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.

NKX2-6 related congenital heart disease: Biallelic homeodomain-disrupting variants and truncus arteriosus.

Congenital heart defects (CHD) are the most common birth defect and are both clinically and genetically heterogeneous. Truncus arteriosus (TA), characterized by a single arterial vessel arising from both ventricles giving rise to the coronary, pulmonary and systemic arteries, is rare and only responsible for 1% of all CHD. Two consanguineous families with TA were previously identified to have homozygous nonsense variants within the gene NKX2-6. NKX2-6 is a known downstream target of TBX1, an important transcriptional regulator implicated in the cardiac phenotype of 22q11.2 microdeletion syndrome. Herein, we report two siblings with TA presumably caused by compound heterozygous NKX2-6 variants without a history of consanguinity. Two in-house cohorts with conotruncal defects (CTD) were sequenced for variants in NKX2-6 and no additional cases of biallelic NKX2-6 variants were identified. The similar phenotype of these cases, and the clustering of variants that likely result in a truncated protein that disrupts the homeobox domain, suggest that biallelic loss of function for NKX2-6 is a rare genetic etiology for TA in particular, and possibly other types of CHD.

Origen anómalo de la arteria coronaria derecha desde el tronco de la arteria pulmonar (ARCAPA) / Anomalous origin of the right coronary artery originating from the pulmonary trunk; ARCAPA / Origem anômala da artéria coronária direita do tronco da artéria pulmonar; ARCAPA

Las anomalías de las arterias coronarias son una condición clínica de muy baja incidencia y de estas el origen anómalo de la arteria coronaria derecha desde el tronco de la arteria pulmonar (ARCAPA) representa cerca de 0,002% en la población general. Se puede asociar a la presencia de otras anomalías cardíacas congénitas. Presentamos el caso de una recién nacida, pretérmino de 33 semanas, gemelar, a la cual se le realiza el diagnóstico de un probable origen anómalo de coronaria derecha en un estudio ecocardiográfico de rutina realizado en la unidad de terapia intensiva. Se confirma el diagnóstico mediante cateterismo cardíaco y se realiza la corrección quirúrgica definitiva a los 6 meses de edad, estando la niña actualmente asintomática y con una calidad de vida normal. Destacamos la baja frecuencia de la ocurrencia de dicha patología, realizamos una revisión sobre los tópicos principales en el desarrollo del árbol vascular coronario y las principales anomalías del mismo. Jerarquizamos la importancia de realizar un estudio ecocardiográfico adecuado como valoración de pacientes internados en unidades de terapia intensiva neonatal.

Coronary artery anomalies are a clinical condition of very low incidence. Out of these, the anomalous origin of the right coronary artery from the trunk of the pulmonary artery (ARCAPA) is estimated to represent 0.002% of the general population. It may be associated with the presence of other congenital cardiac anomalies. The study presents the case of a 33 week preterm newborn twin who is diagnosed with an anomalous origin of the right coronary in a routine echocardiographic study performed in the Intensive Care Unit. The diagnosis is confirmed by cardiac catheterization and definitive surgical correction is performed at 6 months of age, the child being currently asymptomatic and enjoying a normal quality of life. We stand out the low frequency of the occurrence of this pathology. We performed a review of the main topics in the development of the coronary vascular tree and their main anomalies. We emphasize on the importance of performing an adequate Echocardiographic study as an assessment of patients admitted to Neonatal Intensive Care Units.

As anomalias das artérias coronárias representam uma condição clínica de incidência muito baixa; e a origem anômala da artéria coronária direita do tronco da artéria pulmonar (ARCAPA) representa somente uma estimativa de 0,002% na população geral. Pode estar associada à presença de outras anomalias cardíacas congênitas. Apresentamos o caso de um recém-nascido, prematuro de 33 semanas, gêmeo, diagnosticado com provável origem anômala de coronária direita em estudo ecocardiográfico de rotina realizado na Unidade de Terapia Intensiva. Confirmou-se o diagnóstico através de cateterismo cardíaco e realizou-se a correção cirúrgica definitiva aos 6 meses de idade; a doença atualmente é assintomática e a menina tem uma qualidade de vida normal. Ressaltamos a baixa frequência da ocorrência da referida patologia; realizamos uma revisão dos principais tópicos no desenvolvimento da árvore vascular coronariana e suas principais anomalias. Destacamos a importância de realizar um estudo ecocardiográfico adequado como estratégia de avaliação de pacientes internados em Unidades de Terapia Intensiva Neonatal.

Long-term Outcomes after Truncus Arteriosus Repair: A Single-center Experience for More than 40 Years.

