Molecular Pathways and Animal Models of Truncus Arteriosus.

In normal cardiovascular development in birds and mammals, the outflow tract of the heart is divided into two distinct channels to separate the oxygenated systemic blood flow from the deoxygenated pulmonary circulation. When the process of outflow tract septation fails, a single common outflow vessel persists resulting in a serious clinical condition known as persistent truncus arteriosus or common arterial trunk. In this chapter, we will review molecular pathways and the cells that are known to play a role in the formation and development of the outflow tract and how genetic manipulation of these pathways in animal models can result in common arterial trunk.

Cardiac Development and Animal Models of Congenital Heart Defects.

The major events of cardiac development, including early heart formation, chamber morphogenesis and septation, and conduction system and coronary artery development, are briefly reviewed together with a short introduction to the animal species commonly used to study heart development and model congenital heart defects (CHDs).

Fetal Echocardiographic Variables Associated with Pre-Surgical Mortality in Truncus Arteriosus: A Pilot Study.

Truncus arteriosus (TA) is a rare congenital heart defect that can be prenatally detected by fetal echocardiography. However, prognostication and prenatal counseling focus primarily on surgical outcomes due to limited fetal and neonatal pre-surgical mortality data. We aimed to describe the incidence and identify predictors of pre-surgical mortality in prenatally detected TA. This two-center, retrospective cohort study included fetuses diagnosed with TA between 01/2010 and 04/2020. The primary outcome was pre-surgical mortality, defined by fetal or neonatal pre-surgical death or primary listing for transplantation prior to discharge. Univariable regression modeling, Chi-square tests, and t tests assessed for associations between prenatal clinical, demographic, and fetal echocardiographic (fetal-echo) variables and pre-surgical mortality. Of 23 pregnancies with prenatal diagnosis of TA, 4 (17%) were terminated. Of the remaining 19, pre-surgical mortality occurred in 4 (26%), including 2 (11%) fetal deaths and 2 (11%) neonatal pre-surgical deaths. No transplantation listings. Of liveborn fetuses (n = 17), 15 (88%) underwent a neonatal surgery, and 1 (6%) required ECMO. As compared to the survivors, the pre-surgical mortality group had a higher likelihood of having left ventricular dysfunction (0% vs. 40%; p = 0.01), right ventricular dysfunction (0% vs. 60%; p = 0.002), cardiovascular profile score < 7 (0% vs. 40%; p = 0.01), skin edema (0% vs. 40%; p = 0.01), and abnormal umbilical venous (UV) Doppler (0% vs. 60%; p = 0.002). The presence of truncal valve regurgitation or stenosis neared significance. In this cohort with prenatally diagnosed TA, there is significant pre-surgical mortality, including fetal death and neonatal pre-surgical death. Termination rate is also high. Fetal-echo variables associated with pre-surgical mortality in this cohort include ventricular dysfunction, low CVP, skin edema, and abnormal UV Doppler. Knowledge about prenatal risk factors for pre-surgical mortality may guide parental counseling and postnatal planning in prenatally diagnosed TA.

Common arterial trunk in functionally univentricular hearts: a case series.

INTRODUCTION: The association of a univentricular heart defect with common arterial trunk is extremely rare. There is a lack of population-based outcome studies reported in the literature. METHODS: The hospital records, echocardiographic and other imaging modality data, outpatients' records, operation notes, and other electronic data were reviewed. Patients were reviewed, and the final outcomes of surgery were observed. RESULTS: Six cases (two males) with common arterial trunk presented over a 30-year period. Five had a complete unbalanced atrioventricular septal defect (83%) and one (17%) had tricuspid atresia associated with common arterial trunk. All had antenatal diagnosis. Two cases (33%) were excluded from initial surgical palliation due to Trisomy 21 in one and severe truncal valve regurgitation in one. Initial surgical palliation was performed in four cases (67%) at median age of 31 days (2-60) and consisted of disconnection and reconstruction of the pulmonary arteries and establishing controlled pulmonary blood flow. There were no early deaths. Conversion to cavopulmonary shunt was not possible in two due to severe airway problems in one and pulmonary arteries anatomy in one. They died at 11 and 16 months, respectively. Two patients (33%) underwent cavopulmonary shunt with 1 (17%) being alive at 18 months - 12 months after cavopulmonary shunt. The second patient proceeded to Fontan completion at 19 months but required catheter takedown 3 months later and died 3.5 years later. CONCLUSIONS: Univentricular hearts with common arterial trunk carry extremely poor short- to medium-term outcomes. This should inform antenatal and postnatal counselling and decision-making.

