Design and rationale of re-energize fontan: Randomized exercise intervention designed to maximize fitness in fontan patients

In this manuscript, we describe the design and rationale of a randomized controlled trial in pediatric Fontan patients to test the hypothesis that a live-video-supervised exercise (aerobic+resistance) intervention will improve cardiac and physical capacity; muscle mass, strength, and function; and endothelial function. Survival of children with single ventricles beyond the neonatal period has increased dramatically with the staged Fontan palliation. Yet, long-term morbidity remains high. By age 40, 50% of Fontan patients will have died or undergone heart transplantation. Factors that contribute to onset and progression of heart failure in Fontan patients remain incompletely understood. However, it is established that Fontan patients have poor exercise capacity which is associated with a greater risk of morbidity and mortality. Furthermore, decreased muscle mass, abnormal muscle function, and endothelial dysfunction in this patient population is known to contribute to disease progression. In adult patients with 2 ventricles and heart failure, reduced exercise capacity, muscle mass, and muscle strength are powerful predictors of poor outcomes, and exercise interventions can not only improve exercise capacity and muscle mass, but also reverse endothelial dysfunction. Despite these known benefits of exercise, pediatric Fontan patients do not exercise routinely due to their chronic condition, perceived restrictions to exercise, and parental overprotection. Limited exercise interventions in children with congenital heart disease have demonstrated that exercise is safe and effective; however, these studies have been conducted in small, heterogeneous groups, and most had few Fontan patients. Critically, adherence is a major limitation in pediatric exercise interventions delivered on-site, with adherence rates as low as 10%, due to distance from site, transportation difficulties, and missed school or workdays. To overcome these challenges, we utilize live-video conferencing to deliver the supervised exercise sessions. Our multidisciplinary team of experts will assess the effectiveness of a live-video-supervised exercise intervention, rigorously designed to maximize adherence, and improve key and novel measures of health in pediatric Fontan patients associated with poor long-term outcomes. Our ultimate goal is the translation of this model to clinical application as an "exercise prescription" to intervene early in pediatric Fontan patients and decrease long-term morbidity and mortality.

Optimizing Referral Timing of Patients With Fontan Circulatory Failure for Heart Transplant

BACKGROUND

There are no criteria guiding the timing of heart transplant referral for Fontan patients, nor are there any characteristics of those deferred or declined listing reported. This study examines comprehensive transplant evaluations for Fontan patients of all ages, listing decisions, and outcomes to inform referral practices.

METHODS

Retrospective review of 63 Fontan patients formally assessed by the advanced heart failure service and presented at Mayo Clinic transplant selection committee meetings (TSM) January 2006 to April 2021. The study is compliant with the Helsinki Congress and Declaration of Istanbul and included no prisoners. Statistical analysis was performed with Wilcoxon Rank Sum and Fisher's Exact tests.

RESULTS

Median age at TSM was 26 years (17.5, 36.5). Most were approved (38/63 [60%]); 9 of 63 (14%) were deferred and 16 of 63 (25%) were declined. Approved patients more commonly were <18 years old at TSM (15/38 [40%] vs 1/25 [4%], P = .002) compared with those deferred/declined. Complications of Fontan circulatory failure were less common in approved vs deferred/declined patients: ascites (15/38 [40%] vs 17/25 [68%], P = .039), cirrhosis (16/38 [42%] vs 19/25 [76%], P = .01), and renal insufficiency (6/38 [16%] vs 11/25 [44%], P = .02). Ejection fraction and atrioventricular valve regurgitation did not differ between groups. Pulmonary artery wedge pressure was overall high normal (12 mm Hg [9,16]) but higher in deferred/declined vs approved patients, 14.5 (11, 19) vs 10 (8, 13.5) mm Hg, P = .015. Overall survival was significantly lower in deferred/declined patients (P = .0018).

CONCLUSION

Fontan patient referral for heart transplant at younger age and before the onset of end-organ complications is associated with increased approval for transplant listing.

Quality of life in adults with congenital heart disease with and without pulmonary hypertension: a comparative study

Background

Pulmonary vascular disease and pulmonary hypertension (PH) belong to the most relevant complications of congenital heart disease (CHD) in the long-term course. Although PH might lead to a severely impaired quality of life (QOL), there are no current studies comparing QOL in adults with CHD (ACHD) with and without PH. Therefore, this study aimed to systematically examine QOL in ACHD with and without PH in order to generate a more differentiated understanding of their overall health-status and to employ newly gained findings into general care of this particular patient population.

Methods

In this comparative cross-sectional study, a representative sample of 803 adults with various forms of CHD with or without PH was analyzed. Data collection took place between September 2017 until February 2018 in a tertiary care center for ACHD. Medical data was retrieved from medical records. QOL was assessed using the EQ-5D-5L questionnaire. Descriptive methods, chi-square and t-tests were used to compare QOL of patients with and without PH.

Results

Of 803 patients, 752 patients had no PH [93.6%; 47.3% female; mean age: 34.9±11.83 (range, 18-86) years], 51 were identified with manifest PH [6.4%; 55.8% female; mean age: 41.9±12.17 (range, 21-69) years]. PH patients showed significantly worse overall QOL [mean no PH: 86.78±13.30 (8.2-100) vs. mean PH: 81.79±12.77 (43.6-100); 95% confidence interval (CI): 1.43 to 9.46; P=0.013], worse crosswalk index [mean no PH: 93.29±12.86 (-11, 100) vs. mean PH: 89.73±11.77 (47-100); 95% CI: 0.08 to 7.56; P=0.043], and worse VAS [mean no PH: 80.12±16.50 (15-100) vs. mean PH: 72.56±16.80 (40-100); 95% CI: 3.29 to 12.17; P=0.004]. However, after adjusting for age, only the VAS stayed significant (P=0.039). The QOL within the dimensions mobility (P<0.001), self-care (P=0.002), and usual activities (P=0.007), were significantly decreased in PH patients. Overall, anxiety and depression (11.08%) as well as pain and discomfort (11.03%) were the most impaired dimensions in both patient groups.

