Considerations for the use of porcine organ donation models in preclinical organ donor intervention research.

Use of animal models in preclinical transplant research is essential to the optimization of human allografts for clinical transplantation. Animal models of organ donation and preservation help to advance and improve technical elements of solid organ recovery and facilitate research of ischemia-reperfusion injury, organ preservation strategies, and future donor-based interventions. Important considerations include cost, public opinion regarding the conduct of animal research, translational value, and relevance of the animal model for clinical practice. We present an overview of two porcine models of organ donation: donation following brain death (DBD) and donation following circulatory death (DCD). The cardiovascular anatomy and physiology of pigs closely resembles those of humans, making this species the most appropriate for pre-clinical research. Pigs are also considered a potential source of organs for human heart and kidney xenotransplantation. It is imperative to minimize animal loss during procedures that are surgically complex. We present our experience with these models and describe in detail the use cases, procedural approach, challenges, alternatives, and limitations of each model.

Financial impact of donation after circulatory death heart transplantation: A single-center analysis.

INTRODUCTION: Clinical success of donation after circulatory death (DCD) heart transplantation is leading to growing adoption of this technique. In comparison to procurement from a brain-dead donor, DCD requires additional resources. The economic impact of DCD heart transplantation from the hospital perspective is not well known. METHODS: We compared the financial data of patients who received DCD allografts to those who received a DBD organ at our institution from January 1, 2021 to December 31, 2022. We also compared the cost of ex-situ machine perfusion to in-situ organ perfusion employed during DCD recovery. RESULTS: We performed 58 DBD and 22 DCD heart-alone transplantations during the study period. Out of 22 DCD grafts, 16 were recovered with thoracoabdominal normothermic regional perfusion (TA-NRP) and six with direct procurement followed by normothermic machine perfusion (DP-NMP). The contribution margin per case for DBD versus DCD was $234,362 and $235,440 (P = .72). The direct costs did not significantly differ between the two groups ($171,949 and 186,250; P = .49). In comparing the two methods of procuring hearts from DCD donors, the direct cost of TA-NRP was $155,955 in comparison to $223,399 for DP-NMP (P = .21). This difference translated into a clinically meaningful but not statistically significant greater contribution margin for TA-NRP ($242, 657 vs. $175,768; P = .34). CONCLUSIONS: Our data showed that the adoption of DCD procurement did not have a negative financial impact on the contribution margin in our institution. Programs considering starting DCD heart transplantation, and those who are currently performing DCD procurement should evaluate their own financial situation.

Does concomitant tricuspid valve intervention at the time of left ventricular assist device placement for patients with significant tricuspid regurgitation lead to improved outcomes compared to isolated left ventricular assist device placement?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'In patients with advanced heart failure (HF) and moderate to severe functional tricuspid regurgitation (TR) undergoing left ventricular assist device (LVAD) placement is concomitant tricuspid valve intervention (TVI) superior for the clinical outcomes of survival, right ventricular failure, rehospitalizations for HF, functional status, and quality of life?' Altogether, 56 papers were found using the reported search, of which 12 papers represented the best evidence to answer the clinical question. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Our search found no significant clinical benefit for concomitant TVI at the time of LVAD placement. We conclude that patient with moderate-to-severe TR should not routinely undergo concomitant TVI with LVAD placement.

Improved Early Post-Transplant Outcomes and Organ Use in Kidney Transplant Using Normothermic Regional Perfusion for Donation after Circulatory Death: National Experience in the US.

BACKGROUND: Normothermic regional perfusion (NRP) is a technique that is intended to enhance organ transplant outcomes from donation circulatory death (DCD) donors. STUDY DESIGN: A retrospective analysis of data from the Scientific Registry of Transplant Recipients was performed. DCD donors were screened for inclusion based on date of donation 2020 or later, and whether the heart was also recovered for transplantation. We grouped donors as either donation after brain death or DCD. DCD donors were further divided into groups including those in which the heart was not recovered for transplant (Non-Heart DCD) and those in which it was, based on recovery technique (thoracoabdominal-NRP [TA-NRP] Heart DCD and Super Rapid Recovery Heart DCD). RESULTS: A total of 219 kidney transplant recipients receiving organs from TA-NRP Heart DCD donors were compared to 436 SRR Super Rapid Recovery DCD, 10,630 Super Rapid Recovery non-heart DCD, and 27,820 donations after brain death recipients. Kidney transplant recipients of TA-NRP DCD allografts experienced shorter length of stay, lower rates of delayed graft function, and lower serum creatinine at the time of discharge when compared with recipients of other DCD allografts. CONCLUSIONS: Our analysis demonstrates superior early kidney allograft function when TA-NRP is used for DCD organ recovery.

