Atrioventricular Septal Defect Research Articles

Anatomic considerations in the management of complete atrioventricular canal.

Patients with complete atrioventricular canal have a variable clinical course prior to repair. Many patients balance their circulations well prior to elective repair. Others manifest clinically significant pulmonary over circulation early in life and require either palliative pulmonary artery banding or complete repair. The objective of this study was to assess anatomic features that impact the clinical course of patients. In total, 222 patients underwent complete atrioventricular canal repair between 2012 and 2022 at a single institution. Twenty-seven (12%) patients underwent either pulmonary artery banding (n = 15) or complete repair (n = 12) at less than 3 months of age (Group 1). The remaining 195 (88%) underwent repair after 3 months of age (Group 2). Patient records and imaging were reviewed. The median post-operative length of stay following complete repair was 25 [7,46] days for those patients in Group 1 and 7 [5,12] days for those in Group 2 (p < 0.0001). There was relative hypoplasia of left-sided structures in Group 1 versus Group 2. Mean z-score for the ascending aorta was -1.2 (±0.8) versus -0.3 (±0.9) (p < 0.0001), the aortic isthmus was -2.1 (±0.8) versus -1.4 (±0.8) (p = 0.005). The pulmonary valve to aortic valve diameter ratio was median 1.47 [1.38,1.71] versus 1.38 [1.17,1.53] (p 0.008). Echocardiographic evaluation of the systemic and pulmonary outflow of patients with complete atrioventricular canal may assist in predicting the clinical course and need for early repair vs pulmonary artery banding.

Modeling of large-scale hoxbb cluster deletions in zebrafish uncovers a role for segmentation pathways in atrioventricular boundary specification.

Hox genes orchestrate the segmental specification of the muscular circulatory system in invertebrates but it has not proven straightforward to decipher segmental parallels in the vertebrate heart. Recently, patients with HOXB gene cluster deletion were found to exhibit abnormalities including atrioventricular canal defects. Using CRISPR, we established a mutant with the orthologous hoxbb cluster deletion in zebrafish. The mutant exhibited heart failure and atrioventricular regurgitation at 5days. Analyzing the four genes in the hoxbb cluster, isolated deletion of hoxb1b-/- recapitulated the cardiac abnormalities, supporting hoxb1b as the causal gene. Both in situ and in vitro data indicated that hoxb1b regulates gata5 to inhibit hand2 expression and ultimately is required to pattern the vertebrate atrioventricular boundary. Together, these data reveal a role for segmental specification in vertebrate cardiac development and highlight the utility of CRISPR techniques for efficiently exploring the function of large structural genomic lesions.

Redo mitral valve replacement in an adult with severe pulmonary hypertension resulting from structural valve deterioration and left ventricular outflow tract obstruction and a history of atrioventricular septal defect repair: a case report

BackgroundPulmonary hypertension (PH)-associated with left heart disease (Nice PH classification group II) improves when the latter is treated; however, the treatment of PH concomitant with group I PH due to congenital heart disease is difficult, and the optimal pharmacotherapy is controversial. Intervention strategies for the left-sided atrioventricular valve in partial atrioventricular septal defect (AVSD) are problematic.Case presentationA 37-year-old woman who had undergone patch closure for a partial AVSD and mitral valve replacement with a rather large bioprosthesis at the juxta-annular position for mitral regurgitation 12 years earlier was referred to our institute because of severe PH. Echocardiography revealed calcification resulting in severe stenosis of the bioprosthesis and protrusion of its stent post into the left ventricular outflow tract; therefore, redo mitral valve replacement at the supra-annular position was performed using a mechanical valve. Combined group I and II PH gradually improved with meticulous postoperative medical management.ConclusionsSevere PH due to stent post protrusion and structural valve deterioration in AVSD was successfully treated with redo mitral valve replacement. The present case was complicated with group I and II PH, for which medical therapy in conjunction with surgical treatment yielded an optimal therapeutic effect.

