Molecular Pathways and Animal Models of Atrial Septal Defect.

The relative simplicity of the clinical presentation and management of an atrial septal defect belies the complexity of the developmental pathogenesis. Here, we describe the anatomic development of the atrial septum and the venous return to the atrial chambers. Experimental models suggest how mutations and naturally occurring genetic variation could affect developmental steps to cause a defect within the oval fossa, the so-called secundum defect, or other interatrial communications, such as the sinus venosus defect or ostium primum defect.

Molecular Pathways and Animal Models of Atrioventricular Septal Defect.

The development of a fully functional four-chambered heart is critically dependent on the correct formation of the structures that separate the atrial and ventricular chambers. Perturbation of this process typically results in defects that allow mixing of oxygenated and deoxygenated blood. Atrioventricular septal defects (AVSD) form a class of congenital heart malformations that are characterized by the presence of a primary atrial septal defect (pASD), a common atrioventricular valve (cAVV), and frequently also a ventricular septal defect (VSD). While AVSD were historically considered to result from failure of the endocardial atrioventricular cushions to properly develop and fuse, more recent studies have determined that inhibition of the development of other components of the atrioventricular mesenchymal complex can lead to AVSDs as well. The role of the dorsal mesenchymal protrusion (DMP) in AVSD pathogenesis has been well-documented in studies using animal models for AVSDs, and in addition, preliminary data suggest that the mesenchymal cap situated on the leading edge of the primary atrial septum may be involved in certain situations as well. In this chapter, we review what is currently known about the molecular mechanisms and animal models that are associated with the pathogenesis of AVSD.

Quantitative evaluation of right ventricular myocardial function changes in patients with atrial septal defect before and after occlusion by noninvasive right ventricular pressure-strain loop.

OBJECTIVE: The noninvasive right ventricular pressure-strain loop (PSL) represents a novel method for the quantitative assessment of right ventricular myocardial function. Given that atrial septal defect (ASD) is a prevalent congenital heart anomaly associated with right ventricular volume overload, this study aimed to quantitatively assess the myocardial function of the right ventricle in ASD patients pre- and post-occlusion by noninvasive right ventricular PSL. METHODS: This study included 36 patients diagnosed with secundum ASD group and 30 healthy adults (control group). We compared conventional right ventricular echocardiographic parameters, right ventricular strain, and myocardial work in the ASD group before occlusion, two days post-occlusion, and three months post-occlusion, with those in the control group. RESULTS: Prior to and two days following occlusion, the ASD group exhibited higher right ventricular global work index (RVGWI), right ventricular global wasted work (RVGWW), and right ventricular global constructive work (RVGCW) compared to the control group (P < .05). Within the ASD group, post-occlusion, RVGWI, RVGCW, and RVGWW values were significantly reduced compared to pre-occlusion values (P < .001). Furthermore, RVGWI and RVGCW showed a significant decrease three months after occlusion compared to two days post-occlusion (P < .05). Multivariate regression analysis identified ASD diameter and pulmonary artery systolic pressure (PASP) as independent predictors of RVGWI (ß = .405, P < .001; ß = 2.307, P = .037) and RVGCW(ß = .350, P<.001; ß = 1.967, P = .023). CONCLUSIONS: The noninvasive right ventricular PSL effectively demonstrates the alterations in right ventricular myocardial function in ASD patients, pre- and post-occlusion. The metrics of right ventricular myocardial work (RVMW) offer a novel indicator for evaluating right ventricular myocardial function in these patients. Moreover, ASD diameter and PASP emerge as independent determinants of RVGWI and RVGCW.

The association of right ventricular-pulmonary arterial coupling and pulmonary vascular resistance in adult patients with uncorrected atrial septal defect.