Utilization of Paragonix Sherpapak Cardiac Transport System for the Preservation of Donor Hearts After Circulatory Death.

BACKGROUND: Donation after circulatory death (DCD) heart transplantation is being increasingly adopted by transplant centers. The optimal method of DCD heart preservation during transport after in situ thoracoabdominal normothermic regional perfusion (TA-NRP) is not known. METHODS: We evaluated our experience with the Paragonix SherpaPak Cardiac Transport System (SCTS) for the transport of DCD cardiac allografts after TA-NRP recovery between January 2021 and December 2022. We collected and evaluated donor characteristics, allograft ischemic intervals, and recipient baseline demographic and clinical variables, and short-term outcomes. RESULTS: Twelve recipients received DCD grafts recovered with TA-NRP and transported in SCTS during the study period. The median age of 10 male and 2 female donors was 32 years (min 15, max 38). The median duration of functional warm ischemia was 12 minutes (min 8, max 22). Hearts were preserved in SCTS for a median of 158 minutes (min 37, max 224). Median recipient age was 61 years (min 28, max 70). Ten recipients (83%) survived to hospital discharge, with one death attributable to graft dysfunction (8%). The median vasoactive-inotropic (VIS) score at 72 hours post-transplantation of the entire cohort was 6 (min 0, max 15). The median length of intensive care unit stay in hospital survivors was 5 days (min 3, max 17) days and hospital stay 17 days (min 9, max 37). CONCLUSIONS: The Paragonix SCTS provides efficacious preservation of DCD grafts for ≥3.5 hours. Organs transported with this device showed satisfactory post-transplantation function.

Does Tracheostomy Improve Outcomes in Those Receiving Venovenous Extracorporeal Membrane Oxygenation?

Patients receiving venovenous extracorporeal membrane oxygenation (VV-ECMO) often require extended periods of ventilation. We examined the role of tracheostomy on outcomes of patients supported with VV-ECMO. We reviewed all patients at our institution who received VV-ECMO between 2013 and 2019. Patients who received a tracheostomy were compared with VV-ECMO-supported patients without tracheostomy. The primary outcome measure was survival to hospital discharge. Secondary outcome measures included length of intensive care unit (ICU) and hospital stay and adverse events related to the tracheostomy procedure. Multivariable analysis was performed to identify predictors of in-hospital mortality. We dichotomized patients receiving tracheostomy into an "early" and "late" group based on median days to tracheostomy following ECMO cannulation and separate analysis was performed. One hundred and fifty patients met inclusion criteria, 32 received a tracheostomy. Survival to discharge was comparable between the groups (53.1% vs. 57.5%, p = 0.658). Predictors of mortality on multivariable analysis included Respiratory ECMO Survival Prediction (RESP) score (odds ratio [OR] = 0.831, p = .015) and blood urea nitrogen (BUN) (OR = 1.026, p = 0.011). Tracheostomy performance was not predictive of mortality (OR = 0.837, p = 0.658). Bleeding requiring intervention occurred in 18.7% of patients following tracheostomy. Early tracheostomy (<7 days from the initiation of VV-ECMO) was associated with shorter ICU (25 vs. 36 days, p = 0.04) and hospital (33 vs. 47, p = 0.017) length of stay compared with late tracheostomy. We conclude that tracheostomy can be performed safely in patients receiving VV-ECMO. Mortality in these patients is predicted by severity of the underlying disease. Performance of tracheostomy does not impact survival. Early tracheostomy may decrease length of stay.

The international experience of in-situ recovery of the DCD heart: a multicentre retrospective observational study.