Early and mid-term results of surgical treatment of atrioventricular septal defect; analysis of risk factors for adverse outcomes: left atrioventricular valve regurgitation

Background Advances in the perioperative management and optimization of the timing of primary repair have gradually improved the early clinical outcome of surgical correction of atrioventricular septal defects (AVSDs). However, the late outcome still remains compromised by the substantial risk of reoperation, of which mainly the development of left ventricular outflow tract obstruction (LVOTO) and left atrioventricular valve (LAVV) dysfunction challenge the long-term survival and morbidity of these children. In particular, LAVV regurgitation (LAVVR) is responsible for a reoperation rate between 5 and 19%, both for complete AVSD (cAVSD) and partial AVSD (PAVSD) children. Results of surgical correction of AVSDs) have improved over the last decades; however, the need for reoperation after primary AVSD repair remains a major concern. We conducted this study to analyze risk factors leading to LAVVR in the early and mid-term follow-up postsurgical repair of AVSD. Patients and methods All patients who underwent biventricular repair for AVSD at our institute, in the time between Jan 2015 and Jan 2021, meeting the inclusion criteria and none of the exclusion criteria were enrolled in the study. Preoperative, operative and postoperative data were collected from the patients’ medical file. Last follow-up Echoes were reviewed. Results Patients who had preoperative and early postoperative more than moderate LAVVR are more likely to develop LAVVR in the late follow-up and also have a more risk to need a reoperation in their midterm follow-up. Conclusions Patients who had preoperative and early postoperative more than mod LAVVR are more likely to develop LAVVR in the late follow-up and also more likely to need reoperation.

Contemporary outcomes for functional single ventricle with total anomalous pulmonary venous connection

ObjectiveIn 2004, we reported improved early survival for patients with functional single ventricle anatomy and total anomalous pulmonary venous connection. This study sought to discover if outcomes have been ameliorated in the contemporary era. MethodsThis was a single-center review of patients with single ventricle anatomy and total anomalous pulmonary venous connection who were admitted from 1984 to 2021. The cohort was divided into similarly sized groups by date of admission: Era 1: 1984 to 1992, Era 2: 1993 to 2007, and Era 3: 2008 to 2021. Survival was compared, and Cox proportional hazards models were used to evaluate the likelihood of mortality. ResultsWe included 190 patients with single ventricle anatomy and total anomalous pulmonary venous connection. Unbalanced atrioventricular canal defect (70%) was the most common primary diagnosis. The most common type of total anomalous pulmonary venous connection was supracardiac (49%). Approximately one-third (32%) of patients had pulmonary venous obstruction. There were no significant differences in patient characteristics across eras. Early survival after initial palliative operation improved between Eras 1 and 2, and then remained stable in Era 3. Overall survival improved from Era 1 to Eras 2 and 3 (P < .001), but not between Era 2 and 3. Survival to 10 years by Eras 1 to 3 was 15%, 51%, and 54%, respectively. The anatomic features associated with worse survival were hypoplastic left heart syndrome diagnosis (hazard ratio, 1.60; 1.04-2.57) and pulmonary venous obstruction (hazard ratio, 1.80; 1.24-2.69). ConclusionsOverall survival for patients with single ventricle anatomy and total anomalous pulmonary venous connection has plateaued since the early 2000s. Even in the most recent era, survival to age 10 years remains less than 60%. Risk factors for mortality include the diagnosis of hypoplastic left heart syndrome and pulmonary venous obstruction. Further studies should focus on identification of the pathophysiological factors underlying the increased mortality.

Lecompte maneuver for compressed left coronary artery after pulmonary artery banding.

A one-month-old baby boy with a complete atrioventricular septal defect underwent pulmonary artery banding. A high take-off of the left coronary artery, overlooked on the echocardiogram, was identified. It was compressed by the right pulmonary artery that was dilated owing to pulmonary artery banding. The patient developed severe heart failure, and a Lecompte maneuver was performed. The procedure helped effectively treat this congenital heart disease with a high take-off coronary artery compressed by the right pulmonary artery.

