Drug Treatment of Fetal Tachycardias

Abstract

The pharmacological treatment of fetal tachycardia (FT) has been described in various publications. We present a study reviewing the necessity for treatment of FT, the regimens of drugs used in the last two decades and their mode of administration. The absence of reliable predictors of fetal hydrops (FH) has led most centers to initiate treatment as soon as the diagnosis of FT has been established, although a small minority advocate nonintervention. As the primary form of pharmacological intervention, oral maternal transplacental therapy is generally preferred. Digoxin is the most common drug used to treat FT; however, effectiveness remains a point of discussion. After digoxin, sotalol seems to be the most promising agent, specifically in atrial flutter and nonhydropic supraventricular tachycardia (SVT). Flecainide is a very effective drug in the treatment of fetal SVT, although concerns about possible pro-arrhythmic effects have limited its use. Amiodarone has been described favorably, but is frequently excluded due to its poor tolerability. Verapamil is contraindicated as it may increase mortality. Conclusions on other less frequently used drugs cannot be drawn. In severely hydropic fetuses and/or therapy-resistant FT, direct fetal therapy is sometimes initiated. To minimize the number of invasive procedures, fetal intramuscular or intraperitoneal injections that provide a more sustained release are preferred. Based on these data we propose a drug protocol of sotalol 160 mg twice daily orally, increased to a maximum of 480 mg daily. Whenever sinus rhythm is not achieved, the addition of digoxin 0.25 mg three times daily is recommended, increased to a maximum of 0.5 mg three times daily. Only in SVT complicated by FH, either maternal digoxin 1 to 2mg IV in 24 hours, and subsequently 0.5 to 1 mg/day IV, or flecainide 200 to 400 mg/day orally is proposed. Initiating direct fetal therapy may follow failure of transplacental therapy.

Congenital heart disease, prenatal diagnosis and management

“…M o s t a r e r e p r e s e n t e d b y r e e n t r a n t supraventricular tachycardia and atrial flutter, and are diagnosed when the fetal heart rate is above 180-190 beats per minute. [43][44][45][46][47][48] In general, the strategy with a greater chance for survival encompasses an attempt to reverse arrhythmia in utero; to this end, since this procedure may be very difficult, it is important to follow strict management protocols. The most commonly used antiarrhythmic agents include digoxin, flecainide, and sotalol and, to a lesser extent, amiodarone, and they may be used alone or in combination (especially in the case of fetuses with hydrops).…”

Fetal dilated cardiomyopathy caused by persistent junctional reciprocating tachycardia

“…PJRT can be suspected when the VA interval exceeds the AV interval, but atrial ectopic tachycardia and sinus tachycardia have a similar appearance10, 11. At a FHR below 200 bpm, differentiation from sinus tachycardia is extremely difficult10, 12, and as such diagnosis of prenatal PJRT has always been retrospective.…”

Cardiopatías congénitas, diagnóstico y manejo prenatal

“…L a m a y o r í a e s t á n r e p r e s e n t a d a s p o r taquicardias supraventriculares por reentrada y aleteo auricular, y se diagnostican ante una frecuencia cardíaca fetal mayor de 180-190 latidos por minutos. [43][44][45][46][47][48] En general, la estrategia con mejor chance de sobrevida es intentar revertir la arritmia durante la etapa intrauterina para lo cual, dado que puede resultar muy dificultoso, es importante seguir protocolos estrictos de manejo. Los antiarrítmicos utilizados con mayor frecuencia son digoxina, flecainida y sotalol y, en menor medida, amiodarona, que se utilizan como monodroga o combinados (sobre todo, en fetos con hidrops).…”