Continuous Perfusion Improves Preservation of Donor Rat Hearts: Importance of the Implantation Phase

Background. Continuous hypothermic perfusion of donor hearts may provide extra protection for long ischemic times and suboptimal donors. The aim of three separate studies was to assess the effect of continuous hypothermic perfusion during simulated donor heart storage and implantation. Methods. In study 1 twelve isolated rat hearts underwent 10 minutes of normothermic ischemia to simulate the effect of brain death on the heart and 5 hours of cardioplegic arrest, using University of Wisconsin solution. Six hearts were statically stored in University of Wisconsin solution at 2°C, and six were perfused with University of Wisconsin solution. To assess the effect of simulated implantation, in study 2 an additional 12 hearts were statically stored for 5.5 hours in University of Wisconsin solution, six of which were rewarmed to a mean of 16°C over the last 30 minutes of arrest. To assess the effect of simulated perfusion, in study 3 during implantation 12 hearts were rewarmed to a mean of 16°C over the last 30 minutes of arrest, during which time six were perfused with 2°C solution. Results. Hearts perfused during storage demonstrated greater recovery of prearrest power, 85.8% ± 1.8%, than hearts preserved by static storage, 72.7% ± 3.0% (p < 0.01). The simulated warm implantation period reduced recovery of power from 68.3% ± 5.1% to 40.2% ± 2.0% (p < 0.001). Perfusion during warm implantation improved recovery to 61.8% ± 3.9% (p < 0.01). In all experiments improved function was accompanied by improved metabolic energy status. Conclusions. During the implantation period of heart transplantation the donor heart sustains injury that could amount to 50% of total ischemic injury. Continuous perfusion during the cold storage phase and during simulated implantation improves recovery of the donor heart.