Cardiovascular Outcomes in Fontan Patients With Right vs Left Univentricular Morphology: A Multicenter Study

Diagnosis of Diastolic Dysfunction in Adults With Failing Fontan Circulation

Since the initial Fontan procedure introduced in 1968 for tricuspid atresia, significant advancements have expanded its application to various congenital cardiac anomalies where a biventricular circulation is unattainable. Despite improved survival rates, Fontan circulation tends to fail over time leading to late morbidity and mortality. Diastolic dysfunction is increasingly recognized as a significant contributor to circulatory insufficiency and failure in Fontan patients. This review aims to assess the current evidence for diagnosing diastolic dysfunction in adults with failing Fontan circulation, including biomarkers, echocardiography, cardiac magnetic resonance imaging, and catheterization. While advancements have been made in understanding diastolic dysfunction in single ventricles, challenges remain due to the unique anatomy and physiology of Fontan patients. Future research should focus on refining diagnostic parameters and exploring potential therapies tailored to the distinct needs of this population.

Respiratory Function of Fontan Pediatric Patients with Hypoplastic Left Heart Syndrome and Other Morphologies of Functionally Single Ventricle-A Pilot Study

Background/Objectives: Management of complex congenital heart defects with functionally single ventricle remains one of the greatest challenges of pediatric cardiology. The multistage surgical treatment completed with Fontan procedure is related to multiple complications. Due to non-pulsatile continuous pulmonary flow and chronic hypoxia, Fontan circulation may induce pulmonary endothelial dysfunction. However, the impact of Fontan physiology on respiratory system function is not well studied. The aim of the research was to assess respiratory function in Fontan pediatric patients with hypoplastic left heart syndrome (HLHS) and other morphologies of functionally single ventricle. The article presents the preliminary results drawn from the pilot study, focusing on Fontan patients, without a healthy children control group. Methods: A cross-sectional study involved Fontan patients hospitalized in the Pediatric Cardiology Clinic of the Medical University of Silesia in Katowice between August 2023 and November 2024. The exclusion criteria were lack of parental and/or patient's consent, age < 6 years old, decompensated heart failure, asthma, atopy, respiratory infection within two weeks before the hospitalization, or significant psychomotor disability. Respiratory function assessment involved spirometry and fractional exhaled nitric oxide (FeNO) measurement. Results: A total of 32 patients who met inclusion criteria performed respiratory measurements. The mean age was 12.9 years old; there were 12 females. A total of 12 patients had HLHS and 20 patients had other morphologies of univentricular heart. FeNO values were relatively high with a mean of 30 ppb. Spirometry showed restrictive or mixed restrictive and obstructive ventilatory pattern. The mean forced vital capacity (FVC) levels were 79.2 ± 12.3% of predicted value (%pv) and forced expiratory volume in the first second (FEV1) 77.3 ± 13.8%pv. Children with HLHS presented statistically significantly lower percentages of predicted value of FEV1. There were statistically significant negative correlations between NT-proBNP concentrations and FEV1, FEV1%pv, MEF25-75 and MEF25-75%pv. Conclusions: Fontan pediatric patients present a restrictive or mixed restrictive and obstructive ventilatory pattern and relatively high FeNO levels. Patients with HLHS have worse pulmonary function than patients with other univentricular heart morphologies. This may be related to worse ventricular function in patients with HLHS.

Right Ventricular Electrophysiology and Arrhythmias in Adults With Congenital Heart Disease: Scientific Basis for Management

Right ventricular (RV) dysfunction and arrhythmias are major concerns in adults with congenital heart disease (CHD). The relationship between RV dysfunction and arrhythmogenesis is bidirectional, with structural and electrical remodeling contributing to arrhythmia development and, conversely, arrhythmias exacerbating RV failure. In addition to an RV in the standard subpulmonary position failing because of pressure and/or volume overload, other phenotypes associated with RV dysfunction in CHD include transposition of the great arteries with a systemic (subaortic) RV and univentricular hearts with a predominant RV morphology. The RV is better suited for low-pressure workloads. When it supports the systemic circulation, the RV undergoes remodeling changes that promote arrhythmias, which can provoke a cycle of worsening dysfunction and arrhythmogenesis. Arrhythmias can worsen RV dysfunction by impairing hemodynamic stability, reducing cardiac output, provoking dyssynchrony, and inducing tachycardia-induced cardiomyopathy. Cellular mechanisms, including myocardial fibrosis, dysregulation of ion channels, and abnormal gap junction function, are central to this process, facilitating both re-entrant and triggered arrhythmias. Conduction disturbances, whether inherent or caused by fibrosis or pacing, compound these effects, aggravating both RV dysfunction and arrhythmia perpetuation. Management strategies must be comprehensive and include pre-emptive approaches to minimize arrhythmias, alongside early detection. Individualized therapies may include catheter ablation and cardiac implantable electronic devices, with treatment tailored to the specific RV phenotype and arrhythmia type. In this review we emphasize the importance of personalized interventions to prevent the vicious cycle of RV dysfunction and arrhythmias in CHD. Further research is essential to optimize therapeutic strategies and address care-limiting knowledge gaps.

