Combined Heart Lung Transplantation: An Updated Review of the Current Literature

Extracorporeal membrane oxygenation as a bridge to thoracic multiorgan transplantation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has emerged as a crucial tool in the care of patients with multiorgan failure and is increasingly utilized as a bridge to transplantation. While data on ECMO as a bridge to isolated heart and lung transplantation have been described, our emerging experience with ECMO as a bridge to thoracic multiorgan transplantation is not yet well understood.

METHODS

The United Network for Organ Sharing database was used to identify adult patients undergoing thoracic multiorgan transplantation between 1987 and 2022. Exclusion criteria were recipient age <18 and bridging with other non-ECMO mechanical circulatory support, Survival analysis was performed to compare outcomes between patients bridged to transplantation with ECMO and those who were not bridged.

RESULTS

Of 3,927 patients undergoing thoracic multiorgan transplantation, a total of 203 (5.2%) patients received ECMO as a bridge to transplantation. Among ECMO recipients, patients were most commonly bridged to heart-lung (45.8%), followed by heart-kidney (34.5%), and lung-kidney transplantation (11.8%). At a median follow-up of 35.5 months, unadjusted survival among patients bridged with ECMO was decreased versus multiorgan transplant recipients who were not bridged (p < 0.001). Among patients surviving past 30 days following transplantation, conditional long-term survival was similar between ECMO and non-ECMO patients (p = 0.82).

CONCLUSIONS

ECMO is increasingly utilized as a bridge to thoracic multiorgan transplantation and is associated with increased 30 day mortality and decreased long-term survival. In select patients surviving to 30 days following transplantation, similar long-term survival is seen between patients bridged with ECMO and those not bridged.

Thirty years of surgical management of pediatric pulmonary hypertension: Mid-term outcomes following reverse Potts shunt and transplantation

BACKGROUND

Reverse Potts shunt (RPS) and lung or heart-lung transplantation are life-extending surgical interventions for pediatric patients with severe pulmonary arterial hypertension (PAH). Robust criteria for identifying patients who will benefit from these procedures remain elusive. Based on 30 years of experience, we sought to refine the surgical indications.

METHODS

This single-center retrospective cohort study included 61 consecutive pediatric patients with PAH managed by RPS (2004-2020) or transplantation (1988-2020). Their mid-term outcomes were assessed.

RESULTS

Compared with the 20 patients managed by RPS, the 41 transplant waitlist patients, of whom 28 were transplanted, were older (14.9 vs 8.0 years, P = .0001), had worse right ventricular impairment (tricuspid annular plane systolic excursion, 12.5 mm vs 18.0 mm, P = .03), and were managed later in the evolution of the disease (6.0 vs 1.7 years, P = .002). After implementation of a high-priority allocation program in 2007, waitlist mortality decreased from 52.6% to 13.6% (P = .02) and 5-year survival increased from 57.1% to 74.7% after RPS and 55.6% to 77.2% after transplantation. At a median follow-up of 8.6 years after RPS and 5.9 years after transplantation, functional capacity had improved significantly, and PAH-specific drug requirements had diminished markedly in the RPS group. Two patients successfully underwent double-lung transplant 6 and 9 years after RPS.

CONCLUSIONS

In selected children with suprasystemic PAH, RPS is associated with functional capacity improvements and decreased pharmacotherapy needs over the midterm. RPS deserves consideration earlier in the course of pediatric PAH, with transplantation being performed in the event of refractory RV failure.

Four decades of progress in heart-lung transplantation: Two hundred seventy-one cases at a single institution

OBJECTIVE

The objective of this study is to evaluate survival for combined heart-lung transplant (HLTx) recipients across 4 decades at a single institution. We aim to summarize our contemporary practice based on more than 271 HLTx procedures over 40 years.