Conclusions

Since QOL is a significant predictor of outcome, PH-CHD patients need an early provision of psychosocial, health promoting support in addition to dedicated care and targeted PH treatment. It is therefore pivotal to timely identify unique psychosocial impairments in order to enhance quantity and QOL in this particularly vulnerable patient population.

Fontan Geometry and Hemodynamics Are Associated With Quality of Life in Adolescents and Young Adults

BACKGROUND

Despite favorable short-term outcomes, Fontan palliation is associated with comorbidities and diminished quality of life (QOL) in the years after completion. We hypothesized that poor Fontan hemodynamics and ventricular function are associated with worse QOL.

METHODS

This was a single-center study of Fontan survivors aged more than 12 years. Subjects completed a cardiac magnetic resonance scan and QOL questionnaire. Cardiac magnetic resonance-derived variables included Fontan geometry, and hemodynamics. Computational fluid dynamics simulations quantified power loss, pressure drop, and total cavopulmonary connection resistance across the Fontan. Quality of life was assessed by completion of the Pediatric Quality of Life Inventory. Longitudinal and cross-sectional comparisons were made between cardiac magnetic resonance and computational fluid dynamics parameters with patient-reported QOL.

RESULTS

We studied 77 Fontan patients, median age 19.7 years (interquartile range, 17.1 to 23.6), median time from Fontan completion 16 years (interquartile range, 13 to 20). Longitudinal data were available for 48 patients; median time between cardiac magnetic resonance and QOL was 8.1 years (interquartile range, 7 to 9.4). Median patient-reported Pediatric Quality of Life Inventory total score was 80 (interquartile range, 67.4 to 88). Greater power loss and smaller left pulmonary artery diameter at baseline were associated with worse QOL at follow-up. Greater pressure drop was associated with worse QOL at the same time point.

CONCLUSIONS

For Fontan survivors, measures of computational fluid dynamics hemodynamics and geometry are associated with worse QOL. Interventional strategies targeted at optimizing the Fontan may improve QOL.

Case report and review of the literature: Successful transition from acute continuous veno-venous hemodiafiltration therapy to chronic peritoneal dialysis in a chronically ventilated child with hypoplastic left heart syndrome following fontan

Fontan palliation depends on low pulmonary vascular resistance in order to maintain pulmonary blood flow and adequate oxygenation. This physiology results in higher central venous pressures with limited renal perfusion pressure and cardiac output. Positive pressure ventilation with mechanical ventilation increases intrathoracic pressure and raises central venous pressure and can further limit pulmonary and renal perfusion. Fluid removal with intermittent hemodialysis can be challenging in Fontan patients and can cause intolerable hypotension, however the increased abdominal filling pressures during peritoneal dialysis dwells can exacerbate systemic venous hypertension seen in Fontan patients and threaten adequate pulmonary blood flow and cardiac output. Successful transition to peritoneal dialysis in a chronically ventilated patient with hypoplastic left heart syndrome, end-stage renal disease and Fontan physiology has not been described. We present details outlining the successful transition across multiple modalities of renal replacement therapy to assist other teams faced with similar challenges in chronically ventilated Fontan patients with end-stage renal disease.

Current Treatment Options for the Failing Fontan Circulation

The Fontan operation was introduced in 1968. For congenital malformations, where biventricular repair is unsuitable, the Fontan procedure has provided a long-term palliation strategy with improved outcomes compared to the initially developed procedures. Despite these improvements, several complications merely due to a failing Fontan circulation, including myocardial dysfunction, arrhythmias, increased pulmonary vascular resistance, protein-losing enteropathy, hepatic dysfunction, plastic bronchitis, and thrombo-embolism, may occur, thereby limiting the life-expectancy in this patient cohort. This review provides an overview of the most common complications of Fontan circulation and the currently available treatment options.

Primary central pulmonary artery plasty for right atrial isomerism with pulmonary coarctation

OBJECTIVE

Patients with unbalanced pulmonary artery growth resulting from pulmonary coarctation are considered unsuitable candidates for the Fontan procedure. Particularly, patients with right isomerism pose a challenge. We aimed to investigate the use of primary central pulmonary artery plasty at initial palliation in patients with right isomerism.

METHODS

We recruited 34 right isomerism patients with pulmonary atresia and pulmonary coarctation who underwent modified Blalock-Taussig shunt with or without primary central pulmonary artery plasty between 1998 and 2014. We classified them into the primary central pulmonary artery plasty (group P) and no primary central pulmonary artery plasty (group N) groups. We retrospectively analyzed reintervention for pulmonary artery after initial palliation, difference in size between the left and right pulmonary arteries, overall survival, success of the Fontan procedure.

RESULTS

The group P and group N included 25 and 9 patients, respectively. Five (20%) and six (67%) patients in group P and group N, respectively, required reintervention for pulmonary artery after initial palliation (p = 0.017). No patient underwent reintervention for the pulmonary artery before bidirectional cavopulmonary shunt in group P. There was a significant difference in the bilateral pulmonary artery size balance between the groups before bidirectional cavopulmonary shunt (p = 0.041). The two-lung Fontan procedure was successful in 14 (56%) and 1 (11%) patient in group P and group N.

