Natural history of TANGO2 deficiency disorder: Baseline assessment of 73 patients.

PURPOSE: TANGO2 deficiency disorder (TDD), an autosomal recessive disease first reported in 2016, is characterized by neurodevelopmental delay, seizures, intermittent ataxia, hypothyroidism, and life-threatening metabolic and cardiac crises. The purpose of this study was to define the natural history of TDD. METHODS: Data were collected from an ongoing natural history study of patients with TDD enrolled between February 2019 and May 2022. Data were obtained through phone or video based parent interviews and medical record review. RESULTS: Data were collected from 73 patients (59% male) from 57 unrelated families living in 16 different countries. The median age of participants at the time of data collection was 9.0 years (interquartile range = 5.3-15.9 years, range = fetal to 31.8 years). A total of 24 different TANGO2 alleles were observed. Patients showed normal development in early infancy, with progressive delay in developmental milestones thereafter. Symptoms included ataxia, dystonia, and speech difficulties, typically starting between the ages of 1 to 3 years. A total of 46/71 (65%) patients suffered metabolic crises, and of those, 30 (65%) developed cardiac crises. Metabolic crises were significantly decreased after the initiation of B-complex or multivitamin supplementation. CONCLUSION: We provide the most comprehensive review of natural history of TDD and important observational data suggesting that B-complex or multivitamins may prevent metabolic crises.

Left ventricular remodelling in rheumatic heart disease - trends over time and implications for follow-up in childhood.

BACKGROUND: Rheumatic heart disease (RHD) is the most common form of acquired heart disease worldwide. In RHD, volume loading from mitral regurgitation leads to left ventricular (LV) dilatation, increased wall stress, and ultimately LV dysfunction. Improved understanding of LV dynamics may contribute to refined timing of intervention. We aimed to characterize and compare left ventricular remodelling between rheumatic heart disease (RHD) severity groups by way of serial echocardiographic assessment of volumes and function in children. METHODS: Children with RHD referred to Perth Children's Hospital (formally Princess Margaret Hospital) (1987-2020) were reviewed. Patients with longitudinal pre-operative echocardiograms at diagnosis, approximately 12 months and at most recent follow-up, were included and stratified into RHD severity groups. Left ventricular (LV) echocardiographic parameters were assessed. Adjusted linear mixed effect models were used to compare interval changes. RESULTS: 146 patients (median age 10 years, IQR 6-14 years) with available longitudinal echocardiograms were analysed. Eighty-five (58.2%) patients had mild, 33 (22.6%) moderate and 28 (19.2%) severe RHD at diagnosis. Mean duration of follow-up was 4.6 years from the initial diagnosis. Severe RHD patients had significantly increased end-systolic volumes (ESV) and end-diastolic volumes (EDV) compared to mild/moderate groups at diagnosis (severe versus mild EDV mean difference 27.05 ml/m2, p < 0.001, severe versus moderate EDV mean difference 14.95 ml/m2, p = 0.006). Mild and moderate groups experienced no significant progression of changes in volume measures. In severe RHD, LV dilatation worsened over time. All groups had preserved cardiac function. CONCLUSIONS: In mild and moderate RHD, the lack of progression of valvular regurgitation and ventricular dimensions suggest a stable longer-term course. Significant LV remodelling occurred at baseline in severe RHD with progression of LV dilatation over time. LV function was preserved across all groups. Our findings may guide clinicians in deciding the frequency and timing of follow-up and may be of clinical utility during further reiterations of the Australia and New Zealand RHD Guidelines.

3D Printed Cardiac Models as an Adjunct to Traditional Teaching of Anatomy in Congenital Heart Disease-A Randomised Controlled Study.