Results of karyotype analysis and 22q11.2 (DiGeorge Syndrome critical region) deletion investigation in fetal cardiac system anomalies

The results of karyotype analysis and 22q11.2 ( DiGeorge Syndrome critical region) deletion investigation in fetal cardiac system anomalies &#x0D; Objective: We aimed to determine the presence of accompanying chromosomal anomalies and 22q11.2 deletion in patients with cardiac system anomalies.&#x0D; Material and Methods: In our retrospective and cross-sectional study, 99 fetuses born with cardiac anomalies were evaluated in terms of chromosomal anomalies. 36 fetuses were evaluated for 22q11.2 deletion. Fetuses who were diagnosed with prenatal congenital heart defect and underwent invasive prenatal diagnostic tests for fetal karyotyping between 01.01.2010 and 30.06.2017 at a tertiary cancer center were included in the study.&#x0D; Results: Of 99 cases, 48 (48.4%) had only cardiac anomalies and 51 (51.5%) had non-cardiac anomalies. Chromosomal anomalies were found in 37 (37.4%) of the cases. Autosomal trisomy 18(43.2%) and autosomal trisomy 21(32.4%) were the most common chromosomal anomalies. The study results support the strong association of chromosomal changes and cardiac malformation, especially in septal defects, atrioventricular septal defects, and conotruncal malformations. Deletion was detected in one(2.8%) of 36 cases evaluated for 22q11.2 deletion. The fetus with this deletion had isolated tetralogy of fallot and had no extracardiac anomaly.&#x0D; Conclusion: In cases with cardiac anomalies, isolated or accompanied by extracardiac anomalies, investigations should be made in terms of underlying chromosomal diseases in the perinatal evaluation. In addition, the investigation of 22q11.2 deletion in fetuses with conotruncal cardiac anomalies should be included in prenatal genetic examination.&#x0D; Keywords: DiGeorge Syndrome, Fetal Anomalies, karyotype, trisomy, 22q11.2 Deletion Syndrome

Early and Mid-Term Outcomes of Primary Repair After Atrioventricular Canal Defect: A Single-Center Eight-Year Experience.

Surgical repair techniques and management of patients with atrioventricular septal defect (AVSD) have progressed over the last few decades. Early and definitive interventions have become the choice of treatment for these patients. Based on this background, we aimed to review the early and mid-term outcomes of primary AVSD repair. A total of 53 patients with a mean age of 3.45 ± 5.67 years underwent definitive repair for AVSD between January 2014 and June 2021. The clinical data including age, type of defect, associated co-anomalies, symptoms, pulmonary hypertension, etc. were collected and assessed retrospectively. Mitral regurgitation (MR) as a clinical outcome was assessed at 0, 1, 2, and 5 years. Among the recruited patients, 35 (66.1%) were male and 18 (33.9%) were female. Of 53 patients, repair for the complete defect was done in 38 (71.69%) patients, repair for intermediate/partial defect was done in 15 (23.1%) patients, and one patient underwent repair for incomplete type. Other associated co-anomalies were anterior mitral leaflet (12 (22.6%)), atrial and ventricular septal defect (VSD) (30 (56.6%)), and patent ductus arteriosus (PDA) (11 (20.8%)). Different procedures for surgical repair included patch closure, cleft repair, and polytetrafluoroethylene (PTFE) VSDclosure. After repair, the mean follow-up period was 46.73 ± 27.37 months. Overall mortality was 3.78% (2/53), and two patients underwent reintervention due to symptomatic severe MR. A definitive and timely correction of AVSD shows satisfactory early and mid-term results.

Atrioventricular Septal Defect With Tetralogy of Fallot and Exclusive Shunting at the Ventricular Level.

Atrioventricular septal defect (AVSD) with shunting restricted to the ventricular level is a rare form of AVSD. To our knowledge, this shunting pattern has not been reported in AVSD with tetralogy of Fallot. We report a child with this unusual combination who underwent a successful single-stage repair at two years of age.

