Atrioventricular septal defect: An extended approach to prenatal sonographic imaging of the atrioventricular valves

An atrioventricular septal defect (AVSD) is diagnosed with prenatal sonography using the 4-chamber view (4CV) of the fetal heart. Prenatal 2D sonographic imaging of normal and AVSD short axis (SAX) atrioventricular (AV) valve views have not been well described. The aim is to describe the 2D sonographic 4-chamber and SAX view of the AV valves when an AVSD is present compared to normal AV valves. The 4CV AVSD heart demonstrates no offset of AV valves due to the abnormal valve structure. Complete and intermediate AVSD has a septum primum defect and inlet ventricular septal defect (VSD). The partial AVSDs have either a septum primum defect or just an inlet VSD with an intact primum septum. The SAX view of AVSD demonstrates the common AV junction and the bridging leaflets. In ventricular diastole valves have a “figure 8” and “dumbbell” shape in partial and complete AVSD, respectively. These appearances are not seen in the normal heart in SAX as both tricuspid and mitral valve are separate valves. The SAX view can be obtained by locating a sagittal aortic arch view and then scanning slightly towards the left side of the fetus, near the base of the heart and the AV valves. An in-depth interrogation of the abnormal fetal heart is obtained without specialised 4D capable ultrasound machines providing information to assist in counselling during the pregnancy and for postnatal surgical planning. Future research to assess the feasibility of incorporating the SAX view into routine practice and by general sonographers is suggested.