Fetal echocardiographic evaluation of atrial morphology and the prediction of laterality in cases of heterotaxy syndromes.

OBJECTIVE: To evaluate whether abnormal atrial morphology, which is well recognized in autopsy series, is detectable by fetal echocardiographic examination of the four-chamber view, and can therefore be utilized to differentiate left from right isomerism in heterotaxy syndromes.
METHODS: This study was a retrospective review of 30 cases with prenatally diagnosed heterotaxy syndromes. Ultrasound video recordings and still images were reviewed with respect to atrial morphology in the four-chamber view. In 25 cases the morphology of both atria was sufficiently well visualized on the recordings to be evaluated and only these were included in the study.
RESULTS: Two types of atrial morphology were distinguished in our cohort: a sickle-shape with the tip pointing laterally and apically, and a blunt shape resembling the usual atrial appearance in the four-chamber view. Nineteen out of the 25 cases (76%) presented with isomerism of the atria in the four-chamber view. Thirteen had bilateral sickle-shaped atrial morphology, all associated with left isomerism. Six had bilateral blunt-shaped atrial morphology, all associated with right isomerism. The atria of the remaining six cases were not isomeric, the right atrium being sickle-shaped and the left blunt-shaped. Five of the latter cases were associated with left and one with right isomerism.
CONCLUSIONS: The majority of prenatally diagnosed heterotaxy syndromes seem to present with isomeric atrial morphology in the four-chamber view. In these cases a differentiation between left and right isomerism can be based on the two distinct types of atrial morphology. This may further enhance the prenatal differentiation of these syndromes. Copyright (c) 2005 ISUOG.