Abstract 83: Preconditioning With Periodic Acceleration (pGz) Prior To Whole Body Ischemia Reperfusion Injury Ameliorates Myocardial Stunning And Arrhythmias
Periodic acceleration (pGz) consists of sinusoidal, head to foot motion of the supine body achieved with a motion platform. pGz produces pulsatile shear stress on the vascular endothelium in vivo and in vitro thereby inducing release of endothelial derived NO (eNO) and prostaglandins. Additionally, pGz when applied as a sole means for CPR decreases myocardial stunning and improves outcome from ventricular fibrillation (VF). VF followed by resuscitation (CPR) is a model of whole body ischemia reperfusion injury (I/R). Pharmacological and ischemic preconditioning prior to I/R have been shown to ameliorate global and focal cardiac ischemia, reduce arrhythmias, and improve myocardial function after reperfusion. This study tests whether pGz applied prior to CPR, also ameliorates reperfusion injury. Twenty male swine (40 –50lbs) were anesthetized, intubated and instrumented to measure blood gases and hemodynamics. They were placed on a motion platform and randomized to 1 hr of active pGz (3 Hz and Gz ± 0.4) (PRE) or no activation for the same time period, control(C). VF was electrically induced and unsupported for 8 min, followed by continuous manual chest compression and defibrillation until return of spontaneous circulation (ROSC) or 10 min. Echocardiograms to measure ejection fraction (EF%), fractional shortening ( FS%) and wall motion score index (WMSI) were performed at baseline (BL), after pGz or control (BL2) and 30, 120 mins after ROSC (ROSC30, ROSC120). All animals had ROSC after a median of 4 defibrillation attempts. There were no differences between groups in defibrillation attempts, time to ROSC, arterial blood gases or hemodynamics over time. PRE animals had less hemodynamically significant arrhythmias in the first 30 mins ROSC; C (35) vs PRE (7) (p< 0.05) and less myocardial stunning. Data mean±SD * p < 0.05 C vs PRE † p< 0.05 time vs BL pGz applied prior to I/R is cardioprotective and a novel means to precondition the myocardium.