The Second Window of Preconditioning (SWOP) Where Are We Now?

Abstract

A standard ischemic preconditioning (IPC) stimulus of one or more brief episodes of non-lethal myocardial ischemia and reperfusion elicits a bi-phasic pattern of cardioprotection. The first phase manifests almost immediately following the IPC stimulus and lasts for 1-2 h, after which its effect disappears (termed classical or early IPC). The second phase of cardioprotection appears 12-24 h later and lasts for 48-72 h (termed the Second Window of Protection [SWOP] or delayed or late IPC). The cardioprotection conferred by delayed IPC is robust and ubiquitous but is not as powerful as early IPC. Although there are some similarities in the mechanisms underlying early and delayed IPC, one of the major distinctions between the two is the latter's requirement for de novo protein synthesis of distal mediators such as iNOS and COX-2 which mediate the cardioprotection 24 h after the IPC stimulus. The phenomenon of delayed IPC has been demonstrated in man using a variety of experimental models. However, its clinical application has been limited by the same factors which affect early IPC- i.e. the need to intervene before the onset of myocardial ischemia, thereby restricting its potential clinical utility to planned settings of acute myocardial ischemia-reperfusion injury such as coronary artery bypass graft surgery, cardiac transplantation and percutaneous coronary intervention. In this article, the focus will be on the origins of delayed IPC, the mechanisms underlying its delayed cardioprotective effect, and the potential areas for its clinical application.

Delayed preconditioning prevents ischemia/reperfusion-induced endothelial injury in rats: role of ROS and eNOS

“…There are two phases of protection afforded by IPC, that is, the early phase and the late phase. 11 This study focuses on the late phase of IPC, termed delayed preconditioning, because delayed IPC confers a longer window of cytoprotection and has greater significance for cardiovascular protection. 12 The molecular mechanisms and mediators that account for delayed IPC have been extensively investigated, and it has emerged that eNOS has a key role in this phenomenon in the heart.…”

Cardioprotection Techniques: Preconditioning, Postconditioning and Remote Con-ditioning (Basic Science)

“…These authors demonstrated in the canine heart that following a standard IPC stimulus, MI size reduction was observed immediately but was lost 6 or 12 hours later and then re-appeared again at 24 hours and lasted until 72 hours [17]. This delayed effect of IPC has been termed the second window of protection or delayed or late preconditioning [18].…”

“…A standard IPC stimulus induces 2 phases of cardioprotection: the first phase (termed classical preconditioning or the first window of protection) begins immediately following the IPC stimulus and lasts for 2-3 hours, after which the cardioprotective effect wanes and disappears, and a second phase (termed delayed or late preconditioning or the second window of cardioprotection) re-appearing 12-24 hours later and lasting up to 72 hours [18].…”

“…In this review article, an overview will be provided of these 3 forms of ischemic conditioning, with respect to the pre-clinical experimental literature exploring their major characteristics and underlying signalling mechanisms. It would be impossible for a single review article to provide a comprehensive account of these individual endogenous cardioprotective phenomena and for this the reader is referred to the following review articles [4][5][6][7].…”

Exercise for cardiac health and regeneration: killing two birds with one stone

“…Translating experimental findings into the clinic, even with safety proven agents, has been challenging (17,18). To date, physical exercise is a strongly recommended intervention with positive effects in the prevention and treatment of established cardiovascular diseases, that acts as a "master polypill" capable to strengthen the heart, improve blood pressure, tackle different risk factors and attenuate injury upon a stressful event (19).…”