Fetal dysrhythmias

Abstract

Fetal dysrhythmias are common, usually manifesting as irregular rhythms. Whilst most irregularities are benign and caused by isolated atrial ectopics, in a few cases, rhythm irregularity may indicate partial atrioventricular block, which has different aetiological and prognostic implications. We provide a flowchart for initial management of irregular rhythm, to help select cases requiring urgent specialist referral. Tachycardias and bradycardias are less frequent, can lead to haemodynamic compromise and may require in-utero therapy. Pharmacological treatment of tachycardia depends on type (supraventricular tachycardia or atrial flutter) and presence of hydrops, with digoxin, flecainide and sotalol being commonly used. An ongoing randomized trial may best inform about their efficacy. Bradycardia due to blocked bigeminy normally resolves spontaneously, but if due to established complete heart block there is no effective treatment. Ongoing research suggests hydroxychloroquine may reduce the risk of auto-immune atrioventricular block. Sinus bradycardia (rate < 3 rd centile) may be a prenatal marker for long QT syndrome.

Treatment of Permanent Junctional Reciprocating Tachycardia in a Preterm Neonate: Case Report

“…There are three or more distinct P wave forms in multifocal atrial tachycardia; however, inverted P waves in the inferior lead in PJRT. 2,9,12 The present case had findings of incessant narrow QRS tachycardia with a heart rate of 215 beats/min, 1:1 AV conduction, prolonged RP interval and inverted P waves in the inferior leads on ECG, and an intravenous adenosine bolus terminated the tachycardia, which then spontaneously restarted after 5 seconds of sinus rhythm. Therefore, the patient was diagnosed with PJRT.…”

“…AV re-entry tachycardia accounts for 90% of fetal and neonatal forms of SVT. 9,10 PJRT is a subtype of AVRT and is a rare form of refractory and persistent SVT. PJRT generally occurs in children and infants and accounts for 1% of SVT in this age group.…”

“…If the tachycardia is incessant (>50% of the time) or hemodynamic compromise is present, prenatal treatment should be commenced. 9 It is recommended that if PJRT is diagnosed in the fetal period, transplacental treatment should be commenced as soon as possible to prevent congestive heart failure. Transplacental treatment should be initiated with a combination of sotalol and digoxin in nonhydropic patients, or flecainide, especially in case of fetal hydrops.…”

Outcomes of sustained fetal tachyarrhythmias after transplacental treatment

“…All consecutive cases of sustained tachyarrhythmias referred to our department for perinatal management following the diagnosis of fetal tachyarrhythmia between January 2008 and August 2019 were reviewed. Tachyarrhythmia was diagnosed when heart rate was ≥180 beats per minute (bpm) and was considered sustained if present during ≥50% of the echocardiographic monitoring time 2 , 14 ; otherwise, it was considered intermittent. We excluded fetuses with congenital heart disease and genetic or chromosomal associations.…”

Treatment of Fetal Arrhythmias

“…In utero therapy options for fetal heart block include: beta-sympathomimetics; intravenous immunoglobulin and apheresis; and fluorinated glucocorticoids [ 2 , 67 , 68 ]. Hydroxychloroquine is used to prevent fetal heart block and neonatal lupus in women with anti-Ro/SSA or anti-La/SSB antibodies with a previous history of fetal heart block or neonatal lupus [ 12 , 14 ].…”