Clinical Presentation and Therapy of Atrioventricular Septal Defect.

Atrioventricular septal defects (AVSDs) consist of a number of cardiac malformations that result from abnormal development of the endocardial cushions. AVSDs occur in 0.19 of 1000 live births and constitute 4-5 % of congenital heart defects. AVSDs can be categorized as incomplete (or partial) or complete, and intermediate or transitional.

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.

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.

Inflow Tract Development.

The development of the inflow tract is undoubtedly one of the most complex remodeling events in the formation of the four-chambered heart. It involves the creation of two separate atrial chambers, the formation of an atrial/atrioventricular (AV) septal complex, the incorporation of the caval veins and coronary sinus into the right atrium, and the remodeling events that result in pulmonary venous return draining into the left atrium. In these processes, the atrioventricular mesenchymal complex, consisting of the major atrioventricular (AV) cushions, the mesenchymal cap on the primary atrial septum (pAS), and the dorsal mesenchymal protrusion (DMP), plays a crucial role.

Cardiac Transcription Factors and Regulatory Networks.

Cardiac development is a fine-tuned process governed by complex transcriptional networks, in which transcription factors (TFs) interact with other regulatory layers. In this chapter, we introduce the core cardiac TFs including Gata, Hand, Nkx2, Mef2, Srf, and Tbx. These factors regulate each other's expression and can also act in a combinatorial manner on their downstream targets. Their disruption leads to various cardiac phenotypes in mice, and mutations in humans have been associated with congenital heart defects. In the second part of the chapter, we discuss different levels of regulation including cis-regulatory elements, chromatin structure, and microRNAs, which can interact with transcription factors, modulate their function, or are downstream targets. Finally, examples of disturbances of the cardiac regulatory network leading to congenital heart diseases in human are provided.

Revisiting Atrioventricular Septal Defects: Exploring Chromosomal Abnormalities, Cardiac and Extracardiac Anomalies in a Contemporary Prenatal Cohort.

To estimate if there is an association between partial AVSD with chromosomal abnormalities, cardiac and extracardiac malformations, and to report the outcomes of prenatally diagnosed AVSD in a large, contemporary cohort. This is a retrospective cohort study of 190 prenatally diagnosed fetal AVSD between 2014 and 2023. Type of AVSD (complete vs partial), additional cardiac findings, extracardiac findings, presence of a heterotaxy, results of prenatal karyotype, and pregnancy outcomes were documented and analyzed. A total of 190 cases of fetal AVSD were analyzed. Complete AVSDs comprised 141 (74.2%) of the cohort, while partial AVSDs comprised 49 (25.7%). Karyotype was completed in 131 cases, and in 98 (74.8%) cases chromosomal abnormalities were identified, with trisomy 21 being the most common (53/131, 40.5%). Complete AVSDs were associated with trisomy 21 (45.5%, p = 0.04), Isolated cases of complete AVSDs (p = 0.03). Partial AVSDs were associated with trisomy 18 (53.1%, p < 0.001). In cases of partial AVSDs with aneuploidies, 7 (70%) had an ostium primum defect and 20 (90.9%) of AV canal type VSD. Isolated partial AVSD had no clear association with aneuploidies. There were additional cardiac anomalies in 96 (50.5%) and extracardiac anomalies in 134 (70.5%) of the cohort. There were no differences between partial and complete AVSD in rate of additional cardiac and extracardiac anomalies. AVSD was part of a heterotaxy in 47 (24.7%) of cases, and heterotaxy was associated with complete AVSD in the majority of cases (43/47, 91.4%, p = 0.003). Fetal partial AVSDs are associated with trisomy 18. Fetal complete AVSDs, even isolated, are associated with trisomy 21. There were no differences in association of other aneuploidies, additional cardiac findings, or extracardiac anomalies between prenatally diagnosed complete AVSDs and partial AVSDs.

The evolving treatment of congenital heart disease in patient with Down syndrome: Current state of knowledge.

