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Idiopathic 2:1 AV Block With Ventriculophasic Sinus Arrhythmia in a Young Male
Christopher Tortorici1, Gustavo Duarte1, Justin D Mark2
1Cleveland Clinic Florida, Weston, Florida, USA.
Background:
Second-degree atrioventricular (AV) block in young adults is rare and typically associated with structural, infectious, or genetic etiologies. Ventriculophasic sinus arrhythmia is classically associated with complete heart block and is rarely described in isolated 2:1 AV block.
Case Summary:
A 23-year-old male with no prior medical history presented to the clinic with influenza-like symptoms and was incidentally found to have marked bradycardia. Electrocardiogram revealed 2:1 AV Block with right bundle branch block, right-axis deviation, and ventriculophasic sinus arrhythmia. Comprehensive workup excluded structural and infiltrative disease. Exercise stress testing demonstrated transient 3:1 and 4:1 AV block, suggesting infranodal disease. A dual-chamber pacemaker was implanted with improved functional capacity.
Discussion:
This case highlights a rare presentation of idiopathic 2:1 AV block with ventriculophasic sinus arrhythmia and underscores the diagnostic value of exercise testing.
Take-Home Message:
Ventriculophasic sinus arrhythmia in 2:1 AV block may suggest intrinsic conduction system disease and supports early permanent pacing, even in minimally symptomatic patients.
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