INTRODUCTION: Three-dimensional (3D) printed cardiac models are increasingly being used for medical education, simulation and training, communication, surgical planning and research. Given the complexities of congenital cardiac anatomy, 3D printing is well suited as an adjunct to traditional teaching methods. This study aims to explore the influence of 3D printed cardiac models as a teaching aid for nurses and paediatric trainees. We hypothesise that using 3D models as an adjunct to didactic teaching methods improves knowledge and confidence levels of participants, regardless of their cardiology experience. METHOD: A prospective randomised study was performed recruiting paediatric nurses and doctors at a tertiary paediatric hospital. All participants undertook traditional congenital cardiac teaching describing normal cardiac anatomy and seven congenital lesions of increasing complexity (atrial septal defect, ventricular septal defect, vascular ring, partial anomalous pulmonary venous return, tetralogy of Fallot, transposition of the great arteries, and double outlet right ventricle). The intervention group received an additional recorded demonstration while handling 3D printed models of a normal heart and the same lesions. Pre- and post-intervention assessments were completed using a subjective Likert-scale questionnaire and objective multiple-choice examination. RESULTS: A total of 73 health practitioners (30 cardiac nurses and 43 paediatric trainees) were included. Subjective knowledge and confidence levels substantially improved in the intervention group (both p<0.001), with no differences observed in the control group. Greater improvement in both subjective and objective post-test scores was observed in the intervention group. A pronounced difference between pre- and post-teaching objective examination scores was found in both groups (p=0.002), with larger improvements observed in the intervention group. The mean score in the intervention group after teaching increased by 4.27 (21.4% improvement), as opposed to 2.28 (11.4% improvement) in the control group. There was no difference in pre-test score or post-test improvement based on previous cardiology experience. DISCUSSION: Three-dimensional (3D) printed cardiac models, when used as an adjunct to traditional teaching methods, substantially improve knowledge and confidence levels of health professionals on a range of congenital cardiac lesions. These models enhance the learners' educational experience and understanding of cardiac anatomy by overcoming the limitation of two-dimensional representations of 3D structures.

The Impact of Prenatal Diagnosis on Clinical Outcomes of Isolated Vascular Rings From a Statewide Paediatric Cardiology Tertiary Service.

BACKGROUND: Vascular rings, including right aortic arch with aberrant left subclavian artery (RAA-ALSCA), double aortic arch (DAA) and pulmonary artery sling (PAS), are congenital anomalies that may cause airway and oesophageal compression. As prenatal detection has improved, literature comparing clinical outcomes of antenatally versus postnatally diagnosed cases continues to emerge. The aim is to define a statewide tertiary paediatric institution's clinical profile and outcomes of prenatal versus postnatally diagnosed isolated vascular rings. METHOD: A retrospective single-centre review of isolated RAA-ALSCA, DAA and PAS between 1 January 1999 and 31 December 2020 was conducted. Clinical characteristics, surgical and follow-up information were collected. Antenatal and postnatally diagnosed groups were compared. RESULTS: Out of 123 cases diagnosed with isolated vascular rings, 98 (79.7%) cases had RAA-ALSCA, 21 (17.1%) with DAA, 4 (3.3%) with PAS. The antenatal detection rate was 73.6% in the past decade; 20.3% had a genetic disorder, of which 48% had 22q11.21 microdeletion. Of prenatally diagnosed cases, 31.3% developed symptoms, commonly stridor and dysphagia, at a median age of 2.0 months (IQR 0.0-3.0), compared to a median age of diagnosis for the postnatal cohort of 9 months (IQR 1.0-40.7). Postnatally diagnosed cases were more likely to present with symptoms, primarily respiratory distress, than prenatally diagnosed cases (p=0.006). Fifty-nine (59) cases (50% antenatally diagnosed) required vascular ring division; 6.8% had residual symptoms following surgery. DISCUSSION: Antenatal diagnosis has improved and leads to better parental awareness and more timely, appropriate intervention. Postnatally diagnosed patients were older, more likely to be symptomatic, underwent more investigations and were commenced on more medications for symptom management prior to diagnosis. One in five cases of isolated vascular ring anomalies carried a genetic diagnosis, which has important implications on prenatal counselling and genetic testing.

Birth prevalence of congenital heart defects in Western Australia, 1990-2016.

