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A new portable hypothermic perfusion apparatus for long-term heart preservation in canine models
A New Portable Hypothermic Perfusion Apparatus for Long-Term Heart Preservation in Canine Models K. Oshima, Y. Morishita, T. Yamagishi, J. Mohara, T. Takahashi, S. Ishikawa, and Y. Hasegawa
S
TORAGE of donor hearts for the long-term period could allow heart transport to a suitable recipient, a larger donor pool, and more detailed tissue typing. In spite of the superiority of coronary perfusion storage compared with simple immersion,1,2 the former is not clinically used because of its demanding management. We developed a new apparatus for long-term hypothermic preservation with a combination of coronary perfusion and immersion methods. This study was designed to estimate the efficacy of this apparatus by comparing it with a simple immersion procedure in 12-hour preservation of canine hearts. MATERIALS AND METHODS The main characteristics of this apparatus are (1) hypothermic storage, (2) nondependent energy source, (3) portability, and (4) variable perfusion pressure. This apparatus is composed of a storage chamber, a cooling chamber, and metal bars on which a perfusate bag is hung. A storage chamber filled with a cold (4°C) solution is fixed in a cooling chamber, and the space between a storage chamber and a cooling chamber is filled which ice slush. Therefore, a donor heart is immersed in a cold (4°C) solution during continuous coronary perfusion. Twelve adult mongrel dogs, weighing 8 to 10 kg, were used in this study. Following cardiac arrest with a GIK solution, coronary vascular beds were washed out via the aortic root with a 4°C University of Wisconsin (UW) solution at a pressure of 80 cm H2O. The heart was then excised and preserved for 12 hours. The study was divided into two groups; the coronary perfusion (CP) group (n 5 6) and the simple immersion (SI) group (n 5 6). In the CP group, the graft, which was immersed in a cold (4°C) UW solution, was perfused with a 4°C UW solution at a flow rate of 0.5 ; 0.7 mL/min using a new perfusion apparatus. In the SI group, the graft was simply immersed in a 4°C UW solution. Myocardial highenergy phosphates were measured using 31P-nuclear magnetic resonance (31P-NMR) spectroscopy prior to storage and at 3, 6, and 12 hours of preservation. b-adenosine triphosphate (b-ATP), phosphocreatine (Pcr), and inorganic phosphate (Pi) were calculated by observing the peak area on the spectrum. These values were expressed as a percentage of control values that were obtained prior to storage. Water content (WC) was measured immediately after removal of the heart and after preservation.
RESULTS
There were no problems during the period of continuous coronary perfusion storage using this apparatus, and 12hour preservation was safely and easily performed. 0041-1345/99/$–see front matter PII S0041-1345(98)01910-1
Table 1. b-ATP/Pi and Pcr/Pi Levels During Preservation b-ATP/Pi (%)
Pcr/Pi (%)
Preservation Period (h)
CP group SI group
Preservation Period (h)
3
6
12
3
78 6 8 64 6 2
62 6 5* 39 6 7
48 6 5* 23 6 8
48 6 6 31 6 13
6
12
30 6 9 22 6 8 — —
Data are expressed as mean 6 SEM. *P , .05 compared with SI group.
There was no significant difference in b-ATP/Pi levels between the two groups after 3 hours of preservation. b-ATP/Pi levels were significantly (P , .05) higher in the CP group than in the SI group at 6 and 12 hours after preservation (Table 1). As regards Pcr/Pi levels, there was no significant difference between the two groups after 3 hours of preservation. Pcr/Pi levels at 6 and 12 hours after preservation were 30 6 9% and 22 6 8%, respectively, in the CP group. Meanwhile, Pcr/Pi levels after 6 hours of preservation were detected only in one case of the SI group, and after 12 hours of preservation these were not detected in all cases of the SI group (Table 1). WC immediately after excision of the heart and after 12 hours of preservation was 76 6 1% and 75 6 0.5%, respectively, in the CP group and 77 6 0.1% and 77 6 1%, respectively, in the SI group. There was no significant difference in WC between the two groups. DISCUSSION
The capacity to prolong safe storage of the donor heart could expand a donor pool and increase the number of allografts available for heart transplantation. In addition, improved methods of preservation for the donor heart may enhance functional recovery after transplantation. Hypothermic simple immersion is clinically used as the method for donor heart storage, but the limit of storage with simple immersion has been reported to be 4 to 6 hours.3,4 The predominance of continuous coronary perfusion storage From the Second Department of Surgery, Gunma University School of Medicine, Gunma, Japan. Address reprint requests to Kiyohiro Oshima, MD, Second Department of Surgery, Gunma University School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan. © 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
1072
