([ 3 H]DMI) deposition. Methods and Results A laser channel was created in the left ventricular wall using a YAG-laser in 6 nonischemic rabbit hearts. After 8 weeks, [ 3 H]DMI(1.11 MBq) was injected into the left atrium and the TMLRtreated myocardium was sectioned. Another 6 hearts were examined as controls. We measured [ 3 H]DMI density in arbitrary units with digital radiography in the channel remnant, the surrounding area and a remote area. Flow distribution was quantified by the coefficient of variation of flows (CV). The surrounding area had the highest density (p<0.001) and the lowest CV (p<0.001), and had higher density (p<0.001) and lower CV (p<0.001) than the controls. There was no transmural difference in the density in all domains. The CV increased with depth in the remote area, as well as in controls (p<0.001), but there was no transmural difference in the surrounding area. Conclusions The TMLR increases myocardial blood flow and decreases flow heterogeneity in the surrounding area. The disappearance of transmural difference in flow heterogeneity might indicate the remodeling of microcirculation to improve regional oxygen delivery. (Circ J 2005; 69: 488 -492)