title: Improved cardioprotection using a novel stepwise ischemic preconditioning protocol in rabbit heart.
abstract: BACKGROUND
  The current commonly used cardiac ischemic preconditioning (IPC) protocol, involving three 5-min cycles of ischemia-reperfusion (I/R), may not be clinically beneficial because of its acutely deleterious effects on hemodynamics. This study attempted to assess the effects of a novel stepwise IPC scheme on cardiac function, infarct size, and arrhythmogenesis in a rabbit model of prolonged I/R.
  
  
  METHODS
  Anesthetized open-chest rabbits were subjected to 60-min occlusion of a proximal branch of the left coronary artery followed by 180-min reperfusion. Animals were divided into five groups (n = 6 each): (1) control group (no IPC); (2) 2-min IPC group (three cycles of 2-min IPC); (3) 5-min IPC group (three cycles of 5-min IPC); (4) 10-min IPC group (three cycles of 10-min IPC); and (5) stepwise IPC group (2-, 5-, and 10-min I/R).
  
  
  RESULTS
  Compared with control group, 2-, 5-, and 10-min IPC decreased arrhythmia score by 16%, 67%, and 33%, respectively. Remarkably, stepwise IPC resulted in a 78% reduction of arrhythmias. Stepwise IPC also produced the least ventricular infarct size when compared with 2-, 5-, and 10-min IPC groups (16.4% versus 39.3%, 28.1%, and 38.5%, P < 0.05).
  
  
  CONCLUSIONS
  These results suggest that stepwise IPC has better cardioprotective effects against prolonged I/R injury and may serve as an acceptable approach to clinical revascularization procedures on the heart, including catheter-based and surgical approaches.
authors: Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California.
authors: Kentaro
authors: K
authors: Yamakawa
authors: Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California.
authors: Wei
authors: W
authors: Zhou
authors: Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California.
authors: Yoshihiro
authors: Y
authors: Ko
authors: Department of Cardiovascular Surgery, David Geffen School of Medicine, University of California, Los Angeles, California.
authors: Peyman
authors: P
authors: Benharash
authors: Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California.
authors: Mariko
authors: M
authors: Takemoto
authors: Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California. Electronic address: amahajan@mednet.ucla.edu.
authors: Aman
authors: A
authors: Mahajan
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000473:pathology; D003971:Diastole; D006339:Heart Rate; D006439:Hemodynamics; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D023421:Models, Animal; D009203:Myocardial Infarction / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D009206:Myocardium / Q000473:pathology; D011817:Rabbits; D013599:Systole; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
keywords: Arrhythmia; LV work efficiency; Myocardial ischemia; Preconditioning