Atrioventricular Valve Failure in Fontan Palliation

Advances in Diagnostic and Interventional Catheterization in Adults with Fontan Circulation

Over the past five decades, the Fontan procedure has been developed to improve the life expectancy of patients with congenital heart defects characterized by a functionally single ventricle. The Fontan circulation aims at redirecting systemic venous return to the pulmonary circulation in the absence of an impelling subpulmonary ventricle, which makes this physiology quite fragile and leads to several long-term complications. Despite the importance of hemodynamic assessment through cardiac catheterization in the management and follow-up of these patients, a thorough understanding of the ultimate functioning of this type of circulation is lacking, and the interpretation of the hemodynamic data is often complex. In recent years, new tools such as combined catheterization with cardiopulmonary exercise testing have been incorporated to improve the understanding of the hemodynamic profile of these patients. Furthermore, extensive percutaneous treatment options have been developed, addressing issues ranging from obstructive problems in Fontan pathway and acquired shunts through compensatory collaterals to the percutaneous treatment of lymphatic circulation disorders and transcatheter edge-to-edge repair of atrioventricular valves. The aim of this review is to detail the various tools used in cardiac catheterization for patients with Fontan circulation, analyze different percutaneous treatment strategies, and discuss the latest advancements in this field.

Optimal timing of bridging annuloplasty and patch augmentation for heterotaxy syndrome associated with functional single ventricles

OBJECTIVE

Although the challenging prognosis of functional single ventricles with common atrioventricular valves due to complex morphology and uncontrollable regurgitation by valvuloplasty has been highlighted, reports on when and how these extremely complicated atrioventricular valves should be repaired are few. This study investigated the timing and risk factors for valve intervention in these patients.

METHODS

Between April 2006 and March 2023, 40 patients with heterotaxy syndrome associated with functional single ventricles underwent surgery. Valve intervention was performed in 14 of the 40 patients with moderate or severe atrioventricular valve regurgitation.

RESULTS

The timing of the first valve intervention varied, with four, five, three, and two patients undergoing valve intervention before the cavopulmonary shunt, simultaneously with the cavopulmonary shunt, before total cavopulmonary connection, and simultaneously with total cavopulmonary connection, respectively. Mechanical valve replacements were performed in three patients. Among the 14 patients undergoing valve intervention, four died. Three of the four patients underwent valvuloplasty before the cavopulmonary shunt, including two who could undergo the cavopulmonary shunt but died after the procedure. Eight of the fourteen patients completed total cavopulmonary connection. The cumulative survival rate was not significantly different between the 14 patients who underwent and 26 who did not undergo intervention (hazard ratio, 2.52; 95% confidence interval, 0.56-11.24; P = 0.23).

CONCLUSION

Our surgical strategies provide a chance for the next staged repair of common atrioventricular valves in patients with both heterotaxy and valvular regurgitation. Including patch augmentation, advanced valve intervention is possible at or after the cavopulmonary shunt.

Long-term impact of anatomic subtype in hypoplastic left heart syndrome after Fontan completion

BACKGROUND

Aortic atresia (AA)/mitral stenosis (MS) is a well-known risk factor for survival after Norwood; however, the effect of anatomical subtypes in those who survive surgical palliation is unknown.

METHODS

We performed a retrospective single-center study of patients with classic hypoplastic left heart syndrome (HLHS) who underwent Fontan at our center between August 1989 and July 2017. Clinical outcomes, as well as ventricular and atrioventricular-valve (AVV) function, were determined for each patient, and the effects of HLHS subtype were estimated using multivariable statistical analyses.

RESULTS

We included 418 patients with HLHS (AA/mitral atresia [MA] 153, AA/MS 100, aortic stenosis [AS]/MS 154, and AS/MA 11). The median follow-up period was 8.6 (interquartile range, 2.9-15.8) years. Overall transplant-free survival, cumulative incidence of AVV failure, and ventricular failure, which were defined by moderate dysfunction or greater or the necessity of surgical interventions, were 70.1%, 35.9%, and 17.9% at 20 years, respectively. Of the 3 major subtypes, AA/MS was associated with lower survival rate (AA/MA 74.6% vs AS/MS 79.1% vs AA/MS 56.1% at 17 years, P = .04). The subanalysis between AA/MA and AA/MS revealed AA/MS tended to have a greater rate of ventricular failure without a significant difference of AVV failure (AA/MA 11.2% vs AA/MS 26.2% at 17 years, P = .053).

CONCLUSIONS

The survival risk of the anatomic subtype AA/MS persisted long term after Fontan completion and was likely due to a greater rate of single ventricle rather than AVV failure. These findings suggest that the abnormal pressure overload condition of the hypoplastic left ventricle created by AA/MS has a detrimental effect on single right ventricle function.

Adult Congenital Heart Disease Transplantation: Does Univentricle Physiology Impact Early Mortality?

BACKGROUND

With patients with congenital heart disease increasingly living into adulthood, there is a growing population of patients with adult congenital heart disease (ACHD) who have heart failure. Limited data exist on evaluating heart transplantation in this population.

METHODS

A retrospective review was performed of patients with ACHD who underwent heart transplantation from November 1990 to January 2023. Kaplan-Meier, cumulative incidence accounting for competing risk of death, and subgroup analyses comparing those patients with biventricular (BiV) and univentricular (UniV) physiology were performed. Data are presented as median (interquartile range [IQR]) or counts (%).

RESULTS

A total of 77 patients with a median age of 36 years (IQR, 27-45 years) were identified, including 57 (74%) BiV and 20 (26%) UniV patients. Preoperatively, UniV patients were more likely to have cirrhosis (9 of 20 [45.0%] vs 4 of 57 [7.0%]; P < .001) and protein losing enteropathy (4 of 20 [20.0%] vs 1 of 57 [1.8%]; P = .015). Multiorgan transplantation was performed in 23 patients (30%) and more frequently in UniV patients (10 [50%] vs 13 [23%]; P = .04). Operative mortality was 6.5%, 2 of 20 (10%) among UniV patients and 2 of 57 (4%) among BiV patients (P = .276). Median clinical follow-up was 6.0 years (IQR, 1.4-13.1 years). Survival tended to be lower among UniV patients compared with BiV patients, particularly within the first year (P = .09), but it was similar for survivors beyond 1 year. At 5 years, the incidence of rejection was 28% (IQR, 17%-38%) and that of coronary allograft vasculopathy was 16% (IQR, 7%-24%).