CONCLUSION

Primary central pulmonary artery plasty may contribute toward improving the balance in the size of the PA and preclude the need for reintervention for PA.

Percutaneous transcatheter occlusion of left atrioventricular valve in a patient with single ventricle and severe atrioventricular valve regurgitation

Many patients with single ventricle physiology suffer from atrioventricular valve (AVV) regurgitation which may worsen their cardiac function and cause symptoms. It has been postulated that elimination of the nondominant hypoplastic AVV regurgitation, might improve the clinical status in patients post-Fontan surgery. We describe a case of hypoplastic left heart variant, post Fontan surgery who had severe left AVV regurgitation and underwent percutaneous transcatheter occlusion of the hypoplastic left AVV, using a VSD occluder device. At 3 months post procedure, the patient is improved. Transcatheter closure of a regurgitant hypoplastic AVV in a patient with single ventricle helps to improve the patient's cardiac function and clinical status.

A Randomized, Controlled Pharmacokinetic and Pharmacodynamics Trial of Ambrisentan After Fontan Surgery

OBJECTIVES

To determine the pharmacokinetics, pharmacodynamics, and safety of the hepatically metabolized endothelin receptor antagonist, ambrisentan in children after Fontan surgery.

DESIGN

Prospective, randomized, double-blind, placebo-controlled pharmacokinetic/pharmacodynamics and safety trial.

SETTING

Single-center, postoperative cardiac ICU.

PATIENTS

Children undergoing elective Fontan surgery.

INTERVENTIONS

Subjects randomized on postoperative day number 1 to short-term (3 d) treatment with oral ambrisentan (2.5 mg in suspension, daily) versus placebo (4:1 randomization).

MEASUREMENTS AND MAIN RESULTS

Plasma drug concentrations were measured at 0.5, 1, 2, 4, and 18-36 hours after the first dose. We developed a population pharmacokinetic model in NONMEM 7.2 (Icon Solutions, Ellicott City, MD) and applied the model to dose-exposure simulations. Pharmacodynamics endpoints were assessed at baseline and 3 hours after study drug administration, using postoperative hemodynamic monitoring lines. The analysis included 16 patients, 13 on ambrisentan (77 plasma samples); median age 36 months (range, 26-72 mo), weight 13.3 kg (11.1-17.6 kg), and nine males. There were no differences in baseline characteristics between ambrisentan and controls. A one-compartment model with first-order absorption and lag-time characterized the data well. Allometrically scaled weight was the only covariate retained in the final model. Typical values for clearance and volume of distribution were lower than previously reported in adults, 1 L/hr/70 kg and 13.7 L/70 kg, respectively. Simulated exposures with doses of 0.1-0.2 mg/kg approximated therapeutic exposures in adults with pulmonary arterial hypertension receiving 5 mg or 10 mg doses. Ambrisentan lowered plasma brain natriuretic peptide concentrations (452 ± 479 to 413 ± 462; p = 0.046), Fontan pressures (16.8 ± 2.9 to 15.6 ± 2.9; p = 0.01), and indexed pulmonary vascular resistance (2.3 ± 0.9 to 1.8 ± 0.6; p = 0.01) with no drug-related adverse events.

CONCLUSIONS

Ambrisentan clearance is reduced following Fontan surgery, perhaps reflecting abnormal hepatic metabolism in this population. The observed safety profile appears favorable and hemodynamic effects of ambrisentan may be beneficial for Fontan patients.

Optimizing Computed Tomography for Detection of Pulmonary Thromboembolism in Patients With Fontan Circulation

Congenital heart disease (CHD) patients who have undergone the Fontan procedure or one of its variants usually have altered vascular anatomy. Consequently, this poses a challenge when diagnosing pulmonary thromboembolism (PTE) with computed tomography (CT). Detailed review of the type of surgery performed and the person’s individual anatomy beforehand can help in choosing the appropriate diagnostic CT modality and technique. It would also help reduce false-positive and false-negative test results that would otherwise result in unnecessary anticoagulation, as well as avoid needless radiation exposure and additional cost, respectively.

Adults With Complex Congenital Heart Disease: Cerebrovascular Considerations for the Neurologist

As infant and childhood mortality has decreased in congenital heart disease, this population is increasingly reaching adulthood. Adults with congenital heart disease (ACHD) represent a group with increased risk of stroke, silent brain infarcts, and vascular cognitive impairment. Cyanotic and other complex cardiac lesions confer the greatest risk of these cerebrovascular insults. ACHD patients, in addition to having an increased risk of stroke from structural cardiac issues and associated physiological changes, may have an accelerated burden of conventional vascular risk factors, including hypertension and impaired glucose metabolism. Adult neurologists should be aware of the risks of clinically evident and subclinical cerebrovascular disease in this population. We review the existing evidence on primary and secondary stroke prevention in individuals with complex congenital heart disease, and identify knowledge gaps in need of further research, including treatment of acute stroke in this population. Multisystemic genetic syndromes are outside the scope of this review.

Impact of the Fontan Operation on Organ Systems

In patients having undergone the Fontan operation, besides the well discussed changes in the cardiac, pulmonary and gastrointestinal system, alterations of further organ systems including the hematologic, immunologic, endocrinological and metabolic are reported. As a medical adjunct to Fontan surgery, the systematic study of the central role of the liver as a metabolizing and synthesizing organ should allow for a better understanding of the pathomechanism underlying the typical problems in Fontan patients, and in this context, the profiling of endocrinological and metabolic patterns might offer a tool for the optimization of Fontan follow-up, targeted monitoring and specific adjunct treatment.