METHODS

Data were collected from a departmental database and the United Network for Organ Sharing. Recipients younger than age 18 years, those undergoing redo HLTx, or triple-organ system transplantation were excluded, leaving 271 patients for analysis. The pioneering era was defined by date of transplant between 1981 and 2000 (n = 155), and the modern era between 2001 and 2022 (n = 116). Survival analysis was performed using cardinality matching of populations based on donor and recipient age, donor and recipient sex, ischemic time, and sex matching.

RESULTS

Between 1981 and 2022, 271 HLTx were performed at a single institution. Recipients in the modern era were older (age 42 vs 34 y; P < .001) and had shorter waitlist times (78 vs 234 days; P < .001). Allografts from female donors were more common in the modern era (59% vs 39%; P = .002). In the matched survival analysis, 30-day survival (97% vs 84%; P = .005), 1-year survival (89% vs 77%; P = .041), and 10-year survival (53% vs 26%; P = .012) significantly improved in the modern era relative to the pioneering era, respectively.

CONCLUSIONS

Long-term survival in HLTx is achievable with institutional experience and may continue to improve in the coming decades. Advances in mechanical circulatory support, improved maintenance immunosuppression, and early recognition and management of acute complications such as primary graft dysfunction and acute rejection have dramatically improved the prognosis for recipients of HLTx in our contemporary institutional experience.

Trends and Outcomes of Combined Heart-Kidney and Heart-Lung Transplantation Over the Past Two Decades

INTRODUCTION

Combined heart-kidney transplantation (HKTx) and combined heart-lung transplantation (HLTx) remain the definitive therapy for patients with end-stage heart failure with concomitant end-stage renal or lung failure. We sought to study trends and outcomes of HKTx and HLTx over the last two decades.

METHODS

The United Network for Organ Sharing registry was used to identify all adult patients (aged >18 y) who underwent HKTx and HLTx between 2001 and 2021. Patients were divided into 5-y groups by the year of transplantation (2001-2006, 2007-2011, 2012-2016, and 2017-2021). Primary outcome was 1-y posttransplantation mortality. Kaplan-Meier and multivariable Cox proportional hazards models were used for unadjusted and risk-adjusted survival analyses, respectively.

RESULTS

A total of 2301 HKTx and 567 HLTx patients were included. Between 2001 and 2021, HKTx volume increased from 25 to 344 patients (P < 0.001) and centers performing HKTx increased from 19 to 76 (P < 0.001). On unadjusted analysis, 1-y survival after HKTx improved from 86.7% in 2001-2006 to 89.0% in 2017-2021 (log-rank, P = 0.005). On risk-adjusted analysis, the hazard ratio of 1-y mortality for 2017-2021 was 0.62 (0.39-1.00, P = 0.048) compared with that for 2001-2006. Between 2001 and 2021, HLTx volume increased from 21 to 43 patients (P < 0.001) and centers performing HLTx increased from 12 to 20 (P = 0.047). On unadjusted analysis, 1-y survival after HLTx improved from 68.9% in 2001-2006 to 83.9% in 2017-2021 (log-rank, P = 0.600). On risk-adjusted analysis, the hazard ratio of 1-y mortality for 2017-2021 was 0.37 (0.21-0.67, P = 0.001) compared with that for 2001-2006.

CONCLUSIONS

Over the last two decades, HKTx volume substantially increased and HLTx experienced resurgent growth. One-year survival persistently improved for both procedures, especially over the past 5 y.

Normothermic Machine Perfusion Systems: Where Do We Go From Here?

Normothermic machine perfusion (NMP) aims to preserve organs ex vivo by simulating physiological conditions such as body temperature. Recent advancements in NMP system design have prompted the development of clinically effective devices for liver, heart, lung, and kidney transplantation that preserve organs for several hours/up to 1 d. In preclinical studies, adjustments to circuit structure, perfusate composition, and automatic supervision have extended perfusion times up to 1 wk of preservation. Emerging NMP platforms for ex vivo preservation of the pancreas, intestine, uterus, ovary, and vascularized composite allografts represent exciting prospects. Thus, NMP may become a valuable tool in transplantation and provide significant advantages to biomedical research. This review recaps recent NMP research, including discussions of devices in clinical trials, innovative preclinical systems for extended preservation, and platforms developed for other organs. We will also discuss NMP strategies using a global approach while focusing on technical specifications and preservation times.