Background: Heart transplantation is an effective treatment offering the best recovery in both quality and quantity of life in those affected by refractory, severe heart failure. However, transplantation is limited by donor organ availability. The reintroduction of heart donation after the circulatory determination of death (DCD) in 2014 offered an uplift in transplant activity by 30%. Thoraco-abdominal normothermic regional perfusion (taNRP) enables in-situ reperfusion of the DCD heart. The objective of this paper is to assess the clinical outcomes of DCD donor hearts recovered and transplanted from donors undergoing taNRP. Method: This was a multicentre retrospective observational study. Outcomes included functional warm ischaemic time, use of mechanical support immediately following transplantation, perioperative and long-term actuarial survival and incidence of acute rejection requiring treatment. 157 taNRP DCD heart transplants, performed between February 2, 2015, and July 29, 2022, have been included from 15 major transplant centres worldwide including the UK, Spain, the USA and Belgium. 673 donations after the neurological determination of death (DBD) heart transplantations from the same centres were used as a comparison group for survival. Findings: taNRP resulted in a 23% increase in heart transplantation activity. Survival was similar in the taNRP group when compared to DBD. 30-day survival was 96.8% ([92.5%-98.6%] 95% CI, n = 156), 1-year survival was 93.2% ([87.7%-96.3%] 95% CI, n = 72) and 5-year survival was 84.3% ([69.6%-92.2%] 95% CI, n = 13). Interpretation: Our study suggests that taNRP provides a significant boost to heart transplantation activity. The survival rates of taNRP are comparable to those obtained for DBD transplantation in this study. The similar survival may in part be related to a short warm ischaemic time or through a possible selection bias of younger donors, this being an uncontrolled observational study. Therefore, our study suggests that taNRP offers an effective method of organ preservation and procurement. This early success of the technique warrants further investigation and use. Funding: None of the authors have a financial relationship with a commercial entity that has an interest in the subject.

Impact of donation after circulatory death heart transplantation on waitlist outcomes and transplantation activity.

INTRODUCTION: Donation after circulatory death (DCD) heart transplantation has been shown to have comparable outcomes to transplantation using brain death donors (DBDs). This study evaluates the impact of this alternative source of allografts on waitlist mortality and transplant volume. METHODS: We compared waitlist mortality and transplant rates in patients who were registered before (2019 period) and after we adopted DCD heart transplantation (2021 period). RESULTS: We identified 111 patients who were on the waiting list in 2019 and 77 patients who were registered during 2021. Total number of donor organ offers received in 2019 was 385 (178 unique donors) versus 3450 (1145 unique donors) in 2021. More than 40% of all donors in 2021 were DCDs. Waitlist mortality was comparable for patients in 2019 and 2021 (18/100 person-years in 2019 vs. 26/100 person-years in 2021, p = .49). The transplant rate was 67/100 person-years in 2019 versus 207/100 person-years in 2021 (p < .001). After adjusting for acuity status, gender, blood type, and weight, patients listed in 2021 had 2.08 times greater chance of transplantation compared to patients listed in 2019 (HR 2.08, 95% confidence interval [CI] 1.26-3.45, p = .004). CONCLUSIONS: Use of DCD donor hearts significantly increased heart transplant rate in our institution.

Cardiac function unchanged following reanimation with normothermic regional perfusion in donation after circulatory death.

Objectives: To determine whether hearts reanimated with normothermic regional perfusion (NRP) have clinically detectable changes in function using echocardiography comparing the prearrest and post-NRP imaging. As heart transplantation from donation after circulatory death (DCD) continues to increase, preliminary results suggest outcomes comparable with donation after brain death. It is unknown whether the obligatory period of warm ischemia experienced during DCD withdrawal process causes immediate changes in cardiac allograft function following in situ reanimation. Methods: We retrospectively reviewed and compared predonation with postreanimation echocardiographic findings in all DCD donors at our institution from January to October 2021. All DCD donor organs were reanimated with in situ thoracoabdominal NRP after circulatory death. Echocardiographic assessment included (1) 2-dimensional and speckle-tracking measures of chamber size and function; (2) ejection fraction; (3) fractional area change; and (4) global longitudinal strain. Results: Altogether, 4 DCD heart donations were performed during the study period. Basic demographics and withdrawal ischemic time periods are reported. There were no changes in left ventricular ejection fraction and right ventricular fractional area change when comparing the predonation and the postreanimation echocardiogram. There was a minimal, nonstatistically significant decrease in left ventricular global longitudinal strain and right ventricular free-wall systolic strain in 3 of the 4 donors following reanimation. Conclusions: DCD cardiac allografts reanimated with NRP demonstrated no change in echocardiographic parameters used for a standard predonation donor heart evaluation. Findings suggest cardiac function of DCD allografts reanimated with thoracoabdominal NRP is not adversely impacted by limited period of warm ischemia following circulatory arrest.

