title: Cardioprotective effect of ischemic preconditioning on global myocardial ischemia in a sheep right heart bypass model.
abstract: OBJECTIVE
  Ischemic preconditioning has been used to induce the myocardium to adapt to ischemic stress preceded by short periods of ischemia and reperfusion. We used a sheep right heart bypass model with a conductance catheter to assess the cardioprotective effect of ischemic preconditioning on 30-minute normothermic global myocardial ischemia.
  
  
  METHODS
  Ischemic preconditioning was conducted in 6 sheep in 35-minute aortic cross-clampings interspersed with 5 minutes of reperfusion during cardiopulmonary bypass, with 6 sheep as time-matched controls. Global myocardial ischemia was subsequently achieved in 30-minute aortic cross-clamping with left ventricular unloading during normothermic cardiopulmonary bypass. Weaning from cardiopulmonary bypass was conducted 40 minutes after reperfusion. Before ischemia and 40, 70, and 100 minutes after reperfusion, left ventricular pressure-volume loops were measured using a conductance catheter during right heart bypass preparation. Left ventricular contractility, diastolic function, and mechanical efficiency were then evaluated. Right heart bypass was instituted to control the preload and to decompress the right ventricle completely, thereby eliminating parallel conductance variation.
  
  
  RESULTS
  No differences in the studied parameters were seen between ischemic-preconditioning and control groups before ischemia. Left ventricular contractility, diastolic function, and mechanical efficiency in the ischemic-preconditioning group were significantly superior to those in the control group after reperfusion.
  
  
  CONCLUSIONS
  Ischemic preconditioning attenuates postischemic myocardial dysfunction in a sheep model using 30-minute unloaded normothermic global myocardial ischemia. Ischemic preconditioning would thus be clinically significant when the ischemic damage is severe.
authors.affiliation: Department of Cardiac Surgery, Katholieke Universiteit Leuven, Belgium.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Tanoue
authors.forename: Paul
authors.initials: P
authors.lastname: Herijgers
authors.forename: Bart
authors.initials: B
authors.lastname: Meuris
authors.forename: Veerle
authors.initials: V
authors.lastname: Leunens
authors.forename: Marleen
authors.initials: M
authors.lastname: Lox
authors.forename: Willem
authors.initials: W
authors.lastname: Flameng
mesh_terms: D000818:Animals; D005112:Extracorporeal Circulation; D018610:Heart Bypass, Right; D006439:Hemodynamics / Q000502:physiology*; D019157:Ischemic Preconditioning, Myocardial; D023421:Models, Animal; D012756:Sheep; D016277:Ventricular Function, Left / Q000502:physiology*