CONCLUSIONS

Underlying liver disease and the need for heart-liver transplantation were significantly higher among UniV patients. Survival tended to be lower among UniV patients, particularly within the first year, but it was similar for survivors beyond 1 year.

Impact of heart failure on reoperation in adult congenital heart disease: An innovative machine learning model

OBJECTIVES

The study objectives were to evaluate the association between preoperative heart failure and reoperative cardiac surgical outcomes in adult congenital heart disease and to develop a risk model for postoperative morbidity/mortality.

METHODS

Single-institution retrospective cohort study of adult patients with congenital heart disease undergoing reoperative cardiac surgery between January 1, 2010, and March 30, 2022. Heart failure defined clinically as preoperative diuretic use and either New York Heart Association Class II to IV or systemic ventricular ejection fraction less than 40%. Composite outcome included operative mortality, mechanical circulatory support, dialysis, unplanned noncardiac reoperation, persistent neurologic deficit, and cardiac arrest. Multivariable logistic regression and machine learning analysis using gradient boosting technology were performed. Shapley statistics determined feature influence, or impact, on model output.

RESULTS

Preoperative heart failure was present in 376 of 1011 patients (37%); those patients had longer postoperative length of stay (6 [5-8] vs 5 [4-7] days, P < .001), increased postoperative mechanical circulatory support (21/376 [6%] vs 16/635 [3%], P = .015), and decreased long-term survival (84% [80%-89%] vs 90% [86%-93%]) at 10 years (P = .002). A 7-feature machine learning risk model for the composite outcome achieved higher area under the curve (0.76) than logistic regression, and ejection fraction was most influential (highest mean |Shapley value|). Additional risk factors for the composite outcome included age, number of prior cardiopulmonary bypass operations, urgent/emergency procedure, and functionally univentricular physiology.

CONCLUSIONS

Heart failure is common among adult patients with congenital heart disease undergoing cardiac reoperation and associated with longer length of stay, increased postoperative mechanical circulatory support, and decreased long-term survival. Machine learning yields a novel 7-feature risk model for postoperative morbidity/mortality, in which ejection fraction was the most influential.

Contemporary Management of the Failing Fontan

Adult patients with congenital heart disease have now surpassed the pediatric population due to advances in surgery and improved survival. One such complex congenital heart disease seen in adult patients is the Fontan circulation. These patients have complex physiology and are at risk for several complications, including thrombosis of the Fontan pathway, pulmonary vascular disease, heart failure, atrial arrhythmias, atrioventricular valve regurgitation, and protein-losing enteropathy. This review discusses the commonly encountered phenotypes of Fontan circulatory failure and their contemporary management.

Surgical Considerations in Adult Congenital Heart Disease Heart Failure

Surgical intervention is often used in the management of heart failure in patients with adult congenital heart disease. This review addresses anatomic variations and complications due to prior surgical interventions, including sternal reentry, collateral vessels, and the neo-aortic root after the Damus-Kaye-Stansel procedure. Surgical considerations for systemic atrioventricular valvular surgery, Fontan revision, and advanced heart failure therapies including ventricular assist devices, heart transplant, and combined heart-liver transplant are discussed, with a focus on unique patient populations including those with systemic right ventricles and those with Fontan circulation.

Introduction of transcatheter edge-to-edge repair in patients with congenital heart disease at a children's hospital

BACKGROUND

Atrioventricular valve regurgitation (AVVR) is a devastating complication in children and young adults with congenital heart disease (CHD), particularly in patients with single ventricle physiology. Transcatheter edge-to-edge repair (TEER) is a rapidly expanding, minimally invasive option for the treatment of AVVR in adults that avoids the morbidity and mortality associated with open heart surgery. However, application of TEER in in CHD and in children is quite novel. We describe the development of a peri-procedural protocol including image-derived pre-intervention simulation, with successful application to four patients.

AIMS

To describe the initial experience using the MitraClip system for TEER of dysfunctional systemic atrioventricular valves in patients with congential heart disease within a pediatric hospital.

METHODS

A standardized screening and planning process was developed using cardiac magnetic resonance imaging, three dimensional echocardiography and both virtual and physical simulation. Procedures were performed using the MitraClip G4 system and patients were clinically followed post-intervention.

RESULTS

A series of four CHD patients with at least severe AVVR were screened for suitability for TEER with the MitraClip system: three patients had single ventricle physiology and Fontan palliation, and one had repair of a common atrioventricular canal defect. Each patient had at least severe systemic AVVR and was considered at prohibitively high risk for surgical repair. Each patient underwent a standardized preprocedural screening protocol and image-derived modeling followed by the TEER procedure with successful clip placement at the intended location in all cases.

CONCLUSIONS

The early results of our protocolized efforts to introduce TEER repair of severe AV valve regurgitation with MitraClip into the CHD population within our institution are encouraging. Further investigations of the use of TEER in this challenging population are warranted.

Does leaving native antegrade pulmonary blood flow at the time of the superior cavopulmonary connection impact long-term outcomes after the Fontan?

Objectives

Antegrade pulmonary blood flow (APBF) may be left or eliminated at the time of the superior cavopulmonary connection (SCPC). Our aim was to assess the impact of leaving native APBF at the SCPC on long-term Fontan outcomes.

Methods

In the Australia and New Zealand Fontan Registry (1985-2021), 587 patients had pre-existing native APBF at the SCPC. At the SCPC, 302 patients had APBF eliminated (APBF-) and 285 patients had APBF maintained (APBF+). The incidence of Fontan failure (composite end point of Fontan takedown, transplant, plastic bronchitis, protein losing enteropathy and death) and atrioventricular (AV) valve repair/replacement post SCPC was compared between the 2 groups.