AIM: To describe the birth prevalence and characteristics of congenital heart defects in a geographically defined Australian population. METHODS: This descriptive, population-based study examined congenital heart defects in live births, stillbirths and pregnancy terminations ascertained by the Western Australian Register of Developmental Anomalies, 1990-2016. Birth prevalence (per 1000 births) was stratified by severity, known cause, maternal and birth characteristics, and primary diagnosis; and prevalence ratios were calculated for Aboriginal versus non-Aboriginal births. Temporal trends in prevalence, diagnosis age and infant mortality were examined. RESULTS: For births 1990-2010 (allowing 6 years for complete case ascertainment by 2016), 6419 cases were identified; prevalence was 11.5 per 1000 births (95% confidence interval (CI), 11.2-11.8). Severe defects were ascertained in 2.5 per 1000 births (95% CI 2.4-2.7). Most cases were liveborn (5842, 91.0%), and 28.9% had other birth defects. Prevalence was slightly higher in Aboriginal births (prevalence ratio 1.1; 95% CI 1.0-1.2); and the infant mortality rate more than doubled (13.4% vs. 5.8%, P < 0.001). Prenatal diagnosis increased over time but, in remote areas, was significantly lower for Aboriginal versus non-Aboriginal cases (3.1% vs. 9.3%; P = 0.008). A cause was identified in 920 cases (14.3%), more often for severe defects (347, 24.4%); 63% of known causes were rare diseases. Congenital heart defects associated with fetal alcohol spectrum disorder were much more common in Aboriginal births (prevalence ratio 82; 95% CI 28-239). CONCLUSIONS: Earlier detection of congenital heart defects and improved survival has occurred over time, although discrepancies between ethnic groups and regions warrant further investigation and strategic action.

Intraoperative echocardiographic coronary artery imaging in congenital and acquired heart disease.

Transoesophageal and epicardial echocardiography are indispensible intraoperative imaging modalities to guide paediatric heart disease surgeries and influence surgical decision-making. A less well-described role of intraoperative imaging is its utility in evaluating coronary artery patency and flow. Focused two-dimensional, colour, and spectral Doppler imaging of the coronary arteries should be performed during surgeries involving coronary manipulation or re-implantation, or in cases where there is unexpected ventricular dysfunction or electrographic signs concerning for ischaemia. Intraoperative imaging allows for any anatomical issues to be detected and addressed promptly in the operating room. Imaging of the coronary arteries should identify unobstructed coronary ostia and proximal course without kinking, angulation, narrowing, or significant calibre change to suggest stenosis or extrinsic compression from neighbouring structures. The aim of this review is to highlight the usefulness of transoesophageal and epicardial echocardiography in evaluating coronary artery patency and flow, provide a how-to guide for optimal imaging, and to introduce a practical guideline to achieve best clinical practice.

Right ventricular function in patients with pulmonary regurgitation with versus without tetralogy of Fallot.

BACKGROUND: Right ventricular (RV) dilation from pulmonary valve regurgitation (PR) is common after intervention(s) for pulmonary stenosis (PS) or atresia and intact ventricular septum (PA/IVS). It is not well established whether PR and RV dilation have similar effects on RV function and exercise capacity in these patients compared to patients after repair of tetralogy of Fallot (rToF). The aims of this study were to compare exercise tolerance, RV function and myocardial mechanics in non-ToF versus rToF children with significantly increased and comparable RV volumes. METHODS: Thirty PS or PA/IVS children after intervention(s) with significant PR and RV dilation (non-ToF group) were retrospectively matched for RV end-diastolic volume index (RVEDVi) and age with 30 rToF patients. Clinical characteristics, RV function by echocardiography and CMR, ECG and exercise capacity were compared between groups. RESULTS: The groups were well matched for RVEDVi and age. Global RV function (RVEF: 48.7 ±â€¯6.4% vs. 48.5 ±â€¯7.2%, P = .81) and exercise capacity (% predicted peak VO2:82.5 ±â€¯17.7% vs. 75.6 ±â€¯20.4%, P = .27) were similarly reduced between groups. RVEDVi correlated inversely with RVEF in both groups (non-ToF:r = -0.39, P = .04, rToF:r = -0.40, P = .03). QRS duration was wider in rToF patients, and in both groups inversely correlated with RVEF (non-ToF:r = -0.77, P < .001, rToF:r = -0.69, P < .001). In contrast to global function, longitudinal RV strain was lower in rTOF vs non-TOF (-20.1 ±â€¯3.9 vs.-25.7 ±â€¯4.4, P < .001). CONCLUSIONS: Global RV function and exercise capacity are similarly reduced in non-ToF and rToF patients with severely dilated RV, after matching by RVEDVi, suggesting a comparable impact of RV dilation on RV global function. The significance of reduced RV longitudinal function and worse dyssynchrony in rToF patients require further exploration.

