EFFECTS OF CALCIUM-CONCENTRATION, LACTOBIONATE CONTENT, AND SODIUM POTASSIUM RATIO OF PRESERVATION SOLUTIONS ON RESTING LEFT-VENTRICULAR PRESSURE AND POSTREPERFUSION FUNCTION OF RABBIT HETEROTOPIC HEART-TRANSPLANTS/

Background: We tested the hypothesis that the University of Wisconsin solution has a ionic composition (i.e., intracellular, calcium-free, l actobionate-enriched) that may be beneficial for cold heart graft pres ervation independently from any additives. Methods: St. Thomas' Hospit al and University of Wisconsin solutions were compared with the follow ing: (1) C solution, a simplified University of Wisconsin-like solutio n (i.e., intracellular, calcium-free, lactobionate-enriched); (2) A so lution, an St. Thomas' Hospital-like solution (extracellular, calcium [Ca2+] = 1.2 mmol/L) in which chloride was replaced by lactobionate; ( 3) B solution, an intracellular, lactobionate-enriched, calcium-contai ning solution ([Ca2+] = 1.2 mmol/L). Rabbit hearts were transplanted h eterotopically in the abdomen of recipient animals either immediately or after 6 hours of storage. Hemodynamic parameters were recorded 60 m inutes after unclamping. Results: After a 6-hour storage, University o f Wisconsin and C solutions provided better preservation than B and St . Thomas' Hospital solutions: diastolic pressures were lower; develope d pressure and rate of pressure rise were higher. C solution was super ior to University of Wisconsin solution only for rate of pressure rise . A solution was intermediary. A significant alteration of resting pre ssure and hemodynamic parameters was generally observed during the 6-h our storage. Nonsignificant changes of developed pressure and rate of pressure rise were only observed in C and B solutions: This is explain ed by systolic alteration after immediate reimplantation for the B gro up and good preservation for the C group. Resting pressure was unchang ed over a 6-hour storage only for the C group, but this measure was no t determined for University of Wisconsin. A correlation exists for var ious left ventricular volumes between resting pressure and postreperfu sion hemodynamic data. Replacement of chloride by lactobionate (A vers us St. Thomas' Hospital) may have improved resting and diastolic press ures by other mechanisms than limitation of net water gain during stor age. Conclusions: The importance of additives contained in University of Wisconsin solution has not been proven to be significant in our mod el for B-hour adult rabbit heart preservation (University of Wisconsin versus C). The low sodium/potassium ratio, and the absence of calcium addition may have protected myocytes from calcium inflow during stora ge in C and University of Wisconsin solutions. Prevention of a calcium -induced increase in resting tone during storage can be considered a c rucial goal for heart graft preservation.