BACKGROUND: Atrial septal defects (ASD) are the most common type of adult congenital heart disease (ACHD) associated with a high risk developing of pulmonary arterial hypertension (PAH). ASD closure is not recommended in patients with PAH and Pulmonary Vascular Resistance (PVR) ≥ 5 Wood Unit (WU). Noninvasive methods have been proposed to measure PVR; however, their accuracy remains low. Right Ventricle (RV) - Pulmonary Artery (PA) coupling is defined as the ability of the RV to adapt to high-resistance conditions. Tricuspid Annular Plane Systolic Excursion (TAPSE)/estimated pulmonary artery systolic pressure (ePASP) calculation using echocardiography is a noninvasive technique that has been proposed as a surrogate equation to evaluate RV-PA coupling. Currently, no research has demonstrated a relationship between RV-PA coupling and PVR in patients with ASD. METHODS: The study participants were consecutive eligible patients with ASD who underwent right heart catheterization (RHC) and echocardiography at Hasan Sadikin General Hospital, Bandung. Both the procedures were performed on the same day. RV-PA Coupling, defined as TAPSE/ePASP > 0.31, was assessed using echocardiography. The PVR was calculated during RHC using the indirect Fick method. RESULTS: There were 58 patients with ASD underwent RHC and echocardiography. Among them, 18 had RV/PA Coupling and 40 had RV/PA Uncoupling. The PVR values were significantly different between the two groups (p = 0.000). Correlation test between TAPSE/ePASP with PVR showed moderate negative correlation (r= -0.502, p = 0.001). TAPSE/ePASP ≤ 0.34 is the cutoff point to predict PVR > 5 WU with sensitivity of 91.7% and specificity 63.6%. CONCLUSION: This study showed a moderate negative correlation between TAPSE/ePASP and PVR. TAPSE/ePASP ≤ 0.34 could predict PVR > 5 WU with good sensitivity.

Evaluation of Inter-atrial Septal Defect Diameter and Left Ventricular Systolic Function in Children with Ostium Secundum Atrial Septal Defect in Enugu, Nigeria.

BACKGROUND: Children with ostium secundum atrial septal defect (OS ASD) usually present with varying degrees of ventricular dysfunction. OBJECTIVES: This study aimed to evaluate the left ventricular systolic function of children with OS ASD compared with control. METHODS: This was a cross-sectional study involving 113 children with OS ASD and 113 age- and sex- matched controls. Their age ranged from 1 month to 16 years. There were 49 males and 64 females in each group. Left ventricular systolic function of children with isolated OS ASD were compared with that of controls using echocardiography. Subjects and controls who fulfilled the inclusion criteria were consecutively recruited in the study. The data elicited from the study were analyzed with the IBM SPSS version 20 (IBM Corp, Chicago). RESULTS: The mean left ventricular mass (LV mass) of the control, 93.9±113.6 gm was significantly higher than that of subjects with OS ASD, 39.4±74.3 gm, (Mann Whitney U= 4.266, p< 0.001). Similarly, the mean left ventricular internal diameter in diastole (LVIDd) of the control,25.8±11.7 mm was significantly higher than that of participants with OS ASD, 19.9±7.1 mm (Mann Whitney U=4.522, p<0.001). The mean interventricular septal diameter in systole (IVSs) of the control, 7.2±3.5 mm was higher than that of participants with OS ASD, 5.0±1.9 mm and the mean difference was found to be statistically significant, (Student t=5.738, p<0.001). The mean left ventricular internal diameter in systole (LVIDs) of the control, 16.2±7.6 mm was significantly higher than that of participants with OS ASD, 12.9±5.8 mm, (Student t= 3.660, p< 0.001). There was no significant correlation between the size of interatrial septal defect of children with OS ASD and left ventricular systolic function and age :(Corr. Coef. 0.065, p= 0.492) ; EF( Corr. Coef. 0.121,p=0.202), FS (Corr. Coef. 0.139, p=0.143). CONCLUSION: Children with OS ASD had lower left ventricular mass compared with those with control. Females seem to have higher function than males.

