Semaphorin 3d signaling defects are associated with anomalous pulmonary venous connections.
ABSTRACT: Total anomalous pulmonary venous connection (TAPVC) is a potentially lethal congenital disorder that occurs when the pulmonary veins do not connect normally to the left atrium, allowing mixing of pulmonary and systemic blood. In contrast to the extensive knowledge of arterial vascular patterning, little is known about the patterning of veins. Here we show that the secreted guidance molecule semaphorin 3d (Sema3d) is crucial for the normal patterning of pulmonary veins. Prevailing models suggest that TAPVC occurs when the midpharyngeal endothelial strand (MES), the precursor of the common pulmonary vein, does not form at the proper location on the dorsal surface of the embryonic common atrium. However, we found that TAPVC occurs in Sema3d mutant mice despite normal formation of the MES. In these embryos, the maturing pulmonary venous plexus does not anastomose uniquely with the properly formed MES. In the absence of Sema3d, endothelial tubes form in a region that is normally avascular, resulting in aberrant connections. Normally, Sema3d provides a repulsive cue to endothelial cells in this area, establishing a boundary. Sequencing of SEMA3D in individuals with anomalous pulmonary veins identified a phenylalanine-to-leucine substitution that adversely affects SEMA3D function. These results identify Sema3d as a crucial pulmonary venous patterning cue and provide experimental evidence for an alternate developmental model to explain abnormal pulmonary venous connections.
Project description:OBJECTIVES: Total anomalous pulmonary venous connection (TAPVC) is a rare congenital heart disease. This study aimed to evaluate the outcomes of TAPVC repair in neonates, controlling for anatomic subtypes and surgical techniques. METHODS: Between 1997 and 2013, 88 patients (median age: 16 days) underwent repair for supracardiac (31), cardiac (18), infracardiac (36), or mixed (3) TAPVC. All the patients underwent emergency operation due to obstructed drainage. Supracardiac and infracardiac TAPVC repair included a side-to-side anastomosis between the pulmonary venous confluence and left atrium. Coronary sinus unroofing was preferred for cardiac TAPVC repair. RESULTS: The early mortality rate was 2.3% (2/88 patients). The echocardiogram showed no obstruction in the pulmonary vein anastomosis, and flow rate was 1.1-1.42 m/s in the 3-year follow-up period. CONCLUSIONS: The accurate preoperative diagnosis, improved protection of heart function, use of pulmonary vein tissue to anastomose and avoid damage of the pulmonary vein, and delayed sternum closure can reduce the risk of mortality. The preoperative severity of pulmonary vein obstruction, the timing of the emergency operation, and infracardiac or mixed-type TAPVC can affect prognosis. Using our surgical technique, the TAPVC mortality among our patients was gradually reduced with remarkable results. However, careful monitoring of the patient with pulmonary vein restenosis and the timing and method of reoperation should also be given importance.
Project description:BACKGROUND:Total anomalous pulmonary venous connection (TAPVC) is recognized as a rare congenital heart defect (CHD). With a high mortality rate of approximately 80%, the survival rate and outcomes of TAPVC patients are not satisfactory. However, the genetic aetiology and mechanism of TAPVC remain elusive. This study aimed to investigate the underlying genomic risks of TAPVC through next-generation sequencing (NGS). METHODS:Rare variants were identified through whole exome sequencing (WES) of 78 sporadic TAPVC cases and 100 healthy controls using Fisher's exact test and gene-based burden test. We then detected candidate gene expression patterns in cells, pulmonary vein tissues, and embryos. Finally, we validated these genes using target sequencing (TS) in another 100 TAPVC cases. FINDINGS:We identified 42 rare variants of 7 genes (CLTCL1, CST3, GXYLT1, HMGA2, SNAI1, VAV2, ZDHHC8) in TAPVC cases compared with controls. These genes were highly expressed in human umbilical vein endothelial cells (HUVECs), mouse pulmonary veins and human embryonic hearts. mRNA levels of these genes in human pulmonary vein samples were significantly different between cases and controls. Through network analysis and expression patterns in zebrafish embryos, we revealed that SNAI1, HMGA2 and VAV2 are the most important genes for TAPVC. INTERPRETATION:Our study identifies novel candidate genes potentially related to TAPVC and elucidates the possible molecular pathogenesis of this rare congenital birth defect. Furthermore, SNAI1, HMGA2 and VAV2 are novel TAPVC candidate genes that have not been reported previously in either humans or animals. FUND: National Natural Science Foundation of China.
Project description:BACKGROUND:Scimitar syndrome consists of anomalous pulmonary vein drainage to the inferior vena cava. Its name derives from the image this anomalous pulmonary vein creates on a chest radiograph. We describe a case of normal venous pulmonary vein drainage that also presented the scimitar sign due to an aorto-collateral vessel. CASE SUMMARY:A 15-month-old girl presented with mild dyspnoea and fever. Control chest X-ray showed an image of cardiac dextroposition, hypoplastic right lung, and the 'scimitar sign'. Although the transthoracic echocardiogram confirmed the initial suspicion of anomalous pulmonary venous drainage, the computed tomography (CT) scan showed normal right pulmonary veins connected to the left atrium and revealed that an aorto-collateral vessel caused the scimitar sign. DISCUSSION:Although the patient had several typical alterations of the scimitar syndrome, the pulmonary venous connection was normal, and the scimitar sign was due to an aorto-collateral vessel. It might be difficult to describe venous pulmonary connections on the basis of echocardiography, so an angio CT scan proved to be a valuable tool in this scenario.
