ABC | Volume 112, Nº5, May 2019

Guideline Brazilian Fetal Cardiology Guidelines – 2019 Arq Bras Cardiol. 2019; 112(5):600-648 Figure 7.5 – Flowchart treatment for supraventricular tachycardias. ECV: electric cardioversion; IV: intravenous; PO: orally. Sustained or paroxysmal supraventricular tachycardia Atrial flutter Hospitalization With hydrops 1° line – Maternal digoxin: loading dose of 0.5 mg every 8 hrs until 2–3 mg has been completed, following by maintenance dose of 0.25–0.75 mg/day, keeping maternal digoxin levels at 1–2 ng/ml IB 1° line – maternal sotalol: start with 80–160 mg/day, increasing 40–80 mg every 3 days (maximum: 480 mg/day) [Check maternal QTc] IB Discharge after 5 days Sinus rhythm reversed Not reversed Outpatient follow-up every 2–3 weeks until birth Without hydrops With hydrops Has not reached pulmonary maturity IB Maintain maternal digoxin for 1–2 weeks Has reached pulmonary maturity 2° line – maternal sotalol: start with 160 mg/day, increasing 40–80 mg every 5 days (maximum: 480 mg/day) Elective delivery at term, without requiring immediate cardiological treatment Reversed Not reversed Elective C section for neonatal treatment (ECV or medication) Has not reached pulmonary maturity Has reached pulmonary maturity Reversed Not reversed IB 3° line – maternal amiodarone: 800 mg – 1.2 g IV/10 min + continuous infusion 1 mg/min, monitor maternal ECG (or PO) IB 2° line – maternal sotalol: start with 160 mg/day, increasing 40–80 mg every 5 days (maximum: 480 mg/day) Reversed – maintain amiodarone PO 200–600 mg/day Not reversed Maintain Sotalol for 2–3 weeks without changing dosage. Then, decrease 40 mg every 3 days, until interruption, maintaining only digoxin. If tachyarrhythmia returns, restart initial treatment plan. Not reversed Reversed Has reached pulmonary maturity Cordocentesis: amiodarone (15 mg/ kg estimated weight) If sinus rhythm persists for more than 10 days, weekly outpatient follow-up. Elective delivery with neonatal cardiological follow-up (delivery at the fetal cardiology center or tertiary hospital) Has not developed hydrops Has developed hydrops Wait for pulmonary maturity Delivery for ECV Interrupt gestation for C section at tertiary hospital for neonatal treatment (ECV) Has not reached pulmonary maturity Reversed: maintain amiodarone PO 200–600 mg/day + weekly follow-up and elective delivery Not reversed: Wait for fetal pulmonary maturity and C section at a tertiary hospital for neonatal treatment (ECV) Some centers use flecainide (not commercially available in Brazil) or sotalol as first-choice drugs. 130,177,183,184 After birth, treatment should be based on the therapy used in utero and on the tachycardia mechanism. It is recommended to maintain therapy for 6 months to 1 year, in accordance with the outcome. About 50% of cases of fetal SVT do not recur after birth. 185 For AF, recommended medication for initial treatment may be either digoxin and/or sotalol. 185 Sotalol is also safe and efficient with a reversal rate to sinus rhythm of 50–80%, without mortality. 177 Doses and forms of administration for AF are as previously described for SVT. Following delivery, synchronized cardioversion is indicated when there is no in utero reversal. After birth, AF does not usually recur once it has been reversed and maintenance of medical treatment is not recommended. Sustained ventricular tachycardia with ventricular rate < 200 bpm is usually well tolerated; when it exceeds this rate, transplacental magnesium is recommended. This infusion should not be administered for more than 48 hours. 172,186,187 If ventricular tachycardia recurs, a new dose of magnesium may be used, provided that maternal serum levels are < 6 mEq/L and there are no signs of toxicity. Therapeutic options for pharmacological treatment of sustained ventricular tachycardias include oral administration of amiodarone, propranolol, and mexiletine or maternal intravenous lidocaine. Amiodarone, sotalol, and flecainide cannot be used when there is long QT syndrome. 186,187 When ventricular tachycardia is secondary to myocarditis or maternal antibodies, intravenous dexamethasone and immunoglobulin may be administered to the mother. This treatment should be continued after birth. One should consider that treatment of fetal sustained tachycardias is slow and its goal is to bring gestation to term. Total reversal of arrhythmia and hydrops may occur several weeks after initiation of medical treatment. A concomitant Doppler ultrasound, performed by the obstetrician, is essential to decide if the delivery should be anticipated. Delivery anticipation should be limited to fetuses with imminent risk of in utero death. If sustained tachycardia persists in fetuses with severe hydrops and proven pulmonary maturity (after week 34 of gestation), it 635