Microperfusion techniques for long-term hypothermic preservation

Background: The aim of this study was to compare several methods of hypothe rmic heart preservation. Methods: We preserved isolated pig hearts for 24 hours in cold cardioplegia (4 degrees C), using either continuous microperfusion (Group I) or simple storage (Group II), and with a new preservative solution (NPS, groups IA an d IIA) vs St. Thomas' solution (groups IB and IIB). The main characteristic s of the NPS include (1) prevention of cell swelling with polyethelene glyc ol (PEG), (2) low calcium and magnesium, and (3) presence of metabolic subs trates, such as glucose, insulin, pyruvate, aspartate, alanylglutamine, and membrane stabilization compounds such as ethanol and chlorpromazine. Results: The 4 above groups were compared with hearts harvested and immedia tely reperfused (control group). During preservation, only Group IB showed significant edema (40% +/- 8.4% water gain). Adenylate charge was 25%; to 5 0% higher in microperfused Groups LA and IB (0.678 +/- 0.049 and 0.795 +/- 0.071, respectively) as compared with simple-storage groups IIA and IIB (0. 605 +/- 0.048 and 0.524 +/- 0.160, respectively). Ultrastructural analysis showed that tissue injury occurred mainly in Group IIB (altered mitochondri a, chromatin clumping). Functional data showed better recovery of NPS group s as compared with St. Thomas groups: coronary flow was identical in Group IB and control (57.8 +/- 22 and 56.6 +/- 14 ml/min/100 g, respectively), an d in IA > IB (p < 0.001) and IIA > IIB (p < 0.01); the rate pressure produc ts were higher in NPS groups compared with St. Thomas groups (IA > IB, p < 0.01); IIA > IIB, (p < 0.05). Conclusions: The microperfusion method associated with the NPS provides exc ellent protection in long-term hypothermic heart preservation.