Transcontinental heart transplant using SherpaPak cold static storage system

Abstract

Organ preservation in heart transplantation is key to preventing primary graft dysfunction, the most common cause of early graft loss. Historically, the standard of care was preservation on ice, with no monitoring ability and problems with even temperature distribution. Recently, the SherpaPak, an Food & Drug Administration-approved transport device, has emerged as a solution to these 2 issues, allowing for even temperature distribution, no organ contact with ice, and continuous monitoring during transport. This method of transport falls under static cold preservation, but may allow for longer ischemic times beyond the recommended 4-hour limit. Here, we report a case of heart transplantation using the SherpaPak transport device for a distance of almost 3000 miles and total ischemic time over 7 hours—the longest yet reported for a donor heart transported using the SherpaPak system. The patient had excellent functional outcomes with no evidence of primary graft dysfunction. This case suggests that, with careful donor and recipient selection, SherpaPak may potentially be used for longer distances and ischemic times than initially recommended, as a safe and cheaper alternative to ex-vivo perfusion devices.

Case presentation

A 49-year-old man with multivessel coronary artery disease presented with a non-ST elevation myocardial infarction and underwent CABG and left ventricle aneurysm patch repair. Within 1 month, he required durable left ventricular assist device placement (HeartMate III) for ischemic cardiomyopathy. He was listed for heart transplantation, and after 9 months on the waitlist, a suitable donation after brain death organ was identified. The patient consented to the longer distance transplant and publication of this case.

The donor was a 27-year-old man of similar size who suffered anoxic brain injury after asphyxiation. The organ was procured without complications and placed in the Paragonix SherpaPak Cardiac Transport System (CTS). Distance traveled was 2952.51 miles, and cold ischemic time was 414 minutes. The average probe temperature was 4.4°C with minimal variation (Figure 1A).

Figure 1.

Cold static temperatures during transportation in Paragonix SherpaPak Cardiac Transport System and the recipient’s Inotropic Scores postimplantation. (A) The exported temperatures during transportation is shown. (B) Inotropic score is shown for the recipient in the postoperative period, defined as inotrope score = dopamine (×1) + dobutamine (×1) + amrinone (×1) + milrinone (×15) + epinephrine (×100) + norepinephrine (×100). Doses are in μg/kg/min.

Transplantation was performed via redo median sternotomy, including dense adhesiolysis with left ventricular assist device explant. Intraoperatively, upon placement of cross-clamp, alterations in the aortic cannula flows were noted, and an aortic intramural hematoma was identified on echocardiography. The patient was cannulated via the femoral artery, cooled to 18°C, and after circulatory arrest, an aortic hemiarch replacement was performed. At this time, the heart arrived at the recipient hospital, and the implantation began. The implant was performed with left atrial and aortic anastomoses before cross-clamp removal, followed by inferior vena cava, superior vena cava, and pulmonary artery anastomoses on the beating heart. The total bypass time was 247 minutes, recipient aortic cross-clamp time was 34 minutes, and total donor organ ischemic time was 447 minutes. The chest was closed and he was transported to the intensive care unit. He was extubated on postoperative day 1 and was weaned off vasoactive medications by postoperative day 7 (Figure 1B). He did not require post-transplant mechanical support or meet criteria for any level of primary graft dysfunction. Echocardiography on postoperative day 8 showed ejection fraction 70% and normal biventricular function. He transferred from the intensive care unit to the floor on postoperative day 9. The first and second endomyocardial biopsies showed 1A/1R by International Society for Heart and Lung Transplantation grading for acute rejection. He was discharged on postoperative day 16.

At 3- and 6-month follow-up, he continued to have good heart function (left ventricular ejection fraction 54% and 51%, normal biventricular function) and tolerates cardiac rehab exercise sessions without difficulty. His 3- and 6-month endomyocardial biopsies showed 0R for rejection status.

Discussion

Optimal cardiac preservation is thought to be of paramount importance in preventing severe primary graft dysfunction, the most common cause of early graft loss.¹ For decades, the standard of care has been storage on ice, with no monitoring ability and problems with even temperature distribution, resulting in freeze injury or suboptimal preservation. The SherpaPak CTS is a commercially available, Food & Drug Administration-approved static storage device that addresses these issues, allowing uniform temperature distribution, monitoring, and maintaining temperature between 4°C and 8°C with promising outcomes.¹ Normothermic perfusion using the TransMedics Organ Care System (OCS) Heart (TransMedics; Andover, MA) provides another option, reanimating and maintaining a beating donor heart using warm blood to minimize cold ischemia time.²

In donation after brain death heart transplantation, all 3 transport techniques are used, the latter 2 employed for longer distances and ischemic times.1, 2 International Society for Heart and Lung Transplantation guidelines recommend a maximum 4-hour cold ischemia time and use of OCS for longer times.³ However, recent reports suggest that these temporal boundaries may be safely expanded using the SherpaPak.⁴ Controlled hypothermia offers the advantages of improved portability and superior protection which allow longer travel distances without complicating logistics. A maximum safe cold static storage duration with this technique has not been explored experimentally. However, recent publications have suggested that the SherpaPak CTS can be used to transport donor hearts over longer distances and ischemic times, where a comparison of outcomes from the GUARDIAN registry of transplants using hearts transported after >4 hours of ischemic time in either SherpaPak or Ice, demonstrated a reduction in the incidence of severe PGD by almost 80%.⁵ This data and our institution’s previous success in utilizing SherpaPak for 6 hours cold ischemia time influenced our decision to use the SherpaPak in this case, with a donor heart with excellent function and no evidence of deterioration.

At almost 3000 miles and over 7 hours, the distance traveled and longest total ischemic time are the longest yet reported for a donor heart transported using the SherpaPak system. At almost double the recommended preservation time, the observation of excellent early graft function in this case supports recent data. SherpaPak usage in donors with long cardiac arrest times (>20 minutes) and ischemic times (>3 hours) is associated with a reduced need for postoperative mechanical support (40.0% vs 6.9%, p = 0.01) and trends toward decreased rates of early PGD (20.0% vs 6.9%, p = 0.24) relative to historically used heart storage methodology.⁶ Ultimately, the OCS or similar normothermic perfusion systems are expensive, and their use requires significant amount of expertise and expense, so it is imperative to determine the true upper limit of cold ischemia time with SherpaPak and when it is absolutely necessary to use OCS. Further translational work is needed to delineate this question.

In the ongoing struggle to expand the organ donor pool, we demonstrate a transcontinental reach with cold static preservation of the heart. This case suggests that, with careful donor and recipient selection, SherpaPak is a potentially safe alternative to ex vivo perfusion. This may have benefits in cost-effectiveness and accessibility, but further investigation and comparative studies are first warranted.

Patient Consent

The authors confirm that relevant patient consent is received for publication of this case report.

Disclosure statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Selena Li reports financial support was provided by National Institutes of Health. Selena Li reports financial support was provided by Thoracic Surgery Foundation. David D’Alessandro reports a relationship with Paragonix Technologies, Inc. that includes consulting or advisory. Coauthor (David D’Alessandro) consulting for Abiomed Inc. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Selena Li is funded by the NIH/NIAID R25 AI 147393 award (Pathways to Mentorship and Research: Training the Next Generation Physician Scientist) and the Thoracic Surgery Foundation Nina Starr Braunwald Research Fellowship.