Extracardiac Fontan Conversion, Cryoablation, and Pacemaker Placement for Patients with a Failed Fontan

Acute Kidney Injury and Mid-term Outcomes After Extra-Cardiac Fontan Conversion

The aim of this study was to investigate the association of postoperative acute kidney injury and unplanned re-admission rate due to heart failure at 2 years follow-up in patients who had extra-cardiac Fontan conversion. This was a retrospective single-center study of patients who underwent conversion from classic Fontan to extra-cardiac Fontan between January 2014 and December 2021. Acute kidney injury was defined using the Kidney Disease Improving Global Outcomes criteria. A total of 47 patients underwent Fontan conversion. Acute kidney injury occurred in 22 patients (46.8%) and 5 patients with acute kidney injury needed renal replacement therapy. Unplanned re-admission rate at 2-year follow-up was significantly higher in patients with acute kidney injury even when renal function returned to baseline (8 [36.4%] vs. 3 [12.0%], p = 0.026 by the log-rank test). In conclusion, postoperative acute kidney injury after extra-cardiac Fontan conversion was associated with unplanned re-admission due to heart failure at 2-year follow-up even though renal function was recovered.

Impact of Atrial Fibrillation on Fontan Circulation: Fontan Computational Model

BACKGROUND

Patients with Fontan circulation may develop heart failure resulting in atrial fibrillation during the late phase. Inotropic effects to ameliorate hemodynamics on the Fontan circulation are not well understood, especially when in atrial fibrillation. This study was performed to determine whether dobutamine therapy in patients with Fontan circulation has limited effects on improving hemodynamics.

METHODS

Lumped computational models (sinus and atrial fibrillation) were employed including biventricular, atriopulmonary connection (APC), and extracardiac total cavopulmonary connection (TCPC) Fontan models. The condition of atrial fibrillation including lack of atrial beat, irregular ventricular contraction, and time-varying elastance for the ventricle was introduced. A different dose of dobutamine was given by varying the elastance of the ventricle, heart rate, and peripheral resistance.

RESULTS

In all models, the cardiac output decreased by 22.5% to 25.8% in atrial fibrillation. At 10 μg/kg/min of dobutamine in sinus rhythm, the cardiac output increased by 32.3% in the biventricular model but by only 9.2% (p<0.001) and 9.1% (p<0.001) in the APC and TCPC Fontan models, respectively. At 10 μg/kg/min of dobutamine in atrial fibrillation, the percent increase in the cardiac output in the Fontan circulation [11.8% increase in APC (p<0.001) and 11.9% increase in TCPC (p<0.001)] was significantly less than that in the biventricular circulation (32.3% increase).

CONCLUSIONS

In the Fontan circulation, atrial fibrillation itself reduced the cardiac output by approximately 25%, and dobutamine had a limited effect on increasing the cardiac output, especially when in atrial fibrillation. Maintaining sinus rhythm in patients with Fontan circulation is very important.

Management of the failing Fontan

With and increasing number of early survivors after the palliation of the single ventricle physiology there is a burgeoning Fontan population worldwide that will pose unique challenges because of the inevitable sequelae related to the absence of the alleged "needless" sub-pulmonic ventricle. The increasing number and older-age single-ventricle patients highlights the results of successful contemporary surgical palliation in children, leading to the development of an adult single-ventricle population with unpredictable socio-economic and health service impacts. The wide variability in clinical status of patients with Fontan circulation reflects not only the broadened spectrum of morphological substrates involved, but also the evolving surgical techniques during the last four decades. This has come in the wake of a gradual understanding of an incredibly tricky physiology. The magnitude of the disease, the physio-pathological mechanisms, and the therapeutic options to optimize the "failing Fontan" status and to delay the irreversible deterioration of "Fontan failure" condition are discussed in this review.

Total Cavopulmonary Connection is Superior to Atriopulmonary Connection Fontan in Preventing Thrombus Formation: Computer Simulation of Flow-Related Blood Coagulation