CONTEXTE: Les enfants atteints de communication interauriculaire type ostium secundum (CIASOS) présentent généralement des degrés variables de dysfonction ventriculaire. OBJECTIFS: Cette étude visait à évaluer la fonction systolique ventriculaire gauche des enfants atteints de CIASOS par rapport à des témoins. MÉTHODES: Il s'agissait d'une étude transversale portant sur 113 enfants atteints de CIASOS et 113 témoins appariés selon l'âge et le sexe. Leur âge variait de 1 mois à 16 ans. Il y avait 49 garçons et 64 filles dans chaque groupe. La fonction systolique ventriculaire gauche des enfants présentant un CIASOS isolé a été comparée à celle des témoins à l'aide de l'échocardiographie. Les sujets et les témoins qui remplissaient les critères d'inclusion ont été recrutés consécutivement dans l'étude. Les données recueillies ont été analysées avec la version 20 d'IBM SPSS (IBM Corp, Chicago). RÉSULTATS: La masse moyenne du ventricule gauche (VG) du groupe témoin, 93,9±113,6 g, était significativement plus élevée que celle des sujets atteints d'OS ASD, 39,4±74,3 g (Mann-Whitney U = 4,266, p < 0,001). De même, le diamètre interne moyen du ventricule gauche en diastole (LVIDd) du groupe témoin, 25,8±11,7 mm, était significativement plus élevé que celui des participants atteints d'OS ASD, 19,9±7,1 mm (Mann-Whitney U = 4,522, p < 0,001). Le diamètre moyen du septum interventriculaire en systole (IVSs) du groupe témoin, 7,2±3,5 mm, était plus élevé que celui des participants atteints d'OS ASD, 5,0±1,9 mm, et la différence moyenne était statistiquement significative (Student t = 5,738, p < 0,001). Le diamètre interne moyen du ventricule gauche en systole (LVIDs) du groupe témoin, 16,2±7,6 mm, était significativement plus élevé que celui des participants atteints d'OS ASD, 12,9±5,8 mm (Student t = 3,660, p < 0,001). Il n'y avait pas de corrélation significative entre la taille du défaut septal interauriculaire chez les enfants atteints d'OS ASD et la fonction systolique du ventricule gauche et l'âge : (Coef. Corr. 0,065, p = 0,492) ; FE (Coef. Corr. 0,121, p = 0,202), FS (Coef. Corr. 0,139, p = 0,143). CONCLUSION: Les enfants atteints de CIASOS avaient une masse ventriculaire gauche plus faible que ceux du groupe témoin. Les filles semblent avoir une fonction plus élevée que les garçons. MOTS-CLÉS: Fonction ventriculaire gauche; Communication interauriculaire type ostium secundum (CIASOS); Malformation septale interauriculaire; Enfants; Échocardiographie.

Cardiopulmonary functional capacity in Taiwanese children with atrial septal defects.

BACKGROUND: Most existing studies measure atrial septal defect (ASD) outcomes based on morbidity rates such as atrial arrhythmias and heart failure rather than the functional assessment of physical capacity postprocedure. Few studies have evaluated cardiopulmonary function in ASD children. This study represents the largest sample population in the current research, encompassing a total of 122 Taiwanese children with ASD who had undergone treatment, to evaluate cardiopulmonary functional capacity through the implementation of cardiopulmonary exercise testing (CPET), and to investigate whether variations in treatment may impact their cardiopulmonary function. METHODS: This is a retrospective cohort study with the data collected from January 2010 to December 2021. All patients and controls (age-, sex-, and body mass index-matched) underwent CPET and pulmonary function testing. RESULTS: In total, 122 ASD patients (surgically closed ASDs 27, transcatheter-closed ASDs 48, and follow-up unrepaired ASD 47) and 244 healthy controls were recruited. The ASD group exhibited lower peak metabolic equivalent (MET), peak oxygen consumption (VO 2 , p < 0.001), and peak minute ventilation ( p = 0.028) along with MET and VO 2 at the anaerobic threshold (AT) ( p = 0.012) compared to the control group. No statistically significant differences were observed in the pulmonary function test. Among surgically closed, transcatheter closed and unrepaired ASD subgroups, no significant variances were seen in CPET and pulmonary function tests. CONCLUSION: Taiwanese ASD children exhibited diminished exercise capacity and cardiopulmonary performance compared to their healthy counterparts. Differences among specific ASD treatments in cardiopulmonary tests were non-significant.

