Fetal arrhythmias: the Saint-Justine hospital experience

We intend to review our experience with the investigation and management of foetal arrhythmia on the basis of superior vena cava/ascending aorta (SVC/AA) Doppler flow velocity recordings. Irregular rhythms n = 307. Premature atrial and ventricular contractions were easily identified and generally self-limited in time. Sustained bradycardia n = 19. Four had sinus bradycardia, six presented with blocked atrial bigeminism, three showed 2:1, and five had a complete atrio-ventricular (AV) block. Another foetus that presented with first-degree AV block developed a Luciani–Wenckebach phenomenon 1 week later. These different types of bradycardia were all identified on SVC/AA Doppler recordings. Tachyarrhythmia n = 30. Five types of tachyarrhythmia were observed: Type I: Short ventriculo-atrial (VA) tachycardia (VA < AV) , n = 11. Ten foetuses of this group presented a distinctive Doppler flow velocity pattern characterised by 1:1 AV conduction and a tall atrial wave (‘a’ wave) superimposed on the aortic ejection wave. They were considered to have re-entrant tachycardia through a fast-conducting AV accessory pathway; all 10 responded to digoxin therapy. The eleventh foetus with short VA tachycardia had atrial ectopic tachycardia with AV node dysfunction; he was treated successfully with sotalol. Type II: Long VA tachycardia (VA > AV): n = 8. In seven cases, an ‘a’ wave of normal amplitude with normal AV time interval could be clearly identified in front of the aortic ejection wave: one foetus in this group was considered to be in sinus tachycardia based on the variability of its heart rate; in another, sudden onset of tachycardia triggered by extrasystoles led to the possibility of permanent junctional reciprocating tachycardia (PJRT). The five other foetuses had atrial ectopic tachycardia. The last foetus presented with AV and VA intervals of the same duration and a heart rate of 210 beats/min; he did not respond either to digoxin or to sotalol, and was found after birth to have PJRT. The drug of first choice in this group was sotalol. Type III: Simultaneous onset of atrial and ventricular contractions : n = 3. These foetuses were classified as junctional ectopic tachycardia. Two responded to amiodarone. The other foetus converted spontaneously to sinus rhythm. Type IV: Flutter : n = 7. All presented with 2:1 AV relationship except one who had a variable block. Digoxin was prescribed as a first choice associated with sotalol in three cases. Conversion to sinus rhythm was documented in all; however, one hydropic foetus with advanced cardiomyopathy died one day after birth. Type V: Ventricular tachycardia : n = 1. This 30-week foetus presented alternance of AV dissociation (atrial rate: 130, ventricular rate: 170 beats/min) and atrial capture (ventricular rate of 138 beats/min). The arrhythmia responded well to propanol, and no recurrence was recorded after birth. Precise prenatal identification of arrhythmia type can be achieved with the SVC/AA Doppler approach. Such information allows for a better management and a rational choice of appropriate anti-arrhythmic drug. Copyright © 2004 John Wiley & Sons, Ltd.