Results

Sex, predominant-ventricle morphology, isomerism, primary diagnosis, and age/type of Fontan were similar between groups. APBF- versus APBF+ had a higher incidence of arch obstruction/coarctation (17% vs 7%) and previous pulmonary artery band (54% vs 45%) and a lower rate of Fontan fenestration (27% vs 41%). The risk of Fontan failure was similar between the 2 groups (hazard ratio [HR], 1.01; 95% confidence interval [CI], 0.58-1.78; P = .96). The risk of AV-valve repair/replacement was greater in APBF+ versus APBF- (HR, 2.32; CI, 1.13-4.75; P = .022). The risk of AV-valve repair/replacement remained after adjustment for arch obstruction/coarctation, previous pulmonary artery band and Fontan fenestration (HR, 2.27; CI, 1.07-4.81; P = .033).

Conclusions

Maintaining APBF at the time of the SCPC does not impact the risk of Fontan failure but may increase the incidence of AV-valve repair and/or replacement post-SCPC.

Long-term outcomes of tricuspid valve intervention during stage 2 palliation in patients with a single right ventricle

OBJECTIVES

In patients with single ventricle physiology and a systemic right ventricle, tricuspid valve regurgitation increases the risk of adverse outcomes, and tricuspid valve intervention at the time of staged palliation further increases that risk in the postoperative period. However, long-term outcomes of valve intervention in patients with significant regurgitation during stage 2 palliation have not been established. The purpose of this study is to evaluate the long-term outcomes after tricuspid valve intervention during stage 2 palliation in patients with right ventricular dominant circulation in a multicenter study.

METHODS

The study was performed using the Single Ventricle Reconstruction Trial and Single Ventricle Reconstruction Follow-up 2 Trial datasets. Survival analysis was performed to describe the association among valve regurgitation, intervention, and long-term survival. Cox proportional hazards modeling was used to estimate the longitudinal association of tricuspid intervention and transplant-free survival.

RESULTS

Patients with tricuspid regurgitation at stage 1 or 2 had worse transplant-free survival (hazard ratio, 1.61; 95% confidence interval, 1.12-2.32; hazard ratio, 2.3; 95% confidence interval 1.39-3.82). Those with regurgitation who underwent concomitant valve intervention at stage 2 were significantly more likely to die or undergo heart transplantation compared with those with regurgitation who did not (hazard ratio, 2.93; confidence interval, 2.16-3.99). Patients with tricuspid regurgitation at the time of the Fontan had favorable outcomes regardless of valve intervention.

CONCLUSIONS

The risks associated with tricuspid regurgitation in patients with single ventricle physiology do not appear to be mitigated by valve intervention at the time of stage 2 palliation. Patients who underwent valve intervention for tricuspid regurgitation at stage 2 had significantly worse survival compared with patients with tricuspid regurgitation who did not.

Five decades of Fontan palliation: What have we learned? What should we expect?

The Fontan procedure is the final palliative surgery in a series of staged surgeries to reroute the systemic venous blood flow directly to the lungs, with the ventricle(s) pumping oxygenated blood to the body. Advances in medical and surgical techniques have improved patients' overall survival after the Fontan procedure. However, Fontan-associated chronic comorbidities are common. In addition to chronic cardiac dysfunction and arrhythmias, complications involving other organs such as the liver, lungs, intestine, lymphatic system, brain, and blood frequently occur. This narrative review focuses on the immediate and late consequences in children, pregnant women, and other adults with Fontan circulation. In addition, we describe the technical advancements that might change the way single-ventricle patients are managed in future.

Valvular Regurgitation in Adults with Congenital Heart Disease and Heart Failure: Current Status and Potential Interventions

The great majority of patients born with congenital heart disease (CHD) are living well into adulthood, yet they often have residual hemodynamic lesions, including valvar regurgitation. As these complex patients grow older, they are at risk of developing heart failure, which can be exacerbated by the underlying valvular regurgitation. In this review, we describe the etiologies of heart failure related to valvular regurgitation in the CHD population and discuss potential interventions.

Ex Vivo Modeling of Atrioventricular Valve Mechanics in Single Ventricle Physiology

Single ventricle physiology (SVP) is used to describe any congenital heart lesion that is unable to support independent pulmonary and systemic circulations. Current treatment strategies rely on a series of palliation surgeries that culminate in the Fontan physiology, which relies on the single functioning ventricle to provide systemic circulation while passively routing venous return through the pulmonary circulation. Despite significant reductions in early mortality, the presence of atrioventricular valve (AVV) regurgitation is a key predictor of heart failure in these patients. We sought to evaluate the biomechanical changes associated with the AVV in SVP physiologies. Left and right ventricles were sutured onto patient-derived 3D-printed mounts and mounted into an ex vivo systemic heart simulator capable of reproducing Norwood, Glenn, Fontan and Late Fontan physiologies. We found that the tricuspid anterior leaflet experienced elevated maximum force, average force, and maximum yank compared to the posterior and septal leaflets. Between physiologies, maximum yank was greatest in the Norwood physiology relative to the Glenn, Fontan, and Late Fontan physiologies. These contrasting trends suggest that long- and short-term mechanics of AVV failure in single ventricle differ and that AVV interventions should account for asymmetries in force profiles between leaflets and physiologies.

Liver Cirrhosis After the Fontan Procedure: Impact of Atrioventricular Valve Failure

BACKGROUND

Liver cirrhosis is now well recognized as a potential complication after the Fontan procedure, although associated risk factors and optimal timing of liver screening remain unclear.

METHODS

All patients who underwent an extracardiac conduit Fontan procedure at The Royal Children's Hospital, Melbourne, were identified using the Australia and New Zealand Fontan Registry. Cirrhosis was diagnosed based on liver biopsy, or a combination of imaging findings and clinical evaluation by a hepatologist.