OBJECTIVES: This study aimed to analyze long-term survival and functional outcomes after truncus arteriosus repair in a single institution with more than 40 years of follow-up. METHODS: Medical records were analyzed retrospectively in 52 patients who underwent the Rastelli procedure for truncus arteriosus repair between 1974 and 2002. Thirty-five patients survived the initial repair. The median age at the initial operation was 2.8 months (range, 0.1-123 months) and the body weight was 3.9 kg (range, 1.6 to 15.0 kg). RESULTS: The median age at follow-up was 23.6 years (range, 12.4 to 44.5 years). The median follow-up duration was 23.4 years (range, 12.3 to 40.7 years). The actuarial survival rate was 97% at 10 years and 93% at both 20 years and 40 years after the initial operation. At follow-up, most patients were in New York Heart Association (NYHA) functional classes I (73%) and II (24%). Thirty-six percent of patients had full-time jobs, 40% were students, and 21% were unemployed. Most patients (97%) had undergone conduit reoperations. Freedom from reoperation for right ventricular (RV) outflow and pulmonary artery (PA) stenosis was 59% at 5 years, 28% at 10 years, and 3% at 20 years after the initial operation. Freedom from catheter interventions for RV outflow and PA stenosis was 59% at 5 years, 47% at 10 years, and 38% at 20 years after the initial operation. Freedom from truncal valve replacement was 88% at 5 years, 85% at 10 years, and 70% at 20 years after the initial operation. CONCLUSIONS: In this single-center retrospective study, with long-term follow-up after repair of truncus arteriosus, long-term survival and functional outcomes were acceptable, despite the requirement for reoperation and multiple catheter interventions for RV outflow and PA stenosis in almost all patients, and the frequent requirement for late truncal valve operations.

Outcomes of Truncus Arteriosus Repair in Children: 35 Years of Experience From a Single Institution.

We evaluated the long-term outcomes following repair of truncus arteriosus (TA) from a single institution. We conducted a retrospective review of children (n = 171) who underwent TA repair between 1979 and 2014. Early mortality rate was 11.7% (20/171). There were 19 late deaths. Most deaths (74%, 29/39) occurred within the first year following surgery. The 1-year mortality rate in 1979-2004 was 18% (25/136) and decreased to 11% (4/35) in 2005-2014. The overall survival rate was 73.6% at 30 years. Multivariate analysis identified postoperative extracorporeal membrane oxygenation (P = 0.003), operative weight <2.5kg (P = 0.012), prior surgical intervention (P = 0.018), and coronary artery anomaly (P = 0.037) as risk factors for early mortality. A Cox regression model identified DiGeorge syndrome (P = 0.008) as a risk factor for late mortality. Freedom from right ventricular outflow tract reoperation was 4.6% at 20 years. Concomitant truncal valve (TV) repair or replacement was undertaken in 20 patients. Additionally, 14 patients underwent late TV repair or replacement. The overall survival rate in patients who underwent TV operation was 76.9% at 20 years. A total of 19 patients had concomitant interrupted aortic arch with a survival rate of 89.5% at 20 years. Median follow-up was 19 years (mean = 17 years, range: 1-34 years). All patients were in New York Heart Association Class I/II at last follow-up. Following repair of TA, patients had good long-term functional status but had high reoperation rates. Repair of interrupted aortic arch and TV were not risk factors for mortality. Postoperative extracorporeal membrane oxygenation, operative weight <2.5kg, prior surgical intervention, and coronary artery anomaly were risk factors for early death. DiGeorge syndrome was associated with late death, most commonly from infection.

Isolated truncus arteriosus associated with a mutation in the plexin-D1 gene.

Truncus arteriosus accounts for approximately 1% of congenital heart defects and the cause of isolated non-syndromic truncus arteriosus is largely unknown. In order to identify the underlying molecular defect in a consanguineous family with recurrent tuncus arteriosus, homozygosity mapping followed by whole exome sequencing was performed. This resulted in the identification of a homozygous mutation, Arg1299Cys, in the PLXND1 gene. The mutation affected a highly conserved residue, segregated with the disease in the family and was absent from available SNP databases and ethnic matched controls. in silico comparative modeling revealed that the mutation resides in the N-terminal segment of the human plexin-D1 intracellular region which interacts with the catalytic GTPase-activating protein homology region. The mutation likely destabilizes the intracellular region, perturbing its anchoring and catalytic activity. The phenotype in human PLXND1 mutation is closely related to that of knockout mice for PLXND1, its co-receptor neuropilin-1 or its ligand SEMA3C. It is therefore suggested that SEMA3C signaling, propagated through the heterodimer receptor plexin-D1/neuropilin, is important for truncus arteriosus septation. Confirmation of this observation will require the identification of PLXND1 mutations in additional patients. Exome analysis is valuable for molecular investigation of single patients with congenital heart defects in whom chromosomal copy number variants have been excluded.

Extreme windkessel effect can cause right heart failure early after truncus repair.

