A rare cause of neonatal bradycardia: Blocked atrial bigeminal beat

Abstract

Bradycardia is defined as a heart rate below the lowest normal value adjusted for age. It is caused by intrinsic dysfunction, injury to the heart’s conduction system or by extrinsic factors acting on a normal heart and its conduction system (1). Premature atrial contractions (PACs), are a rare cause of bradycardia. A slow heart rate may occur in that the sinus node discharges a PAC that’s blocked before causing the atria to contract (2,3). Herein, we report a newborn with frequent premature atrial contractions in bigeminal pattern. The bradycardiac patient with bradycardia was successfully treated with propafenone. Herein, we present the case of a 10-day-old infant that was referred to our department for bradycardia. A female neonate of 3100 gr and Apgar score of 8/10 at 1/5 minutes was born by normal spontaneous vaginal delivery at 39. gestational weeks. Her physical examination was normal except bradycardia. Pulse rate was 72 bpm, and blood pressure was 68/32 mmHg. Careful review of her electrocardiogram (ECG) revealed that closely coupled bigeminy PACs were blocked at the atrioventricular junction, mimicking severe sinus bradycardia (Figure 1). No significant abnormalities were found on her echocardiogram, and laboratory test results (complete blood count, biochemical panel and brain natriuretic peptide) were normal. Holter ECG monitoring showed a sinus rhythm with very frequent blocked atrial bigeminy, and short runs of atrial tachycardia. Mean heart rate was 83 bpm, while the minimal, and maximal heart rates was 63 bpm, and 98 bpm, respectively. An antiarrhythmic medication (propranolol) was started without any improvement in the antiarrhytmic control. This treatment was stopped and therapy with propafenone (300 mg/m2/d) was initiat-