Abstract 344: Periodic Acceleration (pGz) Improves Left Ventricular Function and Remodeling in Rats After Myocardial Infarction

Abstract

BACKGROUND: Heart Failure (HF) post MI remains a important cause of mortality and morbidity Whole body periodic acceleration (pGz) is the repetitive motion of the supine body in a sinusoidal head to foot direction achieved with a motorized platform. pGz induces pulsatile shear stress on the vascular endothelium. Pulsatile shear stress activates endothelial nitric oxide synthase (eNOS) to produce increased release of nitric oxide (eNO). pGz pre-and postconditioning can induce cardioprotective affects in an in-vivo rat model of myocardial infarction (MI) reducing mortality, arrhythmias and infarct size. The effects of pGz on myocardial function and remodeling after MI are unknown. Left ventricular (LV) pressure-volume (PV) relationships are an invasive but comprehensive method to assess myocardial function. OBJECTIVE: We investigated the effects of pGz on LV function and remodeling induced by chronic MI in rats. Methods: After MI, rats (SD-300gms) were randomized to receive pGz (MI-pGz) (n=5) Control (MI-C) (n=5) for 4 weeks and a separate sham surgery group (n=5). In vivo LV pressure-volume relationships were analyzed using a conductance catheter (Millar Instruments, Texas). LV fibrosis was analyzed using trichrome staining and digital microscopy. RESULTS: pGz after MI reduced left ventricular fibrosis by 40% [MI-C 36( 4 )% vs MI-pGz 21(2)% (p < 0.01) as a % of the LV]. There were no differences in heart rate between groups. pGz significantly improved ejection fraction (EF), left ventricular end systolic pressure (LVESP), dP/dtmax, and both end systolic (ESPVR) and diastolic (EDPVR) pressure volume relations (Table). Data: X(SD) * p< 0.01 (Sham vs. MI-C) and † p< 0.01 (MI-C vs MI-pGz) Conclusions: In a rat model HF induced by chronic MI, pGz markedly improved LV function. These findings have implications for cardiac rehabilitation post MI.