Twenty-Five Year Outcomes of the Lateral Tunnel Fontan Procedure

Neonates and Infants with Left Heart Obstruction and Borderline Left Ventricle Undergoing Biventricular Repair: What Do We Know about Long-Term Outcomes? A Critical Review

BACKGROUND

The decision to perform biventricular repair (BVR) in neonates and infants presenting with either single or multiple left ventricle outflow obstructions (LVOTOs) and a borderline left ventricle (BLV) is subject to extensive discussion, and limited information is known regarding the long-term outcomes. As a result, the objective of this study is to critically assess and summarize the available data regarding the prognosis of neonates and infants with LVOTO and BLV who underwent BVR.

METHODS

In February 2023, we conducted a review study with three different medical search engines (the National Library of Medicine, Science Direct, and Cochrane Library) for Medical Subject Headings and free text terms including "congenital heart disease", "outcome", and "borderline left ventricle". The search was refined by adding keywords for "Shone's complex", "complex LVOT obstruction", "hypoplastic left heart syndrome/complex", and "critical aortic stenosis".

RESULTS

Out of a total of 51 studies, 15 studies were included in the final analysis. The authors utilized heterogeneous definitions to characterize BLV, resulting in considerable variation in inclusion criteria among studies. Three distinct categories of studies were identified, encompassing those specifically designed to evaluate BLV, those focused on Shone's complex, and finally those on aortic stenosis. Despite the challenges associated with comparing data originating from slightly different cardiac defects and from different eras, our results indicate a favorable survival rate and clinical outcome following BVR. However, the incidence of reintervention remains high, and concerns persist regarding residual pulmonary hypertension, which has been inadequately investigated.

CONCLUSIONS

The available data concerning neonates and infants with LVOTO and BLV who undergo BVR are inadequate and fragmented. Consequently, large-scale studies are necessary to fully ascertain the long-term outcome of these complex defects.

Coagulation and Anticoagulation in Fontan Patients

Patients with a Fontan circulation for single-ventricle physiology are at increased risk of developing thromboembolic events. Thromboembolic events can lead to failure of the Fontan circulation, chronic sequelae in case of stroke, and early mortality. Controversies exist regarding the substrates, risk factors, and optimal detection methods for thromboembolic events. Despite the major clinical implications, there is currently no consensus regarding the optimal antithrombotic therapy to prevent or treat thromboembolic events after the Fontan procedure. In this review we aimed to untangle the available literature regarding antithrombotic prophylaxis and treatment for pediatric and adult Fontan patients. A decision-tree algorithm for thromboprophylaxis in Fontan patients is proposed. Additionally, the current state of knowledge is reviewed with respect to the epidemiology, pathophysiology, and detection of thromboembolic events in Fontan patients, and important evidence gaps are highlighted.

The Epidemiology of Persons Living with Fontan in 2020 and Projections for 2030: Development of an Epidemiology Model Providing Multinational Estimates

Introduction

Fontan surgery is a palliative procedure performed in children with a functionally univentricular heart. Improvements in surgical technique over the past 30 years have increased life expectancy in this rare population. However, the epidemiology of persons living with Fontan is poorly understood. This study aimed to estimate the 2020 and 2030 prevalence of persons living with a Fontan circulation in 11 countries across the US, Europe, Australia and New Zealand, by procedure type: [atriopulmonary connection (AP), lateral tunnel total cavopulmonary connection (LT-TCPC) or extracardiac total cavopulmonary connection (EC-TCPC)]; and age group: [children (< 12 years), adolescents (12–17 years), and adults (≥ 18 years old)] by building an epidemiologic model.

Methods

The annual number of Fontan surgeries by country in 2010–2020 were extracted from hospital or claims databases, via procedure codes. The epidemiology of persons living with Fontan was modelled by applying these surgery frequencies to mid-year populations from 1972 to 2020 and overlaying an uptake curve. A literature search identified: 30-day mortality rates, long-term survival, and median age at surgery. Averages of these estimates were inputted into the model to project prevalence in 2030.

Results

The number of persons living with Fontan in 2020 across the 11 countries was estimated to be 47,881 [66 people per million (ppm)], rising to 59,777 (79 ppm) by 2030. In 2020, this population was 55% adults, 17% adolescents and 28% children shifting to 64%, 13% and 23%, respectively, in 2030. Among all persons living with Fontan, 74%/18%/9% are estimated to have EC-TCPC/LT-TCPC/AP, respectively, in 2020, and 83%/14%/4% in 2030.