Controlled DCD lung transplantation: Circumventing imagined and real barriers-time for an international taskforce?

Controlled donation after circulatory death (DCD) has the potential to substantially increase the number of lung transplants thus offsetting some of the imbalance between need and organ availability. We examine the potential benefits associated with increased DCD utilization as well as the perceived barriers to the expansion of DCD. Solutions are offered as a means to expand DCD utilization across centers and nations.

In a large-volume multidisciplinary setting individual surgeon volume does not impact LVAD outcomes.

BACKGROUND: In complex operations surgeon volume may impact outcomes. We sought to understand if individual surgeon volume affects left ventricular assist device (LVAD) outcomes. METHODS: We reviewed primary LVAD implants at an experienced ventricular assist devices (VAD)/transplant center between 2013 and 2019. Cases were dichotomized into a high-volume group (surgeons averaging 11 or more LVAD cases per year), and a low-volume group (10 or less per year). Propensity score matching was performed. Survival to discharge, 1-year survival, and incidence of major adverse events were compared between the low- and high-volume groups. Predictors of survival were identified with multivariate analysis. RESULTS: There were 315 patients who met inclusion criteria-45 in the low-volume group, 270 in the high-volume group. There was no difference in survival to hospital discharge between the low (91.9%) and high (83.3%) volume matched groups (p = .22). Survival at 1-year was also similar (85.4% vs. 80.6%, p = .55). There was no difference in the incidence of major adverse events between the groups. Predictors of mortality in the first year included: age (hazards ratio [HR]: 1.061, p < .001), prior sternotomy (HR: 1.991, p = .01), increasing international normalized ratio (HR: 4.748, p < .001), increasing AST (HR: 1.001, p < .001), increasing bilirubin (HR: 1.081, p = .01), and preoperative mechanical ventilation (HR: 2.662, p = .005). Individual surgeon volume was not an independent predictor of discharge or 1-year survival. CONCLUSION: There was no difference in survival or adverse events between high and low volume surgeons suggesting that, in an experienced multidisciplinary setting, low-volume VAD surgeons can achieve similar outcomes to their high-volume colleagues.

Transapical ischemic ventricular septal defect repair with simultaneous centrifugal left ventricular assist device placement: A case report.

INTRODUCTION AND IMPORTANCE: Post-infarct ventricular septal defect (PIVSD) is an often-fatal complication of myocardial infarction despite the use of temporary mechanical circulatory support. CASE PRESENTATION: A 46-year-old male presented with myocardial infarction complicated by PIVSD. Clinical course was characterized by declining systolic function and hemodynamic instability. To provide hemodynamic support, a ventricular assist device was placed at surgical repair of the defect. The patient successfully recovered with no complications 21 months post-repair. He has undergone evaluation for heart transplantation. CLINICAL DISCUSSION: Mortality among patients with PIVSD is high. For patients with cardiogenic shock at the time of defect repair, concomitant ventricular assist device therapy shows promise to decrease morbidity through durable hemodynamic support following surgery. CONCLUSION: Placement of a durable left ventricular assist device (LVAD) at the time of PIVSD repair through a single ventriculotomy may be an effective strategy for this lethal condition.

Thoracoabdominal Normothermic Perfusion in Donation After Circulatory Death.

Donation after circulatory death is emerging as an alternative pathway to donation after brain death to expand the cardiac organ donor pool. We describe the surgical technique and circuit configuration for in-situ organ reperfusion with thoracoabdominal normothermic regional perfusion using portable venoarterial extracorporeal membrane oxygenation.

Successful lung transplantation with graft recovered after thoracoabdominal normothermic perfusion from donor after circulatory death.

Lung transplantation with lungs procured from donors after circulatory death (DCD) has been established as an alternative technique to traditional donation after brain death (DBD) with comparable outcomes. Recently, in situ thoracoabdominal normothermic regional perfusion (TA-NRP) has emerged as a novel technique employed in the procurement of cardiac allografts after circulatory death. TA-NRP, in contrast to ex situ machine perfusion, has the advantage of allowing in situ assessment of donor organs prior to final acceptance. However, there are some concerns that this technique may adversely impact the quality of lung allografts. Here, we present a case of a successful bilateral sequential lung transplantation in a patient with postinflammatory pulmonary fibrosis due to acute respiratory distress syndrome (ARDS), with lungs procured after normothermic in situ lung perfusion. Apart from the lungs, heart, liver, and kidneys were also successfully transplanted from this donor.

