Rapid induction of hypothermia by the Thermosuit system profoundly reduces infarct size and anatomic zone of no‐reflow following ischemia/reperfusion in rabbit and rat hearts (547.12)

Abstract

Background: While hypothermia reduces myocardial infarct size, non‐invasive and rapid cooling methods are lacking. This study tests the effectiveness of a novel cooling apparatus on myocardial infarct size and no‐reflow area in two models of coronary artery occlusion (CAO).Methods and Results: Anesthetized rabbits (protocol 1) and anesthetized rats (protocol 2) were randomized to Normothermic (N) or Hypothermic (H) groups after isolation of a proximal coronary artery. Animals were subjected to 30 minutes CAO and 3 hours reperfusion. In protocol 1, hypothermia was initiated, using the Thermosuit apparatus (convective‐immersion cooling), 5 minutes after the onset of CAO to a goal temperature of ~32°C. In protocol 2, hypothermia was initiated 2 minutes after the onset of CAO to a goal temperature of ~30°C. Goal temperature was reached in ~20 minutes. In protocol 1, hypothermia caused an 82% reduction of infarct size as a percentage of the ischemic risk zone (N, 44±5%; H; 8±2%, P<0.001) and an 89% reduction of the no‐reflow area (N, 44±4%; H, 5±1%, P<0.001). In protocol 2, hypothermia caused a 73% infarct size reduction (N, 51%±5%; H, 14±6%, P<0.001) and a 99% reduction of the no‐reflow area (N, 33±5%; H, 0.4±0.3%, P<0.001).Conclusion: The Thermosuit device induced rapid hypothermia and limited infarct size and no‐reflow to the greatest extent ever observed in this laboratory with a single intervention.