OBJECTIVES: Children with Down syndrome are usually seen as not worthy of high-risk cardiac surgery. Through this review, we try to show the results of curative and palliative surgery for functional single ventricle syndrome in patients with Down syndrome, as there is currently no standard protocol for the treatment of this category of patients. METHODS: An exhaustive search of all related published medical literature included the following domains: Down syndrome and diagnosis, Down syndrome and taxonomy, Down syndrome, and natural history, Down syndrome and cardiovascular abnormalities, Down syndrome and pulmonary hypertension, Down syndrome and institutionalization, Down syndrome and surgical repair, Down syndrome, and single ventricle palliation, Down syndrome and Glenn, Down syndrome, and Fontan. RESULTS: 12 articles were included from 775 identified. Low-risk cardiac surgery procedure should be provided for Down syndrome with a balanced ventricular septal defect. There is no universal agreement about the surgical approach for Down syndrome with unbalanced ventricular septal defects, but it can be performed at relatively low risk. CONCLUSIONS: TCPC in Down syndrome patients could be a relatively low-risk procedure if patients are prepared well and their pulmonary vascular resistance is low. Randomized prospective studies are required to show the long-term impact of TCPC palliation and develop a better understanding of standardized care of these patients.

CE-BART: Cause-and-Effect BART for Visual Commonsense Generation.

"A Picture is worth a thousand words". Given an image, humans are able to deduce various cause-and-effect captions of past, current, and future events beyond the image. The task of visual commonsense generation has the aim of generating three cause-and-effect captions for a given image: (1) what needed to happen before, (2) what is the current intent, and (3) what will happen after. However, this task is challenging for machines, owing to two limitations: existing approaches (1) directly utilize conventional vision-language transformers to learn relationships between input modalities and (2) ignore relations among target cause-and-effect captions, but consider each caption independently. Herein, we propose Cause-and-Effect BART (CE-BART), which is based on (1) a structured graph reasoner that captures intra- and inter-modality relationships among visual and textual representations and (2) a cause-and-effect generator that generates cause-and-effect captions by considering the causal relations among inferences. We demonstrate the validity of CE-BART on the VisualCOMET and AVSD benchmarks. CE-BART achieved SOTA performance on both benchmarks, while an extensive ablation study and qualitative analysis demonstrated the performance gain and improved interpretability.

Major Septal Defects: Comparative Study of Down Syndrome and Non-Down Syndrome Infants, Before and After Surgery.

OBJECTIVE: To compare pre-operative, intra-operative, and post-operative parameters in Down syndrome (DS) and non-DS patients with atrioventricular septal defects (AVSD) and inlet ventricular septal defects (VSD) in a tertiary care hospital in Pakistan. METHODS: We conducted a retrospective study at Aga Khan University, Pakistan. All complete atrioventricular septal defect (CAVSD), partial atrioventricular septal defect (PAVSD), and VSD with inlet extension surgical cases from January 2007 to January 2019 were included. Patients with congenital heart diseases other than those listed above were excluded. RESULTS: In 61 cases, 18 had DS. Median age, mean body surface area (BSA), and height were lower in DS patients compared to non-DS patients: 7.0 vs 23.0 months, 0.311 vs 0.487 m2, and 63 vs 82 cm, respectively. Bypass duration, aortic cross clamp time, post-operative ventilator hours, dose of inotropes, CICU stay, and total hospital stay were all significantly higher in the DS group. The odds ratio (955% CI) for mortality in DS babies was 6.2 (1.4, 27.1), p=0.015, after adjusting for age, weight, and height. The overall morbidity was comparable between the two groups, demonstrating no significant difference after adjusting for confounders. CONCLUSION: DS babies with AVSD and inlet VSD are at a greater risk of mortality compared to non-DS babies, particularly those with CAVSD. Furthermore, DS babies undergo surgery at a younger age and require more aggressive post-operative therapy and monitoring due to the development of complications.

Reoperation for left atrioventricular valve failure in repaired atrioventricular septal defect: Can more valves be preserved in the current era?

OBJECTIVE: Left atrio-ventricular valve (LAVV) regurgitation after repair of an atrio-ventricular septal defect (AVSD) may necessitate further surgery. However, redo-LAVV repair remains challenging. We sought to determine if more LAVV valves are preserved in the current era, and analyze early and longer-term results. PATIENTS: All consecutive patients with repaired AVSD who underwent redo-LAVV surgery from January 2004 to April 2017 were included. Patients with single ventricles, atrial isomerism, and complex associated anomalies were excluded. METHODS: This was a single-center study using retrospective chart review and an institutional database for follow-up information. Data analyzed included number and year of primary AVSD and redo-LAVV operation, presence of trisomy 21, morphology of AVSD, mortality, and reoperation. Univariate analysis included repair and replacement rates and early and long-term survival. RESULTS: During the study period 36 redo-LAVV operations were performed, with repair in 28 and replacement in eight. The number of redo-operations increased from 13 in the first part to 23 in the second part of the study. The rate of LAVV preservation significantly increased over time (54% vs 91%, P < 0.01), and was not affected by morphology of AVSD or trisomy 21. There was one in-hospital death at Day 42 and overall estimated survival was 94.5% at 5 years. Freedom from reoperation after redo-LAVV repair was 87% at 5 years with no significant difference between repair and replacement groups. CONCLUSION: In the current era, more LAVVs can be preserved at the time of redo-operation with excellent early and long-term survival and acceptable reoperation rates. LAVV morphology and presence of trisomy 21 did not affect outcome.