Mapping versus source methods for quantifying myocardial T1 in controls and in repaired tetralogy of Fallot: interchangeability and reproducibility in children.

BACKGROUND: Myocardial T1 relaxometry can be performed by contouring on individual T1-weighted source images (source method) or on a single T1 map (mapping method). OBJECTIVE: This study compares (a) agreement between native T1 and extracellular volume results of the two methods and (b) interobserver reproducibility of the two methods in children without heart disease and those with tetralogy of Fallot (TOF). MATERIALS AND METHODS: We retrospectively analyzed pediatric patients (controls and those with repaired TOF) with cardiac magnetic resonance examinations including extracellular volume quantification using the modified Look-Locker inversion recovery (MOLLI) sequence. We compared native T1 and extracellular volume of the entire left ventricle and interventricular septum derived using the source and the mapping approaches. RESULTS: In the control group (n=25, median age 14.0 years, interquartile range [IQR] 11.5-16.5 years), the mapping method produced lower native T1 values than the source method in the interventricular septum (mean difference ± standard deviation [SD] = 12±15 ms, P<0.001). In the TOF group (n=50, median age 13.3 years, IQR 9.9-15.0 years), the mapping method produced lower values for native T1 and extracellular volume in the interventricular septum (mean difference 9±14 ms and 0.6±1.1%, P<0.001). In 6-12% of the children, differences were >3 standard deviations from the mean difference. Interobserver reproducibility between the two methods by intraclass correlation coefficients were clinically equivalent. CONCLUSION: T1 and extracellular volume values generated by the source and mapping methods show systematic differences and can vary significantly in an individual child, and thus cannot be used interchangeably in clinical practice. The source method might allow for easier detection and, in some cases, mitigation of artifacts that are not infrequent in children and can be difficult to appreciate on the T1 map.

Effect of anti-heart failure therapy on diastolic function in children with single-ventricle circulations.

BACKGROUND: Children with functionally univentricular circulations have chronic volume loading of the systemic ventricle, potentially affecting ventricular function. Medications including angiotensin-converting enzyme inhibitors and ß-blockers are used to treat ventricular dysfunction, despite limited evidence of their efficacy in this population. OBJECTIVE: To determine the effects of angiotensin-converting enzyme inhibitors on elevated filling pressures in children with single ventricle physiology. METHODS: We performed a single-centre, retrospective review of patients with single ventricle physiology who underwent multiple cardiac catheterisations between 1991 and 2013. Study population comprised of patients who commenced or had optimised dosing of angiotensin-converting enzyme inhibitors between assessments in response to high ventricular filling pressures. Patients undergoing interventions influencing loading conditions between assessments were excluded. RESULTS: A total of 17 patients were identified, with dominant morphologic right ventricle in eight patients (47.1%). Among them, 11 (64.7%) were pre-Fontan and six (35.3%) were post-Fontan completion. Median inter-assessment interval was 9.4 months (range 7.3-19.1). There was a reduction in end-diastolic pressure from 13 to 10 mmHg (p=0.002), mean pulmonary artery pressure from 16 to 13 mmHg (p=0.049), and mean atrial pressure from 12 to 9 mmHg (p=0.001). There was one cardiac transplant, and there were no patient deaths at median follow-up after 31 months. CONCLUSIONS: We observed a reduction in ventricular end-diastolic pressure, pulmonary artery pressure, and mean atrial pressure following treatment with angiotensin-converting enzyme inhibitors in patients with single ventricle physiology. Our study provides insights into the potential impact of anti-heart failure therapy in single ventricle circulations and calls for larger, controlled studies to assess for a therapeutic response.