Use of 3D volume-rendered CT imaging in analysing the anatomy of an unusual type of common arterial trunk.

A common arterial trunk with pulmonary dominance is rare. We report the use of 3D volume-rendered CT imaging to define common arterial trunk with pulmonary arterial dominance and associated abnormalities.

Tricuspid atresia and common arterial trunk: a rare form of CHD.

Tricuspid atresia with common arterial trunk is a very rare association in complex CHD. This association has even more infrequently been documented concomitantly with interrupted aortic arch. We present the diagnosis and initial surgical management of an infant with a fetal diagnosis of tricuspid atresia and common arterial trunk, with additional postnatal finding of interrupted aortic arch with interruption between the left common carotid and left subclavian artery. Due to the infant's small size, she was initially palliated with bilateral pulmonary artery bands and a ductal stent. This was followed by septation of the common arterial trunk and interrupted aortic arch repair and 4 mm right subclavian artery to main pulmonary artery shunt placement at two months of age. She was discharged home on day of life 81.

Heart failure in a newborn with tetralogy of Fallot: uncommon association of a common anomaly.

Heart failure in tetralogy of Fallot in the newborn period is rare and is usually due to either large aortopulmonary collaterals or absent pulmonary valve syndrome with severe pulmonary regurgitation. Pink tetralogy of Fallot and tetralogy of Fallot with disconnected pulmonary arteries from the aorta may present beyond the newborn period with heart failure when Pulmonary vascular resistance (PVR) falls. We describe the diagnostic and therapeutic pathway in a rare case of heart failure in newborn with tetralogy of Fallot.

Clinical value of prenatal ultrasound in diagnosis and classification of common arterial trunk.

OBJECTIVES: To investigate the clinical value of prenatal ultrasound in the diagnosis of the common arterial trunk (CAT) classification and associated malformations. MATERIALS AND METHODS: The 2D ultrasound images, spatiotemporal image correlations (STICs) and clinical data of 88 fetuses diagnosed with CAT malformations by prenatal ultrasound were retrospectively analyzed and classified. The correlation between different types, fetal malformation and pregnancy outcomes were analyzed. RESULTS: Among the 88 fetuses, there were 39 cases (44.32%) of type A1, 40 cases (45.45%) of type A2, 8 cases (9.09%) of type A3, and 1 case of type A4 (1.14%). There were 16 cases (18.18%) with isolated CAT, 48 cases (54.55%) with complex intra-cardiac structural abnormalities, and 24 cases (27.27%) with intra-cardiac and extra-cardiac structural abnormalities. In extra-cardiac structural malformations, 14 cases were associated with 1 other system abnormality, 4 cases with 2 other system abnormalities, 3 cases with 3 other system abnormalities, while 3 cases were combined with 4 other system abnormalities, among which the facial and physical abnormalities had the highest incidence (39.13%). The STIC images were completely displayed in all 88 cases. There was a statistical difference between isolated CAT and CAT combined with other abnormalities in fetal pregnancy outcomes. CONCLUSIONS: Prenatal ultrasound had a high clinical application value in CAT classification. Pregnancy outcomes were highly correlated with the classification and associated intra-cardiac and extra-cardiac structural malformations. The early evaluation of fetal prognosis before birth has important value for clinical intervention.

Accuracy and impact of prenatal diagnosis of common arterial trunk.

