Amelioration of postischemic stunning by deferoxamine-blood cardioplegia

Limitation of oxygen free-radical injury was assessed in canine hearts by sonomicrometrically quantifying regional stroke work (RSW) in areas of myocardium perfused by the left anterior descending (LAD) and left circumflex (LCX) arteries. Volume loading of the left ventricle was performed on modified right-heart bypass before and 30 minutes after 20 minutes of LAD occlusion followed by 60 minutes of global cardioplegic arrest with either blood cardioplegia (group 1), blood cardioplegia with adjuvant deferoxamine (500 mg/l) plus 100 mg infused into the aortic root for 5 minutes after unclamping (group 2), or blood cardioplegia with adjuvant deferoxamine (600 mg/l) with unmodified reperfusion (group 3). Surgical revascularization was modeled by reopening the LAD with the first cardioplegia reinfusion. The slope of the RSW versus preload relation (a load-independent index of contractility) was decreased by a mean amount of 44% in the LAD region of group 1 hearts but was preserved in group 2 and 3 hearts. The slope of the LCX region was preserved in all groups. The use of adjuvant deferoxamine in this model of early surgical reperfusion eliminates measurable postischemic stunning.