Late outcomes after the Fontan procedure in patients with single ventricle: a meta-analysis

OBJECTIVE

More patients with Fontan physiology are reaching adulthood. The purpose of this meta-analysis was to evaluate the late outcomes of patients palliated with Fontan procedure and to assess the risk factors for mortality.

METHODS

PubMed, Embase and Web of Science were queried to retrieve observational studies of survival in patients following the Fontan procedure with ≥5 years of follow-up. A random-effects model was used to determine pooled survival estimates at 5, 10 and 15 years. Meta-regression was used to assess potential moderators for death.

RESULTS

Nineteen articles with a total of 5859 patients were included. The weighted mean follow-up time was 8.94±2.64 years with overall 8.3% deaths and 1.5% transplants. Pooled survival estimates at 5, 10 and 15 years were 90.7%, 87.2% and 87.5%, respectively; and 88.4%, 85.7% and 84.1%, respectively, for studies that included all three time intervals (n=4). Earliest surgical year included in the study, proportion of atriopulmonary connections versus extracardiac conduit or lateral tunnel, and older age at Fontan were associated with higher rates of death, but ventricular morphology was not. Protein-losing enteropathy, reoperation and pacemaker insertion were reported in 2.1%, 5.6% and 6.8% patients, respectively.

CONCLUSIONS

Survival following the Fontan procedure has improved with time and is influenced by Fontan type and age at the time of Fontan. At a mean follow-up of 8.9 years, there was no significant association between survival and ventricular morphology, not taking into account the mortality prior to Fontan.

Evaluation of the anatomic and hemodynamic abnormalities in tricuspid atresia before and after surgery using computational fluid dynamics

Analysis of hemodynamics inside tricuspid atresia (TA) chamber is essential to the understanding of TA for optimal treatment. In this study, we introduced a combined computational fluid dynamics (CFD) to simulate blood flow in the left ventricle (LV) to study the diastolic flow changes in TA.Real-time 3-dimentional echocardiography loops (ECHO) were acquired in normal control group, in TA patients before surgery (pre-op group) and after surgery (post-op group). ECHO loops were reconstructed and simulated by CFD, the geometric, volumetric changes, and vortices in the LV were studies and compare among 3 groups.Compared with the control group, pre-op TA patients demonstrated significant LV remodeling, manifesting with smaller LV length, larger diameter, width and spherical index, as well as lager volumes; post-op TA group showed revisions in values of both geometric and volumetric measurements. CDF also demonstrated the abnormality of vortices in the pre-op TA patients and the alteration of existence and measurements of vortex in postoperation group.Echo-based CFD modeling can show the abnormality of TA in both LV geometric, volumetric measurements and intracardiac vortices; and CFD is capable to demonstrate the alterations of LV after Fontan and Glenn surgical procedure.

Extracorporeal Membrane Oxygenation (ECMO) Support in Special Patient Populations-The Bidirectional Glenn and Fontan Circulations

Extracorporeal membrane oxygenation (ECMO) is a support modality used within the pediatric cardiac ICU population as a bridge to recovery or decision in the setting of acute myocardial decompensation, support for combined cardiopulmonary failure or in the setting of refractory cardiopulmonary arrest. Patients with univentricular physiology are at particular risk for decompensation requiring ECMO support. This review will focus upon current evidence and techniques for ECMO support of single ventricle patients who have undergone a stage II bidirectional Glenn procedure or the stage III Fontan procedure.

Anesthetic Management of Pheochromocytoma Resection in Adults with Single Ventricle Physiology

Survival rates for patients with palliated congenital heart disease are increasing, and an increasing number of adults with cyanotic congenital heart disease (CCHD) might require surgical resection of pheochromocytoma-paraganglioma (PHEO-PGL). A recent study supports the idea that patients with a history of CCHD and current or historical cyanosis might be at increased risk for developing PHEO-PGL. We review the anesthetic management of two adults with single-ventricle physiology following Fontan palliation presenting for PHEO-PGL resection and review prior published case reports. We found the use of epidural analgesia to be safe and effective in the operative and postoperative management of our patients.

Surgical Resection for Hepatocellular Carcinoma with Cardiac Cirrhosis after the Fontan Procedure

A 29-year-old woman who underwent the Fontan procedure at 10 years of age had an incidental finding of liver masses on abdominal ultrasonography. Subsequent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid magnetic resonance imaging showed a 15 mm hypervascular mass with washout in the hepatobiliary phase in liver segment 4 (S4), and an 18 mm hypervascular mass without washout in the hepatobiliary phase in liver segment 2 (S2). The S2 liver mass was pathologically diagnosed to be a regenerative nodule by an ultrasound-guided needle biopsy, and the S4 liver mass was pathologically diagnosed as a poorly differentiated hepatocellular carcinoma after partial hepatectomy.

Clinical Evaluation of the Hemodynamic Effects of the High-Flow Nasal Cannula Therapy on the Fontan Circulation

High-flow nasal cannula (HFNC) therapy supports respiratory effort with a minimal elevation in airway pressure. We examined hemodynamic effects of HFNC therapy in a 10-year-old girl with Fontan circulation, in which positive airway pressure has deleterious hemodynamic effects. The HFNC therapy at 30 L/min improved oxygenation without an increase in central venous pressure. It also reduced heart rate, and systemic and pulmonary vascular resistance, and increased cardiac output. In addition, the HFNC therapy improved the cerebral circulation measured by near-infrared spectroscopy. Thus, HFNC therapy may be a potentially useful noninvasive ventilation modality, particularly for patients with Fontan circulation.