Clinical profile, prenatal detection and predictors of outcome of heterotaxy syndromes in Western Australia

BackgroundHeterotaxy syndromes encompass left and right atrial isomerism (LAI and RAI respectively) and are associated with variable cardiac and non-cardiac anomalies which greatly influence outcomes. RAI is usually associated with complex congenital heart disease (CHD), early surgical intervention and increased mortality. LAI is less commonly associated with complex CHD but can be associated with heart block. The objective of this study was to review the clinical features and outcomes of patients with heterotaxy syndromes in Western Australia (WA). MethodsA retrospective review was performed of live born patients diagnosed with heterotaxy from 2003 to 2022 in a statewide tertiary cardiac service, representing all cases in WA with a view to compare the outcomes between LAI and RAI at our centre. Results30 patients (53% male) were diagnosed with heterotaxy; 16 (53%) with LAI and 14 (47%) with RAI. Overall incidence was 0.48 per 10,000 live births over the defined period. RAI patients were significantly more likely to have an antenatal diagnosis (81.8% versus LAI 28.6%, p = 0.03). Overall, 5-year survival was 56% for RAI and 87% for LAI. No deaths occurred after the first 12 months of life with a median follow-up of 65 months (IQR 114.8). RAI was associated with asplenia (91%), atrioventricular septal defect (91%) and a functionally univentricular circulation (71%). LAI was associated with polysplenia (100%) and complete heart block in 3 patients (19%). Surgical pathways included repair of anomalous pulmonary venous return (45%), Blalock Taussig shunt (60%), bidirectional cavopulmonary connection (50%) and Fontan completion (30%). ConclusionsPatients with RAI suffer high mortality and early surgical intervention, with few making it to Fontan completion. By comparison patients with LAI have less morbidity and mortality. The management of heterotaxy continues to be challenging due to widely associated cardiac and extracardiac manifestations.

Maternal Blood Group Is a Possible Predictor for Developing Congenital Heart Disease in Turkish Children with Down's Syndrome.

We aimed to evaluate the clinical characteristics and the risk factors for the anomalies of Down's syndrome (DS) patients and reviewed the relation of blood groups of the patients and the mothers with these anomalies. Pediatric patients who were diagnosed with trisomy 21 between 2010 and 2022 were enrolled in this study. The medical records of the DS patients and their parents were retrospectively reviewed. A total of 48 patients applied to our clinic. 24 (50%) patients were diagnosed with congenital heart disease. 21 (43.75%) patients had hypothyroidism. The distribution of individual congenital heart defects (CHDs) was as follows: ventricular septal defect in eight (33.3%) patients, one of which also had patent ductus arteriosus (PDA); atrioventricular septal defects in seven (29.1%) patients; atrial septal defects in four (16.6%) patients, one of which also had patent ducus arteriosus; and PDA in five (20.8%) patients. One (4.2%) patient had tetralogy of Fallot. The incidence of CHD in patients with maternal blood group A was significantly higher than those without CHD, with a prevalence of 63.6 and 21.1%, respectively ( p = 0.020). Binary logistic regression analysis showed that maternal blood group A was a risk factor for CHDs (odds ratio = 6.563; 95% confidence interval: 1.259-34.204; p = 0.025). Although we found that the rate of advanced father age was high in hypothyroidism type, the regression analysis showed that it was not a risk factor. We found that maternal blood group A increased the likelihood of being born with CHDs in DS.

Outcomes of atrioventricular septal defects with and without down syndrome: analysis of the national inpatient database.

