Episodic long-lasting atrial standstill associated with an SCN5A variant resulting in atrial pacing failure: Is an atrial lead necessary for familial atrial standstill?

Figures

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  Figure 1. Patient history and admission findings. A: Patient pedigree. He and his father had a heterozygous missense variant of the SCN5A gene (D1275N). His father was diagnosed with first-degree atrioventricular block in childhood and has not undergone pacemaker implantation. His paternal aunt and great-aunt had histories of pacemaker therapy, but genetic testing was not performed. B: Monitor electrocardiogram showing paroxysmal complete atrioventricular block during sleep. The full arrows show the P waves. C: Resting electrocardiogram in sinus rhythm of 62 beats/min with prolonged PQ interval (234 ms) on admission.

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  Figure 2. Electrocardiography findings during pacemaker implantation. A: When sedation was initiated, the patient’s cardiac rhythm changed from sinus rhythm to ventricular escape rhythm. B: During ventricular escape rhythm, we could find no atrial capture site in the right atrium. The full arrows indicate failed atrial pacing. C: When the patient was awakened and isoproterenol was administered, his cardiac rhythm returned to sinus rhythm. D: Atrial pacing capture was achieved at low power over a wide area in right atrium. The arrowheads indicate atrial pacing capture.

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  Figure 3. Postprocedural testing results. A: Electrocardiography findings before administering pilsicainide during ventricular pacing and junctional escape rhythm. The first beat is ventricular pacing, and the second beat is junctional escape rhythm. The hollow arrow shows atrial pacing failure. B: Electrocardiography findings after administering pilsicainide at 1 mg/kg intraveneously during ventricular pacing and junctional escape rhythm. The hollow arrows show atrial pacing failure, and the full arrows show coved-type ST elevation in leads V1 and V2. The first beat is ventricular pacing, and the second beat is junctional escape rhythm. C: Sequence of the proband’s genomic DNA. The arrow indicates the heterozygous G to A variant at site 3823 in the SCN5A gene (c.3823G>A, p.D1275N).