RESULTS

Between 1997 and 2020, 398 patients underwent an extracardiac conduit Fontan procedure at our center, and 276 had ongoing follow-up in Victoria. Ninety-five patients (34%) underwent liver assessment at a mean age of 18.2 ± 6.7 years (11.8 ± 5.5 years post-Fontan). Fifteen patients (16%) were diagnosed with cirrhosis at a mean age of 22.7 ± 5.9 years (14.0 ± 5.2 years post-Fontan). The need for prior or concomitant atrioventricular valve repair or replacement was associated with an increased risk of cirrhosis (univariable hazard ratio [HR] 7.09, 95% confidence interval [CI] 2.13-23.61, P = .001). By multivariable analysis, factors associated with development of cirrhosis were atrioventricular valve failure prior to Fontan (HR 3.27, 95% CI 1.15-9.31, P = .026) and older age at Fontan operation (HR 1.13 per year increase, 95% CI 1.01-1.26, P = .034). The proportion of patients alive, nontransplanted, and without cirrhosis at 10, 15, and 20 years was 93.4% (95% CI 88.4%-98.7%), 79.6% (95% CI 69.7%-90.8%), and 64.6% (95% CI 51.0%-81.9%), respectively.

CONCLUSIONS

Early commencement of liver screening should be considered for patients with a history of atrioventricular failure during Fontan palliation.

Atrioventricular septal defect in Fontan circulation: Right ventricular dominance, not valve surgery, adversely affects survival

OBJECTIVE

The effect of ventricular dominance and previous atrioventricular valve (AVV) surgery on patient outcomes after Fontan operation remains unclear. We sought to determine the effect of ventricular dominance and previous AVV surgery on transplantation-free survival and long-term AVV competency in patients with atrioventricular septal defect (AVSD) and Fontan circulation.

METHODS

We conducted a retrospective study of 1703 patients in the Australia and New Zealand Fontan Registry, who survived Fontan operation between 1987 and 2021.

RESULTS

Of 174 patients with AVSD, 60% (105/174) had right ventricular (RV) dominance and 40% (69/174) had left ventricular (LV) dominance. The cumulative incidence of moderate or greater AVV regurgitation at 25 years after Fontan operation in patients with LV dominance was 56% (95% CI, 35%-72%), compared with 54% (95% CI, 40%-67%) in patients with RV dominance (P = .6). Nonetheless, transplantation-free survival at 25 years in patients with LV dominance was 94% (95% CI, 86%-100%), compared with 67% (95% CI, 52%-87%) in patients with RV dominance (hazard ratio, 5.9; 95% CI, 1.4-25.4; P < .01). Of note, transplantation-free survival was not different in patients who underwent AVV surgery before or at Fontan completion compared with those who did not (15 years: 81% [95% CI, 62%-100%] vs 88% [95% CI, 81%-95%]; P = .3).

CONCLUSIONS

In patients with AVSD and Fontan circulation the rate of moderate or greater common AVV regurgitation is similar in those with LV and RV dominance. RV dominance, rather than previous AVV surgery, is a risk factor for death or transplantation.

First described mitral clip in an adult extracardiac Fontan patient: a case report

Background

The use of transcatheter edge-to-edge repair (TEER) in patients with advanced heart failure has been shown to reduce hospitalizations and increase survival. As patients with Fontan circulations grow older, a significant proportion of them will develop severe atrioventricular (AV) valve regurgitation in the systemic ventricle. Conventional surgical repair and transplant carry high mortality risk for the adult Fontan patient with progressive heart failure.

Case summary

A 51-year-old female extracardiac Fontan patient developed severe AV valve regurgitation and progressive functional decline. Based on her operative risk for conventional surgical intervention or transplant, TEER using the Abbott MitraClip device was performed. The degree of mitral regurgitation was decreased from severe to moderate regurgitation.

Discussion

This is the first known case describing the use of a successful TEER in an adult patient with an extracardiac Fontan. Given the increasing numbers of patients surviving into adulthood with a Fontan circulation, transcatheter interventions may provide an alternative treatment option to conventional surgeries and medical therapies.

Force Profiles of Single Ventricle Atrioventricular Leaflets in Response to Annular Dilation and Leaflet Tethering

We sought to understand how leaflet forces change in response to annular dilation and leaflet tethering (LT) in single ventricle physiology. Explanted fetal bovine tricuspid valves were sutured onto image-derived annuli and ventricular mounts. Control valves (CON) were secured to a size-matched hypoplastic left heart syndrome (HLHS)-type annulus and compared to: (1) normal tricuspid valves secured to a size-matched saddle-shaped annulus, (2) HLHS-type annulus with LT, (3) HLHS-type annulus with annular dilation (dilation valves), or (4) a combined disease model with both dilation and tethering (disease valves). The specimens were tested in a systemic heart simulator at various single ventricle physiologies. Leaflet forces were measured using optical strain sensors sutured to each leaflet edge. Average force in the anterior leaflet was 43.2% lower in CON compared to normal tricuspid valves (P < 0.001). LT resulted in a 6.6% increase in average forces on the anterior leaflet (P = 0.04), 10.7% increase on the posterior leaflet (P = 0.03), and 14.1% increase on the septal leaflet (P < 0.001). In dilation valves, average septal leaflet forces increased relative to the CON by 42.2% (P = 0.01). In disease valves, average leaflet forces increased by 54.8% in the anterior leaflet (P < 0.001), 37.6% in the posterior leaflet (P = 0.03), and 79.9% in the septal leaflet (P < 0.001). The anterior leaflet experiences the highest forces in the normal tricuspid annulus under single ventricle physiology conditions. Annular dilation resulted in an increase in forces on the septal leaflet and LT resulted in an increase in forces across all 3 leaflets. Annular dilation and LT combined resulted in the largest increase in leaflet forces across all 3 leaflets.

Predictive factors contributing to prolonged recovery in patients after Fontan operation

Background

Prolonged recovery is a severe issue in patients after Fontan operation. However, predictive factors related to this issue are not adequately evaluated. The present study aimed to investigate potential predictive factors which can predict Fontan postoperative recovery.

Methods

We retrospectively reviewed the perioperative medical records of patients with Fontan surgery between January 2015 and December 2018, and divided patients with > 75%ile cardiac intensive care unit stay into prolonged recovery group. The others were assigned to standard recovery group. Patients that died or underwent a Fontan takedown were excluded. Statistical analysis was performed to compare data difference of the two groups.