Update on Kawasaki disease: epidemiology, aetiology and pathogenesis.

Kawasaki disease is an acute systemic vasculitis predominantly affecting young children. It is due to an abnormal host response to as yet unidentified infectious trigger(s). Kawasaki disease may cause coronary artery damage, long-term cardiovascular morbidity and occasionally mortality, especially if the diagnosis is missed or timely treatment is not given. This is the first of two updates on Kawasaki disease. Here we review recent advances in epidemiology, possible aetiologies, host susceptibility and pathogenesis of this fascinating condition.

An update on Kawasaki disease II: clinical features, diagnosis, treatment and outcomes.

This is the second of two updates on Kawasaki disease. The first review focused on epidemiology and aetio-pathogenesis. Here, we review the clinical features and diagnosis of Kawasaki disease, as well as recent evidence on treatment, follow-up and cardiovascular outcomes.

Cinematic versus volume rendered imaging for the depiction of complex congenital heart disease.

INTRODUCTION: Planning for surgical intervention for patients with complex congenital heart disease requires a comprehensive understanding of the individual's anatomy. Cinematic rendering (CR) is a novel technique that purportedly builds on traditional volume rendering (VR) by converting CT image data into clearly defined 3D reconstructions through the stimulation and propagation of light rays. The purpose of this study was to compare CR to VR for the understanding of critical anatomy in unoperated complex congenital heart disease. METHODS: In this retrospective study, CT data sets from 20 sequential scanned cases of unoperated paediatric patients with complex congenital heart disease were included. 3D images were produced at standardised and selected orientations, matched for both VR and CR. The images were then independently reviewed by two cardiologists, two radiologists and two surgeons for overall image quality, depth perception and the visualisation of surgically relevant anatomy, the coronary arteries and the pulmonary veins. RESULTS: Cinematic rendering demonstrated significantly superior image quality, depth perception and visualisation of surgically relevant anatomy than VR. CONCLUSION: Cinematic rendering is a novel 3D CT-rendering technique that may surpass the traditionally used volumetric rendering technique in the provision of actionable pre-operative anatomical detail for complex congenital heart disease.

Longitudinal cohort study investigating neurodevelopmental and socioemotional outcomes in school-entry aged children after open heart surgery in Australia and New Zealand: the NITRIC follow-up study protocol.

INTRODUCTION: Despite growing awareness of neurodevelopmental impairments in children with congenital heart disease (CHD), there is a lack of large, longitudinal, population-based cohorts. Little is known about the contemporary neurodevelopmental profile and the emergence of specific impairments in children with CHD entering school. The performance of standardised screening tools to predict neurodevelopmental outcomes at school age in this high-risk population remains poorly understood. The NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC) trial randomised 1371 children <2 years of age, investigating the effect of gaseous nitric oxide applied into the cardiopulmonary bypass oxygenator during heart surgery. The NITRIC follow-up study will follow this cohort annually until 5 years of age to assess outcomes related to cognition and socioemotional behaviour at school entry, identify risk factors for adverse outcomes and evaluate the performance of screening tools. METHODS AND ANALYSIS: Approximately 1150 children from the NITRIC trial across five sites in Australia and New Zealand will be eligible. Follow-up assessments will occur in two stages: (1) annual online screening of global neurodevelopment, socioemotional and executive functioning, health-related quality of life and parenting stress at ages 2-5 years; and (2) face-to-face assessment at age 5 years assessing intellectual ability, attention, memory and processing speed; fine motor skills; language and communication; and socioemotional outcomes. Cognitive and socioemotional outcomes and trajectories of neurodevelopment will be described and demographic, clinical, genetic and environmental predictors of these outcomes will be explored. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Children's Health Queensland (HREC/20/QCHQ/70626) and New Zealand Health and Disability (21/NTA/83) Research Ethics Committees. The findings will inform the development of clinical decision tools and improve preventative and intervention strategies in children with CHD. Dissemination of the outcomes of the study is expected via publications in peer-reviewed journals, presentation at conferences, via social media, podcast presentations and medical education resources, and through CHD family partners. TRIAL REGISTRATION NUMBER: The trial was prospectively registered with the Australian New Zealand Clinical Trials Registry as 'Gene Expression to Predict Long-Term Neurodevelopmental Outcome in Infants from the NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC) Study - A Multicentre Prospective Trial'. TRIAL REGISTRATION: ACTRN12621000904875.

