Residency · Residency · Cardiothoracic Surgery
Heart Transplant: Donor Selection and Organ Preservation
Introduction
The success of cardiac transplantation depends critically on appropriate donor selection, meticulous organ procurement, and effective preservation strategies. With the persistent shortage of donor organs, the field has evolved toward expanded donor criteria, donation after circulatory death (DCD), and ex-vivo perfusion technologies to maximize the usable donor pool while maintaining excellent outcomes.
Donor Evaluation
Standard Donor Criteria
Standard criteria for cardiac donors include age traditionally below 55 years (though older donors are considered with careful evaluation), confirmed brain death declaration by neurological examination and ancillary testing per institutional protocol, cardiac function with an ejection fraction above 45% on echocardiography without significant structural abnormalities, hemodynamic stability with the ability to maintain adequate perfusion on minimal or moderate vasopressor support, and absence of significant coronary artery disease (with coronary angiography recommended for male donors over 45 and female donors over 50). Serological testing must be negative for HIV and hepatitis B surface antigen, though hepatitis C positive donors are now considered for consenting recipients.
Extended Criteria Donors
Extended criteria donors include those with mild LV hypertrophy (wall thickness less than 14 mm), older donors aged 55-65 with otherwise favorable profiles, donors requiring moderate inotropic support after aggressive management, and hepatitis C positive donors who can be successfully treated with direct-acting antiviral therapy post-transplant. Each extended criteria donor requires careful risk-benefit analysis matching donor quality to recipient urgency.
Donor-Recipient Matching
ABO blood group compatibility is mandatory. Size matching aims for a donor-to-recipient body weight ratio of 0.8-1.2, with undersized hearts risking failure in recipients with pulmonary hypertension. Crossmatch is performed for sensitized recipients with panel reactive antibody above 10%, and virtual crossmatch is increasingly used. Predicted heart mass ratios calculated using height, weight, age, and sex provide more accurate size matching than body weight alone. Geographic distance factors into total ischemic time, which ideally remains below 4 hours but can be extended with modern preservation strategies.
Donor Management
Goals of Donor Optimization
The primary goals are maintaining hemodynamic stability to preserve myocardial function and replacing hormonal deficiencies resulting from brain death.
Hormonal Resuscitation Protocol
The hormonal resuscitation protocol consists of methylprednisolone 15 mg/kg IV bolus, vasopressin 1 unit IV bolus followed by 0.5-4 units/hour infusion, triiodothyronine (T3) 4 mcg IV bolus followed by 3 mcg/hour infusion, and insulin infusion to maintain blood glucose between 120 and 180 mg/dL.
Hemodynamic Targets
Hemodynamic targets include a mean arterial pressure above 60 mmHg, central venous pressure of 6-10 mmHg, left ventricular ejection fraction above 45%, and minimization of vasopressor requirements (dopamine below 10 mcg/kg/min).
Organ Procurement
Standard Cold Static Storage
Procurement proceeds through a median sternotomy with inspection of the heart for coronary disease, contusion, or structural abnormality. After systemic heparinization (30,000 units IV), cardioplegia is delivered in an antegrade fashion via the aortic root after aortic cross-clamp, using cold crystalloid or blood cardioplegia. Topical cooling with cold saline slush supplements myocardial protection. Cardiectomy involves dividing the SVC, IVC, pulmonary veins (leaving an LA cuff), aorta, and pulmonary artery. The heart is immediately immersed in cold preservation solution at 4 degrees C and transported in triple-bagged sterile containers on ice. The target ischemic time is less than 4 hours, as outcomes decline progressively beyond 4-6 hours.