An infant developed severe right heart failure early after truncal repair with a pulmonary homograft. A mechanical obstruction by narrowing could not be identified at the homograft or pulmonary arteries. However, functional obstruction was caused by an extreme windkessel effect in a massively dilated homograft that absorbed rather than transmitted the pulse wave. Effective treatment consisted of replacing the dilated homograft by a rigid aortic homograft of equal size as the initial homograft. When confronted with circulatory failure after allograft placement, the clinician should not only look for obstruction by narrowing, but also consider the windkessel phenomenon.

Diagnosis and management of cyanotic congenital heart disease: part I.

Most commonly encountered cyanotic cardiac lesions in children, namely, tetralogy of Fallot, transposition of the great arteries and tricuspid atresia are reviewed. Pathology, pathophysiology, clinical features, non-invasive and invasive laboratory studies and management are discussed. The clinical and non-invasive laboratory features are sufficiently characteristic for making the diagnosis and invasive cardiac catheterization and angiographic studies are not routinely required and are needed either to define features, not clearly defined by non-invasive studies or as a part of catheter-based intervention. Surgical correction or effective palliation can be undertaken with relatively low risk. However, residual defects, some requiring repeat catheter or surgical intervention, are present in a significant percentage of patients and therefore, continued follow-up after surgery is mandatory.

Fate of the truncal valve in truncus arteriosus.

BACKGROUND: The fate of the truncal valve (TV) after truncus arteriosus repair remains poorly defined. The purpose of this report was to analyze how the TV influences outcome of truncus arteriosus repair. METHODS: From January 1986 to December 2003, 153 patients underwent complete repair of the truncus arteriosus. Median age was 35 days. Preoperative TV insufficiency was absent or trivial in 59 patients (39%), mild in 72 patients (47%), moderate in 13 patients (8%), and severe in 9 patients (6%). The TV was quadricuspid in 36 patients (24 %), bicuspid in 10 patients (7%), and tricuspid in the remaining patients. At surgery, TV plasty (n = 6) or replacement (n = 3) was associated with truncus arteriosus repair. Truncal valve-aorta continuity was restored by patch interposition in 27 patients (17%), by conduit in 7 patients (5%), and directly in the remaining patients. RESULTS: A 97-month mean follow-up was achieved in all survivors. The actuarial survival rates were 81.7% +/- 3.1% and 79.1% +/- 3.3% at 6 months and 18 years, respectively. Among 85 patients who underwent 113 reoperations, 19 underwent 24 TV reoperations: 5 isolated TV reinterventions and 19 associated with right ventricular-pulmonary artery conduit replacement. Freedom from TV reoperation was 96%, 82.3%, and 62.7% at 1, 10, and 18 years, respectively. Multivariate logistic regression showed that moderate or severe TV insufficiency at initial presentation was a risk factor for late TV reoperation but not for early mortality. Initial TV replacement was associated with lower survival. CONCLUSIONS: Initial TV insufficiency is associated with higher reoperation rate. This condition requires more refined techniques of TV plasty. The overall long-term freedom of TV reintervention rate remains within reasonable ranges. Truncal valve reintervention presents a low risk for mortality.

Double-homograft repair of truncus arteriosus with severe truncal valve dysfunction.

An infant with truncus arteriosus and severe dysfunction of the truncal valve including both stenosis and insufficiency successfully underwent primary repair. This included the insertion of two separate valved homograft conduits. Early outcome has been excellent and the patient is doing well after 6 months with only echocardiographic evidence of mild aortic valve regurgitation. Double-homograft repair is a realistic option in cases of truncus arteriosus with severe malformation of the truncal valve.

Truncus arteriosus and previous pulmonary arterial banding: clinical and hemodynamic assessment.

Twenty-seven patients with truncus arteriosus and previous pulmonary arterial banding were evaluated 1 1/2 to 14 years (mean 7 years) after banding. Ages at the time of cardiac catheterization ranged from 3 to 18 years (mean 9 years). Current symptoms were severe in five patients and were related to truncal valve incompetence or decreased pulmonary blood flow (or both) rather than to age, duration of palliation or band location. Twenty-one of 22 patients with two pulmonary arteries were considered to be in a hemodynamically operable state at the time of study. The condition of three of five patients with a single pulmonary artery was subsequently found inoperable because of severe pulmonary vascular disease in the lung supplied by the single pulmonary artery. In patients with two pulmonary arteries, demonstration of low pressure in at least one normal-sized pulmonary artery established operability. Postoperative pressure measurements correlated well with preoperative prediction of operability, with 19 of 20 patients having a pulmonary arterial pressure less than 70 percent of systemic levels after repair. Bilateral pulmonary arterial binding may be more effective than central arterial banding (which frequently produces severe obstruction to the right pulmonary artery) in preventing pulmonary vascular obstructive disease in patients with truncus arteriosus who have two pulmonary arteries. Patients with truncus arteriosus and a single pulmonary artery with pulmonary arterial banding remain at high risk for the development of pulmonary vascular obstructive disease.