Unsatisfactory Early and Late Outcomes After Fontan Surgery Delayed to Adolescence and Adulthood

The ideal age to perform the Fontan procedure is still unknown. The aim of this study is to determine outcomes after Fontan surgery delayed to adolescence and adulthood in Australia and New Zealand. Patients who had undergone a Fontan procedure at 15 years of age or older were identified in the 1133 patients registered in the Australia and New Zealand Fontan Registry until December 2012. A total of 45 patients underwent the following Fontan procedure at a median age of 18.3 years (16-21 years): 24 atriopulmonary connections, 10 lateral tunnel, and 11 extracardiac conduits. Hospital mortality was 13% (6 of 45). After a mean follow-up of 15.5 ± 9 years, there were 8 late deaths. Survival rates after 10, 20, and 25 years were 79% (95% CI: 64-89), 70% (95% CI: 51-83), and 70% (95% CI: 51-83), respectively. Freedom from Fontan failure (death, heart transplantation, Fontan takedown, protein-losing enteropathy, and poor functional status) after 10 and 20 years was 63% (95% CI: 47-76) and 35% (95% CI: 19-52), respectively. Patients with a single left ventricle had a lower risk of failure (hazard ratio = 0.25, 95% CI: 0.10-0.59; P = 0.002). Arrhythmias developed in 29 patients after a median of 0.1 years (0-9.3 years) and 10 required a permanent pacemaker. Freedom from all adverse events at 10 years was 30% (95% CI: 16-45). Outcomes of the Fontan procedure in adolescents and adults are poor, with disproportionately high hospital mortality and late adverse events. The Fontan procedure should not be delayed to adolescence and adulthood and should be performed electively in childhood.

Estimating equations for cardiopulmonary exercise testing variables in Fontan patients: derivation and validation using a multicenter cross-sectional database

Cardiopulmonary exercise testing (CPET) is a common method of evaluating patients with a Fontan circulation. Equations to calculate predicted CPET values are based on children with normal circulation. This study aims to create predictive equations for CPET variables solely based on patients with Fontan circulation. Patients who performed CPET in the multicenter Pediatric Heart Network Fontan Cross-Sectional Study were screened. Peak variable equations were calculated using patients who performed a maximal test (RER > 1.1) and anaerobic threshold (AT) variable equations on patients where AT was adequately calculated. Eighty percent of each cohort was randomly selected to derive the predictive equation and the remaining served as a validation cohort. Linear regression analysis was performed for each CPET variable within the derivation cohort. The resulting equations were applied to calculate predicted values in the validation cohort. Observed versus predicted variables were compared in the validation cohort using linear regression. 411 patients underwent CPET, 166 performed maximal exercise tests and 317 had adequately calculated AT. Predictive equations for peak CPET variables had good performance; peak VO2, R (2) = 0.61; maximum work, R (2) = 0.61; maximum O2 pulse, R (2) = 0.59. The equations for CPET variables at AT explained less of the variability; VO2 at AT, R (2) = 0.15; work at AT, R (2) = 0.39; O2 pulse at AT, R (2) = 0.34; VE/VCO2 at AT, R (2) = 0.18; VE/VO2 at AT, R (2) = 0.14. Only the models for VE/VCO2 and VE/VO2 at AT had significantly worse performance in validation cohort. Of the 8 equations for commonly measured CPET variables, six were able to be validated. The equations for peak variables were more robust in explaining variation in values than AT equations.

Successful treatment of mediastinitis in a young child by omental translocation following extracardiac Fontan graft placement

Mediastinitis after a midline sternotomy can become a serious complication, especially after implantation of prosthetic vascular grafts. We present a case of a three-year-old boy with hypoplastic left heart syndrome who developed mediastinitis following his third-stage palliation (Fontan operation). Rather than following the "traditional" surgical therapy of graft explantation, debridement, and replacement, we chose to preserve the graft and protect it by omental translocation. The relative merits of this therapeutic approach, which is rarely utilized and underappreciated in children, are outlined and discussed.

Tricuspid annular plane systolic excursion does not correlate with right ventricular ejection fraction in patients with hypoplastic left heart syndrome after Fontan palliation

Tricuspid annular plane systolic excursion (TAPSE) reflects longitudinal myocardial shortening, the main component of right ventricular (RV) contraction in normal hearts. To date, TAPSE has not been extensively studied in patients with hypoplastic left heart syndrome (HLHS) and systemic RVs after Fontan palliation. This retrospective study investigated HLHS patients after Fontan with cardiac magnetic resonance (CMR) performed between 1 January 2010 and 1 August 2012 and transthoracic echocardiogram (TTE) performed within 6 months of CMR. The maximal apical displacement of the lateral tricuspid valve annulus was measured on CMR (using four-chamber cine images) and on TTE (using two-dimensional apical views). To create TTE-TAPSE z-scores, published reference data were used. Intra- and interobserver variability was tested with analysis of variance. Inter-technique agreement of TTE and CMR was tested with Bland-Altman analysis. In this study, 30 CMRs and TTEs from 29 patients were analyzed. The age at CMR was 14.1 ± 7.1 years, performed 11.9 ± 7.8 years after Fontan. For CMR-TAPSE, the intraclass correlation coefficients for inter- and intraobserver variability were 0.89 and 0.91, respectively. The TAPSE measurements were 0.57 ± 0.2 cm on CMR and 0.70 ± 0.2 cm on TTE (TTE-TAPSE z score, -8.7 ± 1.0). The mean difference in TAPSE between CMR and TTE was -0.13 cm [95 % confidence interval (CI) -0.21 to -0.05], with 95 % limits of agreement (-0.55 to 0.29 cm). The study showed no association between CMR-TAPSE and RVEF (R = 0.08; p = 0.67). In patients with HLHS after Fontan, TAPSE is reproducible on CMR and TTE, with good agreement between the two imaging methods. Diminished TAPSE suggests impaired longitudinal shortening in the systemic RV. However, TAPSE is not a surrogate for RVEF in this study population.