The sinister course of an intramural right coronary artery.

We report the case of an adolescent who was presented with long-standing exertional symptoms, and was diagnosed with an anomalous right coronary arterial origin arising above the commissural junction between the left and right aortic sinus, with inter-arterial and intramural compression. The precise origin of this lesion outside the aortic sinuses is unusual, and multi-detector computed tomography gave excellent definition and spatial resolution of the anomalous origin and course. It is crucial to have a high index of suspicion of exertional symptoms, as sudden death may be the first manifestation of an anomalous coronary artery.

Impact of mitral regurgitation on left ventricular remodeling and function in children with rheumatic heart disease.

The impact of mitral regurgitation (MR) from pediatric rheumatic heart disease (RHD) and its effect on left ventricular (LV) remodeling and function following surgical intervention is uncertain. The objective is to explore the impact of mitral valve (MV) surgeries on myocardial mechanics, remodeling and function and identify pre-operative predictors of post-operative dysfunction which may contribute to the optimal timing of intervention. A retrospective review of echocardiographic data was performed of eighteen pediatric patients with RHD (median 9yrs, IQR 6-12) who underwent MV surgery. Echocardiograms pre-operatively and a median of 13.5 months (IQR 10.2-15) following intervention were compared to controls. Pre-operative LV end-diastolic indexed volumes (LVEDVi) were significantly increased compared to controls and remained persistently larger post-operatively. LV ejection fraction (LVEF) (pre 62.6% ± 6.1, post 51.7% ± 9.7, p = 0.002), and global longitudinal strain (GLS) (pre - 24.3 ± 4.1, post - 18.2 ± 2.6, p < 0.001) decreased post-operatively at mid-term follow-up. Pre-operative LVEDVi was a significant predictor of post-operative LVEF, with a cut-off of ≥ 102 ml/m2 associated with LV dysfunction (LVEF < 55%; sensitivity 70%, specificity 75%). Pre-operative LVEDVi also negatively correlated with GLS (r = - 0.58, p = 0.01). LV dimensions and volumes remain persistently larger than controls while LV function decreases post-surgical alleviation of MR in paediatric RHD. Pre-operative LVEDVi predicted post-operative LV dysfunction and utilising LV indexed volumes in directing timing of surgical planning should be considered. Further studies are required to investigate whether timely alleviation of MR before significant LV dilatation and remodeling occur may substantially prevent LV dysfunction and improve outcomes.

Coronary artery dilatation in toxic shock-like syndrome: the Kawasaki disease shock syndrome.

Kawasaki disease is a common systemic vasculitis of childhood that may result in life-threatening coronary artery abnormalities. Despite an overlap of clinical features with toxic shock syndrome, children with Kawasaki disease generally do not develop shock. We report two cases of older children who presented with a toxic shock-like illness, and were diagnosed with Kawasaki disease when coronary artery abnormalities were found on echocardiography, in keeping with the recently described 'Kawasaki disease shock syndrome'. Clinicians should consider Kawasaki disease in all children presenting with toxic shock and assess for coronary artery damage.

Occlusion of a large pulmonary arteriovenous malformation in a paediatric patient using multiple vascular plugs.

