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Single ventricle patients eligible for Fontan completion undergo pre-Fontan catheterization for hemodynamic and anatomic assessment prior to surgery. Cardiac magnetic resonance imaging may be used to evaluate pre-Fontan anatomy, physiology, and collateral burden. We describe our center's outcomes in patients undergoing pre-Fontan catheterization combined with cardiac magnetic resonance imaging. A retrospective review of patients undergoing pre-Fontan catheterization from 10/2018 to 04/2022 at Texas Children's Hospital was performed. Patients were divided into 2 groups: combined cardiac magnetic resonance imaging and catheterization (combined group) and those who underwent catheterization only (catheterization only group). There were 37 patients in the combined group and 40 in the catheterization only group. Both groups were similar in age and weight. Patients undergoing combined procedures received less contrast, and experienced less in-lab time, fluoroscopy time and catheterization procedure time. Median radiation exposure was lower in the combined procedure group but was not statistically significant. Intubation and total anesthesia times were higher in the combined procedure group. Patients undergoing a combined procedure were less likely to have collateral occlusion performed than in the catheterization only group. Bypass time, intensive care unit length of stay, and chest tube duration were similar in both groups at the time of Fontan completion. Combined pre-Fontan assessment decreases catheterization procedure and fluoroscopy time associated with cardiac catheterization at the expense of longer anesthetic times, and results in similar Fontan outcomes compared to when cardiac catheterization alone is utilized., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The Fontan operation creates a circulation characterized by elevated central venous pressure and low cardiac output. Over time, these characteristics result in a predictable and persistent decline in exercise performance that is associated with an increase in morbidity and mortality. A medical therapy that targets the abnormalities of the Fontan circulation might, therefore, be associated with improved outcomes. Udenafil, a phosphodiesterase type 5 inhibitor, has undergone phase I/II testing in adolescents who have had the Fontan operation and has been shown to be safe and well tolerated in the short term. However, there are no data regarding the long-term efficacy of udenafil in this population. The Fontan Udenafil Exercise Longitudinal (FUEL) Trial is a randomized, double-blind, placebo-controlled phase III clinical trial being conducted by the Pediatric Heart Network in collaboration with Mezzion Pharma Co, Ltd. This trial is designed to test the hypothesis that treatment with udenafil will lead to an improvement in exercise capacity in adolescents who have undergone the Fontan operation. A safety extension trial, the FUEL Open-Label Extension Trial (FUEL OLE), offers the opportunity for all FUEL subjects to obtain open-label udenafil for an additional 12 months following completion of FUEL, and evaluates the long-term safety and tolerability of this medication. This manuscript describes the rationale and study design for FUEL and FUEL OLE. Together, these trials provide an opportunity to better understand the role of medical management in the care of those who have undergone the Fontan operation., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Fontan patients may undergo additional surgical modifications to mitigate complications like protein-losing enteropathy, liver cirrhosis, and other issues in their splanchnic circulation. Recent case reports show promise for several types of modifications, but the subtle effects of these surgeries on the circulation are not well understood. In this paper, we employ mathematical modeling of blood flow to systematically quantify the impact of these surgical changes on extracardiac Fontan hemodynamics. We investigate two modifications: (1) the fenestrated Fontan and (2) the Fontan with hepatic vein exclusion. Closed-loop hemodynamic models are used, which consist of one-dimensional networks for the major vessels and zero-dimensional models for the heart and organ beds. Numerical results suggest the hepatic vein exclusion has the greatest overall impact on the hemodynamics, followed by the largest sized fenestration. In particular, the hepatic vein exclusion drastically lowers portal venous pressure while the fenestration decreases pulmonary artery pressure. Both modifications increase flow to the intestines, a finding consistent with their utility in clinical practice for combating complications in the splanchnic circulation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: The objectives of this review are to discuss the pathophysiology of the circulation with a functionally univentricular heart, with a focus on the unique physiologic characteristics, which provide the underpinnings for the management of these complex patients., Data Source: MEDLINE and PubMed., Conclusions: The circulation of the patient with a functionally univentricular heart displays unique physiologic characteristics, which are quite different from those of the normal biventricular circulation. There are profound differences within the heart itself in terms of ventricular function, interventricular interactions, and myocardial architecture, which are likely to have significant implications for the efficiency of ventricular ejection and metabolism. The coupling between the systemic ventricle and the aorta also displays unique features. The 3D orientation of the Fontan anastomosis itself can profoundly impact cardiac output, although the "portal" pulmonary arterial bed is a crucial determinant of overall cardiovascular function. As a result, disease-specific approaches to improve cardiovascular function are required at all stages during the care of these complex patients.