Sildenafil exposure and hemodynamic effect after Fontan surgery

OBJECTIVE

Determine sildenafil exposure and hemodynamic effect in children after Fontan single-ventricle surgery.

DESIGN

Prospective dose-escalation trial.

SETTING

Single-center pediatric catheterization laboratory.

PATIENTS

Nine children post Fontan single-ventricle surgical palliation and undergoing elective cardiac catheterization: median (range) age and weight, 5.2 years (2.5-9.4 yr) and 16.3 kg (9.5-28.1 kg). Five children (55%) were boys, and six of nine (67%) had a systemic right ventricle.

INTERVENTIONS

Catheterization and echocardiography performed before and immediately after single-dose IV sildenafil (0.25, 0.35, or 0.45 mg/kg over 20 min).

MEASUREMENTS AND MAIN RESULTS

Peak sildenafil and desmethyl sildenafil concentration, change in hemodynamic variables measured by cardiac catheterization and echocardiography. Maximum sildenafil concentrations ranged from 124 to 646 ng/mL and were above the in vitro threshold needed for 77% phosphodiesterase type-5 inhibition in eight of nine children and 90% inhibition in seven of seven children with doses more than or equal to 0.35 mg/kg. Sildenafil improved stroke volume (+22%, p = 0.05) and cardiac output (+10%, p = 0.01) with no significant change in heart rate in eight of nine children. Sildenafil also lowered systemic (-16%, p = 0.01) and pulmonary vascular resistance index in all nine children (median baseline pulmonary vascular resistance index 2.4 [range, 1.3-3.7]; decreased to 1.9 [0.8-2.7] Wood Units × m; p = 0.01) with no dose-response effect. Pulmonary arterial pressures decreased (-10%, p = 0.02) and pulmonary blood flow increased (9%, p = 0.02). There was no change in myocardial performance index and no adverse events.

CONCLUSIONS

After Fontan surgery, sildenafil infusion acutely improves cardiopulmonary hemodynamics, increasing cardiac index. For the range of doses studied, exposure was within the acute safety range reported in adult subjects.

Contractility-afterload mismatch in patients with protein-losing enteropathy after the Fontan operation

This study aimed to clarify the relationship between onset of protein-losing enteropathy (PLE) and Fontan circulation, with special reference to the development of contractility-afterload mismatch. The PLE group comprised 9 patients who experienced PLE after undergoing the Fontan operation, and the control group consisted of 32 patients had did not experienced PLE more than 10 years after the Fontan operation. The study compared the pre- and postoperative values of arterial elastance (Ea), end-systolic elastance (Ees), and contractility-afterload mismatch (Ea/Ees). Furthermore, the variations in the values were examined during the preoperative, postoperative, and midterm postoperative periods in seven PLE patients who underwent cardiac catheterization at the onset of PLE and during the pre- and postintervention periods in three PLE patients who underwent surgical intervention to improve the Fontan circulation after the onset of PLE. Comparison of the values obtained before and after Fontan operations showed that the Ea values increased significantly in the PLE group. However, the pre- and postoperative Ees values did not differ in the two groups. During the postoperative period, Ea/Ees increased significantly, and the Ea and Ea/Ees values increased continuously until the onset of PLE in the PLE group. In the patients who underwent surgical intervention to improve the Fontan circulation after the onset of PLE, the Ea/Ees decreased significantly, and the serum albumin levels improved after the intervention. Contractility-afterload mismatch, mainly caused by the increase in the afterload of the systemic ventricle, may have an important role in the development of PLE after the Fontan operation.

Response to a single dose of sildenafil in single-ventricle patients: an echocardiographic evaluation

New evidence of increased phosphodiesterase-5 (PDE-5) in hypertrophied human myocardium suggests that sildenafil, a selective PDE-5 inhibitor, may improve muscle contraction and therefore improve ventricular function. The purpose of this study was to compare ventricular function as assessed by echocardiography in 10 surgically palliated single-ventricle patients at baseline and again after a single dose of sildenafil. The velocity time integral of the ventricular outflow tract was increased 2 h after sildenafil administration (p = 0.01), thus suggesting an improvement in cardiac output.

Cardiac performance and quality of life in patients who have undergone the Fontan procedure with and without prior superior cavopulmonary connection

BACKGROUND

A superior cavopulmonary connection is commonly performed before the Fontan procedure in patients with a functionally univentricular heart. Data are limited regarding associations between a prior superior cavopulmonary connection and functional and ventricular performance late after the Fontan procedure.

METHODS

We compared characteristics of those with and without prior superior cavopulmonary connection among 546 subjects enrolled in the Pediatric Heart Network Fontan Cross-Sectional Study. We further compared different superior cavopulmonary connection techniques: bidirectional cavopulmonary anastomosis (n equals 229), bilateral bidirectional cavopulmonary anastomosis (n equals 39), and hemi-Fontan (n equals 114).

