Partial Anomalous Pulmonary Venous Connection and the Nature of Associated Sinus Venosus Defect

Background:Partial anomalous pulmonary venous connection(PAPVC)is frequently associated with atrial septal defect(ASD),especially sinus venosus defect(SVD).Although Waggstaffe described the pathology of SVDs in 1868,the exact anatomic features and the nature of SVD remains controversial.SVDs with no posterior atrial rim were observed in recent years.However,no studies suggested that absence of the residual posterior atrial septal tissue might be the key feature of SVD.The aims of this study were to investigate if absence of posterior rim of atrial septum played a crucial role in patients with SVD.Methods:From January 2011 to December 2019,256 children with PAPVC combined ASD and 878 children with isolated ASD who underwent corrective cardiac surgery were consecutively enrolled.Comprehensive review of preoperative transthoracic echocardiography,computed-tomography images and surgical findings were performed by experienced pediatric cardiologists.The subtypes of PAPVC,locations and types of ASD,and presence of posterior atrial rim of associated ASD were investigated.Results:PAPVC was right-sided in 244 children,left-sided in 6 children,and bilateral in 6 children.In PAPVC cases,ASD without posterior atrial rim existed in 226 SVD cases.ASD without posterior atrial septum only existed in cases with one or more right pulmonary veins returning to right atrium(RA)or to RA-superior vena cava junction.In cases with isolated ASD,there were 3 SVD,and the other 875 cases were secundum ASD.Conclusions:ASD without posterior atrial rims was associated with one or more right pulmonary veins returning to RA or RA-superior venous cava(SVC)junction.For SVD,the key feature is that the defect is in the posterior of the interatrial septum with no posterior septal rim,rather than adjacent to the SVC or to the inferior vena cava.