Project description:Introduction:Obstructed total anomalous pulmonary venous connection (TAPVC) is one of the commonest seen emergencies in pediatric cardiology centers. Case presentation:Our case was diagnosed to have this anomaly, showing early respiratory distress resulting from severe pulmonary congestion. Palliative stenting of the obstruction was done, which helped in stabilizing the debilitated hemodynamics of the baby before surgery, thus a good surgical outcome and prognosis are expected. Conclusion:This intervention may be listed as a vital measurement in the preoperative cardiac stabilization plan for infants with obstructed TAPVC.
Project description:We present an unusual variant of the sinus venosus defect in which an obvious window is formed between a single pulmonary vein and the superior vena cava, the pulmonary vein retaining its connection to the left atrium. Two patients were operated on via right anterior minithoracotomy. A large single right pulmonary vein was found connecting to the left atrium. There was a large side-to-side communication between the superior vena cava and the pulmonary vein resulting in partially anomalous pulmonary venous drainage. A side-biting clamp was applied in the superior vena cava and the pulmonary vein at both sides of the communication, and the vein was divided. The incision in both veins was closed with a running suture.
Project description:The description of totally anomalous systemic venous connection is limited to case reports. In this review, we seek to clarify anatomic, physiologic, and hemodynamic aspects of this extremely rare anomaly. We also present findings of two patients in whom connection of all the systemic veins was anomalous. In the first patient, with usual atrial arrangement, all systemic veins, including the coronary sinus, were connected anomalously to the morphologically left atrium. Limited left-to-right shunt across an atrial septal defect provided the only source of blood flow to the lungs. The diagnosis was established by saline contrast echocardiography and cardiac catheterization. Extreme hypoplasia of the right ventricle precluded corrective surgery, so we performed a bidirectional Glenn operation, along with atrial septectomy. The second patient had isomerism of the left atrial appendages, which creates problems in the definition in anatomic terms since the connection of the systemic veins can never be normal anatomically when both atriums possess a morphologically left appendage. Our patient, nonetheless, had all the systemic and pulmonary veins, connected to the left-sided atrial chamber which then connected to the left ventricle, thus producing hemodynamics of totally anomalous systemic venous connection. We propose an algorithm for evaluation of this hemodynamic combination and discuss management options. We also intend to clarify the potential differences between connection and drainage, with particular attention to the arrangement of atrial appendages. Even though the hemodynamics may be comparable, in anatomic terms, both systemic and pulmonary venoatrial connection will always be anomalous with isomeric atrial appendages.
Project description:Pulmonary venous (PV) obstruction is associated with a poor prognosis, as well as a high risk of recurrence, following surgical treatment. It can also interfere with the successful completion of Fontan circulation in patients with complex congenital heart disease. A case of a patient who had right isomerism (also known as asplenia syndrome), total anomalous pulmonary venous connection (TAPVC), and a single right ventricle is presented. Although bilateral total occlusion of the inferior PVs was identified postoperatively, the formation of the anastomosis and collateral vessels into the superior and middle PVs enabled successful completion of Fontan circulation. Anastomoses and collateral flow of the PVs were found largely in the interlobar pleura and not in the lung parenchyma.
Project description:We sought to evaluate the value of echocardiography in the diagnosis of different types of anomalous pulmonary venous connections (APVCs) and summarize the diagnostic experience. A total of 84 patients with APVC were confirmed by surgery (n?=?82) or computerized tomography angiography (CTA) (n?=?2) in the last 6 years (2008-2014) at the Wuhan Union Hospital. The total anomalous pulmonary venous connection (TAPVC) cases account for 60.7%, and partial anomalous pulmonary venous connection (PAPVC) cases account for 39.3% among the 84 cases that were identified. The 51 TAPVCs were classified by the Darling method-type I (41.1%), type II (52.9%), type III (1.9%), and type IV (3.9%). The most common drainage path of type I was common pulmonary drainage to the left innominate vein via vertical vein, and the coronary sinus drainage was the most common path in type II. Compared with surgical or CTA results, the sensitivity and specificity of echocardiography in the diagnosis of APVCs were 97.6% and 99.9%, respectively. The echocardiography misdiagnoses were mainly seen in PAPVCs. Of the TAPVCs and PAPVCs correctly diagnosed by echocardiography, the diagnostic accuracy of classification were 94% and 100%, respectively. Echocardiography has specific value in diagnosing and classification of APVC, especially the supracardiac and cardiac TAPVCs. Multiplane scan views and color Doppler improve the display of drainage pathway.
Project description:Scimitar syndrome is a rare but serious congenital condition that consists of anomalous pulmonary venous drainage of the right lung to the inferior vena cava. The appearance on chest radiography resembles a curved Turkish sword, or scimitar. Scimitar syndrome is associated with other anomalies, including hypoplasia of the right lung, dextroposition of the heart, anomalous systemic arterial supply to the right lung, and atrial septal defect. Clinical manifestations in infants include severe tachypnea and cyanosis. Adult patients may present with dyspnea and increased fatigue. Few adult cases have been reported in the medical literature. Classical surgical repair involves diversion of the scimitar venous flow into the left atrium with a baffle, requiring the use of cardiopulmonary bypass and deep hypothermic circulatory arrest. Herein, we report the case of a 42-year-old woman with 2 scimitar veins who underwent corrective surgery at our center without the use of cardiopulmonary bypass. We also comment on the importance of a patient's lung hypoplasia in the decision to repair the defect through a right thoracotomy.