Discussion :
Tachyarrhythmias has been reported in fetuses with complete heart block.
The reported tachyarrhythmias were junctional ectopic tachycardia,
atrial flutter and ventricular tachycardia.(3,5,6) Immune-mediated
atrial inflammation and atrial dilatation secondary to myocardial
dysfunction can result in atrial flutter. Ventricular tachycardia occur
as a result of abnormal ventricular repolarization. Immune-mediated
focal necrosis and fibrosis in the AV node can result in junctional
ectopic tachycardia.(7) To our knowledge, immune-mediated
tachy-bradycardia syndrome is not reported in fetus so far. Presystolic
flow in ascending aorta has been reported in adults with ventricular
diastolic dysfunction. It occurs due to impaired relaxation of left
ventricle resulting in decreased filling of left ventricle in early
diastole which is compensated by forceful contraction of left atrium to
complete left ventricle filling.(8) Immune-mediated SA node injury has
discordances between the echocardiographic and pathologic findings.(9)
Hemodynamic evaluation using Doppler echocardiography helps in
understanding the electrophysiological mechanism and to make an accurate
diagnosis of fetal arrhythmias. (10) In this case, Doppler
echocardiography helped to understand both the arrhythmia mechanism and
cardiac function. Though the cardiac function stabilized after
transplacental with oral steroids, the arrhythmia persistent probably
due to immune-mediated fibrosis of the sinoatrial node and the atrium.