Biventricular conversion after Fontan completion: A preliminary experience

Comparison of definitive approaches for conotruncal defects following bidirectional Glenn procedure

BACKGROUND

Staged repair is common for complex conotruncal defects, often involving bidirectional Glenn (BDG) procedure. Following the cavopulmonary shunt, both Fontan completion and biventricular conversion (BiVC) serve as definitive approaches. The optimal strategy remains controversial.

METHODS

The baseline, perioperative and follow-up data were obtained for all paediatric patients with conotruncal defects who underwent BDG procedure as palliation in Fuwai Hospital from 2013 to 2022. Patients with single ventricle were excluded. The primary outcome was mortality. The secondary outcome was reintervention, including any cardiovascular surgeries and non-diagnostic catheterisations.

RESULTS

A total of 232 patients were included in the cohort, with 142 underwent Fontan (61.2%) and 90 underwent BiVC (38.8%). The median interstage period from BDG to the definitive procedure was 3.83 years (IQR: 2.72-5.42) in the overall cohort, 3.62 years (IQR: 2.57-5.15) in the Fontan group and 4.15 years (IQR: 3.05-6.13) in the BiVC group (p=0.03). The in-hospital outcomes favoured the Fontan group, including duration of cardiopulmonary bypass, aortic cross-clamp, mechanical ventilation and intensive care unit stay. Postoperative mortality was generally low and comparable, as was the reintervention rate (HR=1.42, 95% CI: 0.708 to 2.85, p=0.32). The left ventricular size was smaller at baseline and within the normal range at follow-up for both Fontan and BiVC groups; however, it was significantly larger with BiVC at follow-up.

CONCLUSION

In paediatric patients with conotruncal heart defects who underwent BDG procedure, BiVC is a feasible option, especially for patients with certain Fontan risk factors, and are not ideal candidates for successful Fontan completion.

Impact of the Rudimentary Chamber on Outcomes in Fontan Patients

Background: We sought to evaluate the influence of the rudimentary ventricle on long-term outcomes after the Fontan operation, focusing on exercise capacity and cardiac performance. Methods: Between 1995 and 2021, 290 patients underwent a total cavopulmonary connection. "Two-ventricle" Fontan circulation was defined as a rudimentary ventricle >30% of the dominant ventricle or >50% of its predicted normal value. This cohort was compared with patients with single-ventricle Fontan circulation. The primary endpoint was Fontan failure, and the secondary endpoints were VO2 and cardiac catheterization data at ten years postoperatively. Results: The median follow-up after the Fontan operation was 7.9 years (interquartile range: 1.9-13.9). No significant difference was found in Fontan failure-free survival between the "two-ventricle" Fontan circulation group and the single-ventricle Fontan circulation group (83/91, 93% vs 156/199, 78%), respectively at 20 years; P = .11). No significant difference was found in VO2 or cardiac performance except cardiac index, with 2.9 (2.3-4.8) versus 2.5 (2.3-4.3) L/min/m2 (P = .047). Fifty-one patients in the "two-ventricle" Fontan circulation group were followed up for over ten years after the Fontan operation. In the subgroup analysis of this cohort, the rudimentary ventricular end-diastolic volume/dominant ventricular end-diastolic volume ratio showed a significant positive correlation with dominant ventricular end-diastolic pressure (r = 0.58 [95% CI 0.35-0.74], P = .002) and a significant negative correlation with VO2 (r = -0.61 [95% CI -0.80 to -0.28], P = .001). Conclusions: The rudimentary ventricle was not significantly associated with any clinical disadvantages regarding Fontan failure. However, a large rudimentary ventricle was significantly associated with higher end-diastolic pressure and lower exercise capacity.

A Review of Biventricular Repair for the Congenital Cardiac Anesthesiologist

The management of children with a borderline ventricle has been debated for many years. The pursuit of a biventricular repair in these children aims to avoid the long-term sequelae of single ventricle palliation. There is a lack of anesthesia literature relating to the care of this complex heterogenous patient population. Anesthesiologists caring for these patients should have an understanding on the many different forms of physiology and the impact on provision of anesthesia and hemodynamic parameters, the goals of biventricular staging and completion as well as the pre-operative, intra-operative, and post-operative considerations relating to this high-risk group of patients.

Improved Exercise Tolerance in an Adolescent Female After Failed Fontan and Subsequent Biventricular Conversion

We report a case of improved exercise tolerance in a single-ventricle patient following biventricular conversion. An 11 year old with a fenestrated extracardiac failing Fontan was accepted for a biventricular conversion repair at an out-of-town institution. The patient had multiple adverse cardiac events following Fontan surgery including recurrent pleural effusions, arteriovenous malformations, protein-losing enteropathy, and marked exercise intolerance. Serial cardiac catheterizations revealed chronic elevated pulmonary artery and Fontan pressures, normal left ventricular end-diastolic pressure and an adequately sized left ventricle. Cardiopulmonary exercise testing demonstrated severely reduced exercise tolerance due to ventilatory and cardiac limitations with significant arterial desaturations during exercise. Following a successful biventricular conversion, exercise tolerance improved remarkably, as evidenced by improved oxygen uptake and ventilatory efficiency. Our case demonstrates that biventricular conversion surgery may offer improvement in quality of life and exercise capacity in selected patients with failing Fontan physiology.