Heart-Lung Transplantation From Donation After Circulatory Death Using Mobile Normothermic Regional Perfusion

Combined heart-lung transplant (HTLx) is the most durable treatment available for end-stage heart and lung failure. Many patients are unable to receive combined organs due to organ availability and allocation policies prioritizing separate heart or lung transplantation. While an average of 45 HTLxs have been performed per year in the United States half the listed patients do not receive organs. Recently, donation after circulatory death (DCD) utilizing normothermic regional perfusion (NRP) has been utilized for heart allografts with excellent results, and here, we present a case utilizing mobile NRP to procure a heart and lung block from a circulatory death donor and successful implantation for a recipient in a separate center.

Screening gene signatures for clinical response subtypes of lung transplantation

Lung is the most important organ in the human respiratory system, whose normal functions are quite essential for human beings. Under certain pathological conditions, the normal lung functions could no longer be maintained in patients, and lung transplantation is generally applied to ease patients' breathing and prolong their lives. However, several risk factors exist during and after lung transplantation, including bleeding, infection, and transplant rejections. In particular, transplant rejections are difficult to predict or prevent, leading to the most dangerous complications and severe status in patients undergoing lung transplantation. Given that most common monitoring and validation methods for lung transplantation rejections may take quite a long time and have low reproducibility, new technologies and methods are required to improve the efficacy and accuracy of rejection monitoring after lung transplantation. Recently, one previous study set up the gene expression profiles of patients who underwent lung transplantation. However, it did not provide a tool to predict lung transplantation responses. Here, a further deep investigation was conducted on such profiling data. A computational framework, incorporating several machine learning algorithms, such as feature selection methods and classification algorithms, was built to establish an effective prediction model distinguishing patient into different clinical subgroups, corresponding to different rejection responses after lung transplantation. Furthermore, the framework also screened essential genes with functional enrichments and create quantitative rules for the distinction of patients with different rejection responses to lung transplantation. The outcome of this contribution could provide guidelines for clinical treatment of each rejection subtype and contribute to the revealing of complicated rejection mechanisms of lung transplantation.

Evaluation of Risk Factors for Heart-Lung Transplant Recipient Outcome: An Analysis of the United Network for Organ Sharing Database

BACKGROUND

Heart-lung transplantation (HLTx) is an effective treatment for patients with advanced cardiopulmonary failure. However, no large multicenter study has focused on the relationship between donor and recipient risk factors and post-HLTx outcomes. Thus, we investigated this issue using data from the United Network for Organ Sharing database.

METHODS

All adult patients (age ≥18 years) registered in the United Network for Organ Sharing database who underwent HLTx between 1987 and 2017 were included (n=997). We stratified the cohort by patients who were alive without retransplant at 1 year (n=664) and patients who died or underwent retransplant within 1 year of HLTx (n=333). The primary outcome was the influence of donor and recipient characteristics on 1-year post-HLTx recipient death or retransplant. Kaplan-Meier curves were created to assess overall freedom from death or retransplant. To obtain a better effect estimation on hazard and survival time, the parametric Accelerated Failure Time model was chosen to perform time-to-event modeling analyses.

RESULTS

Overall graft survival at 1-year post-HLTx was 66.6%. Of donors, 53% were male, and the mean age was 28.2 years. Univariable analysis showed advanced donor age, recipient male sex, recipient creatinine, recipient history of prior cardiac or lung surgery, recipient extracorporeal membrane oxygenation support, transplant year, and transplant center volume were associated with 1-year post-HLTx death or retransplant. On multivariable analysis, advanced donor age (hazard ratio [HR], 1.017; P=0.0007), recipient male sex (HR, 1.701; P=0.0002), recipient extracorporeal membrane oxygenation support (HR, 4.854; P<0.0001), transplant year (HR, 0.962; P<0.0001), and transplantation at low-volume (HR, 1.694) and medium-volume centers (HR, 1.455) in comparison with high-volume centers (P=0.0007) remained as significant predictors of death or retransplant. These predictors were incorporated into an equation capable of estimating the preliminary probability of graft survival at 1-year post-HLTx on the basis of preoperative factors alone.

