Heart Transplantation Using Normothermic Regional Perfusion (NRP) Donation After Circulatory Death (DCD): A Pilot Study

The surgical management of end-stage heart failure generally falls into two categories: mechanical circulatory support and heart transplantation. The availability of suitable organs intrinsically limits the rate of heart transplantation. The vast majority of cadaveric donor hearts are obtained from patients who have had irreversible cessation of neurological function (DBD - Donation after Brain Death). Recently, there has been renewed interest in the possibility of obtaining cadaveric hearts from DCD (Donation after Circulatory Death) donors who have had irreversible cessation of cardiopulmonary function. In contrast to DBD, DCD involves the intentional withdrawal of life support measures to allow controlled circulatory death to occur. If the patient fails to progress to circulatory death within the allotted time, DCD donation is terminated, and the patient is placed on comfort measures until they expire.

The concept of DCD heart transplantation is not new. Barnard used DCD hearts in his early series of heart transplants because the idea of brain death had not yet been well established. Clinical DCD heart transplant programs have been established in the UK, Belgium, and Australia. However, DCD heart transplantation currently remains virtually nonexistent in the US. DCD can increase the available US heart donor pool by as much as 20%. Of the more than 41,000 adult heart transplants performed in the US over the past 20 years, only 4 have been from DCD donors. Perhaps understandably, there is some hesitance in using a donor heart that has just undergone circulatory death.

Potential DCD donors are stratified according to the Maastricht classification system: 1) dead on arrival at the hospital, 2) out-of-hospital arrest with unsuccessful resuscitation, 3) circulatory arrest as a result of a planned withdrawal of life support, 4) circulatory arrest in a patient who is already brain-dead, and 5) circulatory arrest while in the hospital with unsuccessful resuscitation. Categories 1, 2, and 5 would be considered "uncontrolled" DCD. Categories 3 and 4 are considered "controlled" DCD, where the duration and conditions of warm ischemia are known, and the precise course of circulatory arrest can be followed.

The current procedure of DCD organ donation and procurement follows a well-established course for lung, liver, kidney, and pancreas transplantation in the United States. After consent has been obtained, the organs are allocated through the United Network of Organ Sharing (UNOS). When all parties are present and ready, the donor is withdrawn from life support (i.e., discontinuation of mechanical ventilation and any vasoactive medications). The surgical teams are generally present on the premises but not at the donor's bedside. After circulatory arrest occurs, which is determined by the absence of pulse and organized rhythmic cardiac activity, death is declared by a physician not associated with the transplant teams. Subsequently, a standoff period is observed (5 minutes) to ensure a complete cessation of the circulation before organ procurement is commenced. If after withdrawal of life support, the patient does not progress to circulatory death within the allotted time (variable among hospitals, but 60 minutes in this study), the procurement is abandoned, and the patient is transferred out of the operating room and placed on palliative measures.

Given that DCD organ donation is already currently practiced in the US, the same standard approach defined by each state and locality can also be applied to DCD heart donation. However, this protocol will utilize a normothermic regional perfusion (NRP) strategy that involves the re-establishment of circulatory blood flow after the period of circulatory arrest has been established and the 5 minutes of standoff time has passed. The local Organ Procurement Organization (Donor Network of Arizona-DNAZ) and BUMCP Leadership have reviewed and approved this approach to DCD heart donation. Specifically, normothermic regional perfusion involves the following steps: