Tutorial
Utilization of Paragonix SherpaPak for human donor heart preservation
A heart transplant is the gold standard treatment for end stage heart failure. Preservation of the donor heart during its transfer from the hospital of the donor to that of the recipient has a significant impact on the outcome of the transplant procedure. Icebox storage is a conventional method utilized for this purpose that may not provide uniform cooling of the donor heart and does not allow monitoring of the temperature of the donor heart during preservation. The Paragonix SherpaPak Cardiac Transport System offers uniform cooling by suspending the donor heart in a preservation solution and provides continuous temperature monitoring.
Icebox storage is a conventional method of preserving the donor heart during transport. A study of 186 organs showed that the average organ temperature during transport was below +2°C; after 6 hours, it was below ±0°C . Such low temperatures may cause freeze injury to the donor heart whereas prolonged transport or suboptimal storage at a higher temperature may cause ischemic injury. The Paragonix SherpaPak Cardiac Transport System (Paragonix Technologies, Inc., Cambridige, MA, USA) offers uniform cooling through its proprietary CoolSafe technology that is capable of maintaining a consistent temperature of 4 to 8°C .
The intended organ storage time for the Paragonix SherpaPak Cardiac Transport System is up to 4 hours; however, an animal experiment demonstrated the maintenance of a heart temperature from 4 to 8°C using the SherpaPak . The system suspends the donor heart in a preservation solution for even cooling in a pressure-controlled, leak-proof, rigid canister that provides a consistent temperature range, prevents cold injury, and offers real-time monitoring and data reporting.
The heart of a young patient with irreversible brain ischemia was offered for transplantation. The donor heart was assessed functionally with the help of transesophageal echocardiography and a cardiac output study utilizing a Swan-Ganz catheter. The heart demonstrated good biventricular contractile function with no palpable coronary artery disease, and it was formally accepted for transplantation.
1 - Implantation of a donor heart in a SherpaPak system (0:17)
The Paragonix SherpaPak was unboxed, and the shipper was lined with 3 SherpaCool ribbons. The shell base containing the organ canister was handed over to the scrub nurse in a sterile manner. Following an aortic cross-clamp, three liters of Bretschneider cardioplegia was delivered into the ascending aorta and the heart was procured.
On the back table, a suitably sized heart connector was introduced into the donor aorta and fixed with umbilical tape. The heart was anchored to the canister lid with the help of a heart connector and immersed in the organ canister, which contained 3 liters of the Bretschneider solution. The lid was clipped onto the canister. The air inside the canister was forced out by topping up the canister with a similar solution from a port at a lower level on the lid. The organ canister was then inserted into the shell base by carefully inserting the temperature probe of the canister into the base socket of the shell. The shell lid was closed with the 4 clips on the top.
The shell was introduced into the shipper by carefully inserting the temperature probe of the shell into the shipper socket. An ice pack was slid under the shell handle and the shipper lid was closed. Data logger button 1 was pressed to log the temperature and the time.
2 - SherpaPak preservation (3:21)
The real-time temperature could be assessed with the help of the SherpaPak app downloaded to a smartphone. Following 76 minutes of transport, the shipper was opened in the operating room of the recipient’s institution. The shell was removed from the shipper, and its lid was opened. The scrub nurse removed the organ canister in a sterile manner. The canister was opened; the heart was disconnected from the lid and handed over to the surgeon performing the implant.
Outcome
The donor heart was given to a middle-aged recipient with chronic advanced heart failure. The implant procedure was uneventful. The heart was reanimated immediately following removal of the aortic cross-clamp. The recipient made a quick recovery following the transplant procedure.
Discussion
Because the SherpaPak was just recently introduced as a donor heart preservation system, experience using it as part of a human heart transplant procedure is minimal. The first clinical report of a successful heart transplant using this system indicates a cold ischemia time of slightly more than 5 hours .
Conventional ice box storage is a time tested, inexpensive method of donor heart preservation and is considered safe for up to 4 hours. Donor hearts with more than 6 hours of cold ischemia are rarely transplanted, and those with an ischemia time of 4 to 6 hours have a 5% reduced survival at 5 years post-transplant . Whereas the SherpaPak offers optimum, uniform cooling of the donor heart, because of the dearth of information in the literature, there is no evidence that the system can offer better post-transplant outcomes with donor hearts with an ischemia time of more than 4 hours. Because most of the donors are located within reasonable distances from the implant centers, the possibility of obtaining enough donor hearts with ischemia times greater than 4 hours for a randomized trial is small. We will have to rely on the case series utilizing the SherpaPak for donor heart preservation that hopefully will be reported in a few years’ time to evaluate its reliability in preserving donor hearts with prolonged ischemia times.
We advise using the utmost care with the temperature probes when inserting a canister into the shell and the shell into the shipper. A long aorta is harvested so that the part of the aorta that is attached to the heart connector can be discarded before the heart is implanted in the recipient . When the donor heart is removed from the canister, opening the vent on the canister lid avoids the sudden release of the lid and the possibility of spilled fluid. The SherpaPak offers uniform hypothermic preservation of the donor heart and continuous monitoring of the myocardial temperature.
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PubMed Abstract | Publisher Full Text - https://paragonixtechnologies.com/products/sherpapak-cardiac/
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PubMed Abstract | Free Full Text - Naito N, Funamoto M, Pierson RN, D'Alessandro DA. First clinical use of a novel hypothermic storage system for a long-distance donor heart procurement. J Thorac Cardiovasc Surg. 2020 Feb;159(2):e121–e123.
PubMed Abstract | Publisher Full Text - Lund LH, Khush KK, Cherikh WS, Goldfarb S, Kucheryavaya AY, Levvey BJ, et al. The Registry of the International Society for Heart and Lung Transplantation: Thirty-fourth Adult Heart Transplantation Report-2017; Focus Theme: Allograft ischemic time. J Heart Lung Transplant. 2017 Oct;36(10):1037–1046.
PubMed Abstract | Publisher Full Text
None declared.
Authors
Prashant N Mohite, Davorin Sef, Kabeer Umakumar, Olaf Maunz, Hassiba Smail, and Ulric Stock
Authors' Affiliation
Department of Cardiothoracic Transplantation and Mechanical Circulatory Support
Royal Brompton & Harefield NHS Foundation Trust
Hill End Road, Harefield, Middlesex
UB9 6JH, United Kingdom
Corresponding Author
Prashant N Mohite, FRCS.
Department of Cardiothoracic Transplantation and Mechanical Circulatory Support
Royal Brompton & Harefield NHS Foundation Trust
Hill End Road, Harefield, Middlesex
UB9 6JH, United Kingdom
Phone: +44 (0) 1895 82 37 37
Email: p.mohite@rbht.nhs.uk
Keywords
© The Author 2021. Published by MMCTS on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