Right Ventricular Remodeling in Complex Congenital Heart Disease

In congenital heart diseases (CHDs) of moderate to great complexity involving the right ventricle (RV), the morphologic RV can be exposed to significant stressors across the lifespan, either in a biventricular circulation in a subpulmonary or subaortic position or as part of a univentricular circulation. These include pressure and/or volume overload, hypoxia, ischemia, and periprocedural surgical stress, leading to remodeling, maladaptation, dilation, hypertrophy, and dysfunction. In this review we examine the macroscopic remodeling of the RV in various forms of CHD and explore remodeling trajectories, along with the effects of surgeries and residual lesion repair, in tetralogy of Fallot, Ebstein anomaly, congenitally corrected transposition of the great arteries, transposition of the great arteries with atrial switch surgery, and single ventricle palliated by Fontan. In addition, the role of metabolism, genetic markers, and imaging criteria of RV remodeling are explored. Finally, the optimal timing for addressing residual lesions in CHD through surgery or percutaneous interventions is discussed, along with advanced heart failure management strategies and medical therapy aimed at preventing further RV dilation and/or systolic deterioration or promoting reverse remodeling.

Impact of cardiovascular magnetic resonance in single ventricle physiology: a narrative review

Background and Objective

Cardiovascular magnetic resonance (CMR) is a routine cross-sectional imaging modality in adults with congenital heart disease. Developing CMR techniques and the knowledge that CMR is well suited to assess long-term complications and to provide prognostic information for single ventricle (SV) patients makes CMR the ideal assessment tool for this patient cohort. Nevertheless, many of the techniques have not yet been incorporated into day-to-day practice. The aim of this review is to provide a comprehensive overview of CMR applications in SV patients together with recent scientific findings.

Methods

Articles from 2009 to August 2024 retrieved from PubMed on CMR in SV patients were included. Case reports and non-English literature were excluded.

Key Content and Findings

CMR is essential for serial follow-up of SV patients and CMR-derived standard markers can improve patient management and prognosis assessment. Advanced CMR techniques likely will enhance our understanding of Fontan hemodynamics and are promising tools for a comprehensive patient evaluation and care.

Conclusions

There is increasing research that shows the advantages of CMR in Fontan patients. However, further research about the prognostic role of CMR in older Fontan patients and how new methods such as modeling and deep learning pipelines can be clinically implemented is warranted.

Cardiovascular Outcomes Associated With Hypoplastic Left Heart Syndrome Versus Other Types of Single Right Ventricle: A Multicenter Study

BACKGROUND

The univentricular heart with a predominant right ventricle morphology (uRV) has been associated with a higher rate of adverse cardiovascular events. It remains to be determined whether the specific type of uRV influences outcomes.

METHODS AND RESULTS

A North American multicenter retrospective cohort study was conducted by the Alliance for Adult Research in Congenital Cardiology on individuals with a uRV and total cavopulmonary connection Fontan. The incidence of a composite outcome consisting of all-cause mortality, cardiac transplantation, atrial arrhythmias, or thromboembolic events was compared among patients with Fontan palliation who had hypoplastic left heart syndrome (HLHS) versus other forms of uRV (non-HLHS). All components of the composite outcome were classified by a blinded adjudicating committee. Competing risks were taken into account in time-to-event analyses. A total of 171 patients with uRV of whom 76 (44.4%) had HLHS were followed for 10.2±5.7 years. The composite outcome occurred in 7.1 versus 2.1 cases per 100 person-years in patients with HLHS versus non-HLHS (P<0.0001). In multivariable analyses, HLHS was associated with a significantly higher risk of the composite outcome (hazard ratio [HR], 6.13 [95% CI, 2.92-12.69], P<0.001). Moreover, HLHS was associated with significantly higher rates of all components of the primary outcome.

CONCLUSIONS

Among patients with a uRV and Fontan palliation, HLHS is associated with a significantly higher rate of adverse cardiovascular events.

The impact of donor-recipient age difference on graft survival after heart transplant in adults with congenital heart disease

Background

The impact of donor-recipient age difference in adult congenital heart disease (ACHD) patients undergoing heart transplant (HT) is unknown.

Methods

ACHD patients (≥18 years old) who underwent HT (2000-2020) were identified using the United Network for Organ Sharing database. Graft survival through 10 years based on donor-recipient age difference was evaluated by comparing outcomes of donors >5 years older than recipients (Older), donors within 5 years of recipient age (Equal Age), and donors >5 years younger than recipients (Younger, reference group). Cox multivariable analysis was performed to evaluate the effect of donor-recipient age difference on early and late graft survival.

Results

A total of 1,275 ACHD patients underwent HT (60% male, median 35 years old (interquartile range 24-46) with median graft survival of 13.7 years (95% confidence interval [CI] 11.7-16.0). Compared to Younger donors (n = 306 [24%]), graft survival was similar with Equal Age donors (n = 698 [55%]; log-rank p = 0.61), though significantly reduced with Older donors (n = 271 [21%]; log-rank p = 0.03). In multivariable analysis, late graft survival was similar with Equal Age donors but lower with Older donors (adjusted hazard ratio 1.63, 95% CI 1.16-2.28, p = 0.005), with a trend of reduced survival with Older donors in recipients <30 or ≥40 years old.

Conclusions

Graft survival in ACHD patients undergoing HT was similar for those with Younger and Equal Age donors. Recipients with Older donors had reduced 10-year survival, possibly related to increased risk in those <30 and ≥40 years old. These data help inform the optimal donor age for ACHD patients requiring HT.