Controversial data exist about the impact of Down syndrome on outcomes after surgical repair of atrioventricular septal defect. (A) assess trends and outcomes of atrioventricular septal defect with and without Down syndrome and (B) determine risk factors associated with adverse outcomes after atrioventricular septal defect repair. We queried The National Inpatient Sample using International Classification of Disease codes for patients with atrioventricular septal defect < 1 year of age from 2000 to 2018. Patients' characteristics, co-morbidities, mortality, and healthcare utilisation were evaluated by comparing those with versus without Down syndrome. In total, 2,318,706 patients with CHD were examined; of them, 61,101 (2.6%) had atrioventricular septal defect. The incidence of hospitalisation in infants with atrioventricular septal defect ranged from 4.5 to 7.5% of all infants hospitalised with CHD per year. A total of 33,453 (54.7%) patients were associated with Down syndrome. Double outlet right ventricle, coarctation of the aorta, and tetralogy of Fallot were the most commonly associated with CHD in 6.9, 5.7, and 4.3% of patients, respectively. Overall atrioventricular septal defect mortality was 6.3%. Multivariate analysis revealed that prematurity, low birth weight, pulmonary hypertension, and heart block were associated with mortality. Down syndrome was associated with a higher incidence of pulmonary hypertension (4.3 versus 2.8%, p < 0.001), less arrhythmia (6.6 versus 11.2%, p < 0.001), shorter duration for mechanical ventilation, shorter hospital stay, and less perioperative mortality (2.4 versus 11.1%, p < 0.001). Trends in atrioventricular septal defect hospitalisation had been stable over time. Perioperative mortality in atrioventricular septal defect was associated with prematurity, low birth weight, pulmonary hypertension, heart block, acute kidney injury, and septicaemia. Down syndrome was present in more than half of atrioventricular septal defect patients and was associated with a higher incidence of pulmonary hypertension but less arrhythmia, lower mortality, shorter hospital stay, and less resource utilisation.

Plasma proteoglycan 4: a novel biomarker for acute lung injury after pediatric cardiac surgery.

Identification of biological molecules related to post cardiopulmonary bypass (CPB) lung injury could help diagnose, predict and potentially impact patient's clinical course after cardiac surgery. Proteoglycan 4 (PRG4) initially identified as potential biomarker for patients with prolonged mechanical ventilation following CPB in a prior study. To further validate these findings, we sought to understand the association of lower plasma PRG4 with prolonged mechanical ventilation and worse lung compliance in a larger cohort of pediatric patients post CPB. Retrospective chart review study. Pediatric Cardiac Intensive Care Unit, Tertiary Hospital. Infants <1 year old with tetralogy of Fallot, ventricular septal defect, or atrioventricular septal defect who underwent surgical repair 2012-2020 and had stored plasma samples in our biorepository were screened for inclusion. Patients with mechanical ventilation before surgery were excluded. Patients were divided into quartiles based on postoperative duration of mechanical ventilation (control <25th percentile, study >75th percentile). Preoperative and 48-hour postoperative samples for each cohort (20 patients each) were tested for PRG4 level using enzyme-linked immunosorbent assay (ELISA) technique. Study group had lower lung compliance, higher mean airway pressure and higher oxygen need postoperative when compared to control group. Plasma PRG4 levels before surgery and 48 hours postoperative were lower in study group compared to control group (P=0.0232 preoperative; P=0.0016 postoperative). Plasma PRG4 levels were compared preoperative to PRG4 levels postoperative in both group, there was no statistically significant difference (study group: P=0.0869; control group: P=0.6500). Lower levels of plasma PRG4 is associated with longer duration of mechanical ventilation, worse ventilator compliance and higher oxygen requirement after cardiac surgery in our patient population. Further validation of this finding in a larger and more diverse patient population is necessary prior to its application at the bedside.

Atrioventricular Septal Defects Repair: Comparison of Classic Single Patch and Double-Patch Techniques