While exercise stress testing (EST) is an important tool, little is known about its use for determining ischemia in patients with hypoplastic left heart syndrome (HLHS) and Fontan palliation. We sought to determine the frequency of ST segment changes during EST in HLHS patients after Fontan and examine results of further testing performed in response to ST changes. A single-center chart review of HLHS patients post-Fontan from January 1995 to December 2012 was performed. Data collected included demographics, indications for EST, resting electrocardiogram findings, EST and echocardiogram results and outcomes. ESTs were evaluated for ST segment changes concerning for ischemia. Results of additional testing performed based on concerning EST findings were collected. Twenty-seven patients underwent 64 ESTs (mean 2.4 ESTs/patient). Median age at first EST was 9.6 years (range 6.2-16.4). EST was concerning for ischemia in 13 patients (48 %) on 25 (39 %) ESTs. Based on EST results, two patients had stress sestamibi testing, two underwent coronary angiography, and one had both. No reversible perfusion defects or coronary artery obstructions were demonstrated. No patient who underwent EST has died. ST segment depression was not associated with ventricular dysfunction prior to EST or at the end of follow-up (p > 0.05). In patients with HLHS post-Fontan palliation, ST segment depression on EST is common. In patients who underwent further testing, no evidence of ischemia or coronary abnormalities was found. Additional testing may not be necessary in all patients.

Background: Poor long-term outcomes are expected after Fontan surgery, but these perspectives have been tainted by the poorly functioning Fontans suffering from arrhythmias. No predictions of outcome can be quoted to the increasing number of Fontan patients free from arrhythmic complications. The parameters determining improved exercise capacity and quality of life in this subgroup are yet unknown., Methods: Fontan survivors from our institution and living in Victoria were invited to participate in the study if they were more than 10 years of age, and free of arrhythmias. A mean of 17 +/- 4 years after Fontan, 36 patients, 23 with a classical atriopulmonary connection (AP) and 13 with a lateral tunnel (LT) underwent transthoracic echocardiography, cycloergometer exercise study, neurohumoral screening, and assessment of quality of life., Results: The only factor predicting worse exercise capacity was the type of Fontan performed; patients with LT having better exercise capacity than those with AP (percentage of predicted anaerobic threshold: 88 +/- 14% vs 72 +/- 14%, p < 0.005; percentage of predicted VO(2)max: 62 +/- 8% vs 54 +/- 7%, p < 0.005). Endothelin-1 levels were elevated in all patients (2.9 pmol/L, 2.5 to 3.7). Responses from the quality of life measures placed our Fontan cohort mainly within the normal population range. None of the preoperative and postoperative variables adversely affected patients' quality of life., Conclusions: The anaerobic threshold of arrhythmia-free Fontan patients operated with the lateral tunnel technique was relatively preserved. Despite restricted exercise capacity, Fontan patients, provided that they are free of arrhythmias, have a normal quality of life reflected in their reports of psychiatric symptoms and family relationships.

