Myocardial biomechanical effects of fetal aortic valvuloplasty.

Fetal critical aortic stenosis with evolving hypoplastic left heart syndrome (CAS-eHLHS) can progress to a univentricular (UV) birth malformation. Catheter-based fetal aortic valvuloplasty (FAV) can resolve stenosis and reduce the likelihood of malformation progression. However, we have limited understanding of the biomechanical impact of FAV and subsequent LV responses. Therefore, we performed image-based finite element (FE) modeling of 4 CAS-eHLHS fetal hearts, by performing iterative simulations to match image-based characteristics and then back-computing physiological parameters. We used pre-FAV simulations to conduct virtual FAV (vFAV) and compared pre-FAV and post-FAV simulations. vFAV simulations generally enabled partial restoration of several physiological features toward healthy levels, including increased stroke volume and myocardial strains, reduced aortic valve (AV) and mitral valve regurgitation (MVr) velocities, reduced LV and LA pressures, and reduced peak myofiber stress. FAV often leads to aortic valve regurgitation (AVr). Our simulations showed that AVr could compromise LV and LA depressurization but it could also significantly increase stroke volume and myocardial deformational stimuli. Post-FAV scans and simulations showed FAV enabled only partial reduction of the AV dissipative coefficient. Furthermore, LV contractility and peripheral vascular resistance could change in response to FAV, preventing decreases in AV velocity and LV pressure, compared with what would be anticipated from stenosis relief. This suggested that case-specific post-FAV modeling is required to fully capture cardiac functionality. Overall, image-based FE modeling could provide mechanistic details of the effects of FAV, but computational prediction of acute outcomes was difficult due to a patient-dependent physiological response to FAV.

Outcome after extracorporeal membrane oxygenation therapy in Norwood patients before the bidirectional Glenn operation.

OBJECTIVES: Patients after the Norwood procedure are prone to postoperative instability. Extracorporeal membrane oxygenation (ECMO) can help to overcome short-term organ failure. This retrospective single-centre study examines ECMO weaning, hospital discharge and long-term survival after ECMO therapy between Norwood and bidirectional Glenn palliation as well as risk factors for mortality. METHODS: In our institution, over 450 Norwood procedures have been performed. Since the introduction of ECMO therapy, 306 Norwood operations took place between 2007 and 2022, involving ECMO in 59 cases before bidirectional Glenn. In 48.3% of cases, ECMO was initiated intraoperatively post-Norwood. Patient outcomes were tracked and mortality risk factors were analysed using uni- and multivariable testing. RESULTS: ECMO therapy after Norwood (median duration: 5 days; range 0-17 days) saw 31.0% installed under CPR. Weaning was achieved in 46 children (78.0%), with 55.9% discharged home after a median of 45 (36-66) days. Late death occurred in 3 patients after 27, 234 and 1541 days. Currently, 30 children are in a median 4.8 year (3.4-7.7) follow-up. At the time of inquiry, 1 patient awaits bidirectional Glenn, 6 are at stage II palliation, Fontan was completed in 22 and 1 was lost to follow-up post-Norwood. Risk factor analysis revealed dialysis (P < 0.001), cerebral lesions (P = 0.026), longer ECMO duration (P = 0.002), cardiac indication and lower body weight (P = 0.038) as mortality-increasing factors. The 10-year mortality probability after ECMO therapy was 48.5% (95% CI 36.5-62.9%). CONCLUSIONS: ECMO therapy in critically ill patients after the Norwood operation may significantly improve survival of a patient cohort otherwise forfeited and give the opportunity for successful future-stage operations.

Pre-intervention myocardial stress is a good predictor of aortic valvoluplasty outcome for fetal critical aortic stenosis and evolving HLHS.