A 70-Year-Old Woman With Refractory Hypoxemia.

CASE PRESENTATION: A 70-year-old woman was transferred to our ED from an outside ED for hypoxemia. Three weeks earlier, an inpatient evaluation for syncope revealed a right intraventricular filling defect, multiple pulmonary nodules, pulmonary emboli, and a left breast mass. She underwent breast biopsy, was started on rivaroxaban, and was discharged with outpatient follow-up. She experienced progressively worsening dyspnea, prompting a return to the outside ED, where she was found to be severely hypoxemic and was intubated. Her medical history included diabetes, hypertension, hyperlipidemia, COPD, hypothyroidism, diastolic heart failure, and a 40+ pack-year smoking history.

Clinical Significance of Partial Anomalous Pulmonary Venous Connections (Isolated and Atrial Septal Defect Associated) Determined by Cardiovascular Magnetic Resonance.

BACKGROUND: Partial anomalous venous connections (PAPVC) are associated with left to right shunting and right heart dilatation. Identification of PAPVC has increased with widespread use of cross-sectional imaging modalities. However, management strategies are mostly based on expert opinion given the scarcity of data from large series. We aimed to define types and significance of isolated and atrial septal defect (ASD) associated PAPVC detected by cardiovascular magnetic resonance. METHODS: We retrospectively reviewed our cardiovascular magnetic resonance database from 2002 to 2018 to identify isolated or ASD-associated PAPVC cases. RESULTS: A total of 215 patients (median age 46 years; range, 6-83) with isolated or ASD-associated PAPVC were identified among 102 135 clinical cardiovascular magnetic resonance studies. Of these, 104 were isolated and 111 were associated with an ASD. Anomalous connection of right upper pulmonary vein was the most common single venous anomaly (99/215), but in the isolated PAPVC group there were more anomalous left than right upper pulmonary veins (39 versus 34). The Qp/Qs was significantly higher for isolated anomalous single right upper pulmonary vein than left upper pulmonary vein (1.6 versus 1.4 respectively; P=0.01) as were right ventricular end-diastolic volumes (113.7±30.9 versus 90 [57-157] mL/m2, P=0.004). In the PAPVC with an ASD group, sinus venosus ASDs (82%) were associated with right-sided PAPVCs while both right and left-sided venous anomalies were seen in secundum ASDs (18%). In a substantial number of patients (30 out of 91) with sinus venosus ASDs, PAPVCs were more complex and involved more than a single anomalous right upper pulmonary vein; and in 5 patients with ASD, PAPVC was identified only after the ASD closure. CONCLUSIONS: This large series provides descriptive and hemodynamic features for isolated and ASD-associated PAPVCs. Anomalous isolated right upper pulmonary vein may cause a significant shunt (Qp/Qs >1.5). PAPVC associated with sinus venosus and secundum ASDs might be more complex than a single anomalous pulmonary vein and missed before ASD correction.

Electrical storm after correction of an uncomplicated congenital atrial septal defect in an adult: a case report.