Role of HDLive in Imaging the Fetal Heart.

HDLive is a rendering methodology that generates realistic images of the human fetus from sonographic data. The objective of this study is to demonstrate the utility of high-definition live in evaluating fetal heart especially in the first trimester (11-14-week) scan. The normal atrioventricular valve and its abnormalities along with septal defects can be vividly demonstrated with this technique, and eight cases with cardiac defects are illustrated. Its use in the first-trimester evaluation of heart would give a better perspective of the cardiac malformation, which provides the opportunity for counseling options early in pregnancy.

Surgical repair of partial atrioventricular septal defect.

OBJECTIVE: To review the results of surgical correction of partial atrioventricular septal defect and associated cardiac comorbidities. METHODS: Retrospective case analysis of electronic database of department of paediatrics cardiac surgery, CPEIC, Multan was done. Forty consecutive patients operated for partial atrioventricular septal defect repair from September 2011 to October 2016 were included. Mean age was 14.67±7.96 years. 60% (24) patients were male. Regarding echocardiographic findings, pre-operatively 40% (n=16) had mild, 47.5% (19) had moderate and 12.5% (n=5) had severe mitral valve regurgitation. There were 25% (n=10) patients having moderate tricuspid valve regurgitation. Pulmonary hypertension was moderate in 57.5% (n=23) cases and severe in 7.5% (n=3) cases. Among other associated lesions 10% (n=4) patients had secundum ASD, pulmonary artery stenosis was seen in 5% (n=2) patients. Another 5.0% (n=2) patients had bilateral SVCS. While one patient had PDA and one patient had associated common atrium. RESULTS: Post-operatively there were 19 cases (47.5%) having no mitral valve regurgitation while 18 (45%) patients showed mild and 7.5% (n=3) had moderate mitral valve regurgitation. Only one case had moderate tricuspid valve regurgitation post-operatively, while 22.5% (n=9) cases had mild tricuspid regurgitation. Complete heart block and left sided brain infarct developed in one case. There was no mortality, reoperation, residual atrial shunt or left ventricular outflow tract obstruction. CONCLUSION: Repair of partial AV canal carries good overall results with minimal mortality however earlier repair is suggested to reduce post- operative morbidity further.

Risk factors for the recurrence of left atrioventricular valvular regurgitation after surgical repair of partial and transitional atrioventricular septal defect.

Background: Left atrioventricular valvular regurgitation (LAVVR) recurrence after partial and transitional atrioventricular septal defect (AVSD) repair is the main risk factor associated with reoperation or mortality. The purpose of this study was to identify risk factors associated with the recurrence of LAVVR after surgical repair of transitional and partial AVSD at a single institution. Methods: A hundred and fifty-seven patients who underwent anatomical repair for partial and transitional AVSD from January 2013 to December 2021 were included in our institutional database. Demographic characteristics, operative information, comorbidities, complications, and outcomes were retrieved from electronic medical records. Echocardiographic evaluations included cardiac dimensions, the degree of LAVVR, and the anatomy of the atrioventricular valve. Results: After a median follow-up period of 5.8 years, 40 patients had recurrent moderate or even more severe LAVVR. Compared with patients without recurrent LAVVR, those experiencing LAVVR recurrence were more likely to have larger preoperative left atrial (LA) size and larger left ventricular (LV) size after standardization, larger left atrioventricular valve (LAVV) cleft width, higher proportions of preoperative moderate or even more severe LAVVR, and immediately postoperative mild to moderate or even more severe LAVVR. Univariate Cox regression analysis showed that age at first repair, height, LA size after standardization, LV size after standardization, the severity of preoperative LAVVR, immediately postoperative LAVVR, and the LAVV cleft width more than 1cm were risk factors for recurrent LAVVR (P<0.05 for all). Multivariable Cox regression analysis showed that mild to moderate or even more severe LAVVR postoperatively [hazard ratio (HR) 9.53, 95% confidence interval (CI): 3.78-24.01; P<0.001], the width of LAVV cleft more than 1 cm (HR: 3.90, 95% CI: 1.80-8.48; P<0.001) and age at first repair (HR: 0.45, 95% CI: 0.31-0.66; P<0.001) were independently associated with the recurrence of LAVVR. Conclusions: The width of LAVV cleft, mild to moderate or even more severe LAVVR immediately after surgery, and age at initial surgery are risk factors for recurrent LAVVR. The presence of recurrent LAVVR necessitates proactive surveillance to facilitate timely reintervention.