RESULTS

A prior superior cavopulmonary connection was performed in 408 subjects (75%); the proportion differed by year of Fontan surgery and centre (p-value less than 0.0001 for each). The average age at Fontan was similar, 3.5 years in those with superior cavopulmonary connection versus 3.2 years in those without (p-value equals 0.4). The type of superior cavopulmonary connection varied by site (p-value less than 0.001) and was related to the type of Fontan procedure. Exercise performance, echocardiographic variables, and predominant rhythm did not differ by superior cavopulmonary connection status or among superior cavopulmonary connection types. Using a test of interaction, findings did not vary according to an underlying diagnosis of hypoplastic left heart syndrome.

CONCLUSIONS

After controlling for subject and era factors, most long-term outcomes in subjects with a prior superior cavopulmonary connection did not differ substantially from those without this procedure. The type of superior cavopulmonary connection varied significantly by centre, but late outcomes were similar.

Lagrangian analysis of hemodynamics data from FSI simulation

We present the computation of lagrangian-based flow characterization measures for time-dependent, deformable-wall, finite-element blood flow simulations. Applicability of the algorithm is demonstrated in a fluid-structure interaction simulation of blood flow through a total cavopulmonary connection (Fontan procedure), and results are compared with a rigid-vessel simulation. Specifically, we report on several important lagrangian-based measures including flow distributions, finite-time Lyapunov exponent fields, particle residence time, and exposure time calculations. Overall, strong similarity in lagrangian measures of the flow between deformable and rigid-vessel models was observed.

Anaesthesia for a minor procedure in a patient with fontan physiology

Fontan procedure is a palliative surgery done for patients born with single ventricle physiology. An understanding of the hemodynamic alterations in such a patient is important for successful perioperative management. We have discussed the anaesthetic considerations in a 12 year-old girl with complex congenital heart disease ultimately palliated by a Fontan operation, who was posted for Botox injections for upper limb spasticity under general anaesthesia.

Reduction in postoperative high-density lipoprotein cholesterol levels in children undergoing the Fontan operation

Despite the emerging relevance of high-density lipoprotein (HDL) in the inflammatory cascade and vascular barrier integrity, HDL levels in children undergoing cardiac surgery are unexplored. As a measure of HDL levels, the HDL-cholesterol (HDL-C) in single-ventricle patients was quantified before and after the Fontan operation, and it was determined whether relationships existed between the duration and the type of postoperative pleural effusions. The study prospectively enrolled 12 children undergoing the Fontan operation. Plasma HDL-C levels were measured before and after cardiopulmonary bypass. The outcome variables of interest were the duration and type of chest tube drainage (chylous vs. nonchylous). The Kendall rank correlation coefficient and the Wilcoxon rank sum test were used. There were 11 complete observations. The median preoperative HDL-C level for all the subjects was 30 mg/dl (range, 24-53 mg/dl), and the median postcardiopulmonary bypass level was 21 mg/dl (range, 14-46 mg/dl) (p = 0.004). There was a tendency toward a moderate inverse correlation (-0.42) between the postcardiopulmonary bypass HDL-C level and the duration of chest tube drainage, but the result was not statistically significant (p = 0.07). In the chylous effusion group, the median postcardiopulmonary bypass HDL-C tended to be lower (16 vs. 23 mg/dl; p = 0.09). After the Fontan operation, the plasma HDL-C levels in children are significantly reduced. It is reasonable to conclude that the reduction in HDL-C reflects reduced plasma levels of HDL particles, which may have pertinent implications in postoperative pleural effusions given the antiinflammatory and endothelial barrier functions of HDL.

Clinical significance of thrombosis in an intracardiac blind pouch after a Fontan operation

The univentricular heart after the Fontan operation may have a blind pouch formed by the pulmonary stump or rudimentary ventricle according to the anatomy before surgery. Thrombosis in an intracardiac blind pouch of patients with a univentricular heart is a hazardous complication. Because only a few reports have described this complication, the authors evaluated the clinical significance of thrombosis in an intracardiac blind pouch of a univentricular heart. They performed a retrospective review of medical records from August 1986 to December 2007. Four patients were confirmed as having thrombosis in a pulmonary artery stump and one patient as having thrombosis in a rudimentary ventricle shown by cardiac computed tomography (CT). This represents 1.85% (5/271) of patients with ongoing regular follow-up evaluation after the Fontan operation. The median age at diagnosis was 14.2 years. Two of the five patients were taking aspirin and one patient was taking warfarin when they were identified for the development of thrombosis. None of the patients demonstrated thrombosis in the Fontan tract or venous side of the circulation. Brain magnetic resonance imaging (MRI) showed that three patients had cerebral infarction and one patient had suggestive old ischemia. Three patients with thrombus in the pulmonary stump underwent pulmonary artery stump thrombectomy and pulmonary valve obliteration. One patient with thrombus in the rudimentary ventricle underwent ventricular septal defect (VSD) closure with thrombectomy. Thrombus in a blind pouch could cause systemic thromboembolism despite little blood communication. Therefore, surgical modification of the pulmonary stump and VSD closure of the rudimentary ventricle are required to reduce the risk of later thrombus formation. Clinicians should not overlook the possibility of thrombus in a ligated pulmonary artery stump or a rudimentary ventricle after the Fontan operation, which may increase the risk of embolic stroke for patients with single-ventricle physiology.

The role of cardiovascular magnetic resonance in candidates for Fontan operation: proposal of a new algorithm

BACKGROUND

To propose a new diagnostic algorithm for candidates for Fontan and identify those who can skip cardiac catheterization (CC).