BACKGROUND: There is a paucity of published literature describing electrical storm after the correction of uncomplicated atrial septal defect (ASD) in an adult. CASE PRESENTATION: We present a 49-year-old woman with a congenital ASD combined with mild tricuspid regurgitation who denied any history of arrhythmia or other medical history. She suffered from electrical storm (≥ 3 episodes of ventricular tachycardias or ventricular fibrillations) in the early stage after ASD repair with combined tricuspid valvuloplasty. During electrical storm, her electrolytes were within normal ranges and no ischemic electrocardiographic changes were detected, which suggested that retained air embolism or acute coronary thrombosis were unlikely. Additionally, echocardiographic findings and her central venous pressure (5-8 mmHg during the interval between attacks) failed to support the diagnosis of pericardial tamponade. After a thorough discussion, the surgeons conducted an emergent re-exploration and repeated closure of the ASD with combined DeVega's annuloplasty. Eventually, the patient recovered uneventfully, without reoccurring arrhythmias during follow-up. Although we fail to determine the definite cause, we speculate that the causes probably are iatrogenic injury of the conduction system due to a rare anatomic variation, poor intraoperative protection, latent coronary distortion during tricuspid valvuloplasty, or idiopathic or secondary abnormalities of the conduction system. CONCLUSIONS: For most surgeons, performing re-exploration without a known etiology is a difficult decision to make. This case illustrates that re-exploration could be an option when electrical storm occurs in the early stage postoperatively. Nevertheless, surgeons should assess the benefit-risk ratio when taking this unconventional measure.

Elevated Left and Right Atrial Pressures Long-Term After Atrial Septal Defect Correction: An Invasive Exercise Hemodynamic Study.

Background Despite correction of the atrial septal defect (ASD), patients experience atrial fibrillation frequently and have increased morbidity and mortality. We examined physical capacity, cardiac performance, and invasive hemodynamics in patients with corrected ASD. Methods and Results Thirty-eight corrected patients with isolated secundum ASD and 19 age-matched healthy controls underwent right heart catheterization at rest and during exercise with simultaneous expired gas assessment and echocardiography. Maximum oxygen uptake was comparable between groups (ASD 32.7±7.7 mL O2/kg per minute, controls 35.2±7.5 mL O2/kg per minute, P=0.3), as was cardiac index at both rest and peak exercise. In contrast, pulmonary artery wedge v wave pressures were increased at rest and peak exercise (rest: ASD 14±4 mm Hg, controls 10±5 mm Hg, P=0.01; peak: ASD 25±9 mm Hg, controls 14±9 mm Hg, P=0.0001). The right atrial v wave pressures were increased at rest but not at peak exercise. The transmural filling pressure gradient (TMFP) was higher at peak exercise among patients with ASD (10±6 mm Hg, controls 7±3 mm Hg, P=0.03). One third of patients with ASD demonstrated an abnormal hemodynamic exercise response defined as mean pulmonary artery wedge pressure ≥25 mm Hg and/or mean pulmonary artery pressure ≥35 mm Hg at peak exercise. These patients had significantly elevated peak right and left atrial a wave pressures, right atrial v wave pressures, pulmonary artery wedge v wave pressures, and transmural filling pressure compared with both controls and patients with ASD with a normal exercise response. Conclusions Patients with corrected ASD present with elevated right and in particular left atrial pressures at rest and during exercise despite preserved peak exercise capacity. Abnormal atrial compliance and systolic atrial function could predispose to the increased long-term risk of atrial fibrillation. Registration Information clinicaltrials.gov. Identifier: NCT03565471.

Heart failure and atrial fibrillation in patients with an interatrial shunt.

