International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024

The "International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024" updates and replaces the "Listing Criteria for Heart Transplantation: International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates-2006" and the "2016 International Society for Heart Lung Transplantation Listing Criteria for Heart Transplantation: A 10-year Update." The document aims to provide tools to help integrate the numerous variables involved in evaluating patients for transplantation, emphasizing updating the collaborative treatment while waiting for a transplant. There have been significant practice-changing developments in the care of heart transplant recipients since the publication of the International Society for Heart and Lung Transplantation (ISHLT) guidelines in 2006 and the 10-year update in 2016. The changes pertain to 3 aspects of heart transplantation: (1) patient selection criteria, (2) care of selected patient populations, and (3) durable mechanical support. To address these issues, 3 task forces were assembled. Each task force was cochaired by a pediatric heart transplant physician with the specific mandate to highlight issues unique to the pediatric heart transplant population and ensure their adequate representation. This guideline was harmonized with other ISHLT guidelines published through November 2023. The 2024 ISHLT guidelines for the evaluation and care of cardiac transplant candidates provide recommendations based on contemporary scientific evidence and patient management flow diagrams. The American College of Cardiology and American Heart Association modular knowledge chunk format has been implemented, allowing guideline information to be grouped into discrete packages (or modules) of information on a disease-specific topic or management issue. Aiming to improve the quality of care for heart transplant candidates, the recommendations present an evidence-based approach.

Validating the Concept of Mechanical Circulatory Support with a Rotary Blood Pump in the Inferior Vena Cava in an Ovine Fontan Model

Right-sided mechanical support of the Fontan circulation by existing devices has been compounded by the cross-sectional design of vena cava anastomosis to both pulmonary arteries. Our purpose was to investigate whether increasing inferior vena cava (IVC) flow with a rotary blood pump in the IVC only in an ovine animal model of Fontan would lead to acceptable superior vena cava (SVC) pressure. To achieve this, a Fontan circulation was established in four female sheep by anastomosing the SVC to the main pulmonary artery (MPA) and by interposing a Dacron graft between the IVC and the MPA. A rotary blood pump was then introduced in the graft, and the effect of incremental flows was observed at increasing flow regimen. Additionally, to stimulate increased pulmonary resistance, the experience was repeated in each animal with the placement of a restrictive band on the MPA distally to the SVC and Dacron graft anastomosis. Circulatory support of IVC flow alone increased the systemic cardiac output significantly, both with and without banding, indicating the feasibility of mechanical support of the Fontan circulation by increasing the flow only in the inferior vena cava. The increase in SVC pressure remained within acceptable limits, indicating the potential effectiveness of this mode of support. The findings suggest that increasing the flow only in the inferior vena cava is a feasible method for mechanical support of the Fontan circulation, potentially leading to an increase in cardiac output with acceptable increases in superior vena cava pressure.

Lymphatic failure and lymphatic interventions: Knowledge gaps and future directions for a new frontier in congenital heart disease

Lymphatic failure is a broad term that describes the lymphatic circulation's inability to adequately transport fluid and solutes out of the interstitium and into the systemic venous circulation, which can result in dysfunction and dysregulation of immune responses, dietary fat absorption, and fluid balance maintenance. Several investigations have recently elucidated the nexus between lymphatic failure and congenital heart disease, and the associated morbidity and mortality is now well-recognized. However, the precise pathophysiology and pathogenesis of lymphatic failure remains poorly understood and relatively understudied, and there are no targeted therapeutics or interventions to reliably prevent its development and progression. Thus, there is growing enthusiasm towards the development and application of novel percutaneous and surgical lymphatic interventions. Moreover, there is consensus that further investigations are needed to delineate the underlying mechanisms of lymphatic failure, which could help identify novel therapeutic targets and develop innovative procedures to improve the overall quality of life and survival of these patients. With these considerations, this review aims to provide an overview of the lymphatic circulation and its vasculature as it relates to current understandings into the pathophysiology and pathogenesis of lymphatic failure in patients with congenital heart disease, while also summarizing strategies for evaluating and managing lymphatic complications, as well as specific areas of interest for future translational and clinical research efforts.

Improving outcomes for transplantation in failing Fontan—what is the next target?

Objective

To identify the key contributors to postoperative mortality in patients undergoing orthotopic heart transplantation (OHT) for late Fontan failure.

Methods

This retrospective review of failing Fontan patients who underwent OHT in our tertiary care center between 2007 and 2019 included adult patients with congenital heart disease and single ventricle physiology who were palliated with a Fontan circulation for >1 year. We excluded patients undergoing combined heart-liver transplantation.