Preservation Solutions
Several preservation solutions are available. University of Wisconsin (UW) solution is a high-potassium, lactobionate-based solution that has been the standard for years. Custodiol (HTK) is a histidine-tryptophan-ketoglutarate solution that serves as both single-dose cardioplegia and storage solution. Celsior solution was designed specifically for cardiac preservation, with low potassium and reduced viscosity. Del Nido solution is increasingly used for cardioplegia during procurement.
| Solution | Key Composition | Potassium | Features |
|---|---|---|---|
| University of Wisconsin (UW) | Lactobionate, raffinose, hydroxyethyl starch | High (125 mEq/L) | Long-standing standard; higher viscosity |
| Custodiol (HTK) | Histidine, tryptophan, ketoglutarate | Low (9 mEq/L) | Single-dose cardioplegia + storage; low viscosity |
| Celsior | Mannitol, glutamate, reduced glutathione | Low (15 mEq/L) | Designed for cardiac preservation; low viscosity |
| Del Nido | Lidocaine, magnesium, mannitol | Moderate (26 mEq/L) | Single-dose; increasingly used in procurement |
Standard vs. Extended Donor Criteria
| Criterion | Standard Donor | Extended Criteria |
|---|---|---|
| Age | < 55 years | 55-65 years (with favorable profile) |
| Ejection fraction | > 45% | May accept mildly reduced with optimization |
| LV wall thickness | Normal | Mild LVH (< 14 mm acceptable) |
| Inotropic support | Minimal | Moderate (after aggressive management) |
| Hepatitis C status | Negative | Positive (with DAA treatment post-transplant) |
| Coronary disease | Absent | Mild (requires angiography) |
| Donation type | DBD (brain death) | DCD (circulatory death) with ex-vivo perfusion |
Ex-Vivo Perfusion Technology
Organ Care System (OCS Heart - TransMedics)
The OCS Heart is a portable normothermic ex-vivo perfusion device that maintains the heart in a warm, beating, perfused state during transport. A donor blood primed circuit provides continuous oxygenated perfusion, allowing functional assessment of the organ during transport through lactate clearance and hemodynamic parameters. The system extends safe preservation time beyond conventional cold storage limits and enables the use of donation after circulatory death (DCD) hearts.
DCD Heart Transplantation
DCD hearts are procured after controlled withdrawal of life-sustaining treatment and circulatory death. The process requires normothermic regional perfusion or direct procurement with ex-vivo perfusion, and functional warm ischemic time must be minimized to less than 30 minutes. Outcomes are comparable to donation after brain death when proper protocols are followed, and DCD has significantly expanded the donor pool with a 15-30% increase in transplant volume at experienced centers.
Procurement Logistics
Coordination between procurement and recipient teams is essential, with timing of recipient sternotomy relative to procurement being critical. Communication regarding ischemic time estimates must be ongoing, and cross-clamp of the donor should occur only after the recipient team confirms readiness. Transport should include redundant cold storage backup even when using ex-vivo perfusion.
Key Clinical Pearls
Hormonal resuscitation with T3, vasopressin, methylprednisolone, and insulin can recover marginal donor hearts and should be initiated early. Coronary angiography is essential for older donors, as even moderate coronary disease may disqualify the organ. Predicted heart mass ratios outperform simple body weight matching for donor-recipient size compatibility. Ex-vivo perfusion technology and DCD protocols are transforming the donor pool, and surgeons must be familiar with these techniques. Communication and coordination between procurement and recipient teams is as important as surgical technique.
References
- Khush KK, Cherikh WS, Chambers DC, et al. The International Thoracic Organ Transplant Registry of the International Society for Heart and Lung Transplantation: Thirty-sixth adult heart transplantation report. J Heart Lung Transplant. 2019;38(10):1056-1066.
- Dhital KK, Iyer A, Connellan M, et al. Adult heart transplantation with distant procurement and ex-vivo preservation of donor hearts after circulatory death. Lancet. 2015;385(9987):2585-2591.
- Kobashigawa J, Zuckermann A, Macdonald P, et al. Report from a consensus conference on primary graft dysfunction after cardiac transplantation. J Heart Lung Transplant. 2014;33(4):327-340.
- Jawitz OK, Raman V, DeVore AD, et al. Increasing the United States heart transplant donor pool with donation after circulatory death. J Thorac Cardiovasc Surg. 2022;164(4):1096-1105.