Long-term heart preservation using a new portable hypothermic perfusion apparatus

Abstract

Objective: Perfusion storage is not often used clinically compared with simple immersion because of complicated circuits and demanding management. We developed a new apparatus for preservation combined with simple immersion and continuous coronary perfusion. Methods The main characteristics of this apparatus are as follows: (1) hypothermic storage, (2) does not require any energy source, (3) variable perfusion pressure, and (4) portability. The perfusion apparatus is composed of a storage chamber, a cooling chamber, and metal bars from which a perfusate bag is suspended. Adult mongrel dogs were divided into two groups: the coronary perfusion group (CP, n = 6) and the simple immersion group (SI, n = 6). Coronary vascular beds of the dog were washed out with a University of Wisconsin (UW) solution following cardiac arrest obtained using a GIK solution. The hearts were then excised. In the CP group, the heart graft, which was immersed in a 4° C UW solution, was perfused with the same solution at a flow rate of 35 ∼ 50 ml/hr. In the SI group, the heart graft was immersed in a 4° C UW solution only. The heart graft was preserved for 12 hours in both groups. β-adenosine triphosphate (β-ATP), phosphocreatine (Pcr), and inorganic phosphate (Pi) levels were measured immediately after excision of the heart, and at 3, 6, and 12 hours after preservation. β-ATP, Pcr, and Pi values were expressed as a percentage of control values, which had been obtained immediately after excision of the heart. Water content of the myocardium was measured prior to and after 12-hour preservation. The preserved graft was then evaluated through orthotopic transplantation. Results β-ATP/Pi levels at 6 and 12 hours after preservation were significantly higher in the CP group than in the SI group (62 ± 5 versus 39 ± 7%, 48 ± 5 versus 22 ± 8%, respectively, p < 0.05). Pcr/Pi levels at 6 and 12 hours after preservation were 30 ± 9% and 22 ± 8%, respectively in the CP group, while Pcr/Pi levels in the SI group were detected in only one case. There was no significant difference in water content either prior to or after 12-hour preservation between the two groups. Histopathologically, irregular expansion and/or contraction of myocardial fibers were more severe in the SI group than in the CP group. The recovery rate of hemodynamic parameters 2 hours after heart transplantation was significantly ( p < 0.05) higher in the CP group than in the SI group. Conclusion Stable and safe long-term canine heart preservation with continuous coronary perfusion associated with immersion is possible using this new apparatus, and may have broad clinical application.