Results

The study cohort comprised 31 patients, including 18 males (58.1%), with a mean weight of 58.4 kg, median age at Fontan of 6.9 years (interquartile range [IQR], 2-38 years), and a median age at OHT of 27.1 years (IQR, 16.7-53.3). Almost all (93.5%) of the patients were in New York Heart Association class III-IV, and the majority (74.2%) were in Interagency Registry for Mechanically Assisted Circulatory Support class 3. Overall survival at 30 days, 1 year, and 5 years after OHT was 81%, 71%, and 67%, respectively. Major intraoperative bleeding was associated with increased mortality after OHT (odds ratio, 30; 95% confidence interval, 2.8-322; P = .002). Neither preoperative systemic ventricular function nor the development of primary graft dysfunction (PGD) was significantly associated with postoperative death. Nevertheless, PGD determined significant morbidity of this population.

Conclusions

In our cohort, major intraoperative bleeding was the key factor associated with mortality after OHT for late Fontan failure. Novel strategies for the prevention and management of postoperative bleeding will improve outcomes in this group of patients.

Fontan-associated plastic bronchitis waitlist and heart transplant outcomes: A PHTS analysis

Plastic bronchitis is a rare post-Fontan complication with limited treatment options. Heart transplantation has evolved as a potential curative option, but outcomes have not been well-defined. This study aims to assess contemporary waitlist and post-transplant outcomes in patients with plastic bronchitis. All Fontan patients were identified in the PHTS database (2010 - 2018). Waitlist and post-transplant outcomes were compared between Fontan patients with and without plastic bronchitis. Competing outcomes and Kaplan-Meier analyses were used to assess the impact of plastic bronchitis on waitlist and post-transplant survival. A secondary analysis excluded those with PLE from the comparison cohort. Of 645 Fontan patients listed for heart transplant, 69 (11%) had plastic bronchitis. At listing, patients with plastic bronchitis were younger (8.9 vs 11.1 years, P = .02), but had few other differences in baseline characteristics. A fewer Fontan patients with plastic bronchitis were listed in the more recent era (46 [15.4%] in 2010-2014 vs 23 [6.6%] in 2015-2018, P < .01). Overall, there was no difference in waitlist (P = .30) or post-transplant (P = .66) survival for Fontan patients with and without plastic bronchitis. The results were similar after excluding patients with PLE. Contrary to prior reports, this relatively large series showed that plastic bronchitis did not have a negative impact on survival to or after heart transplantation in Fontan patients. Our study also found a 50% reduction in listing in the current era, which may indicate evolution in management of Fontan patients.

Pathophysiology and clinical presentation of paediatric heart failure related to congenital heart disease

Congenital heart disease (CHD) and cardiomyopathies represent the two most important causes of paediatric heart failure (HF) in developed countries. We made a review of the literature on pathophysiology and clinical presentation of paediatric HF in children with CHD. Two main pathophysiologic models can be identified: the 'over-circulation failure', characterised by signs and symptoms of congestion or hypoperfusion, due respectively to volume or pressure overload, and the 'pump failure'. CONCLUSIONS: The comprehension of the HF pathophysiology in paediatric patients with CHD is of paramount importance for the optimal management and for addressing the best therapeutic choices.

The Evolving Surgical Burden of Fontan Failure: An Analysis of The Society of Thoracic Surgeons Congenital Heart Surgery Database

BACKGROUND

Fontan failure often requires surgical therapy in the form of Fontan revision or heart transplantation. We sought to characterize national trends in the surgical burden of Fontan failure and identify risk factors for adverse outcomes.

METHODS

Fontan patients undergoing Fontan revision or transplantation from January 2010 to June 2018 were included. We evaluated baseline characteristics and outcomes and used multivariable logistic regression to identify risk factors for operative mortality and composite mortality and major morbidity.

RESULTS

A total of 1135 patients underwent Fontan revision (n = 598) or transplantation (n = 537) at 100 centers. Transplantations increased from 34 in 2010 to 76 in 2017, largely owing to an increase in patients with hypoplastic left heart syndrome (HLHS) (18 in 2010 to 49 in 2017), while Fontan revision decreased (75 in 2010 to 49 in 2017). Transplantation patients were younger (median 14 years of age vs 18 years of age; P < .001), more often had preoperative risk factors (66% vs 40%; P < .001), and more often had HLHS (51% vs 15%; P < .001). Operative mortality and composite major morbidity and mortality were 7.6% and 35% for transplantation and 7.1% and 22% for Fontan revision, respectively. Multivariable risk factors for mortality included older age (odds ratio [OR], 1.08/y; P = .007), presence of preoperative risk factors (OR, 3.33; P = .002), and concomitant pulmonary artery reconstruction (OR, 2.7; P = .029) for Fontan revision but only older age (OR, 1.06/y; P = .020) for transplantation.