Results

282/307 cases fulfilled the inclusion criteria. Seventy patients were considered in prolonged recovery and 212 patients were defined as standard recovery. Pre- and intra-operative data showed a higher incidence of heterotaxy syndrome, longer cardiopulmonary bypass and aortic cross-clamp time in the prolonged recovery group. Postoperative information analysis displayed that ventilation time, oxygen index after extubation, hemodynamic data, inotropic score (IS), drainage volume, volume resuscitation, pulmonary hypertension (PH) treatment, and surgical reintervention were significantly different between the two groups. Higher IS postoperatively, and PH treatment and higher fluid resuscitation within two days were independent predictive factors for prolonged recovery in our multivariate model. C-statistic model showed a high predictive ability in prolonged recovery by using the three factors.

Conclusions

Ventilation time, higher IS in postoperative day, and PH treatment and higher fluid resuscitation within two days were independent risk factors and have a high predictability for Fontan prolonged recovery.

Comparing Long-Term Sequelae of the Systemic Right Ventricle: An Overview of Single Versus Biventricular Arrangements

Patients with systemic right ventricles (RV) are at risk for heart failure and sudden cardiac death. Contributing factors to RV dysfunction include increased afterload from the systemic circulation, coronary insufficiency, progressive tricuspid valve regurgitation, the presence of residual lesions after palliation and arrhythmias. While all patients with a systemic right ventricle (SRV) are vulnerable to heart failure, there are distinct differences between patients with congenital dextro-transpostion of the great arteries (d-TGA) repaired by atrial switch, unrepaired congenitally corrected transposition of the great arteries (cc-TGA) and single systemic right ventricles palliated with a Fontan operation. Herein, we explore both the similarities and differences in progression of heart failure by phenotype as well as both the advancements and limitations in treatment options by each type of SRV.

Fontan Palliation in Patients with Heterotaxy Syndrome: A Five Decade Experience

BACKGROUND

Patients with heterotaxy syndromes (right and left atrial isomerism) are at high risk of poor outcomes after single-ventricle palliation. However, the long-term outcomes and specific parameters associated with poor outcomes are incompletely understood.

METHODS

A retrospective review was performed of all patients with atrial isomerism who had a Fontan at our institution from 1973 to 2020. Standard demographic, as well as pre-, peri-, and postoperative parameters were collected. Features and outcomes of patients with polysplenia were compared to asplenia. Outcomes were analyzed for effect during 4 eras: (1: 1973-1984; n = 27), (2: 1985-1994; n = 93), (3: 1995-2004; n = 28), and (4: 2005-2020; n = 10).

RESULTS

Of the 1176 patients who had a Fontan operation, 158 (14%) had a heterotaxy syndrome. The median age at the time of Fontan was 8 (9) years. Early mortality was 20% and was greater in patients with asplenia compared to polysplenia (27% vs. 12%, p = .019). But it substantially improved over time (61% in era 1 vs. 7%-10% in the more recent eras (p < .001)), as did transplant-free survival (22% at 10 years in era 1 vs. 88% in era 4, p < .001). Transplant-free survival was significantly lower in patients with asplenia versus those with polysplenia (p = .014), and patients with heterotaxy had lower survival than nonheterotaxy (p = .01). This was largely due to the asplenia group (p < .001) (hazard ratio = 3.05, p = .007).

CONCLUSIONS

After Fontan operation, patients with heterotaxy, particularly asplenia, continue to demonstrate worse transplant-free survival than nonheterotaxy patients. Early mortality and long-term transplant-free survival have improved in more recent eras.

Long-Term Outcomes of Patients Requiring Unplanned Repeated Interventions After Surgery for Congenital Heart Disease

BACKGROUND

Unplanned catheter-based or surgical reinterventions after congenital heart operations are independently associated with operative mortality and increased postoperative length of stay.

OBJECTIVES

This study assessed the long-term outcomes of transplant-free survivors of hospital discharge requiring predischarge reinterventions after congenital cardiac surgery.

METHODS

Data from patients who required predischarge reinterventions in the anatomic area of repair after congenital cardiac surgery and survived to hospital discharge at a quaternary referral center from January 2011 to December 2019 were retrospectively reviewed. Previously published echocardiographic criteria were used to assess the severity of persistent residual lesions at discharge (Grade 1, no residua; Grade 2, minor residua; and Grade 3, major residua). Outcomes included postdischarge (late) mortality or transplant and unplanned reintervention. Associations between predischarge residual lesion severity and outcomes were assessed by using Cox or competing risk models, adjusting for baseline patient characteristics, case complexity, and preoperative risk factors.

RESULTS

Among the 408 patients who met entry criteria, there were 58 (14.2%) postdischarge deaths or transplants and 208 (51.0%) late reinterventions at a median follow-up of 3.0 years (IQR: 1.1-6.8 years). Greater predischarge residual lesion severity was associated with worse transplant-free survival and freedom from reintervention (both, P < 0.05). On multivariable analyses, Grade 3 patients had an increased risk of postdischarge mortality or transplant (HR: 4.8; 95% CI: 2.0-11; P < 0.001) and late reintervention (subdistribution HR: 2.1; 95% CI: 1.4-3.1; P < 0.001) vs Grade 1 patients.

CONCLUSIONS

Among transplant-free survivors requiring predischarge reinterventions after congenital cardiac surgery, those with persistent major residua have significantly worse long-term outcomes. These high-risk patients warrant closer surveillance.

Late Fontan Circulatory Failure. What Drives Systemic Venous Congestion and Low Cardiac Output in Adult Fontan Patients?

The Fontan circulation provides definite palliation for children born with a single anatomical or functional ventricle by diverting systemic venous blood directly to the pulmonary arteries, effectively rendering systemic venous return into portal vessels to the lung. Although this restores pulmonary blood flow and avoids the mixture of oxygenated and deoxygenated blood, it also results in elevated systemic venous pressures and low cardiac output. These are the two hallmarks of any Fontan circulation and the cause of Fontan circulatory failure later in life. We highlight the determinants of systemic venous return, its changed relationship with the pulmonary circulation, how it affects preload, and the changed role of the heart (myocardium, valves, and heart rate). By critically evaluating the components of the Fontan circulation, we hope to give some clues in how to optimize the Fontan circulation and avenues for future research.