Conclusions

According to this epidemiology model, the Fontan population is growing, partly driven by increased survival rates with the more recent LT-TCPC and EC-TCPC procedures (compared with AP). The 2020/2030 prevalence of persons living with Fontan is 66/79 ppm.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-02002-3.

Atrial pacing in Fontan patients: The effect of transvenous lead on clot burden

BACKGROUND

Transvenous permanent pacemaker (PPM) implantation is an available option for Fontan patients with sinus node dysfunction. However, the thrombogenic potential of leads within the Fontan baffle is unknown.

OBJECTIVE

The purpose of this study was to compare the clot burden in Fontan patients with a transvenous atrial PPM to those without a PPM and those with an epicardial PPM.

METHODS

This was a retrospective cohort study of all transvenous PPM implantations in Fontan patients followed at our institution (2000-2018). We performed frequency matching on Fontan type and age group. Primary outcome was identification of intracardiac clot, pulmonary embolus, or embolic stroke.

RESULTS

Of 1920 Fontan patients, 58 patients (median age 23 years; interquartile range [25th-75th percentiles] 14-33) at the time of transvenous PPM implantation and 174 matched subjects formed our cohort. The type of Fontan performed in case subjects was right atrium-pulmonary artery or right atrium-right ventricle conduit (54%), lateral tunnel (43%), and extracardiac (3%). The cumulative incidence of clot was highest in patients with transvenous PPM, followed by patients with epicardial PPM and no PPM (1.2 vs 0.87 vs 0.67 per 100 person-years of follow-up, respectively). In multivariable analysis, anticoagulation and/or antiplatelet therapy were protective against clot and resulted in reduction of clot risk by 3-fold (incidence rate ratio 0.33; 95% confidence interval 0.21-0.53; P <.001).

CONCLUSION

In a large cohort of Fontan patients matched for age and Fontan type, patients with transvenous PPM had a higher but not statistically significant incidence of clot compared to those with no PPM and epicardial PPM. Patients treated with warfarin/aspirin had lower clot risk.

Direct EBUS-guided transtracheal lymphosclerosis for plastic bronchitis after Fontan

We report on a new puncture technique with direct transtracheal mediastinal lymphatic access to treat plastic bronchitis after Fontan repair. High resolution contrast-enhanced spiral CT identified enlarged lymph nodes in the paratracheal region. Inguinal intranodal Gadolinium Dynamic Contrast-enhanced Magnetic Resonance lymphangiography (DCMRL) confirmed the pathologic centrifugal lymph flow passing through these lymph nodes before leaking into the bronchial tree. The abnormal hypertrophic paratracheal, subcarinal, and hilar lymph nodes were punctured with a 22G needle through an endobronchial ultrasound bronchoscope. Occlusion of the lymph vessels was obtained by injecting a mixture of lipiodol/NBCA N-butyl cyanoacrylate (Histoacryl) 5/1 under fluoroscopic control. There was a total remission of PB with now 10 months of follow-up.

Sexual Function in Men Living With a Fontan Circulation

Introduction: It is unknown if the Fontan circulation has an impact on sexual health in men. This study assessed self-reported sexual health and fertility in men with a Fontan circulation. Aims: In this prospective, cross-sectional study, Australian men ≥18 years enrolled in the Fontan Registry of Australia and New Zealand were invited to complete the International Index of Erectile Function (IIEF), alongside questions assessing fertility. These data were compared to historical, age-matched controls. Results: Of 227 eligible men, 54 completed the survey; of those 37 were sexually active and included in the final analysis. Mean age was 28 ± 3 years, age at Fontan was 5 ± 3 years. Fontan type was extra-cardiac conduit in 15 (41%), lateral tunnel in 12 (32%), and atriopulmonary connection (APC) in 10 (27%). Ventricular function was normal in 24 (83%), and all were New York Heart Association Class I (23 patients, 79%) and II (six patients, 21%). Nine participants (24%) had erectile dysfunction (IIEF-EF score ≤25). The severity was mild (IIEF 22-24) in six (16%), mild-moderate (IIEF 17-21) in two (5%), and moderate (IIEF 11-16) in one (3%). Baseline characteristics and current medication usage were similar in those with and without erectile dysfunction. Compared with historical control values, erectile function was not significantly impaired in the Fontan population (p =0.76). Men with a Fontan circulation had decreased levels of sexual desire and overall satisfaction (p < 0.001). There was no correlation between the presence of erectile dysfunction and any assessed parameter. Eleven (30%) of the cohort reported a pregnancy with a prior partner. Conclusion: In our cohort, overall erectile function was comparable between men with a Fontan circulation and historical controls, however sexual desire and overall satisfaction were reduced. There was no correlation between study parameters and the presence of erectile dysfunction. The proportion of the cohort who had a prior pregnancy was congruent with population data.

