Introduction
Organ donation after circulatory or cardiac determination of death (DCDD) has significantly increased the donor pool in various countries. Heart donation after cardiac death is categorized as controlled (where death is planned after withdrawing life-sustaining treatments in the critical care unit) and uncontrolled (after an unexpected and irreversible cardiac arrest). In this process, the donor’s death is confirmed based on cardio-respiratory criteria, primarily the end of cardiac activity.
What Is Heart Transplantation?
Heart transplantation is a procedure reserved for patients facing refractory acute or chronic heart failure. The commonly employed technique is an orthotopic heart transplant, although a heterotrophic transplant is also an option. Indications for transplantation in chronic heart failure encompass disabling symptoms despite optimal medical management or refractory arrhythmias. In cases of acute heart failure, unresponsive to inotropes and mechanical circulatory devices, a heart transplant becomes necessary. Patients with advanced heart failure requiring mechanical circulatory or inotropic support have a bleak prognosis, making cardiac transplantation a viable treatment for a specific cohort.
Managing advanced heart failure, whether acute or chronic, presents significant challenges. Improved surgical techniques and organ preservation strategies have made heart transplantation a viable option for eligible patients. Clear goals and objectives must be established before surgery to achieve favorable outcomes. Factors such as chronic infections, cirrhosis, chronic kidney diseases, and psychosocial considerations may limit cardiac transplant eligibility, necessitating thorough screening for proper patient selection. Given the potential complications from immunosuppression and the procedure, regular surveillance and biopsies are recommended to monitor and address any issues.
What Is Heart Donation After Cardiac Death?
While the first kidney transplant involved a living donor, the initial liver, lungs, and heart transplants were conducted following cardiac death, as was understood previously. Donations predominantly drove the growth in transplant activity after neurologic determination of death (DNDD). However, it became evident that DNDD and living donations could not meet the escalating transplant demand, leading to a resurgence of donation after circulatory determination of death (DCDD) transplants. Over the last two decades, a substantial number of successful DCDD kidney, liver, lung, and heart transplants have been performed globally using rapid retrieval techniques in carefully selected donors. Recent DCDD protocols incorporate innovative approaches such as hypothermic and normothermic, in situ and ex vivo perfusion, with non-oxygenated or oxygenated preservative solutions, either acellular or containing blood. These technologies not only enable longer preservation times, allow organ viability assessment, and reduce urgent logistical challenges but also hold the potential for organ reconditioning.
Global DCDD donations consistently increase annually, with notable contributions from various countries.
The terminologies used in DCDD are:
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Devastating Brain Injury (DBI): Refers to any neurological condition evaluated upon hospital admission that poses an immediate threat to life or is incompatible with a favorable functional recovery. In such cases, early limitation or withdrawal of therapy is being contemplated.
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Withdrawal of Life-Sustaining Treatment (WLST): When a patient’s likelihood of survival with continued life-sustaining treatment is deemed low, a decision is made to cease (withdraw) life-sustaining interventions. This decision is reached by the patient, or if the patient is incapacitated, jointly with the patient’s healthcare proxy and surrogate decision maker in collaboration with the medical team, acting in the patient’s best interests.
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Do Not Attempt Resuscitation (DNAR): A thoughtful decision made by the patient or caregivers, along with the medical team, involves opting not to have one or all components of cardiopulmonary resuscitation (CPR) performed in the event of an expected or impending cardiorespiratory arrest.
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No touch period, agonal or agonic or withdrawal phase, asystole or circulatory phase, or warm ischemic time (WIT) are crucial for understanding and managing DCDD procedures.
What Are the Procedures and Protocols Followed for Heart Donation After Cardiac Death?
Procedures and protocols for different DCDD categories are as follows:
1. Controlled DCDD: Maastricht Category III: Expected Circulatory Death in the ICU (Intensive Care Unit): In cases where curative treatment options have been exhausted, and ongoing treatment is deemed futile, the process of withdrawal of life-sustaining treatment (WLST) or end-of-life care (EOLC) may begin. The determination of futility involves independent evaluation by the primary doctor, ICU doctor, and other specialists.