Pulmonary arteriovenous malformations (PAVMs) are caused by an abnormal vascular communication between a pulmonary artery and vein. They are usually congenital in nature and are associated with considerable morbidity and mortality if left untreated. Transcatheter techniques are the favoured option for PAVM occlusion in children, and large lesions can have multiple feeder vessels that may not be appreciated until selective angiography is performed. We describe the successful occlusion of a large PAVM in a paediatric patient using multiple Amplatzer vascular plugs.

Normative Data for Myocardial Native T1 and Extracellular Volume Fraction in Children.

PURPOSE: To establish normative data for myocardial T1, including extracellular volume (ECV) fraction, in healthy children. MATERIALS AND METHODS: In this retrospective, single-center study, T1 mapping data were collected from 48 healthy pediatric patients (14 years ± 3 [standard deviation]; range, 9-18 years; 27 of 48 [56%] male) referred for cardiac screening 1.5-T MRI between 2014 and 2017. T1 relaxometry was performed using a 5(number of heartbeats [nHB])3 modified Look-Locker inversion recovery (MOLLI) sequence, where nHB was three to five heartbeats depending on the heart rate, and was repeated 15 minutes following the administration of 0.2 mmol per kilogram of body weight of gadobenate dimeglumine, with 19 patients receiving contrast material. T1 values were calculated using a curve-fitting algorithm on average region-of-interest signal and corrected for imperfect inversion pulse efficiency. Comparisons within patients were performed with paired Student t test, between groups with unpaired Student t test or Mann-Whitney U test, and linear regression was performed to examine for associations with other variables. RESULTS: Average native T1 was 1008 msec ± 31, with a nonsignificant increase in females (1017 msec ± 27 vs 1001 msec ± 33, P = .066). Average ECV was 20.8% ± 2.4, with a nonsignificant increase in values in females (21.7% ± 1.9 vs 20.0% ± 2.6, P = .123). T1 and ECV values were increased in the septum versus the free wall. CONCLUSION: Normative data are presented for myocardial native T1 and ECV using the MOLLI T1 mapping sequence at 1.5 T.Supplemental material is available for this article.© RSNA, 2020.

Relative Impact of Right Ventricular Electromechanical Dyssynchrony Versus Pulmonary Regurgitation on Right Ventricular Dysfunction and Exercise Intolerance in Patients After Repair of Tetralogy of Fallot.

Background The relative impact of right ventricular ( RV ) electromechanical dyssynchrony versus pulmonary regurgitation ( PR ) on exercise capacity and RV function after tetralogy of Fallot repair is unknown. We aimed to delineate the relative effects of these factors on RV function and exercise capacity. Methods and Results We retrospectively analyzed 81 children with tetralogy of Fallot repair using multivariable regression. Predictor parameters were electrocardiographic QRS duration reflecting electromechanical dyssynchrony and PR severity by cardiac magnetic resonance. The outcome parameters were exercise capacity (percentage predicted peak oxygen consumption) and cardiac magnetic resonance ejection fraction (RV ejection fraction). To understand the relative effects of RV dyssynchrony versus PR on exercise capacity and RV function, virtual patient simulations were performed using a closed-loop cardiovascular system model (CircAdapt), covering a wide spectrum of disease severity. Eighty-one patients with tetralogy of Fallot repair (median [interquartile range { IQR} ] age, 14.48 [11.55-15.91] years) were analyzed. All had prolonged QRS duration (median [IQR], 144 [123-152] ms), at least moderate PR (median [IQR], 40% [29%-48%]), reduced exercise capacity (median [IQR], 79% [68%-92%] predicted peak oxygen consumption), and reduced RV ejection fraction (median [IQR], 48% [44%-52%]). Longer QRS duration, more than PR , was associated with lower oxygen consumption and lower RV ejection fraction. In a multivariable regression analysis, oxygen consumption decreased with both increasing QRS duration and PR severity. CircAdapt modeling showed that RV dyssynchrony exerts a stronger limiting effect on exercise capacity and on RV ejection fraction than does PR , regardless of contractile function. Conclusions In both patient data and computer simulations, RV dyssynchrony, more than PR , appears to be associated with reduced exercise capacity and RV systolic dysfunction in patients after TOF repair.