Fig. 3

The images show a confluent perimembranous defect as seen from the right ventricle (left hand panel) and the left ventricle (right hand panel). As seen in the right hand panel, there is malalignment of the muscular outlet septum, but the defect also opens to the inlet of the right ventricle. The right hand panel shows the extensive fibrous continuity posteriorly and inferiorly between the leaflets of the aortic, tricuspid and mitral valves (red dotted line), incorporating the atrioventricular component of the membranous septum (black star), but discontinuity cranially between the leaflets of the aortic and tricuspid valves produced by the malaligned muscular outlet septum. Note also the remnant of the interventricular component of the membranous septum in the corner of the roof of the defect (black dotted line)