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