Objective: Different patch techniques were virtually always used in the surgery of pediatric patients with complete atrioventricular septal defects. In this study, we described our single center, single surgeon experiences and results about the classic single patch and double patch techniques to repair complete atrioventricular septal defects. Materials and Methods: This retrospective descriptive study included 30 patients who underwent intracardiac repair of complete atrioventricular septal defect in Ankara Bilkent City Hospital Department of Pediatric Cardiovascular Surgery. The study was conducted between February 2019 to December 2021. Patients in group S underwent surgery using the traditional single-patch method, while group D included patients who underwent repair using the double patch approach (n = 10). Patients’ demographic and clinical information was taken from institutional databases and medical records. Postoperative complications were recorded. Results: When the preoperative/postoperative insufficiency levels of the valves were compared with the Wilcoxon Signed rank test, the findings were not statistically significant for the left atrioventricular valves, but were statistically significant for the right atrioventricular valves. (p=0.02) When we compared postoperative valve regurgitation of both techniques with the Kruskall-Wallis test, no significant difference was found between postoperative valve regurgitation and function, independent of preoperative findings. Conclusion: Both operation techniques did not make a difference between operative or late mortality and morbidity. Depending on the surgeon’s experience, ventricular septal defect size does not play a restrictive role in the selection of the technique to be used. The single-patch and double patch method as described here is methodical, comprehensible, repeatable, and reasonably long-lasting.

Detection of severe congenital heart defects in live-born infants in Norway 2017-2020.

The aims of this nationwide retrospective cohort study were to determine the time and causes of detection of severe congenital heart defects (CHDs) in live-born infants in Norway between 2017 and 2020. Information regarding live-born infants with severe CHDs was retrieved from national registries and medical records. A total of 219 776 infants were born in Norway from 01.01.2017 to 31.12.2020. Severe CHDs were diagnosed in 442 (0.2%) infants. Of these, 376 (85%) infants were diagnosed either prenatally (n = 203, 46%) or before discharge from hospital after birth (n = 173, 39%). A total of 56 (13%) infants were discharged with undetected CHDs. Time of detection was unknown in 10 cases (2%). The most frequent undetected CHDs at discharge were coarctation of the aorta/aortic arch hypoplasia (n = 24), atrioventricular septal defect (n = 13), anomalous pulmonary venous connection (n = 5) and coronary artery anomalies (n = 4). Seven (13%) children with undetected CHD experienced circulatory collapse out of hospital. Most infants with severe CHDs in Norway were identified prior to hospital discharge. However, some infants were discharged undiagnosed. Awareness of undetected CHDs and immediate cardiac assessment in infants with signs of circulatory failure early in life are still important.

Effective and aesthetic results of horizontal right axillary minithoracotomy for congenital heart defects repair in children

Background: horizontal right axillary minithoracotomy is one of the treatment options for many simple congenital heart defects. This approach shows many aesthetic advantages besides effectiveness and safety. This study aims to: comment on the technical characteristics and early results of horizontal right axillary minithoracotomy in children at Hanoi Heart Hospital.&#x0D; Methods: a descriptive cross-sectional study. We retrospectively reviewed 156 patients who underwent horizontal right axillary minithoracotomy at Hanoi Heart Hospital from January 2022 to December 2022.&#x0D; Results: horizontal axillary approach could be applied even for children with low weight, average weight was 12.22 ± 8.67 kg, the lowest was 2.6 kg and the highest was 51.0 kg. A wide range of congenital heart defects were repaired, including ventricular septal defect closure (84 patients), secundum atrial septal defect closure (22 patients), ventricular septal defect with stenosis repair (31 patients), partial atrio-ventricular septal canal repair (6 patients), repair of atrial septal defect with partial abnormal return of the pulmonary veins (3 patients), repair of ventricular septal defect and atrial septal defect (4 patients), Cor triatriatum sinister repair (4 patients), mitral valve repair (1 patient), atrial septal defect and pulmonary valve stenosis repair (1 patient). Cannulation of the aorta and vena cavae was performed through the main incision, whose size ranged from 3.5 to 5.5cm. The average postoperative hospital stay was 7.34 ± 2.16 days, the rate of severe complications and hospital mortality were 0%.&#x0D; Conclusion: horizontal right axillary minithoracotomy was a good approach to correct many simple congenital heart defects in children. This technique is being applied at Hanoi Heart Hospital safely and provided outstanding advantages in terms of aesthetics.

