Atrial septal defect Sinus venosus atrial septal defect 2012-04-08T08:15:24Z HP:0011567 UMLS:C0344730 SNOMEDCT_US:95268002 Fyler:2010 ICD-10:Q21.1 An interatrial communication caused by a deficiency of the common wall between the superior vena cava (SVC) and the right-sided pulmonary veins. SVASD is commonly associated with anomalous pulmonary venous connection (APVC) of some or all of the pulmonary veins, which produces additional left-to-right shunting.