Deep inspiration unmasks Brugada syndrome

Abstract

A 40-year-old man without risk factors presented to the emergency department after a recurrent syncope at rest. Despite his excessive abdominal fat, he underwent physical training (2 h every day). Family history disclosed that his father had died suddenly during sleep at the age of 43 years. Laboratory tests were normal. Baseline ECG showed a sinus rhythm of 91 bpm, first-degree atrioventricular block (PR 220 ms), narrow QRS complex (90 ms) with incomplete right bundle branch block morphology and discrete ST-segment elevation of <0.1 in lead V1 (figure 1A). Intravenous ajmaline (1 mg/kg/5 min) 1 failed to induce diagnostic ECG changes (figure 1B), even after placement of the right precordial leads in a superior position to the third (figure 1C) and second (figure 1D) intercostal space. 1 However, at the end of maximal inspiration a type 1 Brugada pattern was reproducibly observed (figure 1E). The patient received an implantable cardioverter-defibrillator and was discharged. After 6 months he received one shock during sleep for fast ventricular tachycardia degenerating into ventricular fibrillation.Regional conduction delays and local activation gradient reduction on the free right ventricle outflow tract wall have been described in Brugada syndrome. 2 Deep inspiration may unmask a Brugada ECG owing to diaphragmatic descent with heart counterclockwise axial rotation (exposing the right ventricle outflow tract wall), augmented right ventricular filling (increased wall stress amplifying conduction anomalies) and, possibly, augmented vagal tone. The high incidence of ventricular arrhythmias during sleep may also be explained by the respiratory variations in disease expression during apnoea episodes.

Unmasking Brugada-Type Electrocardiogram on Deep Inspiration

“…The previous case report indicated that deep inspiration was useful to unmask BrS because of diaphragmatic descent and possible augmentation of vagal tone. 25 HR typically accelerates during the initial phase of inspiration, followed by deceleration toward the end of inspiration and during expiration. Thus it was suggested that inspiratory cardiac acceleration due to sympathetic tone was somewhat overcome by vagal influence at the end of deep inspiration.…”