ABC | Volume 112, Nº5, May 2019

Guideline Brazilian Fetal Cardiology Guidelines – 2019 Arq Bras Cardiol. 2019; 112(5):600-648 the Doppler sample volume placed at the same time reaching the pulmonary artery and vein flows. 48,129-138 7.2. Extrasystoles Extrasystoles occur in 1–3% of pregnancies. They are, usually, benign, with no consequences for the fetus. In the setting of bigeminy, trigeminy, or very frequent extrasystoles (1 for every 3–5 fetal heartbeats), differential diagnosis with ventricular extrasystoles, long QT syndrome, and second-degree atrioventricular block may be difficult. The presence of blocked bigeminy increases the risk of SVT triggering. 139-141 7.2.1. Isolated Supraventricular Extrasystoles Correspond to premature atrial contractions (A wave), that may or may not be followed by ventricular activity (conducted or blocked, respectively). They may occur with bi- or trigeminy, compensatory pauses, or in series. They are considered benign arrhythmias, and do not require treatment. About 1% of conducted ectopic beats may trigger tachyarrhythmias. 48 7.2.2. Ventricular Extrasystoles Ventricular extrassystoles are ventricular ectopic beats that are not related to atrial activity. Table 7.1 shows the summary of in utero management of irregular rhythms. 7.3. Fetal Bradycardia Fetal bradycardia is considered when the fetal heart rate of < 110 bpm. When treatment is necessary, it is important to identify its cause and mechanism. 7.3.1. Sinus Bradycardia Sinus bradycardia is diagnosed when the heart rate is < 110 bpm with a 1:1 A:V conduction. It is usually a vagal response secondary to hypoxia or umbilical cord Table 7.1 – In utero management of irregular rhythm Diagnosis Cause In utero management GOR/LOE Comments Second-degree AVB Autoimmune Dexamethasone IIb/B This may stop progression to CAVB Structural CHD Weekly follow-up I/C If possible, perform FMCG to rule out LQTS Channelopathy Weekly follow-up I/C VPC or frequent APC Idiopathic Observation with obstetric evaluation of fetal HR weekly until the arrhythmia is resolved (bigeminy, trigeminy, or 1 ES at every 3–5 beats) I/A 2% also have first- or second-degree AVB Oval fossa aneurysm For APC, there is a 0.5–1% risk of developing SVT For VPC, the risk of developing VT is unknown Most episodes are benign and of short duration Evaluate secondary causes Secondary causes VPC or frequent APC Myocarditis Observation with evaluation of FHR at weekly intervals I/C Frequent evaluation (every 1–2 week) of heart function and other parameters of fetal CHF Cardiac tumors Observation with obstetric evaluation of FHR weekly I/C Ventricular or atrial diverticula or aneurysm Observation with FHR assessment by OB weekly I/C Maternal stimulants Observation with FHR assessment by OB I/C APC: atrial premature contractions; AVB: atrioventricular block; CAVB: complete atrioventricular block; CHD: congenital heart disease; CHF: congestive heart failure; FHR: fetal heart rate; FMCG: fetal magnetocardiography; GOR: grade of recommendation; LOE: level of evidence; LQTS: long QT syndrome; SVT: supraventricular tachycardia; VPC: ventricular premature contraction; VT: ventricular tachycardia. Source: adapted from Donofrio et al. 17 627