OBJECTIVES: Outcome of common arterial trunk (CAT) depends mainly on truncal valve function, presence of coronary artery abnormalities and presence of interrupted aortic arch. The main objective of this study was to evaluate the accuracy of prenatal diagnosis of CAT by analyzing prenatal vs postnatal assessment of: (1) anatomic subtypes and (2) truncal valve function. The secondary objective was to assess the potential impact of prenatal diagnosis of CAT on postnatal mortality and morbidity by comparing prenatally vs postnatally diagnosed patients. METHODS: This was a retrospective analysis of all CAT patients diagnosed either prenatally, with postnatal or fetopsy confirmation, or postnatally, from 2011 to 2019 in a single tertiary center. Cohen's kappa statistic was used to evaluate agreement between pre- and postnatal assessment of anatomic subtypes according to Van Praagh and of truncal valve function. Mortality and morbidity variables were compared between prenatally vs postnatally diagnosed CAT patients. RESULTS: A total of 84 patients (62 liveborn with prenatal diagnosis, 16 liveborn with postnatal diagnosis and six terminations of pregnancy with fetopsy) met the inclusion criteria. The accuracy of prenatal diagnosis of CAT anatomic subtype was 80.3%, and prenatal and postnatal concordance for subtype diagnosis was only moderate (κ = 0.43), with no patient with CAT Type A3 (0/4) and only half of patients with CAT Type A4 (8/17) being diagnosed prenatally. Fetal evaluation of truncal valve function underestimated the presence (no agreement; κ = 0.09) and severity (slight agreement; κ = 0.19) of insufficiency. However, four of five cases of postnatally confirmed significant truncal valve stenosis were diagnosed prenatally, with fair agreement for both presence and severity of stenosis (κ = 0.38 and 0.24, respectively). Mortality was comparable in patients with and those without prenatal diagnosis (log-rank P = 0.87). CAT patients with fetal diagnosis underwent earlier intervention (P < 0.001), had shorter intubation time (P = 0.047) and shorter global hospital stay (P = 0.01). CONCLUSIONS: The accuracy of prenatal diagnosis of CAT is insufficient to tailor neonatal management and to predict outcome. Fetal assessment of truncal valve dysfunction appears unreliable due to perinatal transition. Improvement is necessary in the fetal diagnosis of anatomic subtypes of CAT requiring postnatal prostaglandin infusion. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Large aortopulmonary collateral artery exclusively supplying the lower lobe of left lung in an infant with common arterial trunk with aortic dominance with confluent pulmonary arteries.

INTRODUCTION: Common arterial trunk with aortic dominance has well-developed bilateral pulmonary arterial arborization without any essential major aortopulmonary collateral arteries (MAPCAs), whereas "solitary" arterial trunk is characterized by collateral arterial supply to all bronchopulmonary segments and absent pulmonary arteries. CASE REPORT: We report a term female neonate with common arterial trunk with aortic dominance with confluent pulmonary arteries with a large MAPCA as the sole blood supply to the lower lobe of the left lung. RESULTS: Initial diagnostic workup missed this MAPCA from the descending thoracic aorta. It was suspected during surgery due to massive left atrial return and confirmed by cardiac catheterization study in the early postoperative period and treated successfully by unifocalization. DISCUSSION: A large essential MAPCA supplying an entire lobe in the common arterial trunk with aortic dominance has not been described. It can present as heart failure and inability to wean off the ventilator in the early postoperative period following intracardiac repair. CONCLUSION: This is a case hitherto undescribed and possibly falling outside the well-entrenched classifications of the common arterial trunk and a large MAPCA could be an addition to the list of lesion modifiers. Our experience with this case underlines the importance of a thorough and open-minded approach to the initial imaging assessment of even well-described conditions.

Tetralogy of Fallot with pulmonary atresia and aortopulmonary window may mimic common arterial trunk.

Tetralogy of Fallot with pulmonary atresia is a group of congenital cardiac malformations, which is defined by the absence of luminal continuity between both ventricles and the pulmonary artery, and an interventricular communication. Pulmonary arterial supply in patients with tetralogy of Fallot with pulmonary atresia can be via the arterial duct or from collateral arteries arising directly or indirectly from the aorta (systemic-to-pulmonary artery collaterals), or rarely both. The rarest sources of pulmonary blood flow are aortopulmonary window and fistulous communication with the coronary artery.Herein, we describe an outflow tract malformation, tetralogy of Fallot with pulmonary atresia and aortopulmonary window, which was misdiagnosed as common arterial trunk. We emphasise the morphological differences.

Common Arterial Trunk in Fetal Life: Accuracy of Diagnosis and Prediction of Outcome.

