EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Heart transplant is now the treatment of choice in patients with advanced heart failure who are refractory to medical treatment.¹ Initially, the characteristics of a heart donor were very narrowly defined in order to obtain the best possible results.² However, the small number of candidates who meet the traditional criteria of a heart donor has created a dramatic discrepancy between the number of patients who are in need of transplant and those fortunate to receive a suitable donor organ.³

Age is one of the criteria that can be successfully expanded to enlarge the pool of potential heart donors. However, it has been observed that older age is a singular risk factor for coronary artery disease (CAD),⁴ and therefore older age increases the probability that an aged donor has previously undergone coronary artery bypass graft (CABG). To expand the opportunities to use organs from older donors, transplanting hearts from donors who have previously undergone CABG should be considered. In this case report, we report the 1-year follow-up of a status 1A patient (according to the adult heart allocation policy of the Organ Procurement and Transplantation Network, United Network Organ Sharing) who received a marginal heart transplant along with the 3 coronary artery grafts that had previously been implemented to treat triple coronary artery disease in the donor.

Heart donor
A 50-year-old woman, who was referred from another hospital to Shahid-Rajaee Hospital, presented with typical cardiac chest pain and exertional dyspnea (functional class IV) with the diagnosis of 3-vessel disease (confirmed by angiographic results). The patient became a candidate for coronary artery bypass in Shahid-Rajaee Hospital and received 1 graft from the internal mammary artery to the left anterior descending coronary artery (LAD) and 2 venous grafts to the right coronary and left circumflex arteries. After the operation, the patient did not wake up; with suspicion of brain death through a probable cause of the “sandblast” phenomenon and micro emboli entering the cardiovascular system, brain death assessment was initiated.^5,6 Brain death was confirmed by electrical silence in an electroencephalogram, with positive test results for atropine and apnea. After the consent was obtained from the patient’s family for organ donation, she was transferred to the Iran University of Medical Science Transplant Organ Provision Unit (Hazrate Rasoole Akram Hospital).

Heart recipient
A 43-year-old woman with a highly urgent heart requirement (status 1A as classified by the Organ Procurement and Transplantation Network, United Network Organ Sharing) according to acute decompensated heart failure. She had been treated by extracorporeal membrane oxygenation, an intra-aortic balloon pump, and daily high doses of epinephrine, norepinephrine, and dopamine. This patient became unstable after hospitalization. Her level of consciousness decreased from 15 to 11 Glasgow coma score, her diuresis reduced to 0 to 5 mL/kg/h, and her mean arterial pressure was under 60 mm Hg with high doses of epinephrine, norepinephrine, and dopamine. According to the decision and permission of the organ allocation unit of the Ministry of Health and Medical Education, the patient was approved as a candidate for an emergency heart transplant, including with a marginal heart.

Heart transplant
The donor operation was performed as a multiorgan procurement procedure. The initiation of heart retrieval was after the completion of other organ preparations. Following the redo sternotomy, the superior vena cava was ligated, making the inferior vena cava free, and the left atrium was vented to prevent left ventricular distension. Then, the ascending aorta was cross clamped, and subsequently, cold cardioplegia solution was applied through the aortic root to induce hypothermic diastolic arrest. The coronary grafts were carefully inspected manually and checked for functionality and availability of the heart circulatory supply. The heart, distal to the aortic end of the grafts with preservation of venal and arterial grafts, was then extracted (Figure 1). Subsequently, the procured heart was supplied with 1.5 L of cardioplegia solution and packed in ice. The heart was preserved at 4 °C, transferred to Shahid-Rajaee Hospital within 90 minutes, and immediately delivered to the operating room.

For the transplant, the anastomosis of the aortic root was performed distal to the ends of the grafts, and the end of the arterial graft was anastomosed to the recipient’s internal mammary artery. Before the operation, the patient had exertional dyspnea (functional class IV that ameliorated to functional class I after transplant) and left ventricular ejection fraction was developed from 10% to 45%. Furthermore, other assessments produced results within standard reference ranges (25 mm Hg pulmonary artery pressure, 135 mM sodium, 3.6 mM potassium, 1.1 mg/dL creatinine, white blood cell count of 9.0 × 10⁹ cells/L, hemoglobin level of 11, platelet count of 150?000 cells/?L). The patient was out of bed 14 days after the operation and discharged at 8 weeks. She survived for 1 year without any hemodynamic and cardiac deterioration until June 10, 2022.

The major aim of transplant is to avoid transplanting an inferior organ, especially in a critically ill recipient.⁷ On the other hand, the demand for organ transplants has been rising rapidly due to the higher incidence of end-stage failure of many vital organs, including kidney, liver, and heart, while the supply of organs from ideal donors has remained insufficient to meet the higher demand.⁸ One possible solution to this issue is to expand the donor criteria to include organs that would otherwise be considered marginal or high risk. The Institute of Medicine estimates that more than 15?000 patients would potentially benefit from a heart transplant if the acceptance criteria were expanded to include all qualified patients below 55 years of age, and about 40?000 to 70?000 patients would benefit if the acceptance age was extended to 65 years.⁹ Donor hearts that are suspected of CAD are generally judged to be unacceptable according to the traditional donor criteria. However, because CAD is a major cardiovascular disease that affects the global human population,¹⁰ is correlated with a higher age,⁴ and is commonly treated with CABG, we therefore suggest that the results of transplanting marginal organs from donors who have previously undergone CABG should be studied as a way to increase the number of potential donors.

The possibility of transplanting hearts with CAD has been explored; however, in the known cases where CABG was needed, the procedure was performed either concurrent with the transplant or as a separate posttransplant procedure.

A study by Abid and colleagues reported 4 donor hearts with palpable atherosclerosis on the surface of the LAD. In that study, the organs, which would otherwise have been rejected, were transplanted first, and the atherosclerotic lesion was then bypassed with a left internal mammary artery. Annual surveillance angiography showed patent left internal mammary artery in all patients. Of the 4 patients, 1 patient developed significant diffuse graft accelerated coronary disease involving the LAD at 9 years after cardiac transplant. No other patient has subsequently shown significant progression of proximal CAD.¹¹

Marelli and colleagues reported their experiences with the use of donor hearts with mild to moderate CAD transplanted to 22 recipients who were either urgent candidates or who otherwise would not have received a transplant for various reasons. The CABG procedure was undertaken concurrent with the % of the patients. The 2-year survival rate among the patients was 75.6%.¹² Generally, concurrent or postponed CABG is thought to account for the satisfactory results of the studies that have used CAD donor hearts.¹³

There have been no reports in the relevant literature of transplanting marginal hearts from donors who have previously undergone CABG before transplant, and yet this scenario is indeed a rich vein of opportunity that could be tapped. According to our findings, transplant of a marginal heart along with the coronary artery grafts can be successful and hence warrants additional studies with larger samples to further investigate the results of transplanting marginal hearts from donors who have previously undergone CABG.

Volume: 20 Issue: 12 December 2022

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