Abstract 16

Aims To correlate the size and position of ventricular septal defects with closure rate (both spontaneous and surgical) in a cohort of children with isolated ventricular septal defects born in 1991.

Subjects The cohort was identified using the Northern Fetal Abnormality Data Base.

Methods Case notes were retrieved and using original echocardiographic reports the defect size and position was noted. Defects were taken to be closed if on subsequent echocardiography no defect was seen or no flow was detected with colour doppler across the interventricular septum.

Results 71 children were identified (case notes for 2 were not found). 2 children were lost to follow up. 51 defects were small (73.9%) 32 of these were muscular; 12 (17.4%) were moderate of which 2 were muscular, and 6 (8.7%) were large of which 1 was muscular. 14 defects required surgical closure, including 12 perimembranous defects. After 6 years, 46 (66.6%) of the defects had closed spontaneously or after surgery. Of these 33 (71.7%) had closed spontaneously. Of the small defects 11 (34.4%) of the muscular defects remained open whilst 8 (50.0%) of the perimembranous defects remained open.

Conclusion At diagnosis the size and position of a ventricular septal defects is of great relevance to the subsequent natural history. Perimembranous defects account for the vast majority of moderate and large sized defects which require surgical interventions. After 6 years half of the small perimembranous defects remain open.