ZINC-BIS-HISTIDINATE PRESERVES CARDIAC-FUNCTION IN A PORCINE MODEL OFCARDIOPLEGIC ARREST

Background. We examined the ability of zinc-bis-histidinate to preserv e postarrest myocardial function when added to a standard crystalloid cardioplegic solution. Methods. Domestic pigs (35 to 50 kg) on left-si ded cardiopulmonary bypass were subjected to 90 minutes of regional is chemia followed by 60 minutes of hypothermic cardioplegic arrest induc ed by antegrade infusion of 20 mL/kg cold St. Thomas' #2 cardioplegic solution with or without 100 mu mol/L of zinc-bis-histidinate and main tained by infusion of 10 mL/kg of the same every 20 minutes. During re perfusion function was assessed at 1 and 3 hours over increasing prelo ads using the right-sided bypass method. Results. At roller pump flows up to 2,000 mL/min, stroke work index-end-diastolic pressure curves w ere significantly (p < 0.05) higher and shifted to the left in treated hearts. In a series of pigs, echocardiography was used to determine e nd-diastolic and end-systolic volumes. At roller pump flows up to 3,50 0 mL/min, end-systolic pressure-end-systolic volume curves were signif icantly higher and shifted to the left in treated hearts. Left ventric ular ejection fraction, fractional shortening, stroke volume, and card iac output were significantly (p < 0.05) higher in treated hearts. Ele ctron microscopy revealed that mitochondria in tissue not at risk appe ared more swollen in control hearts. Conclusions. The results of this study support the conclusion that zinc-bis-histidinate is effective as a myocardial preservative when added to a crystalloid cardioplegic so lution.