Being Born with a Single Cardiac Ventricle: What Do We Tell Prospective Parents

Being born with a single ventricle remains one of the most extreme congenital cardiac conditions. It encompasses a wide variety of lesions characterized by the existence of one small ventricular cavity. To allow survival, these patients must undergo a series of operations in the first years of life. It was long considered that the success of these interventions would be short-lived and that only a few of these patients would live beyond adulthood. The last decade has seen publication of multiple large outcomes researches on this population, and we now realize that its survival is longer than expected, but with a considerable burden of disease. As a consequence, the size of this single ventricle population is growing rapidly. As primary conveyer of the information on the future of these babies, obstetricians need to be aware of these changes in perspective. This article is protected by copyright. All rights reserved.

Heart transplant indications, considerations and outcomes in Fontan patients: Age-related nuances, transplant listing and disease-specific indications

In the current era, 5-10% of Fontan patients die or need a transplant in childhood, and approximately 50% will experience the same fate by age 40 years. Heart transplant (HTx) can be successful for selected children and adults with Fontan circulatory failure (FCF) of any mechanism, with a 1-year post-transplant survival approaching 90% in children and 80% in the largest single-centre adult Fontan HTx experience. Protein losing enteropathy and plastic bronchitis can be expected to resolve post-transplant and limited data suggests patients with FALD who survive HTx can expect improvement in liver health. Early Fontan failure, within 12 months of Fontan completion, is not easily rescued by HTx and late referrals / failure to refer adult patients remains problematic. Very little is known about the numbers of patients not referred, turned down following assessment for HTx, or dying on the waiting list which are needed to understand the complete picture of HTx in the Fontan population and to identify where best to focus quality improvement efforts. Recent revisions to listing prioritization in Canada with considerations specific to the Fontan population aim to mitigate the fact that the status listing criteria are not tailored to the congenital heart population. Transplanting high-risk children prior to Fontan completion, developing ACHD transplant centres of expertise which can also offer combined heart-liver transplant when appropriate, and improving single ventricle mechanical support options and criteria for both adults and children may help mitigate the early post-listing mortality.

Catheter ablation of atrial arrhythmias in patients post-Fontan

Atrial arrhythmias are highly prevalent in the aging Fontan population and contribute importantly to morbidity and mortality. Although the most common arrhythmia is scar-based intra-atrial re-entrant tachycardia, various other arrhythmias may occur including focal atrial tachycardia, atrioventricular node-dependent tachycardias, and atrial fibrillation. The type and prevalence of atrial arrhythmia is determined, in part, by the underlying congenital defect and variant of Fontan surgery. While the cumulative incidence of atrial tachyarrhythmias has decreased substantially from the atriopulmonary anastomosis to the more recent total cavopulmonary connection Fontan, the burden of atrial arrhythmias remains substantial. Management is often multi-faceted and can include anticoagulation, anti-arrhythmic drug therapy, pacing, and cardioversion. Catheter ablation plays a key role in arrhythmia control. Risks and benefits must be carefully weighed. Among the important considerations are the clinical burden of arrhythmia, ventricular function, hemodynamic stability in tachycardia, suspected arrhythmia mechanisms, risks associated with anaesthesia, venous access, approaches to reaching the pulmonary venous atrium, and accompanying co-morbidities. Careful review of surgical notes, electrocardiographic tracings, and advanced imaging is paramount, with particular attention to anatomic abnormalities such as venous obstructions and displaced conduction systems. Despite numerous challenges, ablation of atrial arrhythmias is effective in improving clinical status. Nevertheless, onset of new arrhythmias is common during long-term follow-up. Advanced technologies such as high-density mapping catheters and remote magnetic guided ablation carry the potential to further improve outcomes. Fontan patients with atrial arrhythmias should be referred to centers with dedicated expertise in congenital heart disease including catheter ablation, anaesthesia support, and advanced imaging.

Transcatheter Edge-to-Edge Repair of Systemic Tricuspid Valve in Extracardiac Fontan Circulation

Transcatheter edge-to-edge valve repair can improve clinical outcomes in otherwise high-risk surgical patients. This is a first-in-human procedure outlining transcatheter edge-to-edge valve repair of a systemic tricuspid valve in an extracardiac Fontan patient born with hypoplastic left heart syndrome with prohibitive surgical risk. (Level of Difficulty: Advanced.)

Skeletal model-based analysis of the tricuspid valve in hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) is a congenital heart disease characterized by incomplete development of the left heart. Children with HLHS undergo a series of operations which result in the tricuspid valve (TV) becoming the only functional atrioventricular valve. Many HLHS patients develop tricuspid regurgitation and right ventricle enlargement which is associated with heart failure and death without surgical intervention on the valve. Understanding the connections between the geometry of the TV and its function remains extremely challenging and hinders TV repair planning. Traditional analysis methods rely on simple anatomical measures which do not capture information about valve geometry in detail. Recently, surface-based shape representations such as SPHARM-PDM have been shown to be useful for tasks such as discriminating between valves with normal or poor function. In this work we propose to use skeletal representations (s-reps), a more feature-rich geometric representation, for modeling the leaflets of the tricuspid valve. We propose an extension to previous s-rep fitting approaches to incorporate application-specific anatomical landmarks and population information to improve correspondence. We use several traditional statistical shape analysis techniques to evaluate the efficiency of this representation: using principal component analysis (PCA) we observe that it takes fewer modes of variation compared to boundary-based approaches to represent 90% of the population variation, while distance-weighted discrimination (DWD) shows that s-reps provide for more significant classification between valves with less regurgitation and those with more. These results show the power of using s-reps for modeling the relationship between structure and function of the tricuspid valve.

