Imaging and Laser Revascularization in Hibernation

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DESCRIPTION (Provided by Applicant): Identifying chronically ischemic dysfunctional or hibernating myocardium is an important clinical endeavor. Patients who are not candidates for CABG or PICA are now being considered for new methods of revascularization such as direct myocardial revascularization with laser channels using catheter based approach (DMR). Electromechanical endocardial (UPV) mapping is used to guide DMR but is not fully validated. Perfusion imaging and dobutamine echocardiography are being used clinically to identify dysfunctional viable myocardium and assess results of novel revascularization techniques. The accuracy of these imaging techniques for these indications have never been fully validated in an animal model. Gold standards for viability used in clinical studies are imperfect. A double ameroid constrictor/swine model for hibernating myocardium shows promise as a good model to compare these technologies against one another and against histopathology and to investigate the efficacy and mechanisms of DMR. In the first aim we propose to use swine models of extensive hibernation and of scar to validate UPV mapping to identify viability vs scar and to compare thallium imaging and dobutamine echocardiography against histopathology to identify viability and sear. Under aims 2 and 3 the double vessel ameroid model will be used to investigate mechanisms for DMR. The effect of laser therapy on angiogenesis will be assessed using combined morphometric tissue analysis and angiographic techniques. The efficacy of noninvasive imaging (adenosine Tc-99m sestamibilrest Tl-201 and dobutamine echo) to detect neovascularization will be assessed. In aim 4 radioiodinated MIBG autoradiography will be used to look at the effects of DMR on regional innervation. The results of these experiments should better define the accuracy of methods to image viability and image angiogenesis, and lead to a better understanding of whether DMR revascularizes the heart and whether or not it denervates the heart.