Fetal critical aortic stenosis with evolving hypoplastic left heart syndrome (CAS-eHLHS) causes biomechanical and functional aberrations, leading to a high risk of progression to hypoplastic left heart syndrome (HLHS) at birth. Fetal aortic valvuloplasty (FAV) can resolve outflow obstruction and may reduce progression risk. However, it is currently difficult to accurately predict which patients will respond to the intervention and become functionally biventricular (BV) at birth, as opposed to becoming functionally univentricular (UV). This prediction is important for patient selection, parental counselling, and surgical planning. Therefore, we investigated whether biomechanics parameters from pre-FAV image-based computations could robustly distinguish between CAS-eHLHS cases with BV or UV outcomes in a retrospective cohort. To do so we performed image-based finite element biomechanics modelling of nine CAS-eHLHS cases undergoing intervention and six healthy fetal control hearts, and found that a biomechanical parameter, peak systolic myofibre stress, showed a uniquely large difference between BV and UV cases, which had a larger magnitude effect than echocardiography parameters. A simplified equation was derived for quick and easy estimation of myofibre stress from echo measurements via principal component analysis. When tested on a retrospective cohort of 37 CAS-eHLHS cases, the parameter outperformed other parameters in predicting UV versus BV outcomes, and thus has a high potential of improving outcome predictions, if incorporated into patient selection procedures. Physiologically, high myocardial stresses likely indicate a healthier myocardium that can withstand high stresses and resist pathological remodelling, which can explain why it is a good predictor of BV outcomes. KEY POINTS: Predicting the morphological birth outcomes (univentricular versus biventricular) of fetal aortic valvuloplasty for fetal aortic stenosis with evolving HLHS is important for accurate patient selection, parental counselling and management decisions. Computational simulations show that a biomechanics parameter, pre-intervention peak systolic myofibre stress, is uniquely robust in distinguishing between such outcomes, outperforming all echo parameters. An empirical equation was developed to quickly compute peak systolic myofibre stress from routine echo measurements and was the best predictor of outcomes among a wide range of parameters tested.

Cardiac MRI six months after the onset of multisystem inflammatory syndrome in children and adolescents temporally related to COVID-19: A retrospective follow-up study.

BACKGROUND: In 2020, reports revealed cases called multisystem inflammatory syndrome in children and adolescents temporally related to COVID-19 or multisystem inflammatory syndrome in children. A small proportion of patients suffer from persistent left ventricular dysfunction at discharge. The primary aim was to investigate if myocardial impairment persists during follow-up in these patients. METHODS: Children fulfilling the criteria for multisystem inflammatory syndrome in children with cardiac involvement hospitalized between December 2020 and February 2022 were included in this retrospective single centre study. Cardiac MRI was performed six months after the onset of symptoms to evaluate possible persistent myocardial damage. RESULTS: Fifteen patients (80% male) with a median age of 8 years (interquartile range 4.5 - 13.5 years) were included. Upon admission, eight patients (53%) presented with reduced left ventricular function, with a median left ventricular ejection fraction of 54% (interquartile range 49.5%-61.5%) on transthoracic echocardiography. Elevated levels of cardiac-specific markers were found in 14 patients (93%). Cardiac MRI was performed in 12 patients at a median of 190.5 days after the onset of symptoms. Nine patients (75%) had normal left ventricular function, with a median left ventricular ejection fraction of 59.45%, while the remaining patients showed mildly to moderately reduced values. None of the patients showed signs of late gadolinium enhancement, indicating the absence of persistent myocardial scarring. CONCLUSION: During a follow-up of 6.2 months, mild to moderate cardiac impairment was revealed in 25% of patients evaluated by cardiac MRI. Although a majority of patients do not show signs of cardiac impairment, close follow-ups should be performed in a proportion of patients.

Current diagnostic and therapeutic strategies for the management of lymphatic insufficiency in patients with hypoplastic left heart syndrome.

