Tissue Oxygen Transfer During Reperfusion and Post-Conditioning

Heart disease is the leading cause of death in the United States. Ischemic heart disease occurs when coronary blood flow to the heart is reduced, limiting the amount of oxygen and nutrients the heart receives. When blood flow is restored after a percutaneous transluminal coronary intervention (PCI), rapid reperfusion from sudden balloon deflation can cause further injury to oxygen-starved tissue, leading to increased cell injury and cell death. Studies in animal models with ischemic heart disease have shown that reperfusion injury may account for up to 50% of the final infarct size [1]. Post-conditioning (PC) may reduce the amount of reperfusion injury by applying intermittent periods of ischemia during the early moments of reperfusion. This procedure periodically occludes blood vessels during reperfusion by periodically inflating and deflating an angioplasty balloon according to a specific algorithm. Zhao et al. showed that PC reduced reperfusion injury in a canine model by applying 3 cycles of 30 seconds of reperfusion followed by 30 seconds of ischemia (re-occlusion) at the onset of reperfusion. PC in this study reduced tissue AN/AAR (area of necrosis/area at risk) by 48% [2]. In 2008, Gao et al. demonstrated that the effectiveness of PC in rats was dependent on the number of cycles in the PC algorithm, as well as the durations of the ischemia/reperfusion phases [3].