PROLONGING MYOCARDIAL PRESERVATION WITH A MODIFIED UNIVERSITY-OF-WISCONSIN SOLUTION CONTAINING 2,3-BUTANEDIONE MONOXIME AND CALCIUM

The University of Wisconsin solution is an effective preservative for cold storage of the cardiac allograft. Tn an earlier study we showed t hat addition of calcium and 2,3-butanedione monoxime, a reversible inh ibitor of myocardial contracture, further improved preservation of the rabbit heart. In this study we investigated the following: (1) the ef fects of different concentrations of 2,3-butanedione monoxime and calc ium on function of the preserved rabbit heart, (2) how heart preservat ion is affected when 2,3-butanedione monoxime and calcium are added to the St Thomas' Hospital and Stanford solutions, and (3) how 2,3-butan edione monoxime and calcium, at optimal concentrations in University o f Wisconsin solution, affect hearts preserved up to 48 hours. Rabbit h earts were flushed with preservative and stored at 4 degrees C for 24, 30, 40, or 48 hours. Myocardial function was assessed during 60 minut es of isolated reperfusion, and myocardial adenine nucleotide content was measured after completion of reperfusion. Three concentrations of 2,3-butanedione monoxime (15, 30, and 60 mmol/ L) in the University of Wisconsin solution were studied in hearts preserved for 30 hours. Sto rage with 2,3-butanedione monoxime at 30 mmol/L resulted in significan tly better left ventricular developed pressure (p < 0.01), left ventri cular end-diastolic volume (p < 0.01), rate of left ventricular pressu re rise (p < 0.01), coronary how (p < 0.05), rate-pressure product (p < 0.001), and adenine nucleotide regeneration (p < 0.05) than with 60 mmol/L, although function was not significantly different when the osm olarity of the solutions was equalized. There was significant reductio n in end-diastolic volume (p < 0.05) and adenine nucleotide recovery ( p < 0.01) when 2,3-butanedione monoxime was lowered to 15 mmol/L. Decr easing the calcium concentration from 1.0 to 0.1 mmol/L also had a del eterious effect on myocardial function (p < 0.05). The addition of 30 mmol/L 2,3-butanedione monoxime and 1.0 mmol/L calcium to the St. Thom as' or Stanford solutions improved preservation of the heart when comp ared with the unmodified solutions, but to a lesser degree than,vith t he modified University of Wisconsin solution. After 24 to 48 hours of storage in University of Wisconsin solution containing 30 mmol/L 2,3-b utanedione monoxime and 1.0 mmol/L calcium, there was substantial impr ovement in developed pressure (p < 0.001), end-diastolic volume (p < 0 .05), and rate pressure product; (p < 0.001), although there was littl e effect on heart rate and coronary flow, then compared with the unmod ified University of Wisconsin solution. We conclude that modification of the University of Wisconsin solution with 30 mmol/L 2,3-butanedione monoxime and 1.0 mmol/L calcium significantly improves long-term pres ervation of the rabbit heart. Further extension in preservation might be accomplished by optimizing the osmolarity of this modified solution .