Fetal arrhythmia: Prenatal diagnosis and perinatal management

Abstract

The importance of managing fetal arrhythmia has increased over the past three decades. Although most fetal arrhythmias are benign, some types cause fetal hydrops and can lead to fetal death. With the aim of improving the outcome in such cases, various studies for prenatal diagnosis and perinatal management have been published. Detailed analysis of the type of arrhythmia in utero is possible using M-mode and Doppler echocardiography. In particular, a simultaneous record of Doppler waveform at the superior venous cava and the ascending aorta has become an important and useful method of assessing the interval between atrial and ventricular contractions. Common causes of fetal tachycardia (ventricular heart rate faster than 180 bpm), are paroxysmal supraventricular tachycardia (SVT) with 1:1 atrioventricular (AV) relation and atrial flutter with 2:1 AV relation. Of fetal SVT, short ventriculo-atrial (VA) interval tachycardia due to atrioventricular reentrant tachycardia is more common than long VA interval. Most fetuses with tachycardia are successfully treated in utero by transplacental administration of antiarrhythmic drugs. Digoxin is widely accepted as a first-line antiarrhythmic drug. Sotalol, flecainide and amiodarone are used as second-line drugs when digoxin fails to achieve conversion to sinus rhythm. Fetal bradycardia is diagnosed when the fetal ventricular heart rate is slower than 100 bpm, mainly due to AV block. Approximately half of all cases are caused by associated congenital heart disease, and the remaining cases that have normal cardiac structure are often caused by maternal SS-A antibody. The efficacy of prenatal treatment for fetal AV block is limited compared with treatment for fetal tachycardia. Beta stimulants and steroids have been reported as effective transplacental treatments for fetal AV block. Perinatal management based on prospective clinical study protocol rather than individual experience is crucial for further improvement of outcome in fetuses with tachycardia and bradycardia.

Non-immune hydrops foetalis due to foetal tachyarrhythmia-management with transplacental amiodarone

“…Digoxin is the usual first-line drug while sotalol, flecainide and amiodarone have been used as second-line drugs. 3,4,9 In a review of published studies, out of 314 cases of foetal SVT, Krapp and colleagues reported digoxin to be significantly less effective in the treatment of SVT in foetuses with hydrops (24.6% success) as compared to foetuses without hydrops (65.4% success). 9 Another study on refractory cases of foetal tachycardia reported a success rate of 93% in the treatment of foetal SVT in hydropic foetuses using amiodarone.…”

“…3 If undiagnosed and untreated, foetal tachycardia may lead to low-output cardiac failure and hydrops, thereby increasing foetal morbidity and mortality. [4][5][6] Ultrasonography can diagnose both, the abnormal foetal heart rate as well as the hydrops.…”

“…Foetal echocardiography is essential to diagnose the exact nature of tachycardia, to rule out underlying structural defects and to monitor response to therapy. 3,8 Our patient was diagnosed to have supraventricular tachycardia (SVT) without any underlying structural cardiac defects.…”

Avances en terapia fetal

“…12,[14][15][16] Los datos son limitados y aún no se han podido demostrar beneficios consistentes y reproducibles.…”

“…12,15,17,18 En fetos no hidrópicos la digoxina logra conversión a ritmo sinusal en el 60% de los casos; en fetos hidrópicos es necesaria la combinación con otras drogas como sotalol, la flecainida, y en menor medida la amiodarona. 12,15,[18][19][20] …”