Application of neural networks in prenatal diagnosis of atrioventricular septal defect.

Background: There is no relevant study on landmarks detection, one of the Convolutional Neural Network algorithms, in the field of fetal echocardiography (FE). This study aimed to explore whether automatic landmarks detection could be used in FE correctly and whether the atrial length (AL) to ventricular length (VL) ratio (AVLR) could be used to diagnose atrioventricular septal defect (AVSD) prenatally. Methods: This was an observational study. Two hundred and seventy-eight four-chamber views in end diastole, divided into the normal, AVSD, and differential diagnosis groups, were retrospectively included in this study. Seven landmarks were labeled sequentially by the experts on these images, and all images were divided into the training and test sets for normal, AVSD, and differential diagnosis groups. U-net, MA-net, and Link-net were used as landmark prediction neural networks. The accuracy of the landmark detection, AL, and VL measurements, as well as the prenatal diagnostic effectiveness of AVLR for AVSD, was compared with the expert labeled. Results: U-net, MA-net, and Link-net could detect the landmarks precisely (within the localization error of 0.09 and 0.13 on X and Y axis) and measure AL and VL accurately (the measured pixel distance error of AL and VL were 0.12 and 0.01 separately). AVLR in AVSD was greater than in other groups (P<0.0001), but the statistical difference was not obvious in the complete, partial, and transitional subgroups (P>0.05). The diagnostic effectiveness of AVLR calculated by three models, area under receiver operating characteristic curve could reach 0.992 (0.968-1.000), was consistent with the expert labeled. Conclusions: U-net, Link-net, and MA-net could detect landmarks and make the measurements accurately. AVLR calculated by three neural networks could be used to make the prenatal diagnosis of AVSD.

Role of ECG in the Accidental Finding of an Atrioventricular Septal Defect in an Asymptomatic Patient Undergoing Cosmetic Surgery.

Electrocardiogram (ECG) is an important diagnostic tool in identifying congenital heart disease (CHD), as demonstrated by this case of a 48-year-old female who presented for a preoperative evaluation for cosmetic surgery. ECG showed a right bundle branch block (RBBB) and first-degree atrioventricular (AV) block, and further testing revealed a primum atrial septal defect (ASD) with mitral valve anterior leaflet cleft and a membranous ventricular septal defect (VSD). She underwent successful surgical repair and was discharged home without complications. This case highlights the importance of performing additional tests like echocardiography or other imaging modalities in cases of abnormal ECG findings to accurately diagnose the underlying heart condition and ensure proper treatment.

Long-term results following atrioventricular septal defect repair.

BACKGROUND: Atrioventricular septal defects (AVSD) represent 4-7% of congenital cardiac malformations. Definitive early repair is favored over prior pulmonary artery banding and delayed definitive repair in many centers. The aim of this study was to analyze long-term outcomes following AVSD repair over a 21-year period. METHODS: A total of 202 consecutive patients underwent surgical AVSD correction between June 1999 and December 2020. Surgery was performed using the double-patch technique. The study data were prospectively collected and retrospectively analyzed. Primary outcomes were In-hospital mortality and overall long-term freedom from reoperation. RESULTS: Median age at operation was 120 days (IQR 94-150), median weight was 5.0 kg (4.2-5.3). None of the patients died within the first 30 postoperative days. In-hospital mortality was 0.5% (1/202 patients). Median follow-up was 57 months (11-121). Overall freedom from reoperation at 5, 10 and 15 years was 91.8%, 86.9% and 86.9%, respectively. CONCLUSION: AVSD repair with the double-patch technique is a safe and effective procedure with good early postoperative outcomes and low long-term reoperation rates.

