///2019 Abstract Details
2019 Abstract Details2019-07-13T07:45:15-05:00

Amiodarone for Refractory Fetal Supraventricular Tachycardia Complicated by Hydrops Fetalis – A Case Report

Abstract Number: RF1BA-548
Abstract Type: Case Report Case Series

Mellany A Stanislaus MD1 ; Courtney James MD2; Robert H Small MD3; Kasey Fiorini MD4

A 25-year-old G1P0 with PMH of cHTN and GERD presented from an outside hospital at 28w6d for fetal tachycardia with HR in the 250s. Upon presentation, there was no evidence of hydrops on ultrasound. Digoxin was initiated with a loading dose of IV 500mcg x1, followed by IV 250mcg Q6h x3 doses. After 48h, FHR remained >200 bpm and PO flecainide 100mg TID was started. On HD 4, Cardiology was consulted as FHR continued to be refractory. Fetal ultrasound now revealed hydrops with pericardial and pleural effusions and ascites. Maternal ECG also showed QT prolongation. The following day, flecainide was discontinued, PO amiodarone 600mg TID was initiated and PO digoxin was decreased to 125mcg QD. Maternal echo revealed a normal EF. On HD 6, amiodarone was increased to 800mg TID. On HD 7, pleural effusions mildly worsened. Maternal TSH was WNL. She was maintained on amiodarone 800mg TID and digoxin 125mcg QD through HD 10, when FHR converted for one hour. On HD 11, sustained conversion was achieved with FHR maintained between 120-130 bpm. Medication totals were digoxin 2500mcg, flecainide 1000mg and amiodarone 14.2g. There were no structural abnormalities detected on fetal echo. The patient was discharged home at 30w3d on an amiodarone taper: 400mg BID x1 week, 400mg BID x4 weeks, 200 mg QD until delivery.

At 39w4d the patient underwent a scheduled cesarean delivery having completed nine weeks of amiodarone totaling 35g. Preoperatively, an epidural was placed, incrementally dosed with 0.5% ropivacaine 20mL total, fentanyl 100 mcg and morphine 2mg. Intraoperative course was uncomplicated. She delivered a 3780g infant, APGARs 8/9. She was discharged on POD3. The baby was transferred to a local children’s hospital for cardiac monitoring.

Discussion: Fetal arrhythmias occur in 1-2% of pregnancies. Of these, supraventricular tachycardia (SVT) is the most common tachyarrhythmia (1). Nonimmune hydrops fetalis (NIHF) is a complication of fetal SVT. SVT with NIHF is associated with an intrauterine or neonatal mortality of 20-46% despite treatment (2).

Digoxin and flecainide are first-line therapies used to treat fetal SVT (2). For SVT with NIHF, digoxin is rarely effective (3), but successful conversion has been reported with flecainide (2). Amiodarone has been used for refractory cases of fetal SVT. A downside of the medication is its long half-life and fetal complications including hypothyroidism (3).

Standard amiodarone dosing is loading with 1600-2400mg/day, usually halved every 24h; maintenance dose 200-400mg/day (3). Sridaran et al. report successful conversion of SVT after six days with a loading strategy of 12-13g over one week with digoxin continued for the duration of gestation (2). We describe successful treatment of refractory SVT complicated by NIHD with amiodarone and maintenance of fetal HR with a monotherapy taper.

References:

1. J Matern Fetal Neonat Med.2018 Feb;31:407-12

2. Heart Rhythm.2016 Sep;13:1913-19

3. Circulation.2004 Jan;109:375-9

SOAP 2019