Early Experience With Reverse Double Switch Operation for the Borderline Left Heart

This study reviews our early experience with the "reverse" double switch operation (R-DSO) for borderline left hearts. A retrospective review of children with borderline left hearts who underwent R-DSO between 2017 and 2021 was conducted. Patient characteristics and early hemodynamic and clinical outcomes were collected. R-DSO was performed in 8 patients with no operative or postoperative deaths; 5 underwent decompressing bidirectional Glenn. Left ventricular (LV) poor-compliance was the dominant pathophysiology. Four patients had undergone staged LV recruitment but were not candidates for anatomical biventricular circulation due to LV hypoplasia and/or diastolic dysfunction. 7/8 patients had risk factors for Fontan circulation including pulmonary vein stenosis, pulmonary hypertension, and pulmonary artery stenosis. Median age at R-DSO was 3.7 years (19 months-12 years). All patients were in sinus rhythm at discharge. At median follow-up of 15 months (57 days-4.1 years) no mortalities, reoperations or heart transplants had occurred. All patients had normal morphologic LV systolic function. In one patient, pre-existing pulmonary hypertension (HTN) resolved after R-DSO. Reinterventions included transcatheter mitral valve replacement for residual mitral stenosis and neo-pulmonary balloon valvuloplasty. In 4 patients follow-up catheterization done at a median of 519 days (320 days-4 years) demonstrated median cardiac index of 3.2 L/min/m2 (2.2-4); median sub-pulmonary left ventricular end diastolic pressure was 9 mm Hg (7-15); median inferior vena cava/baffle pressure was 8 mm Hg (7-13). R-DSO is an alternative to anatomical biventricular repair or single ventricle palliation in patients with borderline left hearts and can result in low inferior vena cava pressures and favorable early results. This approach can also relieve pulmonary HTN and allow future transplant candidacy.

Staged Ventricular Septation in Double-Inlet Ventricle - A Strategy to Avoid Fontan?

Single-stage ventricular septation for double-inlet left or right ventricle (DILV or DIRV) has historically been associated with poor outcomes. We hypothesize that staged ventricular septation may demonstrate favorable clinical outcomes to be an alternative to Fontan palliation. This single-center retrospective study reviewed patients with DILV or DIRV who underwent staged ventricular septation between 2015-2021. The strategy involves pulmonary artery banding or Norwood procedure during infancy (stage 1), followed by partial ventricular septation to anchor the septum, while maintaining systemic RV pressure to avoid septal shift (stage 2). Residual septal defects are closed with pulmonary artery band removal at stage 3. Results are reported as median (interquartile range). Twelve patients underwent partial ventricular septation. At a median follow-up time of 17 months (8-30) after stage 2, there were no interstage deaths or cardiac transplants; LV dysfunction was observed in one patient. Hemodynamic evaluation after stage 2 demonstrated median left atrial pressure of 9.5 mm Hg (8.9-11.5), cardiac index of 3.4 L/min/m2 (3.2-3.6), and RV and LV indexed end-diastolic volumes of 52 ml/m2 (41-67) and 105 ml/m2 (81-115), respectively. Five patients have progressed to stage 3; one required pacemaker for complete heart block. Unplanned reintervention was required in 4 patients after stage 1, 2 patients after stage 2, and 3 patients after stage 3. Staged ventricular septation is an alternative to single-ventricle palliation in a subset of double-inlet ventricle patients and is associated with acceptable early outcomes. Further studies are necessary to determine long-term outcomes.

Management of the Borderline Left Heart and Alternatives to Fontan

Management of borderline left heart can be divided into single ventricle and biventricular repair strategies. Recently, the strategy of left heart recruitment has been applied to select patients. Left heart recruitment strategies and alternatives to Fontan circulation are reviewed. The criteria utilized for decision-making include size and function of left heart structures as well as hemodynamics measured by cardiac catheterization.

Biventricular Conversion for Hypoplastic Left Heart Variants: An Update

Ongoing concerns with single-ventricle palliation morbidity and poor outcomes from primary biventricular strategies for neonates with borderline left heart structures have led some centers to attempt alternative strategies to obviate the need for ultimate Fontan palliation and limit the risk to the child during the vulnerable neonatal period. In certain patients who are traditionally palliated toward single-ventricle circulation, biventricular circulation is possible. This review aims to delineate the current knowledge regarding converting certain patients with borderline left heart structures from single-ventricle palliation toward biventricular circulation.

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.