Zinc-bis-Histidinate Preserves Cardiac Function in a Porcine Model of Cardioplegic Arrest

Background. We examined the ability of zinc-bis-histidinate to preserve postarrest myocardial function when added to a standard crystalloid cardioplegic solution. Methods. Domestic pigs (35 to 50 kg) on left-sided cardiopulmonary bypass were subjected to 90 minutes of regional ischemia followed by 60 minutes of hypothermic cardioplegic arrest induced by antegrade infusion of 20 mL/kg cold St. Thomas’ #2 cardioplegic solution with or without 100 μmol/L of zinc-bis-histidinate and maintained by infusion of 10 mL/kg of the same every 20 minutes. During reperfusion function was assessed at 1 and 3 hours over increasing preloads using the right-sided bypass method. Results. At roller pump flows up to 2,000 mL/min, stroke work index–end-diastolic pressure curves were significantly ( p < 0.05) higher and shifted to the left in treated hearts. In a series of pigs, echocardiography was used to determine end-diastolic and end-systolic volumes. At roller pump flows up to 3,500 mL/min, end-systolic pressure–end-systolic volume curves were significantly higher and shifted to the left in treated hearts. Left ventricular ejection fraction, fractional shortening, stroke volume, and cardiac output were significantly ( p < 0.05) higher in treated hearts. Electron microscopy revealed that mitochondria in tissue not at risk appeared 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 solution.