Background: To determine whether patients undergoing the lateral tunnel and extracardiac conduit modifications of the Fontan procedure have better outcomes than patients undergoing a classical atriopulmonary connection., Methods and Results: Between 1980 and 2000, 305 consecutive patients underwent a Fontan procedure at our institution. There were 10 hospital deaths (mortality: 3%) with no death after 1990. Independent risk factors for mortality were preoperative elevated pulmonary artery pressures (P=0.002) and common atrioventricular valve (P=0.04). Fontan was taken down during hospital stay in 7 patients. A mean of 12+/-6 years of follow-up was obtained in the 257 nonforeign Fontan survivors. Completeness of concurrent follow-up was 96%. Twenty-year survival was 84% (95% CI: 79 to 89%). Recent techniques improved late survival. The 15-year survival after atriopulmonary connection was 81% (95% CI: 73% to 87%) versus 94% (95% CI: 79% to 98%) for lateral tunnel (P=0.004). Nine pts required heart transplantation (8 atriopulmonary connection, 1 lateral tunnel). Undergoing a Fontan modification independently predicted decreased occurrence of arrhythmia, and 15-year freedom from SVT was 61% (95% CI: 51% to 70%) for atriopulmonary connection versus 87% (95% CI: 76% to 93%) for lateral tunnel (P=0.02). Freedom from Fontan failure (death, take-down, transplantation, or NYHA class III-IV) was 70% (95% CI: 58% to 79%) at 20 years. After extra-cardiac conduits, no death, SVT, or failure was observed., Conclusions: The Fontan procedure remains a palliation, but outcomes of patients have improved. Better patient selection minimizes hospital mortality. Patients with lateral tunnel and extracardiac conduit modifications experience less arrhythmia and are likely to have failure of their Fontan circulation postponed.

Objective: To assess longitudinal changes in systemic ventricular diastolic function late after the Fontan procedure., Design and Patients: Prospective study of 13 patients at 2.8 (2.0) years (early) and again at 11.4 (2.0) years (late) after the Fontan procedure by Doppler echocardiography with simultaneous ECG, phonocardiogram, and respirometer., Setting: Tertiary paediatric cardiac centre., Results: The isovolumic relaxation time (IVRT) was significantly longer, and E wave deceleration time, E and A wave velocities, and E:A velocity ratio were reduced compared to normal both early and late after the procedure. The mean (SD) z score of IVRT decreased significantly from +2.50 (1.00) to +1.24 (0.80) (p = 0.002), and the z score of the E wave deceleration time decreased from -1.69 (1.31) to -2.40 (1.47) (p = 0.03) during follow up. The A wave deceleration time also tended to decrease (early 80 (12) ms v late 73 (11) ms, p = 0.13) with increased follow up. There were no changes of the E and A wave velocities and E:A velocity ratio. The E wave velocity was inversely related to IVRT both early (r = -0.82, p = 0.001) and late (r = -0.59, p = 0.034) after the operation. The prevalence of diastolic flow during isovolumic relaxation decreased from 85% (11/13) to 38% (5/13) (p = 0.04), while that of mid diastolic flow increased from 23% (3/13) to 77% (10/13) (p = 0.02) between the two assessments., Conclusions: Left ventricular diastolic function remains highly abnormal late after the Fontan procedure. The longitudinal changes demonstrated on follow up are compatible with reduction of left ventricular compliance in addition to persisting abnormalities of relaxation.

Objective: To assess the impact of the bidirectional cavopulmonary shunt, total cavopulmonary connection, and baffle fenestration on outcome of the Fontan operation in our unit., Method: We reviewed 123 bidirectional cavopulmonary shunts and 264 Fontan operations performed from 1980 to 1995. Analysis of pulmonary artery size (right and left main and lower lobe branches) before and after bidirectional cavopulmonary shunt was performed. Outcome of the Fontan operation was analysed in various time periods to assess the effect of prior bidirectional cavopulmonary shunt, use of the lateral tunnel, and fenestration., Results: Operative risk for the bidirectional cavopulmonary shunt was 4% (CI = 2-10%) with a survival of 89% (CI = 83-95%) at 36 months. Probability of conversion to Fontan operation at 36 months was 49% (CI = 38-61%). Pulmonary artery size (Nakata and lower lobe indices) fell after bidirectional cavopulmonary shunt (P = 0.0006). Fontan risk dropped from 8.5% (1980-1987) to 1.8% (1988-1995) (P = 0.02), coinciding with the use of the bidirectional cavopulmonary shunt. There was no further risk reduction after introduction of the lateral tunnel and baffle fenestration, although these comparisons are limited by relatively small numbers. Duration of hospital stay related to pleural effusions was lowest for patients with a fenestrated lateral tunnel operation (P < 0.05)., Conclusion: The bidirectional cavopulmonary shunt is a suboptimal stimulus for pulmonary artery enlargement, but may reduce the risk of Fontan operation in selected children. Fenestrated lateral tunnel operations have reduced the duration of postoperative pleural effusions.