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.