OBJECTIVE: Congenital interatrial shunt can unload the left atrium (LA) and may lower the risk of new-onset heart failure (HF) or atrial fibrillation (AF). We evaluated the risk of new-onset HF or AF in patients with and without interatrial shunt. METHODS: We enrolled 2660 consecutive patients with acute stroke or transient ischemic attack (TIA) who underwent transesophageal echocardiography at Seoul National University Bundang Hospital from January 1, 2006 to December 31, 2018. The primary outcomes were 10-year new-onset HF, new-onset AF, and new-onset HF or AF composite. RESULTS: Overall, 466 (17.5%) patients with an interatrial shunt had smaller E velocity (0.66 ± 0.21 vs. 0.69 ± 0.22 m/s, P = 0.037) and smaller E/e' (9.1 ± 4.0 vs. 10.0 ± 5.0, P = 0.001) than 2194 (82.5%) patients without an interatrial shunt. The 10-year incidence of AF, HF, and AF or HF composite was lower in patients with an interatrial shunt (10-year AF, 11.2 vs. 17.8%, P < 0.001; 10-year HF, 6.2 vs. 10.4%, P = 0.005; 10-year AF or HF composite, 16.5 vs. 23.4%, P = 0.001). In multivariable analysis, the presence of an interatrial shunt was associated with a 38% (HR 0.62, 95% CI 0.40-0.96), 40% (HR 0.60; 95% CI 0.39-0.93), and 26% (HR 0.74; 95% CI 0.57-0.96) reduced risk for new-onset HF, AF, and new-onset HF or AF composite, respectively. CONCLUSION: In patients with interatrial shunt, the risk of AF and HF was lower. Interatrial shunt may be beneficial, and the closure of an interatrial shunt should be performed only in carefully selected patients. An interatrial shunt can unload the left atrium. In patients with stroke or TIA, the presence of an interatrial shunt was associated with a reduced risk for new-onset HF and AF. AF atrial fibrillation, HF heart failure, HR hazard ratio, LA left atrium.

Transthoracic echocardiography monitoring during atrial septal defect and ventricular septal defect device closures using a three-dimensional printed transducer holder.

Transthoracic echocardiography (TTE) is noninvasive but can only be performed intermittently during fluoroscopy. In a prior study, we created a transducer holder device to allow for hemodynamic monitoring in the intensive care unit. The current study is the first instance of the use of a three-dimensional (3D)-printed TTE transducer holder, which is easily customized and personalized to a previous transducer holder at relatively low cost and short production time, to enable continuous TTE monitoring during device closure of an atrial septal defect (ASD) and ventricular septal defect (VSD). There were 14 ASD patients and 9 VSD patients scheduled to undergo device closure. The study's real-time TTE monitoring was performed by using a 3D-printed transducer holder over the course of the entire implantation procedure. There were 23 patients who successfully underwent septal closures using the 3D-printed holder that enabled real-time images over the entire procedure. The median duration for real-time TTE guidance was 15 minutes for the ASD and 36 minutes for the VSD and the median fluoroscopy time was 11 minutes for the ASD and 30 minutes for the VSD. One migrating VSD occluder and one case of aortic regurgitation after occluder deployment were noted by real-time TTE monitoring during the procedure. Our novel 3D-printed transducer holder can provide transesophageal echocardiography-like real-time imaging during device closure of an ASD and a VSD and may become a new alternative method in ASD and VSD closures. It can also prevent radiation exposure for the intervention team who would otherwise need to perform TTE during live fluoroscopy.

Right Ventricular Flow Dynamics in Dilated Right Ventricles: Energy Loss Estimation Based on Blood Speckle Tracking Echocardiography-A Pilot Study in Children.

Using blood speckle tracking (BST) based on high-frame-rate echocardiography (HFRE), we compared right ventricle (RV) flow dynamics in children with atrial septal defects (ASDs) and repaired tetralogy of Fallot (rTOF). Fifty-seven children with rTOF with severe pulmonary insufficiency (PI) (n = 21), large ASDs (n = 11) and healthy controls (CTL, n = 25) were included. Using a flow phantom, we studied the effects of imaging plane and smoothing parameters on 2-D energy loss (EL). RV diastolic EL was similar in ASD and rTOF, but both were greater than in CTL. Locations of high EL were similar in all groups in systole, occurring in the RV outflow tract and around the tricuspid valve leaflets in early diastole. An additional apical early diastolic area of EL was noted in rTOF, corresponding to colliding tricuspid inflow and PI. The flow phantom revealed that EL varied with imaging plane and smoothing settings but that the EL trend was preserved if kept consistent.

Effect of Renal and Left Ventricular Function on Serial Pulmonary Arterial Pressure Changes after Device Closure of Atrial Septal Defect.