Children with hypoplastic left heart syndrome share unique hemodynamic features that alter lymphatic integrity at all stages of palliation. Lymphatic congestion is almost universal in this patient group to some extent. It may lead to reversal of lymphatic flow, the development of abnormal lymphatic channels and ultimately decompression and loss of protein rich lymphatic fluid into extra lymphatic compartments in prone individuals. Some of the most devastating complications that are associated with single ventricle physiology, notably plastic bronchitis and protein losing enteropathy, have now been proven to be lymphatic in origin. Based on the new pathophysiologic concept new diagnostic and therapeutic strategies have recently been developed. Dynamic contrast magnetic resonance lymphangiography is now mainstay in diagnosis of lymphatic insufficiency and allows a thorough assessment of anatomy and function of the main lymphatic compartments through intranodal, intrahepatic and intramesenteric lymphatic imaging. Contrast enhanced ultrasound can evaluate thoracic duct patency and conventional fluoroscopic lymphangiography has been refined for evaluation of patients where magnetic resonance imaging cannot be performed. Novel lymphatic interventional techniques, such as thoracic duct embolization, selective lymphatic duct embolization and liver lymphatic embolization allow to seal abnormal lymphatic networks minimally invasive and have shown to resolve symptoms. Innominate vein turn-down procedures, whether surgical or interventional, have been designed to reduce lymphatic afterload and increase systemic preload effectively in the failing Fontan circulation. Outflow obstruction can now be managed with new microsurgical techniques that create lympho-venous anastomosis. Short term results for all of these new approaches are overall promising but evidence is sparse and long-term outcome still has to be defined. This review article aims to summarize current concepts of lymphatic flow disorders in single ventricle patients, discuss new emerging diagnostic and therapeutic strategies and point out lacks in evidence and needs for further research on this rapidly growing topic.

The right age for the en-bloc rotation of the outflow tracts: a single-centre experience.

OBJECTIVES: The en-bloc rotation of the outflow tracts (EBR) enables an anatomic correction of transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction. The anatomical condition or previous palliative procedures may allow choosing an elective date for the anatomic correction. The aim of this study was to evaluate the optimal age for performing the EBR based on the largest series published so far. METHODS: At the Children's Heart Center Linz, the EBR was performed in 33 patients between 2003 and 2021. Median age at operation was 74 [interquartile range (IQR) 17-627] days. Twelve patients were newborns (≤28 days), 9 older than 369 days. These 2 groups were compared to the remaining patients each regarding peri- and postoperative data, complications, reinterventions and mortality. The median follow-up period was 5.4 (IQR 0.99-11.74) years. RESULTS: In-hospital mortality was 6.1%. All-cause mortality was lower in patients younger than 369 days at the time of EBR (4.2% vs 44.4% in patients >369 days old, P = 0.013). In newborns, intensive care unit stay (median 18.5 days vs 8 days, P = 0.008) and in-hospital stay (median 29.5 days vs 15 days, P = 0.026) were significantly longer, the risk for postoperative AV block was higher (33.3 vs 0%, P = 0.012) than in patients who had been corrected anatomically after the neonatal period. CONCLUSIONS: The results of this study suggest the deferral of the EBR to the post-newborn period. A significantly higher mortality rate in patients of older age at operation seems to recommend the anatomic correction during the first year of life.

Fluid Mechanical Effects of Fetal Aortic Valvuloplasty for Cases of Critical Aortic Stenosis with Evolving Hypoplastic Left Heart Syndrome.

Fetuses with critical aortic stenosis (FAS) are at high risk of progression to HLHS by the time of birth (and are thus termed "evolving HLHS"). An in-utero catheter-based intervention, fetal aortic valvuloplasty (FAV), has shown promise as an intervention strategy to circumvent the progression, but its impact on the heart's biomechanics is not well understood. We performed patient-specific computational fluid dynamic (CFD) simulations based on 4D fetal echocardiography to assess the changes in the fluid mechanical environment in the FAS left ventricle (LV) directly before and 2 days after FAV. Echocardiograms of five FAS cases with technically successful FAV were retrospectively analysed. FAS compromised LV stroke volume and ejection fraction, but FAV rescued it significantly. Calculations to match simulations to clinical measurements showed that FAV approximately doubled aortic valve orifice area, but it remained much smaller than in healthy hearts. Diseased LVs had mildly stenotic mitral valves, which generated fast and narrow diastolic mitral inflow jet and vortex rings that remained unresolved directly after FAV. FAV further caused aortic valve damage and high-velocity regurgitation. The high-velocity aortic regurgitation jet and vortex ring caused a chaotic flow field upon impinging the apex, which drastically exacerbated the already high energy losses and poor flow energy efficiency of FAS LVs. Two days after the procedure, FAV did not alter wall shear stress (WSS) spatial patterns of diseased LV but elevated WSS magnitudes, and the poor blood turnover in pre-FAV LVs did not significantly improve directly after FAV. FAV improved FAS LV's flow function, but it also led to highly chaotic flow patterns and excessively high energy losses due to the introduction of aortic regurgitation directly after the intervention. Further studies analysing the effects several weeks after FAV are needed to understand the effects of such biomechanics on morphological development.