INTRODUCTION: Common arterial trunk (CAT) is a congenital heart disease with significant perinatal mortality in which diagnostic agreement remains low. METHODS: We conducted a retrospective cohort study on fetuses with suspected CAT. Diagnostic accuracy was tested considering gold-standard postnatal ultrasound or necropsy. Prenatal sonographic markers were evaluated by logistic regression for perinatal survival. RESULTS: There were 79 fetuses with suspected CAT, and 55 cases had available necropsy/postnatal ultrasound confirming the study population. The diagnostic accuracy was 90.9% for CAT and 83.6% at a subtype level. In those with a confirmed diagnosis and intention-to-treat (n = 28) composite early mortality (intrauterine, presurgical, and early surgery) was of 25%, 10.5% in isolated cases. The OR for early-mortality of isolated cases was 0.13 (95% confidence interval [CI]: 0.03-0.75). After adjusting for isolated cases, the only prognostic prenatal markers of perinatal mortality were a dysplastic truncal valve OR 7.78 (95% CI: 1.23-49.13) and a stenotic flow OR 8.48 (95% CI: 1.40-51.10). CONCLUSION: CAT is a condition that if evaluated by experts, can be diagnosed with a high degree of accuracy. It remains an entity with high perinatal mortality. Its most important prognostic factor is its association with other anomalies. In isolated cases, the presence of a dysplastic truncal valve and a stenotic flow increase the chances of perinatal death.

Prenatal diagnosis of anomalous connection of the inferior caval vein to the left atrium associated with common arterial trunk.

Anomalous connection of the inferior caval vein to the left atrium is exceedingly rare, and has even been considered by some authors an anatomic and embryologic impossibility. This study demonstrates for the first time the existence of this rare malformation, diagnosed on prenatal echo, and confirmed on post-mortem examination in a 24 WG fetus, in association with a common arterial trunk.

Common arterial trunk in the era of high prenatal detection rates: Results of neonatal palliation and primary repair.

OBJECTIVE: We reviewed our center's experience with common arterial trunk. METHODS: We included those with common arterial trunk in Nevada with estimated delivery dates or birth dates between June 2006 and May 2021. We excluded patients with functionally univentricular hearts. RESULTS: We identified a total of 39: 32 prenatally and 7 postnatally. Of the 32 prenatally detected, 2 had elective termination, 2 had fetal demise, and 28 were live-born. Of the 7 postnatally diagnosed, 6 had prenatal care without a fetal echocardiogram, and 1 had no prenatal care. Overall, live-born prenatal detection was 28/34 (82%). Prenatal detection for 2006-2009 was 2/6 (33%) and for 2010-2021 was 26/28 (93%) p = .049. Of the 35 live-born infants, 1 died preoperatively, and 34 underwent neonatal surgery. Of the 34, 8 had palliation (birth weight 1.9±0.7 kg, range 0.8-2.6 kg), and 26 had a primary repair (birth weight 3.0±0.3 kg, range 2.6-4.0 kg) p = .0004. For all 34 neonatal surgical procedures, there were 2 (5.9%) deaths; however, there were no subsequent surgical or interventional catheterization mortalities. CONCLUSIONS: In Nevada, current state-wide, general population prenatal detection of the common arterial trunk was more than 90%. By employing a combination of neonatal palliation and primary repair, surgical mortality was less than 6% in a cohort that included those with birth weights less than 2.5 kg, truncal valve surgery, and interrupted aortic arches.

Prenatal diagnosis, associated findings and postnatal outcome of fetuses with truncus arteriosus communis (TAC).