Management of circulatory failure after Fontan surgery

With improvement in survival after Fontan surgery resulting in an increasing number of older survivors, there are more patients with a Fontan circulation experiencing circulatory failure each year. Fontan circulatory failure may have a number of underlying etiologies. Once Fontan failure manifests, prognosis is poor, with patient freedom from death or transplant at 10 years of only about 40%. Medical treatments used include traditional heart failure medications such as renin-angiotensin-aldosterone system blockers and beta-blockers, diuretics for symptomatic management, antiarrhythmics for rhythm control, and phosphodiesterase-5 inhibitors to decrease PVR and improve preload. These oral medical therapies are typically not very effective and have little data demonstrating benefit; if there are no surgical or catheter-based interventions to improve the Fontan circulation, patients with severe symptoms often require inotropic medications or mechanical circulatory support. Mechanical circulatory support benefits patients with ventricular dysfunction but may not be as useful in patients with other forms of Fontan failure. Transplant remains the definitive treatment for circulatory failure after Fontan, but patients with a Fontan circulation face many challenges both before and after transplant. There remains significant room and urgent need for improvement in the management and outcomes of patients with circulatory failure after Fontan surgery.

Long-term management of Fontan patients: The importance of a multidisciplinary approach

The Fontan operation is a palliative procedure that leads to increased survival of patients with a functional single ventricle (SV). Starting from 1967 when the first operation was performed by Francis Fontan, more and more patients have reached adulthood. Furthermore, it is expected that in the next 20 years, the population with Fontan circulation will reach 150,000 subjects. The absence of right ventricular propulsion and the inability to improve cardiac output because of the low cardiac reserve are the main issues with the Fontan circulation; however, potential complications may also involve multiple organ systems, such as the liver, lungs, brain, bones, and the lymphatic system. As these patients were initially managed mainly by pediatric cardiologists, it was important to assure the appropriate transition to adult care with the involvement of a multidisciplinary team, including adult congenital cardiologists and multiple subspecialists, many of whom are neither yet familiar with the pathophysiology nor the end-organ consequences of the Fontan circulation. Therefore, the aim of our work was to collect all the best available evidence on Fontan's complications management to provide "simple and immediate" information sources for practitioners looking for state of the art evidence to guide their decision-making and work practices. Moreover, we suggest a model of follow-up of patients with Fontan based on a patient-centered multidisciplinary approach.

Segmentation of Tricuspid Valve Leaflets From Transthoracic 3D Echocardiograms of Children With Hypoplastic Left Heart Syndrome Using Deep Learning

Hypoplastic left heart syndrome (HLHS) is a severe congenital heart defect in which the right ventricle and associated tricuspid valve (TV) alone support the circulation. TV failure is thus associated with heart failure, and the outcome of TV valve repair are currently poor. 3D echocardiography (3DE) can generate high-quality images of the valve, but segmentation is necessary for precise modeling and quantification. There is currently no robust methodology for rapid TV segmentation, limiting the clinical application of these technologies to this challenging population. We utilized a Fully Convolutional Network (FCN) to segment tricuspid valves from transthoracic 3DE. We trained on 133 3DE image-segmentation pairs and validated on 28 images. We then assessed the effect of varying inputs to the FCN using Mean Boundary Distance (MBD) and Dice Similarity Coefficient (DSC). The FCN with the input of an annular curve achieved a median DSC of 0.86 [IQR: 0.81-0.88] and MBD of 0.35 [0.23-0.4] mm for the merged segmentation and an average DSC of 0.77 [0.73-0.81] and MBD of 0.6 [0.44-0.74] mm for individual TV leaflet segmentation. The addition of commissural landmarks improved individual leaflet segmentation accuracy to an MBD of 0.38 [0.3-0.46] mm. FCN-based segmentation of the tricuspid valve from transthoracic 3DE is feasible and accurate. The addition of an annular curve and commissural landmarks improved the quality of the segmentations with MBD and DSC within the range of human inter-user variability. Fast and accurate FCN-based segmentation of the tricuspid valve in HLHS may enable rapid modeling and quantification, which in the future may inform surgical planning. We are now working to deploy this network for public use.

Systemic Semilunar Valve Repair/Replacement With Fontan Circulation: The Mayo Clinic Experience

Background: There is a paucity of literature regarding systemic semilunar valve (SSLV) dysfunction in patients with Fontan circulation. We sought to describe our center's 47-year experience with systemic semilunar valve replacement or repair (SSLVR) in patients with Fontan circulation. Methods: The Mayo Clinic Fontan Database is a comprehensive institutional database that stores clinical information of 1176 patients from 1973 to 2021. It was reviewed to identify patients who had a SSLV intervention at the time of or after Fontan. A cohort of 15 patients was identified and a retrospective review of their records was performed. Results: Fourteen patients had SSLV replacement (all mechanical) and one had a repair. SSLVR occurred up to 29 years following the Fontan (mean 11.3 ± 9 years, median 14 years). Thirteen of 14 with SSLVR were performed after Fontan and one was done at the time of initial Fontan. This was an older cohort and mean age at the time of Fontan was 8.7 ± 9.4 years (median 4 years). Indication for the operation was > moderate SSLV regurgitation in all patients. Six patients had decreased ventricular function (EF < 50%) prior to SSLVR and 8 had reduced function after SSLVR. Conclusion: Fortunately, the need for SSLV intervention after Fontan was rare, as evidenced by our small cohort extracted from a large single-institution database spanning a 47-year time period. Reduced preoperative and postoperative ejection fraction was common but did not seem to impact the outcome. Optimal timing for SSLV intervention after Fontan remains unclear.

Surgical outcomes of reoperation after Fontan completion

 

OBJECTIVES

Patients who have achieved Fontan circulation may require reoperation. We reviewed the outcomes of reoperation after Fontan completion and assessed the risk factors for poor outcomes.

METHODS

This was a retrospective study of 106 patients undergoing open-heart reoperations after Fontan completion in 2003 at a single institution.

RESULTS

The mean age at reoperation was 24.6 ± 8.3 years. A history of Fontan failure or end-organ dysfunction was noted in 30 patients. The reoperations included 73 total cavopulmonary connection conversions, 29 atrioventricular or semilunar valve operations (17 with total cavopulmonary connection conversions) and 4 other operations. Eight early deaths occurred. During a median follow-up of 5.5 (0.01–16.2) years, there were 3 late deaths and 9 second cardiac operations. The 10-year survival rate after reoperation was 89.8%, and the 5-year second cardiac operation-free survival was 84.3%. The 10-year survival rates were significantly lower in patients who underwent surgery before 2011 (75.8% vs 100%), had a history of Fontan failure or end-organ dysfunction (71.7% vs 97.3%), had preoperative central venous pressure >15 mmHg (64.9% vs 96.5%) and were operated on with deep hypothermic circulatory arrest (DHCA) (60.0% vs 91.3%). A history of Fontan failure or end-organ dysfunction, preoperative central venous pressure >15 mmHg and requirement of DHCA were identified as risk factors for mortality.