This decision-making process includes transparent, empathetic, and effective communication, requiring multiple sessions of detailed discussions over 72 hours. After consensus is reached, the family is engaged in structured discussions covering disease information, prognosis, futility, DNAR, WLST, EOLC, and palliative care. It is crucial to delink family consent for WLST from the subsequent possibility of organ donation to avoid perceived conflicts of interest.
Once the family consents to WLST, the transplant coordinator or counselor is notified, initiating discussions with the family about the potential for organ donation. This involves a combined approach led by various healthcare professionals, depending on hospital dynamics and training levels. Ongoing communication with the family is key, as well as ensuring emotional support and providing information.
The coordination of WLST leading to organ donation involves recording important steps and timings. The agonal phase starts with WLST, leading to circulatory arrest. Confirmation of circulation cessation is followed by a no-touch period, allowing time for auto-resuscitation/restoration of spontaneous circulation (ROSC). If no cardiac activity is observed after this period, death is certified, and written consent for organ donation is obtained.
These steps may occur in the ICU if normothermic regional perfusion (nRP) is planned. Otherwise, WLST may occur in the operating room to minimize warm ischemia time. Organ preservation using cold solutions marks the beginning of cold ischemia time (CIT). The retrieved organ may undergo ex vivo hypothermic or normothermic preservation before transplantation.
2. Uncontrolled DCDD: Modified Maastricht Category I, II, and V:
In cases of unexpected cardiac arrest, CPR is initiated. If unsuccessful after 30 minutes, death is certified. Anticipated cardiac arrest in the ICU may lead to discussions with the family regarding organ donation. Sensitively handled by an experienced team, counseling for donation may begin even during ongoing resuscitation attempts.
After death certification, chest compressions may be re-initiated, followed by rapid heparinization and femoral cannulation for nRP. Monitoring nRP parameters for a minimum of four hours is crucial. The organ allocation body is informed, and if nRP parameters are favorable, the donor is shifted to the OR for retrieval.
3. Modified Maastricht Category IV: Cardiac Arrest During Brain Death Declaration:
In some countries, instances of cardiac arrest occurring during the declaration of brain death are not uncommon. In cases of eligible donors where brain death has been certified following both sets of tests, CPR and a no-touch period are unnecessary, and a donation can proceed as category IV. For potential donors where either no formal testing or only one set of brainstem death tests has confirmed brain death, CPR is recommended for 30 minutes. However, if a DNAR order is in place, CPR is not required, but a five-minute no-touch period is still necessary.
What Are the Considerations for Heart Donation?
Organ-Specific Considerations: While DCDD kidney and liver transplants are common, an increasing number of centers are also performing DCDD heart and lung transplants. These procedures have shown outcomes equivalent to DNDD transplants, consistently superior to waiting list mortality for most organs.
Heart: The limited myocardial tolerance to ischemia necessitated the introduction of ex-situ donor heart perfusion technology and pharmacological post-conditioning strategies. DCDD heart transplants have been successfully performed, involving rapid retrieval techniques with in situ cardioplegia delivery. The medium-term outcomes have been excellent, with one and five-year survival rates comparable to standard DNDD transplants.
Lungs: Lungs exhibit unique tolerance to warm ischemia due to trapped alveolar air. Category III DCDD lungs using standard cold storage preservation techniques have shown excellent outcomes. Donors under 65 years old without significant pre-existing lung disease, smoking history or lung injury are acceptable for DCDD lung donation.
Liver: DCDD liver grafts, usually retrieved from category III donors, may have slightly higher risks but show outcomes similar to DNDD transplants. Modern perfusion and preservation techniques, such as normothermic machine liver perfusion, have reduced the risks of primary non-function and biliary complications.
Kidneys: Kidneys are highly tolerant to ischemic insults, and the majority of DCDD donations worldwide are from controlled donors. Uncontrolled donations are limited to a few individuals and races. DCDD kidneys can be offered to all recipients on the waiting list, with long-term outcomes similar to DNDD transplants. Category IV donors may be the easiest to start, considering family awareness and existing consent.
These advancements in DCDD transplants highlight the potential for expanding organ availability and improving outcomes across various organs.
Conclusion
Heart donation after cardiac death (DCDD) represents a significant advancement in transplantation, providing a viable option for overcoming organ shortages. Introducing ex-situ donor heart perfusion technologies and careful donor selection have contributed to medium-term outcomes comparable to traditional donations.