Long-term results following atrioventricular septal defect repair

BackgroundAtrioventricular 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.MethodsA 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.ResultsMedian 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.ConclusionAVSD repair with the double-patch technique is a safe and effective procedure with good early postoperative outcomes and low long-term reoperation rates.

Associated congenital heart disease with Hirschsprung's disease: a retrospective cohort study on 2,174 children.

To examine the incidence and phenotypes of congenital heart disease (CHD) in a large cohort of patients with Hirschsprung's disease (HSCR). Retrospective data review of children with HSCR between 2003 and 2020 was conducted at the Provincial Key Laboratory for Structural Birth Defects in Guangzhou, Guangdong, China. HSCR was confirmed by pathological diagnosis. CHD was defined as a gross structural abnormality of the heart or intrathoracic great vessels that is of functional significance. A total of 2,174 HSCR patients (84.7% males) were studied and 306 of them underwent echocardiography. Overall, 27 children (1.2%) had associated CHD. Among them, CHDs mostly presented as atrial and ventricular septal defects (n = 5 and 12 respectively) and patent ductus arteriosus (n = 4). Three patients (1.4‰) presented as a severe CHD including complete atrioventricular canal, congenitally corrected transposition of the great arteries and double-outlet of right ventricle. Among 14 patients carrying a chromosomal abnormality, CHD was detected in 4 infants (28.6%), all being mild forms of septal defects. Some new and severe types of CHD were found in patients with HSCR. Patients with syndromic features had higher incidence of CHD.

Abstract P1169: BubR1 Regulates Cardiac Development Through CamkII In Vivo

Congenital heart defects (CHD), which represent the most common type of congenital defects, are found in 8 out of 1000 births each year in the US. Aneuploidy, defined as an abnormal number of chromosomes in a cell, is the largest contributor to CHD. Defects in mitotic regulators can promote aneuploidy. For instance, mutations in the mitotic checkpoint protein BubR1 can lead to mosaic variegated aneuploidy (MVA). MVA patients display varied phenotypes including growth deficiency and a shortened lifespan. In addition, some patients develop CHDs such as atrioventricular septal defects. To determine whether BubR1 regulates cardiac development we carried out timed matings to harvest heart tissue at various embryonic stages. We found that BubR1 expression dramatically increases in the mouse heart through embryonic development. We engineered a conditional BubR1 knockout mouse model using the Cre-lox system which allows for the generation of cardiac-specific BubR1 knockout animals when crossing this BubR1 fl/fl mice to Nkx2.5-cre mice, which mediates deletion of BubR1 beginning at E7.5. Interestingly, we did not observe any homozygous cardiac-specific BubR1 knockout mice in newborn litters, suggesting that loss of BubR1 in the developing heart is embryonic lethal (n = 120, P &lt; 0.01). We observed that deletion of BubR1 in the embryonic heart leads to cardiac malformations including the absence of trabeculations and reduction in the size of ventricles. Immunofluorescence studies reveal that cardiac-specific BubR1 knockout embryos have an increase in cell death as measured by the apoptosis marker cleaved-caspase 3. These embryos also show an increase in the apoptosis regulator CaMKII, whose upregulation has been previously tied to an increase in cardiomyocyte apoptosis. Therefore, we conclude that BubR1 suppresses the expression of CaMKII in the developing heart to regulate apoptosis during cardiogenesis. Taken together, our data suggest that BubR1 is a critical regulator for cardiac development in vivo , and its mutation or loss may contribute to the development of CHDs.

Fetal Atrial Flutter: Early Detection and Treatment

Fetal atrial flutter (AF) can occur with structurally normal hearts or congenital heart disease, including atrioventricular septal defect, hypoplastic left heart syndrome, pulmonary atresia, and Ebstein's malformation. 1 It is important to detect fetal AF early and treat it appropriately. We present a case of fetal AF that was treated timely, resulting in no associated complications. The infant was born by cesarean section at a gestational age of 37 weeks with an Apgar score of 9 and 9. The birth weight was 2860 grams. The antenatal history was positive for fetal tachycardia.