Detection of fetal atrial flutter and atrial fibrillation by Tissue Doppler Imaging (TDI)

Introduction: Fetal atrial flutter and atrial fibrillation are often accompanied by ventricular tachycardia with a relevant morbidity and mortality. Variable degrees of atrioventricular (AV) conduction block, resulting in slower ventricular rates compared to atrial rates, are described. Atrioventricular re-entry is the most common type of supraventricular tachycardia in the fetus. Some fetuses with atrial flutter showed postnatal an accessory AV pathway.

Methods: Since 2005 we use TDI as a matter of routine in the diagnosis of fetal arrhythmias. After an echocardiographic examination, high-frame rate TDI raw-data of a longitudinal or transverse four-chamber-view (FCV) was recorded with a 5MHz sector scanner on a Toshiba Aplio 80 ultrasound system (Toshiba Medical Systems). At least 3 consecutive fetal cardiac cycles were stored digitally. TDIQ-software (Toshiba Medical Systems) allowed the simultaneous depiction of the contraction of both atria and ventricles.

Results: A mapping of atrial contractions is feasible in atrial flutter or atrial fibrillation of the fetus. In 9 fetuses with tachyarrhythmias we identified atrial flutter (n=2) and atrial fibrillation (n=2). Conduction pattern towards the ventricles are visualisable. In 3 cases interventricular dyssynchrony was observed under therapy. The transverse FCV showed considerable advantages in the advanced diagnosis of fetal arrhythmias.

Conclusion: Atrial arrhythmias such as flutter or fibrillation can be easily detected with TDI. The presence of ventricular dyssynchrony can be indicative for an accessory pathway. These findings could have an impact on the selection of antiarrhythmic drug treatment.