Long-term follow-up after simultaneous arterial switch operation and aortic arch repair.

OBJECTIVES: Taussig-Bing anomaly (TBA) and transposition of the great arteries (TGA) with hypoplastic or interrupted aortic arch (AA) are rare anomalies. Various operative techniques and a high incidence of reinterventions are described. The aim of this retrospective single-centre study was to evaluate operative data, mortality and reintervention rate with special regard to the AA. METHODS: At the Children's Heart Center Linz, 50 patients with the above-mentioned diagnosis have been corrected by a simultaneous repair between 2001 and 2022. Thirty-seven children had TBA, 13 had TGA and 5 of them had an interrupted AA. The median age at operation was 7 [interquartile range (IQR) 5-9] days, weight 3.38 (IQR 2.9-3.8) kg and follow-up 9.3 (IQR 3.1-14.5) years. The AA reconstruction was performed without patch material in 49 cases. RESULTS: There was 1 in-hospital mortality in a TBA patient and 1 late mortality (7 years later, neuroblastoma). 14/49 patients needed at least 1 reoperation (28.6%, all TBA) and 3 further patients had catheter reintervention or radiofrequency ablation only (6.1%, 2 TBA). Seventy-five percent of these procedures affected the right heart/pulmonary arteries; there was 1 re-coarctation repair. CONCLUSIONS: The simultaneous correction of TBA and TGA with AA obstruction or interruption is a safe operation with very low mortality. The AA reconstruction with minimized use of patch material resulted in a low restenosis rate.

Contribution of Ventricular Motion and Sampling Location to Discrepancies in Two-Dimensional Versus Three-Dimensional Fetal Ventricular Strain Measures.

BACKGROUND: Echocardiographic quantification of fetal cardiac strain is important to evaluate function and the need for intervention, with both two-dimensional (2D) and three-dimensional (3D) strain measurements currently feasible. However, discrepancies between 2D and 3D measurements have been reported, the etiologies of which are unclear. This study sought to determine the etiologies of the differences between 2D and 3D strain measurements. METHODS: A validated cardiac motion-tracking algorithm was used on 3D cine ultrasound images acquired in 26 healthy fetuses. Both 2D and 3D myocardial strain quantifications were performed on each image set for controlled comparisons. Finite element modeling of 2 left ventricle (LV) models with minor geometrical differences were performed with various helix angle configurations for validating image processing results. RESULTS: Three-dimensional longitudinal strain (LS) was significantly lower than 2D LS for the LV free wall and septum but not for the right ventricular (RV) free wall, while 3D circumferential strain (CS) was significantly higher than 2D CS for the LV, RV, and septum. The LS discrepancy was due to 2D long-axis imaging not capturing the out-of-plane motions associated with LV twist, while the CS discrepancy was due to the systolic motion of the heart toward the apex that caused out-of-plane motions in 2D short-axis imaging. A timing mismatch between the occurrences of peak longitudinal and circumferential dimensions caused a deviation in zero-strain referencing between 2D and 3D strain measurements, contributing to further discrepancies between the 2. CONCLUSIONS: Mechanisms for discrepancies between 2D and 3D strain measurements in fetal echocardiography were identified, and inaccuracies associated with 2D strains were highlighted. Understanding of this mechanism is useful and important for future standardization of fetal cardiac strain measurements, which we propose to be important in view of large discrepancies in measured values in the literature.

Prenatal aortic valvuloplasty as a definite treatment in fetuses with critical aortic stenosis, severe mitral regurgitation and giant left atrium: a report of two cases with medium-term follow-up.

