Optical Mapping Analysis of Moderate Local Hypothermic Defibrillation

概要

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Recently it has been proposed that global or local hypothermia on heart approve defibrillation success rate in large animal experiment, but precise mechanisms of cardiac excitation propagation was still unclear. We already reported about hypothermic defibrillation simultaneously cooled with cryoprobe on left ventricular of rabbit heart makes less energy to generate new phase singularity (PS) and PS interaction against spiral reentry has been lead spiral stop. Objective of our new approach is to figure out how to stop spiral reentry using local hypothermia only and no electrical stimulus. Cryoprobe was built with copper metal frame and transparent resin. Cooling source was Peltier devices. For wasting heat, we used heat sink for CPU and air exhaust fan both. To monitor probe temperature micro thermocouple thermometer was implanted in the end of cryoprobe. Size and location of setting on heart and local hypothermic temperature were variously changed. The experimental protocol were that (1) to initiate spiral reentry by cross-field stimulation on Langendorff perfused rabbit whole heart specimen, (2) After 1 minute sustained VT, start cooling by turning on peltier devices, (3) Excitation propagation were measured by high speed optical mapping system and images were processed to phase map, and finally each variously changed local cooling results were compared.