CONCLUSIONS

HLTx outcomes may be improved by considering the strong influence of donor age, recipient sex, recipient hemodynamic status, and transplant center volume. Marginal donors and recipients without significant factors contributing to poor post-HLTx outcomes may still be considered for transplantation, potentially with less impact on the risk of early postoperative death or retransplant.

Impaired cardiac autonomic response in lung transplant patients: A retrospective cohort study

BACKGROUND

Cardiac autonomic dysfunction (AD) is associated with adverse prognosis in lung disease; however, its implications in lung transplantation have not been previously described. This study evaluated the prevalence of AD in lung transplant (LTx) candidates, its determinants, prognostic implications, and prevalence post-transplant.

METHODS

Retrospective one-year study of 103 LTx candidates with AD assessed using heart rate (HR) from the six-minute walk test (6MWT). Impaired chronotropic response index (CRI) was defined as <80% age-adjusted HR during 6MWT. Abnormal HR recovery (HRR) was categorized as reduction in HR ≤ 12 beats/minute after the first minute of 6MWT cessation.

RESULTS

Abnormal CRI and HRR were observed in 94% and 76% of patients, respectively. A lower CRI was associated with obstructive lung disease and lower estimated aerobic capacity. CRI was independently associated with 6MW distance [12 m per 10% CRI, P = 0.03], but not with post-transplant cardiovascular events, hospital stay, or one-year mortality. At 3 months post-transplant, no improvement was observed in CRI (99%, n = 66/67, P = 0.25) or HRR (88%, n = 36/41, P = 0.12).

CONCLUSION

Cardiac AD was prevalent in LTx candidates and recipients, with chronotropic incompetence a modest contributor to exercise intolerance pretransplant. Further study may help determine whether direct autonomic measures such as HR variability may be more prognostic of LTx outcomes.

Heart-lung transplantation: current indications, prognosis and specific considerations

Heart-lung transplantation (HLTx) is currently the best treatment for patients who have end-stage heart and lung failure. Idiopathic pulmonary arterial hypertension (IPAH) was the main indication for HLTx in the 1980s. However, when studies showed resolution of right ventricular dysfunction after double-lung transplantation (DLTx), this last procedure became the preferred option for end-stage IPAH. Currently, the main indication of HLTx is congenital heart disease (CHD), followed by acquired heart disease combined with pulmonary hypertension and/or intrinsic lung disease. Although early posttransplant survival remains lower after HLTx than after lung transplantation, careful patient selection combined with surgical advances are producing improvements. Here, we review the practice patterns, trends, and outcomes of HLTx worldwide.

Noteworthy Literature published in 2017 for Congenital Cardiac Anesthesiologists

This review focuses on the literature published during the 13 months from December 2016 to December 2017 that is of interest to anesthesiologists taking care of children and adults with congenital heart disease. Five themes are addressed during this time period and 100 peer-reviewed articles are discussed.

Overview of Lung Transplantation, Heart-Lung Transplantation, Liver-Lung Transplantation, and Combined Hematopoietic Stem Cell Transplantation and Lung Transplantation

Lung transplantation (LTx) has evolved to represent the therapy of choice for many patients with end-stage lung diseases. Appropriate candidate selection for LTx is an important determinant of a positive outcome from transplantation. Posttransplantation survival has steadily improved, but long-term survival continues to be a challenge with a median survival of 5.8 years. Similarly, combined heart-lung transplantation and simultaneous liver-lung transplantation has been performed successfully in select patients who are not expected to survive either organ transplant alone. Moreover, LTx has been performed in patients who develop end-stage pulmonary complications following hematopoietic stem cell transplantation.