Fetuses with critical aortic stenosis, severe mitral regurgitation and left atrial enlargement are at risk to develop heart failure and intrauterine death. We present two cases with this physiology who underwent fetal aortic balloon valvuloplasty at 25 + 5 and 28 + 2 weeks as their only intervention without requiring postnatal treatment during short- to medium-term follow-up of 1.4 and 4.9 years.

Complications Associated with Fetal Cardiac Interventions: Prevalence and Management - Experience from 213 Procedures.

INTRODUCTION: Fetal cardiac interventions (FCIs) were introduced to change the natural history of some congenital heart defects. The aim of this study was to analyze the complications and management strategies associated with FCI at our institution. METHODS: The local FCI database was retrospectively reviewed for all fetuses who underwent FCI in our center since 2000 regarding complications and fetal outcome. RESULTS: 213 FCIs have been performed in 165 fetuses since October 2000: 60 with fetal pulmonary valvuloplasty, 4 with atrial septostomy, 7 with atrial septal stents, and 142 with fetal aortic valvuloplasty (FAV). The median gestational age at intervention was 27+1/7 weeks (21+4/7-38+3/7) for all interventions. The most common complications needing treatment were bradycardia (37%) and pericardial effusions (12%). FAV procedure-related mortality was significantly lower in the recent period since 2014 (14% early vs. 4% recent era, p = 0.03) due to a learning curve and improved management strategies. There were no relevant maternal complications. Premature deliveries occurred in 22.8% percent of all patients. CONCLUSIONS: Complications during FCI were frequent and must be expected. Strategies to reduce their prevalence as well as timely and correct treatment are mandatory to keep mortality rates low.

Hypoplastic Left Heart Syndrome: Is There a Role for Fetal Therapy?

During fetal life some cardiac defects may lead to diminished left heart growth and to the evolution of a form of hypoplastic left heart syndrome (HLHS). In fetuses with an established HLHS, severe restriction or premature closure of the atrial septum leads to left atrial hypertension and remodeling of the pulmonary vasculature, severely worsening an already poor prognosis. Fetal therapy, including invasive fetal cardiac interventions and non-invasive maternal hyperoxygenation, have been introduced to prevent a possible progression of left heart hypoplasia, improve postnatal outcome, or secure fetal survival. The aim of this review is to cover patient selection and possible hemodynamic effects of fetal cardiac procedures and maternal hyperoxygenation in fetuses with an evolving or established hypoplastic left heart syndrome.

Fluid Mechanics of Fetal Left Ventricle During Aortic Stenosis with Evolving Hypoplastic Left Heart Syndrome.

In cases of fetal aortic stenosis and evolving Hypoplastic Left Heart Syndrome (feHLHS), aortic stenosis is associated with specific abnormalities such as retrograde or bidirectional systolic transverse arch flow. Many cases progressed to hypoplastic left heart syndrome (HLHS) malformation at birth, but fetal aortic valvuloplasty can prevent the progression in many cases. Since both disease and intervention involve drastic changes to the biomechanical environment, in-vivo biomechanics likely play a role in inducing and preventing disease progression. However, the fluid mechanics of feHLHS is not well-characterized. Here, we conduct patient-specific echocardiography-based flow simulations of normal and feHLHS left ventricles (LV), to understand the essential fluid dynamics distinction between the two cohorts. We found high variability across feHLHS cases, but also the following unifying features. Firstly, feHLHS diastole mitral inflow was in the form of a narrowed and fast jet that impinged onto the apical region, rather than a wide and gentle inflow in normal LVs. This was likely due to a malformed mitral valve with impaired opening dynamics. This altered inflow caused elevated vorticity dynamics and wall shear stresses (WSS) and reduced oscillatory shear index at the apical zone rather than mid-ventricle. Secondly, feHLHS LV also featured elevated systolic and diastolic energy losses, intraventricular pressure gradients, and vortex formation numbers, suggesting energy inefficiency of flow and additional burden on the LV. Thirdly, feHLHS LV had poor blood turnover, suggesting a hypoxic environment, which could be associated with endocardial fibroelastosis that is often observed in these patients.