Middle to long-term outcomes of surgical repair for atrioventricular septal defect: a single-center study.

Background: The exact incidence and predictors of mortality and left atrioventricular valve (LAVV) re-operation in congenital atrioventricular septal defect (AVSD) repair are still unclear. This study analyzed the middle to long-term outcomes of surgical repair for AVSD. Methods: A total of 150 patients (69 males and 81 females) who underwent AVSD repair at Children's Hospital of Fudan University from January 2013 to December 2021 were divided into complete defect group (C-group, 67 cases), transitional defect group (T-group, 26 cases), and partial defect group (P-group, 57 cases). Outcomes during the peri-operative and 10-year follow-up periods were evaluated. Results: The total mortality was 5.33% (8/150), including seven early deaths (10.4%) and no late deaths in the C-group, no early deaths (0%) and one late death (1.8%) in the P-group, and no early or late deaths in the T-group. Up to the last follow-up, severe LAVV regurgitation had occurred in 27 patients, including 16 in the C-group, four in the T-group, and seven in the P-group. In total, 12 (12/150, 8.0%) patients received LAVV re-operation, including seven in the C-group, three in the T-group, and two in the P-group. Cox regression analysis showed that pre-operative severe pulmonary hypertension (P=0.006) and severe LAVV regurgitation within 24 hours after the first surgery (P=0.023) were independent risk factors for mortality. ≥ Moderate LAVV regurgitation within the first 24 hours after surgery (P=0.014) was an independent risk factor for LAVV re-operation. Conclusions: Complete AVSD repair increased the risk of early death, severe LAVV regurgitation and re-operation. Pre-operative severe pulmonary hypertension and residual severe LAVV regurgitation indicated high risk for mortality. ≥ Moderate LAVV regurgitation within 24 hours after the first surgery predicted a high probability of LAVV re-operation.

Technique for Neo-Pulmonary Valve Creation With Living Tissue for Repair of Atrioventricular Septal Defect and Tetralogy of Fallot.

Long-standing effects of pulmonary regurgitation after transannular patch repair in Tetralogy of Fallot (ToF) can be especially deleterious in the setting of combined ToF and complete atrioventricular septal defect (CAVSD). We present a technique for a complete repair of combined ToF/CAVSD using right atrial appendage tissue to create a competent neo-pulmonary valve. This technique provides advantages of right heart protection via pulmonary valve competence and the use of living tissue capable of growth with the patient, potentially obviating the need for repeat interventions.

Myocardial TGFß2 Is Required for Atrioventricular Cushion Remodeling and Myocardial Development.

Among the three transforming growth factor beta (TGFß) ligands, TGFß2 is essential for heart development and is produced by multiple cell types, including myocardium. Heterozygous mutations in TGFB2 in patients of connective tissue disorders result in congenital heart defects and adult valve malformations, including mitral valve prolapse (MVP) with or without regurgitation. Tgfb2 germline knockout fetuses exhibit multiple cardiac defects but the role of myocardial-TGFß2 in heart development is yet to be elucidated. Here, myocardial Tgfb2 conditional knockout (CKO) embryos were generated by crossing Tgfb2flox mice with Tgfb2+/-; cTntCre mice. Tgfb2flox/- embryos were normal, viable. Cell fate mapping was done using dual-fluorescent mT/mG+/- mice. Cre-mediated Tgfb2 deletion was assessed by genomic PCR. RNAscope in situ hybridization was used to detect the loss of myocardial Tgfb2 expression. Histological, morphometric, immunohistochemical, and in situ hybridization analyses of CKOs and littermate controls at different stages of heart development (E12.5-E18.5) were used to determine the role of myocardium-derived TGFß2 in atrioventricular (AV) cushion remodeling and myocardial development. CKOs exhibit a thin ventricular myocardium, AV cushion remodeling defects and developed incomplete AV septation defects. The loss of myocardial Tgfb2 resulted in impaired cushion maturation and dysregulated cell death. Phosphorylated SMAD2, a surrogate for TGFß signaling, was "paradoxically" increased in both AV cushion mesenchyme and ventricular myocardium in the CKOs. Our results indicate that TGFß2 produced by cardiomyocytes acting as cells autonomously on myocardium and via paracrine signaling on AV cushions are required for heart development.