CONCLUSIONS

Both transplantation and Fontan revision are associated with high morbidity and mortality. There has been evolution of practices in surgical therapy for Fontan failure, perhaps related to rising prevalence of HLHS staged palliation.

Anesthesia for Pediatric Heart Transplantation: Are Patients With a Failing Hemi-Fontan- or Fontan-Physiology Different?

Background. The absolute number of patients presenting with failure of the hemi-Fontan or Fontan circulation for cardiac transplantation (cTx) will continuously rise. We aimed to analyze the intraoperative differences in patients undergoing cTx for a failing hemi-Fontan or Fontan circulation (group A) with those undergoing cTx for cardiomyopathy and congenital heart disease (group B). Methods. Data of patients undergoing cTx during a 10-year period were compared between group A and group B patients. Results. cTx was performed in 83 patients (group A, n = 21; group B, n = 62). Surgical times including median incision-suture time (549 minutes vs 386 minutes, P < .05) and median organ ischemia time (305 minutes vs 233 minutes, P < .05) were longer in group A patients. After weaning off cardiopulmonary bypass a higher median modified Vasoactive Inotropic Score (16 vs 10, P < .05) was necessary in group A patients. During surgery more fresh frozen plasma (44 mL/kg vs 20 mL/kg, P < .05), platelet concentrates (20 mL/kg vs 14 mL/kg, P < .05), and coagulation factor concentrates were given in group A patients. Mortality during the first 90 days after cTx was higher in group A (23.8% vs 6.5%, P < .05). Conclusion. Patients undergoing cTx for a failing hemi-Fontan or Fontan circulation are challenging. They require an intensive vasoactive and inotropic support; furthermore, special attention should be paid to the management of bleeding complications. cTx for this group of patients is associated with higher 90 days mortality.

Research priorities in single-ventricle heart conditions: a United Kingdom national study

OBJECTIVE

To bring together stakeholders in the United Kingdom to establish national priorities for research in single-ventricle heart conditions.

METHODS

This study comprised two surveys and a workshop. The initial public online survey asked respondents up to three questions they would like answered for research. Responses were classified as unanswered, already answered, or unable to be answered by scientific research. In the follow-up survey, unanswered questions were divided into categories and respondents were asked to rank categories and questions by priority. A stakeholder workshop attended by patients, parents, healthcare professionals, researchers, and charities was held to determine the final list of research priorities.

RESULTS

A total of 128 respondents posed 344 research questions, of which 271 were classified as unanswered, and after removing duplicates, 204 questions remained, which were divided into 20 categories. In the second survey, 56 (49.1%) respondents successfully ranked categories and questions. A total of 39 participants attended the workshop, drawing up a list of 30 research priorities across nine priority categories. The nine priority categories are: Associated co-morbidities; Brain &amp; neurodevelopment; Exercise; Fontan failure; Heart function; Living with a single ventricle heart condition; Management of the well-functioning Fontan circulation; Surgery &amp; perioperative care; and Transplantation, mechanical support &amp; novel therapies.

CONCLUSIONS

Through a multi-stage process, we engaged a wide range of interested parties to establish a list of research priorities in single-ventricle heart conditions. This provides a platform for clinicians, researchers, and funders in the United Kingdom and elsewhere to address the most important questions and improve outcomes in these rare but high-impact CHDs.

Long Term Consequences of the Fontan Procedure and How to Manage Them

In 1971, Fontan and Baudet described a surgical technique for successful palliation of patients with tricuspid atresia. Subsequently, this technique has been applied to treat most forms of functional single ventricles and has become the current standard of care for long-term palliation of all patients with single ventricle congenital heart disease. Since 1971, the Fontan procedure has undergone several variations. These patients require lifelong management including a thorough knowledge of their anatomic substrate, hemodynamic status, management of rhythm and ventricular function along with multi organ evaluation. As these patients enter middle age, there is increasing awareness regarding the long-term complications and mortality. This review highlights the long-term outcomes of the Fontan procedure and management of late sequelae.