Surgical and interventional rescue strategies for Fontan failure.

OBJECTIVES: Fontan patients are at lifelong risk for developing complications, which may result in Fontan failure. Survival rates after heart transplantation (HTX) are still unsatisfying in these patients. Long-term survival of extracardiac Fontan patients in the modern era was investigated. The objective of this study was to investigate if surgical and interventional procedures in patients with protein-losing enteropathy (PLE) and/or plastic bronchitis (PB) and a failing Fontan circulation can postpone or avoid HTX. METHODS: Retrospective data collection of all children who underwent a Fontan procedure between January 1999 and July 2021 at our centre was performed. Patients were surveyed regarding the occurrence of PLE or PB and their outcome was reported descriptively. HTX-free survival of patients who underwent a rescue procedure due to PLE/PB was evaluated. RESULTS: Three hundred and seventy [94.1% (95% confidence interval, 91.4-96.3)] Fontan patients were free of HTX or death at last follow-up after a median follow-up time of 6.7 years. PB/PLE was diagnosed in 34 patients during the observation period. A rescue procedure was undertaken in 16 pts. at a median time of 6.5 months (range: 1 day to 9.4 years) since the initial diagnosis of PLE/PB. In these patients, HTX-free survival was 75% (95% confidence interval, 47.6-92.7) at a median follow-up time of 4.0 years after the procedure. Range: 3.5 months to 13.9 years. CONCLUSIONS: Extracardiac Fontan patients in the modern era expect reasonable HTX-free survival rates. Surgical and/or interventional rescue strategies for Fontan failure can postpone HTX for a sustained period of time.

Outcome of patients with tetralogy of Fallot with pulmonary atresia.

Objective: Tetralogy of Fallot patients with pulmonary atresia (TOFPA) have a largely varying source of pulmonary perfusion with often hypoplastic and even absent central pulmonary arteries. A retrospective single center study was undertaken to assess outcome of these patients regarding type of surgical procedures, long-term mortality, achievement of VSD closure and analysis of postoperative interventions. Methods: 76 consecutive patients with TOFPA operated between 01.01.2003 and 31.12.2019 are included in this single center study. Patients with ductus dependent pulmonary circulation underwent primary single stage full correction including VSD closure and right ventricular to pulmonary conduit implantation (RVPAC) or transanular patch reconstruction. Children with hypoplastic pulmonary arteries and MAPCAs without double supply were predominantly treated by unifocalization and RVPAC implantation. The follow up period ranges between 0 and 16,5 years. Results: 31 patients (41%) underwent single stage full correction at a median age of 12 days, 15 patients could be treated by a transanular patch. 30 days mortality rate in this group was 6%. In the remaining 45 patients the VSD could not be closed during their first surgery which was performed at a median age of 89 days. A VSD closure was achieved later in 64% of these patients after median 178 days. 30 days mortality rate after the first surgery was 13% in this group. The estimated 10-year-survival rate after the first surgery is 80,5% ± 4,7% showing no significant difference between the groups with and without MAPCAs (p > 0,999). Median intervention-free interval (surgery and transcatheter intervention) after VSD closure was 1,7 ± 0,5 years [95% CI: 0,7-2,8 years]. Conclusions: A VSD closure could be achieved in 79% of the total cohort. In patients without MAPCAs this was possible at a significant earlier age (p < 0,01). Although patients without MAPCAs predominantly underwent single stage full correction at newborn age, the overall mortality rate and the interval until reintervention after VSD closure did not show significant differences between the two groups with and without MAPCAs. The high rate of proven genetic abnormalities (40%) with non-cardiac malformations did also pay its tribute to impaired life expectancy.

En Block Rotation of the Outflow Tracts: Intermediate Follow-up After 15 Years of Experience.

