P04.10: Antenatal sonographic small head circumference correlates with a small head circumference at birth for neonates with congenital heart disease

Abstract

Introduction:Isomerism of the atrium is the result of a defect in lateralization associated with bilateral morphologically identical atrial appendages. It is commonly associated with gross cardiac and vascular anomalies. Many of the affected individuals die at an early age. Objective: To present our experience in the prenatal diagnosis of anomalies of cardiac isomerism using high-resolution color Doppler ultrasound. Methodology: There were 116,859 low-risk patients scanned in the Antenatal Diagnostic Center as part of their routine screening over a 8-year period from 1998 to 2005. A retrospective review of congenital heart disease (CHD) associated with isomerism was conducted. Results: A total of 36 cases of suspected isomerism were observed among the cases of CHD diagnosed. Isomerism was confirmed by postmortem or postnatal 2D echo in 22 cases. In eighteen out of twenty-two (82%) of these cases, a right-sided isomerism was noted. They typically presented with AVSD (11/18), dextrocardia (8/18), situs inversus (9/18) in antenatal scan. In two of them a large azygous vein was presented. Postmortem showed 3-lobed or 4-lobed lung bilaterally. In four left-sided isomerism cases, only one had azygous drainage of IVC. None of them associated with heart block. Karyotypes were done in 13 of 22 cases and were all normal. Conclusion: There is geographical heterogeneity in the presentation of isomerism. Right isomerism is exceptionally common in our local population. We postulate that there may be a racial predisposition to the presentation of the type of isomerism. There was also a low association with karyotype abnormality.