Transplantation Proceedings, 31, 1072–1073 (1999)
NEW PORTABLE HYPOTHERMIC PERFUSION APPARATUS
compared with simple immersion has been reported.5,6 The merits of coronary perfusion are to continue the anaerobic glucolysis system and to wash out anaerobic metabolites such as lactec acid, dihydronicotinamide-adenine dinucleotide (NADH), and H1 from the donor heart. However, coronary perfusion storage is not used clinically because circuits for coronary perfusion are complex and managements of coronary perfusion are demanding. We developed a new apparatus for coronary perfusion of the donor heart to perform coronary perfusion preservation more simply and more safely. In addition to such merits as hypothermic preservation, nondependent energy source, portability, and variable perfusion pressure, this system is a combined method of simple immersion and coronary perfusion. The donor heart is immersed in a cold (4°C) solution, and myocardial temperature of the graft is maintained around 4°C. Thus, low coronary flow is required for coronary perfusion, resulting in minimal damage of coronary vascular beds. Twelve-hour coronary perfusion using this apparatus was successfully performed with no trouble. Myocardial high-energy phosphate levels at 6 and 12 hours after preservation were significantly (P , .05) higher in the CP group than in the SI group. We used 31P-NMR spectroscopy to evaluate the metabolic and functional effects of 12-hour hypothermic coronary perfusion. This technique is increasingly used for studies on normothermic and hypo-
1073
thermic ischemia of the heart because it allows the noninvasive and repeated measurement of levels of myocardial high-energy phosphate stores.8 These are regarded as important for tissue viability. This experimental study suggests that coronary perfusion can be simply and safely performed with no energy dependence and may have broad clinical application. Further studies are required to determine optimal situations including perfusion pressure, flow rate, and perfusates for longterm preservation with coronary perfusion.
REFERENCES 1. Wicomb WN, Cooper DKC, Hassoulas J, et al: J Thorac Cardiovasc Surg 83:133, 1982 2. Wicomb WN, Cooper DKC, Novtzky D, et al: Ann Thorac Surg 37:243, 1984 3. Lurie KG, Billingham ME, Masek MA, et al: J Thorac Cardiovasc Surg 84:122, 1981 4. Proctor E, Matthews G, Archibald J: Thorax 26:99, 1971 5. Cooper DKC, Wicomb WN, Barnard CN: Heart Transplant 2:104, 1983 6. Ferrera R, Marcsek P, Larese A, et al: J Heart Lung Transplant 12:463, 1993 7. Calhoon JH, Bunegin L, Gelineau JF, et al: Ann Thorac Surg 62:91, 1996 8. Nunnally RL, Bottomley PA: Science 211:177, 1981
S
TORAGE of donor hearts for the long-term period could allow heart transport to a suitable recipient, a larger donor pool, and more detailed tissue typing. In spite of the superiority of coronary perfusion storage compared with simple immersion,1,2 the former is not clinically used because of its demanding management. We developed a new apparatus for long-term hypothermic preservation with a combination of coronary perfusion and immersion methods. This study was designed to estimate the efficacy of this apparatus by comparing it with a simple immersion procedure in 12-hour preservation of canine hearts. MATERIALS AND METHODS The main characteristics of this apparatus are (1) hypothermic storage, (2) nondependent energy source, (3) portability, and (4) variable perfusion pressure. This apparatus is composed of a storage chamber, a cooling chamber, and metal bars on which a perfusate bag is hung. A storage chamber filled with a cold (4°C) solution is fixed in a cooling chamber, and the space between a storage chamber and a cooling chamber is filled which ice slush. Therefore, a donor heart is immersed in a cold (4°C) solution during continuous coronary perfusion. Twelve adult mongrel dogs, weighing 8 to 10 kg, were used in this study. Following cardiac arrest with a GIK solution, coronary vascular beds were washed out via the aortic root with a 4°C University of Wisconsin (UW) solution at a pressure of 80 cm H2O. The heart was then excised and preserved for 12 hours. The study was divided into two groups; the coronary perfusion (CP) group (n 5 6) and the simple immersion (SI) group (n 5 6). In the CP group, the graft, which was immersed in a cold (4°C) UW solution, was perfused with a 4°C UW solution at a flow rate of 0.5 ; 0.7 mL/min using a new perfusion apparatus. In the SI group, the graft was simply immersed in a 4°C UW solution. Myocardial highenergy phosphates were measured using 31P-nuclear magnetic resonance (31P-NMR) spectroscopy prior to storage and at 3, 6, and 12 hours of preservation. b-adenosine triphosphate (b-ATP), phosphocreatine (Pcr), and inorganic phosphate (Pi) were calculated by observing the peak area on the spectrum. These values were expressed as a percentage of control values that were obtained prior to storage. Water content (WC) was measured immediately after removal of the heart and after preservation.
