Atrial septal defect - atrioventricular conduction defects OMIM:108900 Atrial septal defect (ASD) with atrioventricular conduction defects is an extremely rare genetic congenital heart disease characterized by the presence of ASD, mostly of the ostium secundum type (see this term), associated with conduction anomalies like atrioventricular block, atrial fibrillation or right bundle branch block. ICD10:Q21.1 orphanet Rare syndrome with cardiac malformations