Failures of the Fontan System in Univentricular Hearts and Mortality Risk in Heart Transplantation: A Systematic Review and Meta-Analysis

The Fontan procedure (FP) is the standard surgical treatment for Univentricular heart diseases. Over time, the Fontan system fails, leading to pathologies such as protein-losing enteropathy (PLE), plastic bronchitis (PB), and heart failure (HF). FP should be considered as a transitional step to the final treatment: heart transplantation (HT). This systematic review and meta-analysis aims to establish the risk of death following HT according to the presence of FP complications. There was a total of 691 transplanted patients in the 18 articles, immediate survival 88% (n = 448), survival from 1 to 5 years of 78% (n = 427) and survival from 5.1 to 10 years of 69% (n = 208), >10 years 61% (n = 109). The relative risk (RR) was 1.12 for PLE (95% confidence interval [CI] = 0.89–1.40, p = 0.34), 1.03 for HF (0.7–1.51, p = 0.88), 0.70 for Arrhythmias (0.39–1.24, p= 0.22%), 0.46 for PB (0.08–2.72, p = 0.39), and 5.81 for CKD (1.70–19.88, p = 0.005). In patients with two or more failures, the RR was 1.94 (0.99–3.81, p = 0.05). After FP, the risk of death after HT is associated with CKD and with the presence of two or more failures.

Common Arterial Trunk Associated with Functionally Univentricular Heart: Anatomical Study and Review of the Literature

Common arterial trunk (CAT) is a rare congenital heart disease that is commonly included into the spectrum of conotruncal heart defects. CAT is rarely associated with functionally univentricular hearts, and only few cases have been described so far. Here, we describe the anatomical characteristics of CAT associated with a univentricular heart diagnosed in children and fetuses referred to our institution, and we completed the anatomical description of this rare condition through an extensive review of the literature. The complete cohort ultimately gathered 32 cases described in the literature completed by seven cases from our unit (seven fetuses and one child). Four types of univentricular hearts associated with CAT were observed: tricuspid atresia or hypoplastic right ventricle in 16 cases, mitral atresia or hypoplastic left ventricle in 12 cases, double-inlet left ventricle in 2 cases, and unbalanced atrioventricular septal defect in 9 cases. Our study questions the diagnosis of CAT as the exclusive consequence of an anomaly of the wedging process, following the convergence between the embryonic atrioventricular canal and the common outflow tract. We confirm that some forms of CAT can be considered to be due to an arrest of cardiac development at the stages preceding the convergence.

Intraventricular Flow Simulations in Singular Right Ventricles Reveal Deteriorated Washout and Low Vortex Formation

Purpose Patients with a functionally univentricular heart represent one of the most common severe cardiac lesions with a prevalence of 3 per 10,000 live births. Hemodynamics of the singular ventricle is a major research topic in cardiology and there exists a relationship between fluid dynamical features and cardiac behavior in health and disease. The aim of the present work was to compare intraventricular flow in single right ventricle (SRV) patients and subjects with healthy left hearts (LV) through patient-specific CFD simulations. Methods Three-dimensional real-time echocardiographic images were obtained for five SRV patients and two healthy subjects and CFD simulations with a moving mesh methodology were performed. Intraventricular vortex formation and vortex formation time (VFT) as well as the turbulent kinetic energy (TKE) and ventricular washout were evaluated. Results The results show significantly lower values for the VFT and the TKE in SRV patients compared with healthy LV subjects. Furthermore, vortex formation does not progress to the apex in SRV patients. These findings were confirmed by a significantly lower washout in SRV patients. Conclusions The study pinpoints the intriguing role of intraventricular flows to characterize performance of SRVs that goes beyond standard clinical metrics such as ejection fraction.

Analysis and regulation of the cardiovascular system of univentricular heart with different configurations of the total cavopulmonary connection

The cardiovascular system (CVS) is a complex mechanism capable of reacting and regulating various changes in external and internal parameters. A particular problem is the study of CVS with univentricular heart. We studied the hemodynamic response of the CVS to the use of various configurations of bypassing the right side of the heart. During our research, we selected three different configurations of the total cavopulmonary connection. All configurations were made from Clear Flex 50 and tested in an experimental workbench. According to the research results, the TCPC-3 configuration is the most optimal. It has symmetrical output values of flows and pressures and there is no significant increase in inlet pressure. The results of this study can be used to optimize the control of the parameters of the ventricular assist device and the total artificial heart.

