Diagnosis
Even now, it remains difficult to distinguish between the subsets on the basis of clinical identification of the atrial appendages.27-32 Almost all children with right isomerism are in sinus rhythm. Abnormal p wave morphology and slow atrial rhythm are associated with left isomerism, with complete heart block occurring in about 10%.30 Howell-Jolly bodies, a prominent feature in right isomerism, are found on peripheral blood smears.29,30 The status of spleen can be confirmed by abdominal ultrasound or a radionuclide spleen scan.2,3,6-13,15 Since intestinal malrotation is a frequently associated lesion, a barium study is frequently advocated, especially for those with right isomerism.16,30Tracheobronchial anatomy, best revealed using a high voltage aortopulmonary view.6,11,12,30 can be used to distinguish right versus left isomerism.12,23,31.30-32 It is bronchial arrangement that correlates best with the arrangement of the atrial appendages.31-33 This is significant, since it still remains a problem specifically to diagnose specifically the features of the atrial appendages.4,31 When seeking to make the diagnosis by inference, echocardiography assessment of the abdominal great vessels and hepatic venous drainage is more accurate than assessment of the abdominal organs.27,29 Although prenatal diagnosis can be made by echocardiography, this had no impact on survival.32 Transesophageal echocardiography is becoming helpful in confirming the diagnosis (Figure 1). It is computed tomography, and/or three-dimensional cardiac magnetic resonance, nonetheless, that now provides the best comprehensive assessment.34,35