PURPOSE: To assess the spectrum of associated anomalies, the intrauterine course, postnatal outcome and management of fetuses with truncus arteriosus communis (TAC) METHODS: All cases of TAC diagnosed prenatally over a period of 8 years were retrospectively collected in two tertiary referral centers. All additional prenatal findings were assessed and correlated with the outcome. The accuracy of prenatal diagnosis was assessed. RESULTS: Thirty nine cases of TAC were diagnosed prenatally. Mean gestational age at first diagnosis was 22 weeks (range 13-38). Two cases were lost follow-up. Correct prenatal diagnosis of TAC was made in 87.5% and of TAC subtype in 90.5%. Prenatal diagnosis was incorrect in three cases: one newborn had aortic atresia with ventricular septal defect (VSD) postnatally, one had hypo-plastic right ventricle with dextro transposition of the great arteries (d-TGA) with coarctation of the aorta and a third newborn had tetralogy of fallot (TOF) with abnormal origin of the left pulmonary artery arising from the ascending aorta postnatally. These 3 cases were excluded from further analysis. In 26.5% of cases, TAC was an isolated finding. 38.2% of fetuses had additional chromosomal anomalies. Among them, microdeletion 22q11.2 was most common with a prevalence of 17.6% in our cohort. Another 3 fetuses were highly suspicious for non-chromosomal genetic syndromes due to their additional extra-cardiac anomalies, but molecular diagnosis could not be provided. Major cardiac and extra-cardiac anomalies occurred in between 8.8% and 58.8%, respectively. Predominantly, extra-cardiac anomalies occurred in association with chromosomal anomalies. Additionally, severe IUGR occurred in 17.6%. There were 14 terminations of pregnancy (41.2%), 1 (2.9%) intrauterine fetal death, 5 postnatal deaths (14.7%) and 14 (41.2%) infants were alive at last follow-up. Intention-to-treat survival rate was 70%. Mean follow-up among survivors was 42 months (range 6-104). Postoperative health status among survivors was excellent in 78.6%, but 46.2% needed repeated re-interventions due to recurrent pulmonary artery or conduit stenosis. The other 21.4% of survivors were significantly impaired due to non-cardiac problems. CONCLUSION: Truncus arteriosus communis is a rare and complex cardiac anomaly that can be diagnosed prenatally with high precision. TAC is frequently associated with chromosomal and extra-cardiac anomalies, leading to a high intrauterine and postnatal loss rate due to terminations and perioperative mortality. Without severe extra-cardiac anomalies, postoperative health status is excellent, independent of the subtype of TAC, but the prevalence of repeated interventions due to recurrent stenosis is high.

Prenatal diagnosis, associated findings and postnatal outcome of fetuses with truncus arteriosus communis (TAC).

PURPOSE: To assess the spectrum of associated anomalies, the intrauterine course, postnatal outcome and management of fetuses with truncus arteriosus communis (TAC) METHODS: All cases of TAC diagnosed prenatally over a period of 8 years were retrospectively collected in two tertiary referral centers. All additional prenatal findings were assessed and correlated with the outcome. The accuracy of prenatal diagnosis was assessed. RESULTS: 39 cases of TAC were diagnosed prenatally. Mean gestational age at first diagnosis was 22 weeks (range, 13-38). Two cases were lost follow-up. Correct prenatal diagnosis of TAC was made in 21 of 24 (87.5%) cases and of TAC subtype in 19 of 21 (90.5%) cases. Prenatal diagnosis of TAC was incorrect in three cases: one newborn had aortic atresia with ventricular septal defect postnatally, one had hypoplastic right ventricle with dextro Transposition of the Great Arteries with coartation of the aorta and a third newborn had Tetralogy of Fallot with abnormal origin of the left pulmonary artery arising from the ascending aorta postnatally. These three cases were excluded from further analysis. In 9 of 34 (26.5%) cases, TAC was an isolated finding. 13 (38.2%) fetuses had additional chromosomal anomalies. Among them, microdeletion 22q11.2 was most common with a prevalence of 17.6% in our cohort. Another 3 fetuses were highly suspicious for non-chromosomal genetic syndromes due to their additional extra-cardiac anomalies, but molecular diagnosis could not be provided. Major cardiac and extra-cardiac anomalies occurred in 3 (8.8%) and in 20 (58.8%) cases, respectively. Predominantly, extra-cardiac anomalies occurred in association with chromosomal anomalies. Additionally, severe IUGR occurred in 6 (17.6%) cases. There were 14 terminations of pregnancy (41.2%), 1 (2.9%) intrauterine fetal death, 5 postnatal deaths (14.7%) and 14 (41.2%) infants were alive at last follow-up. Intention-to-treat survival rate was 70%. Mean follow-up among survivors was 42 months (range, 6-104). Postoperative health status among survivors was excellent in 11 (78.6%) infants, but 5 (46.2%) of them needed repeated re-interventions due to recurrent pulmonary artery or conduit stenosis. The other 3 (21.4%) survivors were significantly impaired due to non-cardiac problems. CONCLUSION: TAC is a rare and complex cardiac anomaly that can be diagnosed prenatally with high precision. TAC is frequently associated with chromosomal and extra-cardiac anomalies, leading to a high intrauterine and postnatal loss rate due to terminations and perioperative mortality. Without severe extra-cardiac anomalies, postoperative short- and medium-term health status is excellent, independent of the subtype of TAC, but the prevalence of repeated interventions due to recurrent stenosis is high.