Cohort study of intervened functionally univentricular heart in England and Wales (2000–2018)

ObjectiveGiven the paucity of long-term outcome data for complex congenital heart disease (CHD), we aimed to describe the treatment pathways and survival for patients who started interventions for functionally univentricular heart (FUH) conditions, excluding hypoplastic left heart syndrome.MethodsWe performed a retrospective cohort study using all procedure records from the National Congenital Heart Diseases Audit for children born in 2000–2018. The primary outcome was mortality, ascertained from the Office for National Statistics in 2020.ResultsOf 53 615 patients, 1557 had FUH: 55.9% were boys and 67.4% were of White ethnic groups. The largest diagnostic categories were tricuspid atresia (28.9%), double inlet left ventricle (21.0%) and unbalanced atrioventricular septal defect (AVSD) (15.2%). The ages at staged surgery were: initial palliation 11.5 (IQR 5.5–43.5) days, cavopulmonary shunt 9.2 (IQR 6.0–17.1) months and Fontan 56.2 (IQR 45.5–70.3) months. The median follow-up time was 10.8 (IQR 7.0–14.9) years and the 1, 5 and 10-year survival rates after initial palliation were 83.6% (95% CI 81.7% to 85.4%), 79.4% (95% CI 77.3% to 81.4%) and 77.2% (95% CI 75.0% to 79.2%), respectively. Higher hazards were present for unbalanced AVSD HR 2.75 (95% CI 1.82 to 4.17), atrial isomerism HR 1.75 (95% CI 1.14 to 2.70) and low weight HR 1.65 (95% CI 1.13 to 2.41), critical illness HR 2.30 (95% CI 1.67 to 3.18) or acquired comorbidities HR 2.71 (95% CI 1.82 to 4.04) at initial palliation.ConclusionAlthough treatment pathways for FUH are complex and variable, nearly 8 out of 10 children survived to 10 years. Longer-term analyses of outcome based on diagnosis (rather than procedure) can inform parents, patients and clinicians, driving practice improvements for complex CHD.

Main pulmonary artery swing back for univentricular heart

Left pulmonary artery (LPA) surgical arterioplasty done for juxtaductal pulmonary artery coarctation is a challenging technique that has often produced unsatisfactory outcomes because of poor outcome later and incomplete understanding of the evolution of structural changes in these vessels. We report a unique technique for LPA plasty involving main pulmonary artery (MPA) swing back, in a toddler who presented with history of increased work of breathing, cyanosis and failure to thrive since birth, where the MPA was detached and was swung back cranially to be anastomosed to LPA. This technique can be done, especially in univentricular heart (future Fontan candidate), since MPA needs to be interrupted. The patient had heterotaxy syndrome, left atrial isomerism, hypoplastic pulmonary valve with severe sub-valvar stenosis, duct dependent pulmonary circulation, good sized confluent branch pulmonary arteries with LPA narrowing at ductal insertion site, interrupted IVC with hemiazygous continuation and left SVC draining into coronary sinus. Initially underwent right modified Blalock taussig (BT) shunt, atrial septectomy, LPA plasty and PDA ligation at 6 months of age. Upon follow up after a year, diagnostic angiogram confirmed good flow in BT shunt and LPA re-stenosis with malpositioned great arteries. Redo sternotomy and Kawashima procedure was performed. BT shunt and MPA stump were divided. To conclude, the detached MPA segment was swung cranially and anstomosed to LPA (end to end) inferiorly and left SVC-LPA anstomosed superiorly onto this by end to side fashion. The early outcome was satisfactory, however long-term outcome needs to be followed up

The Influence of Respiration on Blood Flow in the Fontan Circulation: Insights for Imaging-Based Clinical Evaluation of the Total Cavopulmonary Connection

Congenital heart disease is the most common birth defect and functionally univentricular heart defects represent the most severe end of this spectrum. The Fontan circulation provides an unique solution for single ventricle patients, by connecting both caval veins directly to the pulmonary arteries. As a result, the pulmonary circulation in Fontan palliated patients is characterized by a passive, low-energy circulation that depends on increased systemic venous pressure to drive blood toward the lungs. The absence of a subpulmonary ventricle led to the widely believed concept that respiration, by sucking blood to the pulmonary circulation during inspiration, is of great importance as a driving force for antegrade blood flow in Fontan patients. However, recent studies show that respiration influences pulsatility, but has a limited effect on net forward flow in the Fontan circulation. Importantly, since MRI examination is recommended every 2 years in Fontan patients, clinicians should be aware that most conventional MRI flow sequences do not capture the pulsatility of the blood flow as a result of the respiration. In this review, the unique flow dynamics influenced by the cardiac and respiratory cycle at multiple locations within the Fontan circulation is discussed. The impact of (not) incorporating respiration in different MRI flow sequences on the interpretation of clinical flow parameters will be covered. Finally, the influence of incorporating respiration in advanced computational fluid dynamic modeling will be outlined.

Double Inlet Left Ventricle with common AV valve, discordant ventriculo-arterial connection and pulmonary atresia: A rare anomaly on fetal echocardiogram with three dimensional spatio-temporal imaging correlation (STIC)

Double Inlet Left Ventricle through a common AV valve is a rare type of functionally univentricular heart. We report a fetus with double inlet left ventricle with discordant ventriculo-arterial connection and pulmonary atresia. The anatomy was readily apparent on three dimensional rendering by spatio-temporal imaging correlation technique(STIC)