BACKGROUND: The age of candidates for device closure of atrial septal defect (ASD) has been increasing. Thus, concerns exist about dyspnea aggravation or atrial fibrillation development after device closure due to augmentation of left ventricular (LV) and left atrial (LA) preload. This study aimed to examine patterns and determinants of serial pulmonary arterial pressure and left ventricular filling pressure changes after device closure of ASD. METHODS: Among the 86 consecutive patients who underwent percutaneous device closure of ASD, those with end-stage renal disease or those without pre- or postprocedural Doppler data were excluded. The clinical, transesophageal, and transthoracic echocardiographic findings of 78 patients were collected at baseline, one-day postprocedure, and one-year follow-up. RESULTS: The mean age of study patients was 49.8 ± 15.0 years, and the average maximal defect diameter and device size were 20.2 ± 6.0 mm and 23.8 ± 6.4 mm. Four patients (5.6%) underwent new-onset atrial fibrillation, and five patients (6.4%) took diuretics within one-year after closure. Some patients (n = 21; 27%) exhibited paradoxically increased tricuspid regurgitant velocity (TRV) one-day postprocedure; they also were older with lower e', glomerular filtration rate, and LV ejection fraction and a higher LA volume index. However, even in these patients, TRV deceased below baseline levels one-year later. Both E/e' and LA volume index significantly increased immediately after device closure, but all decreased one-year later. Larger defect size and higher TRV were significantly correlated with immediate E/e' elevation. CONCLUSION: In older, renal, diastolic, and systolic dysfunctional patients with larger LA and scheduled for larger device implantation, peri-interventional preload reduction therapy would be beneficial.

The M310T mutation in the GATA4 gene is a novel pathogenic target of the familial atrial septal defect.

BACKGROUND: Although most cases of atrial septal defect (ASD) are sporadic, familial cases have been reported, which may be caused by mutation of transcription factor GATA binding protein 4 (GATA4). Herein we combined whole-exome sequencing and bioinformatics strategies to identify a novel mutation in GATA4 accounting for the etiology in a Chinese family with ASD. METHODS: We identified kindred spanning 3 generations in which 3 of 12 (25.0%) individuals had ASD. Punctilious records for the subjects included complete physical examination, transthoracic echocardiography, electrocardiograph and surgical confirming. Whole-exome capture and high-throughput sequencing were performed on the proband III.1. Sanger sequencing was used to validate the candidate variants, and segregation analyses were performed in the family members. RESULTS: Direct sequencing of GATA4 from the genomic DNA of family members identified a T-to-C transition at nucleotide 929 in exon 5 that predicted a methionine to threonine substitution at codon 310 (M310T) in the nuclear localization signal (NLS) region. Two affected members (II.2 and III.3) and the proband (III.1) who was recognized as a carrier exhibited this mutation, whereas the other unaffected family members or control individuals did not. More importantly, the mutation GATA4 (c.T929C: p.M310T) has not been reported previously in either familial or sporadic cases of congenital heart defects (CHD). CONCLUSIONS: We identified for the first time a novel M310T mutation in the GATA4 gene that is located in the NLS region and leads to family ASD with arrhythmias. However, the mechanism by which this pathogenic mutation contributes to the development of heart defect and tachyarrhythmias remains to be ascertained.

Rare case of right ventricular dilatation associated with anomalous pulmonary venous drainage, sinus venosus atrial septal defect and persistent left superior vena cava.

A 34-year-old woman was seen in the emergency department for shortness of breath and chest pain. During a pandemic, it is easy to 'think horses and not zebras', and with a patient presenting with the classic coronavirus symptoms it would have been easy to jump to that as her diagnosis. After a careful history and examination, it became clear that there was another underlying diagnosis. Chest X-ray, echocardiogram and CT scan revealed marked right ventricular dilatation and pulmonary hypertension, alongside a persistent left superior vena cava (PLSVC). Further investigation with cardiac MRI and coronary angiography at a tertiary centre demonstrated that she not only have a PLSVC but also a partial anomalous pulmonary venous drainage and sinus venosus atrial septal defect. This case highlights the importance of considering all differentials and approaching investigations in a logical manner.