BACKGROUND: The en bloc rotation of the outflow tracts is a surgical option for anatomic repair of transposition of the great arteries, ventricular septal defect, and left ventricular outflow tract obstruction with preserved growth potential in all tubular structures and the option for keeping the native pulmonary valve. The aim of this study was to analyze our 15-year experience with this operation. METHODS: A retrospective single-center study including 27 consecutive patients, who underwent the en bloc rotation between 2003 and 2019, was performed. Median age at operation was 103 days (interquartile range [IQR], 17-117 days), and median body weight was 5.2 kg (IQR, 3.66-8.4 kg). Six patients had undergone 1 to 4 previous operations. In 18 patients (66.7%), the pulmonary valve could be preserved, and in 9 patients (33.3%) a transannular patch was performed. Median follow-up was 5.7 years (IQR, 1.6-9.0 years). RESULTS: One patient died of chronic left ventricular failure during the hospital stay. Two more died after discharge: 1 of aspiration after a cerebral hemorrhage and 1 of sudden death. Five other patients required reoperations or had reinterventions: 1 ventricular septal defect closure, 1 aortic valve repair, 1 patch plasty, 2 dilatations of supravalvular pulmonary stenosis, and 1 stent into a left pulmonary artery. During the follow-up period, no gradient in the left ventricular outflow tract was found, and postoperative growth of the pulmonary valve was shown. CONCLUSIONS: The en bloc rotation allows an anatomic correction of the complex transposition with growth potential in all tubular structures. Reoperations or reinterventions on the pulmonary valve or on the left ventricular outflow tract have not been necessary to date.

Biomechanics of Human Fetal Hearts with Critical Aortic Stenosis.

Critical aortic stenosis (AS) of the fetal heart causes a drastic change in the cardiac biomechanical environment. Consequently, a substantial proportion of such cases will lead to a single-ventricular birth outcome. However, the biomechanics of the disease is not well understood. To address this, we performed Finite Element (FE) modelling of the healthy fetal left ventricle (LV) based on patient-specific 4D ultrasound imaging, and simulated various disease features observed in clinical fetal AS to understand their biomechanical impact. These features included aortic stenosis, mitral regurgitation (MR) and LV hypertrophy, reduced contractility, and increased myocardial stiffness. AS was found to elevate LV pressures and myocardial stresses, and depending on severity, can drastically decrease stroke volume and myocardial strains. These effects are moderated by MR. AS alone did not lead to MR velocities above 3 m/s unless LV hypertrophy was included, suggesting that hypertrophy may be involved in clinical cases with high MR velocities. LV hypertrophy substantially elevated LV pressure, valve flow velocities and stroke volume, while reducing LV contractility resulted in diminished LV pressure, stroke volume and wall strains. Typical extent of hypertrophy during fetal AS in the clinic, however, led to excessive LV pressure and valve velocity in the FE model, suggesting that reduced contractility is typically associated with hypertrophy. Increased LV passive stiffness, which might represent fibroelastosis, was found to have minimal impact on LV pressures, stroke volume, and wall strain. This suggested that fibroelastosis could be a by-product of the disease progression and does not significantly impede cardiac function. Our study demonstrates that FE modelling is a valuable tool for elucidating the biomechanics of congenital heart disease and can calculate parameters which are difficult to measure, such as intraventricular pressure and myocardial stresses.

Atrial septum stenting in a foetus with hypoplastic left heart syndrome and restrictive foramen ovale: an alternative to emergency atrioseptectomy in the newborn-a case report.

BACKGROUND: In patients with hypoplastic left heart syndrome (HLHS) premature closure or restriction of the interatrial communication causes severe cyanosis directly after birth with rapid deterioration in clinical state. An ex-utero intrapartum treatment (EXIT) procedure, extracorporal membrane oxygenation (ECMO), and emergency interventional cardiac catheterization or cardiac surgery has to be anticipated and prepared. We report the first case performing foetal atrial septum stenting in such a patient directly before birth to enable uncomplicated interatrial shunting postnatally. CASE SUMMARY: A 31-year-old pregnant woman was referred to our centre for further evaluation of the foetus due to HLHS. In the follow-up study before birth severe restriction of the foramen ovale with increased retrograde flow in the pulmonary veins [0.33 ratio antegrade/retrograde time velocity integral (TVI)] was detected. After careful consideration foetal atrial septum stenting was performed at 38 + 3 weeks of gestation. At 39 + 2 weeks of gestation the baby was born by caesarean section followed by an uncomplicated postnatal adaption. On the 7th day of life a Norwood procedure was performed and the baby was discharged on the 63rd postoperative day. DISCUSSION: Evaluation of the interatrial communication in foetuses with HLHS should be done carefully just before birth. In the case of severe restriction or closure of the foramen ovale atrial septum stenting just before birth can be considered as an alternative treatment to an EXIT procedure, ECMO, or emergency atrioseptectomy on bypass. However, a very experienced team of paediatric cardiologists and perinatologists with expertise in foetal cardiac interventions is needed to perform this technical difficult procedure.