CONCLUSIONS

Reoperation after Fontan completion resulted in excellent mid-term outcomes. A history of failed Fontan circulation and the requirement of DHCA negatively affected survival outcomes.

Long-Term Outcomes of Atrioventricular Valve Surgery in Patients with Functional Single Ventricle: Should We Avoid Valve Replacement?

Atrioventricular valve regurgitation (AVVR) is associated with increased morbidity and mortality in patients with single ventricle physiology. The purpose of this study was to evaluate the long-term results of the surgical management of AVVR and to analyze the effects of AV valve replacement. The medical records of 38 single ventricle patients who underwent atrioventricular valve surgery more than once between January 2001 and March 2018 were retrospectively reviewed. We analyzed and compared clinical data of patients who underwent valve replacement as an initial treatment (n = 8) for AVVR with patients who initially underwent valve repair (n = 30). The median follow-up duration was 98.1 months (range, 0.9-209.6 months). There was one early mortality and seven late mortalities. Freedom from reoperation between the two groups at 15 years of follow-up was significantly different: 18.3% in the repair group and 100% in the replacement group (p = 0.013). The replacement group showed a better overall survival rate (100%) at 15 years than the repair group (68.5%) without statistical significance (p = 0.097). All mortalities occurred in the repair group. Nine patients in the repair group (30%) and one patient in the replacement group (12.5%) showed preoperative ventricular dysfunction. RV-type single ventricle with atrioventricular (AV) valve annular dilatation was found out as a risk factor of AVV replacement both in univariate (p = 0.04) and multivariate (p = 0.004) analysis. AV valve replacement might be considered as a primary treatment option for patients who have an annular dilation with an RV-type single ventricle rather than repeated valvuloplasty.

The pulmonary vascular bed in patients with functionally univentricular physiology and a Fontan circulation

Fontan palliation represents one of the most remarkable surgical advances in the management of individuals born with functionally univentricular physiology. The operation secures adult survival for all but a few with unfavourable anatomy and/or physiology. Inherent to the physiology is passive transpulmonary blood flow, which produces a vulnerability to adequate filling of the systemic ventricle at rest and during exertion. Similarly, the upstream effects of passive flow in the lungs are venous congestion and venous hypertension, especially marked during physical activity. The pulmonary vascular bed has emerged as a defining character on the stage of Fontan circulatory behaviour and clinical outcomes. Its pharmacologic regulation and anatomic rehabilitation therefore seem important strategic therapeutic targets. This review seeks to delineate the important aspects of pulmonary artery development and maturation in functionally univentricular physiology patients, pulmonary artery biology, pulmonary vascular reserve with exercise, and pulmonary artery morphologic and pharmacologic rehabilitation.

Role of cardiac magnetic resonance strain analysis in patients with hypoplastic left heart syndrome in evaluating right ventricular (dys)function: a systematic review

OBJECTIVES

Right ventricular dysfunction predicts death in patients with hypoplastic left heart syndrome (HLHS), but differences in morphology and loading conditions make calculation of the ejection fraction (EF), a challenging measure of its function. Our goal was to evaluate how strain measurements with cardiac magnetic resonance feature tracking could be used to evaluate right ventricular function in patients with HLHS.

METHODS

A systematic search of the literature was performed by 2 independent researchers using the terms 'population', 'intervention', 'comparison', 'outcome' and 'time criteria'. PubMed and the Ovid database were searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Our review included 8 studies with 608 participants with ventricular strain values obtained using cardiac magnetic resonance feature tracking. After stage I palliation, global strain was reduced in patients after a hybrid procedure and a right ventricle-to-pulmonary artery conduit compared with a modified Blalock-Taussig shunt despite similar EFs. Global longitudinal strain did not differ between stage II and stage III (Fontan) palliation. Fontan patients had significantly impaired global longitudinal and circumferential strain compared to the left ventricular strain of the controls. Studies of Fontan patients that included patients with HLHS who were part of a cohort with a single right ventricle showed impaired global circumferential strain compared with the cohort with a single left ventricle, with controls, and over time. In this group, impaired global circumferential strain was associated with major adverse cardiac events.

CONCLUSIONS

Cardiac magnetic resonance feature tracking can be used in patients with HLHS to evaluate RV strain and demonstrate differences between surgical strategies, over time and compared with controls. It could be used alongside clinical symptoms and EF values to detect ventricular dysfunction.

Long-term results of concomitant atrioventricular valve intervention and the Fontan operation

OBJECTIVES

The optimal timing for atrioventricular valve (AVV) repair in patients with a Fontan circulation remains controversial. Few studies have reported the long-term outcomes of AVV repair concomitant with a Fontan operation.

METHODS

From January 2006 to December 2018, a total of 89 patients who developed moderate or severe AVV regurgitation before a Fontan operation were divided into 2 groups: group 1, including 37 patients who did not undergo concomitant AVV repair; and group 2, including 52 patients who received AVV repair concomitant with a Fontan operation.

RESULTS

The mean age at the time of the Fontan operation was 6.74 years for group 1 and 8.96 years for group 2, respectively. Early death occurred in 3 patients [2 patients (5.4%) in group 2, patient 1 (1.9%) in group 1]. Freedom from long-term death, cardiac function reduction and protein-losing enteropathy were similar among the 2 groups. Common AVV function was apparently poorer than mitral valve function after repair [hazard ratio (HR) 3.83, 95% confidence interval (CI) 1.31-11.17; P = 0.014]. The occurrence of AVV valve failure in group 1 was lower than that in group 2 (HR 0.44, 95% CI 0.22-0.91; P = 0.026). AVV function became worse during the follow-up period than that at discharge in both groups (P = 0.03 in group 1 and P = 0.001 in group 2).

CONCLUSIONS

The long-term results of AVV repair concomitant with a Fontan operation are favourable.