Faculty Bibliography

INTRODUCTION:Thoracoabdominal normothermic regional perfusion (TA-NRP) following cardiac death is an emerging multivisceral organ procurement technique. Recent national studies on outcomes of presumptive TA-NRP-procured organs are limited by potential misclassification since TA-NRP is not differentiated from donation after cardiac death (DCD) in registry data. METHODS:We studied 22 donors whose designees consented to TA-NRP and organ procurement performed at our institution between January 20, 2020 and July 3, 2022. We identified these donors in SRTR to describe organ utilization and recipient outcomes and compared them to recipients of traditional DCD (tDCD) and donation after brain death (DBD) organs during the same timeframe. RESULTS:All 22 donors progressed to cardiac arrest and underwent TA-NRP followed by heart, lung, kidney, and/or liver procurement. Median donor age was 41 years, 55% had anoxic brain injury, 45% were hypertensive, 0% were diabetic, and median kidney donor profile index was 40%. TA-NRP utilization was high across all organ types (88%-100%), with a higher percentage of kidneys procured via TA-NRP compared to tDCD (88% vs. 72%, p = .02). Recipient and graft survival ranged from 89% to 100% and were comparable to tDCD and DBD recipients (p ≥ .2). Delayed graft function was lower for kidneys procured from TA-NRP compared to tDCD donors (27% vs. 44%, p = .045). CONCLUSION:Procurement from TA-NRP donors yielded high organ utilization, with outcomes comparable to tDCD and DBD recipients across organ types. Further large-scale study of TA-NRP donors, facilitated by its capture in the national registry, will be critical to fully understand its impact as an organ procurement technique.

As we approach the five-year anniversary of the 2018 heart allocation system in the United States, it is imperative to consider the changing landscape of mechanical circulatory support and the strategies used to bridge patients into heart transplants. This manuscript reviews the history of the heart allocation system, as well as the conditions that led to its multiple revisions. We discuss initial outcomes following the implementation of the new allocation system, including the impact on waitlist mortality and post-transplant outcomes. We also give special consideration to changes in bridging strategies using venoarterial extracorporeal membrane oxygenation (VA ECMO), intra-aortic balloon pumps, and durable left ventricular assist devices (LVADs).

BACKGROUND:The benefits of fast-track extubation in the intensive care unit (ICU) after cardiac surgery are well established. Although extubation in the operating room (OR) is safe in carefully selected patients, widespread use of this strategy in cardiac surgery remains unproven. This study was designed to evaluate perioperative outcomes with OR vs ICU extubation in patients undergoing nonemergency, isolated coronary artery bypass grafting (CABG). METHODS:The Society of Thoracic Surgeons (STS) data for all single-center patients who underwent nonemergency isolated CABG over a 6-year interval were analyzed. Perioperative morbidity and mortality with ICU vs OR extubation were compared. RESULTS:Between January 1, 2017 and December 31, 2022, 1397 patients underwent nonemergency, isolated CABG; 891 (63.8%) of these patients were extubated in the ICU, and 506 (36.2%) were extubated in the OR. Propensity matching resulted in 414 pairs. In the propensity-matched cohort, there were no differences between the 2 groups in incidence of reintubation, reoperation for bleeding, total operative time, stroke or transient ischemic attack, renal failure, or 30-day mortality. OR-extubated patients had shorter ICU hours (14 hours vs 20 hours; P < .0001), shorter postoperative hospital length of stay (3 days vs 5 days; P < .0001), a greater likelihood of being discharged directly to home (97.3% vs 89.9%; P < .0001), and a lower 30-day readmission rate (1.7% vs 4.1%; P = .04). CONCLUSIONS:Routine extubation in the OR is a feasible and safe strategy for a broad spectrum of patients after nonemergency CABG, with no increase in perioperative morbidity or mortality. Wider adoption of routine OR extubation for nonemergency CABG is indicated.

A type A aortic dissection is a challenging condition for both cardiothoracic and vascular surgeons. Although open surgery remains the gold standard, there is considerable interest in the use of endovascular techniques for patients who present with malperfusion. We present the case of an unstable 55-year-old man with visceral malperfusion from a type A dissection who was stabilized using an endovascular technique as a bridge to open surgery. A bare metal thoracic endograft was used in the ascending aorta to rapidly restore perfusion. This hybrid approach to the problem of malperfusion in type A dissection could be useful for these patients with complicated cases.

Use of thoracoabdominal normothermic regional perfusion (TA-NRP) during donation after circulatory death (DCD) is an important advance in organ donation. Prior to establishing TA-NRP, the brachiocephalic, left carotid, and left subclavian arteries are ligated, thereby eliminating anterograde brain blood flow via the carotid and vertebral arteries. While theoretical concerns have been voiced that TA-NRP after DCD may restore brain blood flow via collaterals, there have been no studies to confirm or refute this possibility. We evaluated brain blood flow using intraoperative transcranial Doppler (TCD) in two DCD TA-NRP cases. Pre-extubation, anterior and posterior circulation brain blood flow waveforms were present in both cases, similar to the waveforms detected in a control patient on mechanical circulatory support undergoing cardiothoracic surgery. Following declaration of death and initiation of TA-NRP, no brain blood flow was detected in either case. Additionally, there was absence of brainstem reflexes, no response to noxious stimuli and no respiratory effort. These TCD results demonstrate that DCD with TA-NRP did not restore brain blood flow.

Genetically modified xenografts are one of the most promising solutions to the discrepancy between the numbers of available human organs for transplantation and potential recipients. To date, a porcine heart has been implanted into only one human recipient. Here, using 10-gene-edited pigs, we transplanted porcine hearts into two brain-dead human recipients and monitored xenograft function, hemodynamics and systemic responses over the course of 66 hours. Although both xenografts demonstrated excellent cardiac function immediately after transplantation and continued to function for the duration of the study, cardiac function declined postoperatively in one case, attributed to a size mismatch between the donor pig and the recipient. For both hearts, we confirmed transgene expression and found no evidence of cellular or antibody-mediated rejection, as assessed using histology, flow cytometry and a cytotoxic crossmatch assay. Moreover, we found no evidence of zoonotic transmission from the donor pigs to the human recipients. While substantial additional work will be needed to advance this technology to human trials, these results indicate that pig-to-human heart xenotransplantation can be performed successfully without hyperacute rejection or zoonosis.