The classical Fontan route, namely the atriopulmonary connection (APC), continues to be associated with a risk of thrombus formation in the atrium. A conversion to a total cavopulmonary connection (TCPC) from the APC can ameliorate hemodynamics for the failed Fontan; however, the impact of these surgical operations on thrombus formation remains elusive. This study elucidates the underlying mechanism of thrombus formation in the Fontan route by using a two-dimensional computer hemodynamic simulation based on a simple blood coagulation rule. Hemodynamics in the Fontan route was simulated with Navier-Stokes equations. The blood coagulation and the hemodynamics were combined using a particle method. Three models were created: APC with a square atrium, APC with a round atrium, and TCPC. To examine the effects of the venous blood flow velocity, the velocity at rest and during exercise (0.5 and 1.0 W/kg) was measured. The total area of the thrombi increased over time. The APC square model showed the highest incidence for thrombus formation, followed by the APC round, whereas no thrombus was formed in the TCPC model. Slower blood flow at rest was associated with a higher incidence of thrombus formation. The TCPC was superior to the classical APC in terms of preventing thrombus formation, due to significant blood flow stagnation in the atrium of the APC. Thus, local hemodynamic behavior associated with the complex channel geometry plays a major role in thrombus formation in the Fontan route.

The adult with a fontan: a panacea without a cure? Review of long-term complications

The univentricular heart includes a spectrum of complex cardiac defects that are managed by staged palliative surgical procedures, ultimately resulting in a Fontan procedure. Since 1971, when it was first developed, the procedure has undergone several variations. These patients require lifelong management, including a thorough knowledge of their anatomic substrate, hemodynamic status, management of rhythm and ventricular function, together with multi-organ evaluation. As these patients enter middle age, there is increasing awareness of long-term complications and mortality. This review highlights the concept behind the staged surgical palliations, the unique single ventricle physiology and the long-term complications in this complex cohort of patients.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Oral budesonide as a therapy for protein-losing enteropathy in patients having undergone Fontan palliation

BACKGROUND

  Protein-losing enteropathy is associated with Fontan palliation for single-ventricle physiology and has been difficult to treat. Limited data suggest the successful use of oral budesonide (Entocort, AstraZeneca) as a palliative measure.

METHODS

  We examine our single-institution retrospective experience in eight patients who were treated with this therapy.

RESULTS

  Median pretherapy albumin level was 1.7 g/dL (range 1.0-2.7 g/dL), 3 months after therapy was 3.1 g/dL (range 2-4.8 g/dL), and by the end of the first year was 3.4 g/dL (range 2.1-5.3 g/dL). All patients had at least a transient improvement, and at latest follow-up (median 29 months, range 3-51 months) five patients remain on therapy. Five of eight patients had required pretherapy albumin transfusions; one patient required albumin infusions after therapy. Four patients had side effects associated with the medication.

CONCLUSIONS

  Oral budesonide is an additional therapy that has the potential to improve symptoms and delay need for heart transplantation in this patient population.

Protein-losing enteropathy: integrating a new disease paradigm into recommendations for prevention and treatment

Protein-losing enteropathy is a relatively uncommon complication of Fontan procedures for palliation of complex congenital cardiac disease. However, the relative infrequency of protein-losing enteropathy belies the tremendous medical, psychosocial and financial burdens it places upon afflicted patients, their families and the healthcare system that supports them. Unfortunately, because of the complexity and rarity of this disease process, the pathogenesis and pathophysiology of protein-losing enteropathy remain poorly understood, and attempts at treatment seldom yield long-term success. The most comprehensive analyses of protein-losing enteropathy in this patient population are now over a decade old, and re-evaluation of the prevalence and progress in treatment of this disease is needed. This report describes a single institution experience with the evaluation, management, and treatment of protein-losing enteropathy in patients with congenital cardiac disease in the current era, follows with a comprehensive review of protein-losing enteropathy, focused upon what is known and not known about the pathophysiology of protein-losing enteropathy in this patient population, and concludes with suggestions for prevention and treatment.

Late reoperations for Fontan patients: state of the art invited review

Conversion of the atriopulmonary Fontan to a total cavopulmonary extracardiac connection with concomitant arrhythmia surgery and pacemaker placement is a safe and efficacious procedure for this patient population. From 1994 to 2007 a total of 118 patients have undergone this procedure with one (0.8%) early and nine (7.6%) late deaths. During the course of our experience with Fontan conversion our surgical strategy has evolved to include various ablative techniques to treat macro re-entrant atrial tachycardia, focal (automatic) atrial tachycardia, atrioventricular nodal reentry tachycardia, atrial tachycardia due to accessory connections, atrial fibrillation, and ventricular tachycardia. The various mechanisms that we use to treat the underlying atrial arrhythmias are described in this review. We have also encountered patients with variations of the Fontan and other complex anatomic and pathophysiologic aberrations who were not amenable to standard takedown and ablative procedures. We describe those circumstances and the solutions we found to treat those patients.