Hypothermia Modulates Arrhythmia Substrates During Different Phases of Resuscitation From Ischemic Cardiac Arrest

Joseph S Piktel; Aurelia Cheng; Matthew McCauley; Zack Dale; Michelle Nassal; Danielle Maleski; Gary Pawlowski; Kenneth R Laurita; Lance D Wilson

doi:10.1161/JAHA.117.006472

Hypothermia Modulates Arrhythmia Substrates During Different Phases of Resuscitation From Ischemic Cardiac Arrest

J Am Heart Assoc. 2017 Nov 17;6(11):e006472. doi: 10.1161/JAHA.117.006472.

Authors

Joseph S Piktel¹, Aurelia Cheng², Matthew McCauley², Zack Dale², Michelle Nassal², Danielle Maleski², Gary Pawlowski², Kenneth R Laurita², Lance D Wilson²

Affiliations

¹ Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH jpiktel@metrohealth.org.
² Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH.

Abstract

Background: We designed an innovative porcine model of ischemia-induced arrest to determine dynamic arrhythmia substrates during focal infarct, global ischemia from ventricular tachycardia or fibrillation (VT/VF) and then reperfusion to determine the effect of therapeutic hypothermia (TH) on dynamic arrhythmia substrates and resuscitation outcomes.

Methods and results: Anesthetized adult pigs underwent thoracotomy and regional plunge electrode placement in the left ventricle. Subjects were then maintained at either control (CT; 37°C, n=9) or TH (33°C, n=8). The left anterior descending artery (LAD) was occluded and ventricular fibrillation occurred spontaneously or was induced after 30 minutes. Advanced cardiac life support was started after 8 minutes, and LAD reperfusion occurred 60 minutes after occlusion. Incidences of VF/VT and survival were compared with ventricular ectopy, cardiac alternans, global dispersion of repolarization during LAD occlusion, and LAD reperfusion. There was no difference in incidence of VT/VF between groups during LAD occlusion (44% in CT versus 50% in TH; P=1s). During LAD occlusion, ectopy was increased in CT and suppressed in TH (33±11 ventricular ectopic beats/min versus 4±6 ventricular ectopic beats/min; P=0.009). Global dispersion of repolarization and cardiac alternans were similar between groups. During LAD reperfusion, TH doubled the incidence of cardiac alternans compared with CT, with a marked increase in VF/VT (100% in TH versus 17% in CT; P=0.004). Ectopy and global dispersion of repolarization were similar between groups during LAD reperfusion.

Conclusions: TH alters arrhythmia substrates in a porcine translational model of resuscitation from ischemic cardiac arrest during the complex phases of resuscitation. TH worsens cardiac alternans, which was associated with an increase in spontaneous VT/VF during reperfusion.

Keywords: arrhythmia; hypothermia; myocardial infarction; resuscitation; ventricular fibrillation.

MeSH terms

Animals
Arrhythmias, Cardiac / etiology
Arrhythmias, Cardiac / therapy*
Disease Models, Animal
Heart Arrest / therapy
Hypothermia, Induced / methods*
Myocardial Reperfusion Injury / complications*
Myocardial Reperfusion Injury / therapy
Resuscitation / methods*
Swine