RESULTS
There were no problems during the period of continuous coronary perfusion storage using this apparatus, and 12hour preservation was safely and easily performed. 0041-1345/99/$–see front matter PII S0041-1345(98)01910-1
Table 1. b-ATP/Pi and Pcr/Pi Levels During Preservation b-ATP/Pi (%)
Pcr/Pi (%)
Preservation Period (h)
CP group SI group
Preservation Period (h)
3
6
12
3
78 6 8 64 6 2
62 6 5* 39 6 7
48 6 5* 23 6 8
48 6 6 31 6 13
6
12
30 6 9 22 6 8 — —
Data are expressed as mean 6 SEM. *P , .05 compared with SI group.
There was no significant difference in b-ATP/Pi levels between the two groups after 3 hours of preservation. b-ATP/Pi levels were significantly (P , .05) higher in the CP group than in the SI group at 6 and 12 hours after preservation (Table 1). As regards Pcr/Pi levels, there was no significant difference between the two groups after 3 hours of preservation. Pcr/Pi levels at 6 and 12 hours after preservation were 30 6 9% and 22 6 8%, respectively, in the CP group. Meanwhile, Pcr/Pi levels after 6 hours of preservation were detected only in one case of the SI group, and after 12 hours of preservation these were not detected in all cases of the SI group (Table 1). WC immediately after excision of the heart and after 12 hours of preservation was 76 6 1% and 75 6 0.5%, respectively, in the CP group and 77 6 0.1% and 77 6 1%, respectively, in the SI group. There was no significant difference in WC between the two groups. DISCUSSION
The capacity to prolong safe storage of the donor heart could expand a donor pool and increase the number of allografts available for heart transplantation. In addition, improved methods of preservation for the donor heart may enhance functional recovery after transplantation. Hypothermic simple immersion is clinically used as the method for donor heart storage, but the limit of storage with simple immersion has been reported to be 4 to 6 hours.3,4 The predominance of continuous coronary perfusion storage From the Second Department of Surgery, Gunma University School of Medicine, Gunma, Japan. Address reprint requests to Kiyohiro Oshima, MD, Second Department of Surgery, Gunma University School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan. © 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
1072
Transplantation Proceedings, 31, 1072–1073 (1999)
NEW PORTABLE HYPOTHERMIC PERFUSION APPARATUS
compared with simple immersion has been reported.5,6 The merits of coronary perfusion are to continue the anaerobic glucolysis system and to wash out anaerobic metabolites such as lactec acid, dihydronicotinamide-adenine dinucleotide (NADH), and H1 from the donor heart. However, coronary perfusion storage is not used clinically because circuits for coronary perfusion are complex and managements of coronary perfusion are demanding. We developed a new apparatus for coronary perfusion of the donor heart to perform coronary perfusion preservation more simply and more safely. In addition to such merits as hypothermic preservation, nondependent energy source, portability, and variable perfusion pressure, this system is a combined method of simple immersion and coronary perfusion. The donor heart is immersed in a cold (4°C) solution, and myocardial temperature of the graft is maintained around 4°C. Thus, low coronary flow is required for coronary perfusion, resulting in minimal damage of coronary vascular beds. Twelve-hour coronary perfusion using this apparatus was successfully performed with no trouble. Myocardial high-energy phosphate levels at 6 and 12 hours after preservation were significantly (P , .05) higher in the CP group than in the SI group. We used 31P-NMR spectroscopy to evaluate the metabolic and functional effects of 12-hour hypothermic coronary perfusion. This technique is increasingly used for studies on normothermic and hypo-
1073
thermic ischemia of the heart because it allows the noninvasive and repeated measurement of levels of myocardial high-energy phosphate stores.8 These are regarded as important for tissue viability. This experimental study suggests that coronary perfusion can be simply and safely performed with no energy dependence and may have broad clinical application. Further studies are required to determine optimal situations including perfusion pressure, flow rate, and perfusates for longterm preservation with coronary perfusion.
REFERENCES 1. Wicomb WN, Cooper DKC, Hassoulas J, et al: J Thorac Cardiovasc Surg 83:133, 1982 2. Wicomb WN, Cooper DKC, Novtzky D, et al: Ann Thorac Surg 37:243, 1984 3. Lurie KG, Billingham ME, Masek MA, et al: J Thorac Cardiovasc Surg 84:122, 1981 4. Proctor E, Matthews G, Archibald J: Thorax 26:99, 1971 5. Cooper DKC, Wicomb WN, Barnard CN: Heart Transplant 2:104, 1983 6. Ferrera R, Marcsek P, Larese A, et al: J Heart Lung Transplant 12:463, 1993 7. Calhoon JH, Bunegin L, Gelineau JF, et al: Ann Thorac Surg 62:91, 1996 8. Nunnally RL, Bottomley PA: Science 211:177, 1981