Combination plate and band fixation for primary closure in bilateral lung transplantation.

BACKGROUND: Sternal complications are common following transverse thoracosternotomy in patients undergoing bilateral lung transplantation. We present a single-institution experience using a next generation rigid fixation system for primary sternal closure following transverse sternotomy for bilateral lung transplantation. METHODS: Retrospective review was performed on all patients who had bilateral sequential lung transplants utilizing a transverse thoracosternotomy from 2016 to 2020. Demographics, baseline characteristics, peri-operative data, and outcomes were collected, reviewed and summarized. Two groups of patients were identified: wire cerclage (Group A), combination plate-and-band rigid fixation (Group B). The primary outcome was sternal complications, which were divided into mechanical and non-mechanical. RESULTS: Twenty-two patients met inclusion criteria. Three patients (13.6%) were in Group A, nineteen patients (86.4%) in Group B. Two patients in each Group A (66.6%) and Group B (10.5%) experienced a sternal complication. Sternal complications included sternal dehiscence (2), sternal malunion (1), and surgical site infection (1). One patient with plate-and-band fixation (5.2%) had a mechanical sternal complication. Three patients required reoperation secondary to sternal complication. CONCLUSIONS: The utilization of a combination plate-and-band rigid fixation system for primary closure is safe and may be an effective method to reduce sternal complications following transverse thoracosternotomy for lung transplantation.

Impact of temporary mechanical circulatory support for early graft failure on post-heart transplantation outcomes.

Although temporary mechanical circulatory support (tMCS) for hemodynamic failure following heart transplantation is associated with increased early morbidity and mortality, the impact of etiology of graft dysfunction and long-term clinical implications are less well known. The objective of our study was to evaluate outcomes in patients who required venoarterial extracorporeal membrane oxygenation (VA ECMO) or temporary right ventricular assist device (RVAD) support for either primary or secondary early graft dysfunction. Hospital mortality in 27 patients who required tMCS following heart transplantation at our institution between 2007 and 2017 was 56%, 30% in patients with right ventricular dysfunction secondary to increased afterload, 60% in patients with primary graft dysfunction, and 100% in patients with graft failure secondary to coagulopathy with intraoperative bleeding or overwhelming sepsis. Conditional 1-year and 5-year survival was comparable between patients with, and without, the need for post-transplantation support with tMCS (98% and 89%; 92% and 65% at 1 and 5 years, P = .21). Etiology of early graft failure plays an important part in determining the short-term post-heart transplantation outcome. Although complications associated with tMCS use, such as renal dysfunction and infection, extend beyond index transplant hospitalization, long-term conditional survival is not compromised.

Recurrent pump thrombosis is common after axial continuous-flow left ventricular assist device exchange.

In selected patients with left ventricular assist device-associated infection or malfunction, pump exchange may become necessary after conservative treatment options fail and heart transplantation is not readily available. We examined the survival and complication rate in patients (⩾19 years of age) who underwent HeartMate II to HeartMate II exchange at our institution from 1 January 2010 to 28 February 2018. Clinical outcomes were analyzed and compared for patients who underwent exchange for pump thrombosis (14 patients), breach of driveline integrity (5 patients), and device-associated infection (2 patients). There were no differences in 30-day mortality (p = 0.58), need for temporary renal replacement therapy (p = 0.58), right ventricular mechanical support (p = 0.11), and postoperative stroke (p = 0.80) among groups. Survival at 1 year was 90% ± 7% for the whole cohort and 85% ± 10% for those who underwent exchange for pump thrombosis. In patients exchanged for device thrombosis, freedom from re-thrombosis and survival free from pump re-thrombosis at 1 year were 49% ± 16% and 42% ± 15%, respectively. No association of demographic and clinical variables with the risk of recurrent pump thrombosis after the first exchange was identified. Survival after left ventricular assist device exchange compares well with published results after primary left ventricular assist device implantation. However, recurrence of thrombosis was common among patients who required a left ventricular assist device exchange due to pump thrombosis. In this sub-group, consideration should be given to alternative strategies to improve the outcomes.