A 45-year experience with the Fontan procedure: tachyarrhythmia, an important sign for adverse outcome

OBJECTIVES

This study aims to evaluate our 45-year experience with the Fontan procedure and to identify risk factors for late mortality and morbidity.

METHODS

Demographic, preoperative, perioperative and postoperative characteristics were retrospectively collected for all patients who underwent a Fontan procedure in a single centre between 1972 and 2016.

RESULTS

The study included 277 Fontan procedures (44 atriopulmonary connections, 28 Fontan-Björk, 42 lateral tunnels and 163 extracardiac conduits). Early failure occurred in 17 patients (6.1%). Median follow-up of the study cohort was 11.9 years (Q1-Q3 7.6-17.5). Longest survival estimates were 31% [95% confidence intervals (CI) 18-44%] at 35 years for atriopulmonary connection/Björk, 87% (95% CI 63-96%) at 20 years for lateral tunnel and 99% (95% CI 96-100%) at 15 years for extracardiac conduit. Estimated freedom from Fontan failure (death, heart transplant, take-down, protein-losing enteropathy, New York Heart Association III-IV) at 15 years was 65% (95% CI 52-76%) for atriopulmonary connection/Björk, 90% (95% CI 73-97%) for lateral tunnel and 90% (95% CI 82-94%) for extracardiac conduit. The development of tachyarrhythmia was an important predictor of Fontan failure [hazard ratio (HR) 2.6, 95% CI 1.2-5.8; P = 0.017], thromboembolic/neurological events (HR 3.6, 95% CI 1.4-9.4; P = 0.008) and pacemaker for sinus node dysfunction (HR 3.7, 95% CI 1.4-9.6; P = 0.008). Prolonged pleural effusion (>21 days) increased the risk of experiencing protein-losing enteropathy (HR 4.7, 95% CI 2.0-11.1; P < 0.001).

CONCLUSIONS

With modern techniques, survival and freedom from Fontan failure are good. However, Fontan patients remain subject to general attrition. Tachyarrhythmia is an important sign for an adverse outcome. Prevention and early treatment of tachyarrhythmia may, therefore, be paramount in improving the long-term outcome.

Loss of Ventricular Function After Bidirectional Cavopulmonary Connection: Who Is at Risk?

Decline of single ventricle systolic function after bidirectional cavopulmonary connection (BDCPC) is thought to be a transient phenomenon. We analyzed ventricular function after BDCPC according to ventricular morphology and correlated this evolution to long-term prognosis. A review from Mayo Clinic databases was performed. Visually estimated ejection fraction (EF) was reported from pre-BDCPC to pre-Fontan procedure. The last cardiovascular update was collected to assess long-term prognosis. A freedom from major cardiac event survival curve and a risk factor analysis were performed. 92 patients were included; 52 had left ventricle (LV) morphology and 40 had right ventricle (RV) morphology (28/40 had hypoplastic left heart syndrome (HLHS)). There were no significant differences in groups regarding BDCPC procedure or immediate post-operative outcome. EF showed a significant and relevant decrease from baseline to discharge in the HLHS group: 59 ± 4% to 49 ± 7% or - 9% (p < 0.01) vs. 58 ± 3% to 54 ± 6% or - 4% in the non-HLHS RV group (p = 0.04) and 61 ± 4% to 60 ± 4% or - 1% in the LV group (p = 0.14). Long-term recovery was the least in the HLHS group: EF prior to Fontan 54 ± 2% vs. 56 ± 6% and 60 ± 4%, respectively (p < 0.01). With a median follow-up of 8 years post-BDCPC, six patients had Fontan circulation failure, four died, and three had heart transplantation. EF less than 50% at hospital discharge after BDCPC was strongly correlated to these major cardiac events (HR 3.89; 95% Cl 1.04-14.52). Patients with HLHS are at great risk of ventricular dysfunction after BDCPC. This is not a transient phenomenon and contributes to worse prognosis.

