Percutaneous transmyocardial revascularization induces angiogenesis: a histologic and 3-dimensional micro computed tomography study

The purpose of this study was to visualize the spatial patterns and connection of channels created after percutaneous transmyocardial revascularization (PTMR) in normal porcine hearts, and to estimate the relative contributions of transmyocardial and coronary perfusion. Six pigs underwent PTMR creating channels using radiofrequency ablative energy. Three-dimensional computed tomography imaging of channels 1 hr after PTMR showed the direct connection of PTMR channels to the myocardial capillary network and to epicardial coronary vessels. In the heart, examined 28 day after PTMR, there was a fine, extensive, network of microvessels originating from the site of the original PTMR channel, also connecting the left ventricular cavity to myocardial capillaries. Histopathologic examination of the 1-hr specimens showed numerous regions of myocardial hemorrhage and associated inflammatory cell infiltration. In the 28-day specimens, newly developed new vascular network suggested neovascularization within the core of these channel remnants. The immunoreactivity for basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) were intense within myocardium and neovascular structure surrounding PTMR channel remnants. The vascular connections occur by direct communication with existing myocardial vasculature acutely, and angiogenesis in these channel remnant chronically.