Double-arterial cannulation: a strategy for whole body perfusion during aortic arch reconstruction.

OBJECTIVES: Double-arterial cannulation enables cerebral perfusion and lower body perfusion during aortic arch reconstruction. The aim of this study was to analyse and report our experience of using this cannulation and perfusion technique on paediatric patients. METHODS: A retrospective single-centre study was carried out on 407 consecutive paediatric patients who underwent an aortic arch reconstruction under double-arterial cannulation between 2003 and 2015. The median age of the patients at surgery was 8 (range 2-5570) days, and body weight was 3.3 (range 1.8-60) kg. All operations were performed through standard median sternotomy. One arterial cannula was inserted into the innominate artery and the second one into the supradiaphragmatic descending aorta. Primary end points were 30-day mortality, acute renal failure requiring dialysis and time until lactate level decreased to ≤2 mmol/l postoperatively. RESULTS: We found an in-hospital mortality of 8.6%. Lethal incident was not associated with the cannulation method, and 1 intraoperative lesion of the descending aorta could be repaired immediately. The median lactate level of the patients on arrival at the intensive care unit was 3.5 mmol/l [quartile (Q)1: 2.3-Q3: 4.7] and creatinine was 0.48 mg/100 ml (Q1: 0.40-Q3: 0.58). The longest duration until the lactate level decreased to ≤ 2 mmol/l was found in the group of 264 univentricular patients (median 11 h, Q1: 6-Q3: 24). Seven (1.7%) patients of the whole cohort required peritoneal dialysis postoperatively. CONCLUSIONS: Double-arterial cannulation is a simple and safe method for perfusing the brain and the lower parts of the body during aortic arch reconstruction. Perioperative survival and freedom from procedure-related complications in this demanding patient population are encouraging.

Outcome of aortic arch reconstruction in infants with coarctation: Importance of operative approach.

OBJECTIVES: Coarctation with hypoplastic aortic arch can be treated with resection and extended end-to-end anastomosis (REEEA) as well as end-to-side anastomosis (ESA). The aim of the study was to review our experience with these techniques in newborns and infants and to assess mid-term outcome with regards to morbidity, mortality, and reintervention rate in relation to operative access and technique. PATIENTS AND METHODS: Retrospective review of hospital charts and surgical reports from 183 consecutive newborns and infants with coarctation and hypoplastic aortic arch with or without ventricular septal defect between 1996 and 2013. Median age at surgery was 15 days (0-345). Lateral thoracotomy was used as operative access in 111 patients; 72 patients had a median sternotomy, 71 of them with cardiopulmonary bypass (ESA n = 30, REEEA n = 41). Fifty-two patients (28.4%) had an additional ventricular septal defect closure. Follow-up data were available for 75.96% with a median follow-up of 6.3 years (0.2-18.16 years). RESULTS: Thirty-day mortality was 0.54% with no late mortality occurring during follow-up. There was 1 severe complication: paraplegia and cerebral hypoxemia after REEEA. Freedom from mortality and reintervention at 10 years was 99.27% and 90.12%, respectively. Lateral thoracotomy as operative access was a risk factor for recurrent obstruction (P = .03). CONCLUSIONS: REEEA and ESA were safe and effective treatments in newborns and infants. In borderline cases, aortic arch reconstruction should be performed through a median sternotomy on bypass.