Hypoplastic left heart syndrome: From bedside to bench and back

Hypoplastic Left Heart Syndrome (HLHS) is a complex Congenital Heart Disease (CHD) that was almost universally fatal until the advent of the Norwood operation in 1981. Children with HLHS who largely succumbed to the disease within the first year of life, are now surviving to adulthood. However, this survival is associated with multiple comorbidities and HLHS infants have a higher mortality rate as compared to other non-HLHS single ventricle patients. In this review we (a) discuss current clinical challenges associated in the care of HLHS patients, (b) explore the use of systems biology in understanding the molecular framework of this disease, (c) evaluate induced pluripotent stem cells as a translational model to understand molecular mechanisms and manipulate them to improve outcomes, and (d) investigate cell therapy, gene therapy, and tissue engineering as a potential tool to regenerate hypoplastic cardiac structures and improve outcomes.

Multisite measurement of regional oxygen saturation in Fontan patients with and without protein-losing enteropathy at rest and during exercise

BACKGROUND

Protein-losing enteropathy (PLE) is a severe complication of Fontan circulation with increased risk of end-organ dysfunction. We evaluated tissue oxygenation via near-infrared spectroscopy (NIRS) at different exercise levels in Fontan patients.

METHODS

Assessment of multisite NIRS during cycle ergometer exercise and daily activities in three groups: Fontan patients with PLE; without PLE; patients with dextro-transposition of the great arteries (d-TGA); comparing univentricular with biventricular circulation and Fontan with/without PLE. Renal threshold analysis (<65%;<55%;<45%) of regional oxygen saturation (rSO2) was performed.

RESULTS

Fontan patients showed reduced rSO2 (p < 0.05) in their quadriceps femoris muscle compared with biventricular d-TGA patients at all time points. rSO2 in renal tissue was reduced at baseline (p = 0.002), exercise (p = 0.0062), and daily activities (p = 0.03) in Fontan patients with PLE. Renal threshold analysis identified critically low renal rSO2 (rSO2 < 65%) in Fontan patients with PLE during exercise (95% of monitoring time below threshold) and daily activities (83.7% time below threshold).

CONCLUSION

Fontan circulation is associated with decreased rSO2 values in skeletal muscle and hypoxemia of renal tissue solely in patients with PLE. Reduced rSO2 already during activities of daily life, might contribute to comorbidities in patients with Fontan circulation, including PLE and renal failure.

State of the art of the Fontan strategy for treatment of univentricular heart disease

In patients with a functionally univentricular heart, the Fontan strategy achieves separation of the systemic and pulmonary circulation and reduction of ventricular volume overload. Contemporary modifications of surgical techniques have significantly improved survival. However, the resulting Fontan physiology is associated with high morbidity. In this review, we discuss the state of the art of the Fontan strategy by assessing survival and risk factors for mortality. Complications of the Fontan circulation, such as cardiac arrhythmia, thromboembolism, and protein-losing enteropathy, are discussed. Common surgical and catheter-based interventions following Fontan completion are outlined. We describe functional status measurements such as quality of life and developmental outcomes in the contemporary Fontan patient. The current role of drug therapy in the Fontan patient is explored. Furthermore, we assess the current use and outcomes of mechanical circulatory support in the Fontan circulation and novel surgical innovations. Despite large improvements in outcomes for contemporary Fontan patients, a large burden of disease exists in this patient population. Continued efforts to improve outcomes are warranted. Several remaining challenges in the Fontan field are outlined.

Pathophysiology of thrombosis and anticoagulation post Fontan surgery

The Fontan procedure has transformed the lives of children born with single-ventricle physiology, previously deemed inoperable. Worldwide, there are an increasing number of children with Fontan circulation, with the potential for survival into adulthood. Due to the abnormal circulation, Fontan patients have an increased risk of thromboembolic (TE) events, with up to 25% of events leading to death. Despite the importance of preventing TE events in this patient population, there is currently no clinical consensus on the optimal monitoring, thromboprophylaxis therapies, and treatment of these events. This paper reviews the available literature regarding anticoagulation in the pediatric and adult Fontan population, including the mechanisms for thrombosis and current antithrombotic therapies.