Endocytic Protein Defects in the Neural Crest Cell Lineage and Its Pathway Are Associated with Congenital Heart Defects.

Endocytic trafficking is an under-appreciated pathway in cardiac development. Several genes related to endocytic trafficking have been uncovered in a mutagenic ENU screen, in which mutations led to congenital heart defects (CHDs). In this article, we review the relationship between these genes (including LRP1 and LRP2) and cardiac neural crest cells (CNCCs) during cardiac development. Mice with an ENU-induced Lrp1 mutation exhibit a spectrum of CHDs. Conditional deletion using a floxed Lrp1 allele with different Cre drivers showed that targeting neural crest cells with Wnt1-Cre expression replicated the full cardiac phenotypes of the ENU-induced Lrp1 mutation. In addition, LRP1 function in CNCCs is required for normal OFT lengthening and survival/expansion of the cushion mesenchyme, with other cell lineages along the NCC migratory path playing an additional role. Mice with an ENU-induced and targeted Lrp2 mutation demonstrated the cardiac phenotype of common arterial trunk (CAT). Although there is no impact on CNCCs in Lrp2 mutants, the loss of LRP2 results in the depletion of sonic hedgehog (SHH)-dependent cells in the second heart field. SHH is known to be crucial for CNCC survival and proliferation, which suggests LRP2 has a non-autonomous role in CNCCs. In this article, other endocytic trafficking proteins that are associated with CHDs that may play roles in the NCC pathway during development, such as AP1B1, AP2B1, FUZ, MYH10, and HECTD1, are reviewed.

Foxc2 is required for proper cardiac neural crest cell migration, outflow tract septation, and ventricle expansion.

BACKGROUND: Proper development of the great vessels of the heart and septation of the cardiac outflow tract requires cardiac neural crest cells. These cells give rise to the parasympathetic cardiac ganglia, the smooth muscle layer of the great vessels, some cardiomyocytes, and the conotruncal cushions and aorticopulmonary septum of the outflow tract. Ablation of cardiac neural crest cells results in defective patterning of each of these structures. Previous studies have shown that targeted deletion of the forkhead transcription factor C2 (Foxc2), results in cardiac phenotypes similar to that derived from cardiac neural crest cell ablation. RESULTS: We report that Foxc2-/- embryos on the 129s6/SvEv inbred genetic background display persistent truncus arteriosus and hypoplastic ventricles before embryonic lethality. Foxc2 loss-of-function resulted in perturbed cardiac neural crest cell migration and their reduced contribution to the outflow tract as evidenced by lineage tracing analyses together with perturbed expression of the neural crest cell markers Sox10 and Crabp1. Foxc2 loss-of-function also resulted in alterations in PlexinD1, Twist1, PECAM1, and Hand1/2 expression in association with vascular and ventricular defects. CONCLUSIONS: Our data indicate Foxc2 is required for proper migration of cardiac neural crest cells, septation of the outflow tract, and development of the ventricles. Developmental Dynamics 247:1286-1296, 2018. © 2018 Wiley Periodicals, Inc.

Dysregulated endocardial TGFß signaling and mesenchymal transformation result in heart outflow tract septation failure.

Heart outflow tract septation in mouse embryos carrying mutations in retinoic acid receptor genes fails with complete penetrance. In this mutant background, ectopic TGFß signaling in the distal outflow tract is responsible for septation failure, but it was uncertain what tissue was responsive to ectopic TGFß and why this response interfered with septation. By combining RAR gene mutation with tissue-specific Cre drivers and a conditional type II TGFß receptor (Tgfbr2) allele, we determined that ectopic activation of TGFß signaling in the endocardium is responsible for septation defects. Ectopic TGFß signaling results in ectopic mesenchymal transformation of the endocardium and thereby in improperly constituted distal OFT cushions. Our analysis highlights the interactions between myocardium, endocardium, and neural crest cells in outflow tract morphogenesis, and demonstrates the requirement for proper TGFß signaling in outflow tract cushion organization and septation.