Remote ischemic preconditioning versus intermittent hypoxia training: a comparative analysis for cardioprotection

Ischemic preconditioning (IPC) is an adaptive phenomenon that occurs after one or more short periods of ischemia/reperfusion, and consists in increasing the tolerance of an organ or tissue to the damaging effect of a long period of ischemia/reperfusion. Although IPC was shown to have a protective effect in animal models or during operative interventions, the obvious difficulties involved in subjecting the heart to direct IPC restrict its potential clinical applications. In this perspective, the phenomenon of remote ischemic preconditioning (RIPC: ischemia/reperfusion cycles in the arm or leg) appears extremely encouraging. Intermittent hypoxic training (IHI, periodic exposure of an organism to hypoxic gas mixtures, or stay in the chamber or altitudes) also has powerful adaptogenic effect increasing the resistance to subsequent episodes of severe hypoxia/ischemia. This review discusses main mechanisms and clinical applications of RIPC in cardiology versus IHT technologies. Benefits and disadvantages of both methods are under consideration. Positive and negative effects of hypercapnia during the RIPC technology are also examined. We wish to stimulate a comprehensive understanding of such a complex physiological phenomenon as intermittent hypoxia and ischemic preconditioning in order to prevent or reduce their harmful consequences, while maximize their potential utility as an effective therapeutic tools.