METHODS

Forty-four candidates for Fontan (median age 4.8 years, range: 2-29 years) were prospectively evaluated by trans-thoracic echocardiography (TTE), Cardiovascular magnetic resonance (CMR) and CC. Before CC, according to clinical, echo and CMR findings, patients were divided in two groups: Group I comprised 18 patients deemed suitable for Fontan without requiring CC; group II comprised 26 patients indicated for CC either in order to detect more details, or for interventional procedures.

RESULTS

In Group I ("CC not required") no unexpected new information affecting surgical planning was provided by CC. Conversely, in Group II new information was provided by CC in three patients (0 vs 11.5%, p = 0.35) and in six an interventional procedure was performed. During CC, minor complications occurred in one patient from Group I and in three from Group II (6 vs 14%, p = 0.7). Radiation Dose-Area product was similar in the two groups (Median 20 Gycm(2), range: 5-40 vs 26.5 Gycm(2), range: 9-270 p = 0.37). All 18 Group I patients and 19 Group II patients underwent a total cavo-pulmonary anastomosis; in the remaining seven group II patients, four were excluded from Fontan; two are awaiting Fontan; one refused the intervention.

CONCLUSION

In this paper we propose a new diagnostic algorithm in a pre-Fontan setting. An accurate non-invasive evaluation comprising TTE and CMR could select patients who can skip CC.

What is the clinical utility of routine cardiac catheterization before a Fontan operation?

Patients with single-ventricle circulation presenting for Fontan completion routinely undergo cardiac catheterization despite ongoing debate concerning its additive value. Increasing interest in noninvasive preoperative evaluation alone led the authors to analyze the utility of routine pre-Fontan catheterization and to determine whether a subset of patients could avoid this invasive procedure. Patients younger than 5 years referred for pre-Fontan evaluation were retrospectively reviewed. Medical records and catheter angiograms were examined, and catheterizations were categorized as "additive" based on predetermined criteria. Associations between precatheterization variables, catheterization findings, and short-term postoperative outcomes were evaluated. Cardiac catheterization was clinically nonadditive for 89 of 175 patients undergoing pre-Fontan evaluation (51%). There were no robust precatheterization predictors of a nonadditive catheterization. Echocardiography did not fully demonstrate the relevant anatomy of 115 patients (66%), most frequently due to inadequate visualization of the pulmonary arteries, and 22 patients had additive catheterizations due to new diagnostic findings alone. Interventions at catheterization were frequent and deemed "important" for 64 patients (37%). Catheterization hemodynamic data were not associated with early postoperative outcomes. Minor catheterization complications occurred for 51 patients (29%) and major complications for 4 patients (2%). Although at least 50% of the patients presenting for Fontan completion may be able to avoid routine catheterization safely, an echocardiography-based imaging strategy alone is insufficient to allow proper identification of those who could be evaluated noninvasively. A more comprehensive imaging strategy not based solely on echocardiography should be considered.

Thromboelastography of patients after fontan compared with healthy children

Patients who have undergone a Fontan procedure face an increased risk for thromboembolic complications. This study aimed to evaluate whether thromboelastography, a global whole-blood assay of coagulation, can be used to detect hypercoagulability in pediatric Fontan patients compared with healthy children. This prospective, cross-sectional study investigated 25 Fontan patients and 51 healthy children in three age groups: 1-5 years, 6-10 years, and 11-16 years. Kaolin-activated thromboelastography was performed on citrated samples. No statistically significant differences in thromboelastography parameters were found among the different age groups of the 51 healthy children. None of the 25 Fontan patients demonstrated evidence of hypercoagulability on thromboelastography (95% confidence interval, 0-7%), as defined by two standard deviations above or below the normal mean. The findings suggest that the percentage of Fontan patients demonstrating hypercoagulability on thromboelastography is substantially lower than the reported incidence of thromboembolic complications. Whether thromboelastography could be helpful in predicting patients at increased risk for thromboembolic complications or not still is not known. Further studies comparing the thromboelastography of Fontan patients with the thromboembolic complications of those without Fontan are needed to delineate these issues.

Contemporary outcomes after the Fontan procedure: a Pediatric Heart Network multicenter study

OBJECTIVES

We characterized a large cohort of children who had a Fontan procedure, with measures of functional health status, ventricular size and function, exercise capacity, heart rhythm, and brain natriuretic peptide (BNP).

BACKGROUND

The characteristics of contemporary Fontan survivors are not well described.

METHODS

We enrolled 546 children (age 6 to 18 years, mean 11.9 years) and compared them within pre-specified anatomic and procedure subgroups. History and outcome measures were obtained within a 3-month period.

RESULTS

Predominant ventricular morphology was 49% left ventricular (LV), 34% right ventricular (RV), and 19% mixed. Ejection fraction (EF) was normal for 73% of subjects; diastolic function grade was normal for 28%. Child Health Questionnaire mean summary scores were lower than for control subjects; however, over 80% of subjects were in the normal range. Brain natriuretic peptide concentration ranged from <4 to 652 pg/ml (median 13 pg/ml). Mean percent predicted peak O2 consumption was 65% and decreased with age. Ejection fraction and EF Z score were lowest, and semilunar and atrioventricular (AV) valve regurgitation were more prevalent in the RV subgroup. Older age at Fontan was associated with more severe AV valve regurgitation. Most outcomes were not associated with a superior cavopulmonary connection before Fontan.

CONCLUSIONS

Measures of ventricular systolic function and functional health status, although lower on average in the cohort compared with control subjects, were in the majority of subjects within 2 standard deviations of the mean for control subjects. Right ventricular morphology was associated with poorer ventricular and valvular function. Effective strategies to preserve ventricular and valvular function, particularly for patients with RV morphology, are needed.