Transient Complete Atrioventricular Block During Routine Colonoscopy: A Benign Vagal Reflex Mimicking Conduction System Disease.

Complete heart block during gastrointestinal procedures is rare but clinically significant. These episodes are most commonly mediated by excessive vagal stimulation induced by sedation or endoscopic manipulation, and they typically resolve spontaneously without the need for emergent intervention. We report the case of a 68-year-old woman who developed transient complete heart block during routine colonoscopy and upper endoscopy performed under anesthesia. Her rhythm normalized without pharmacologic therapy or pacing. This case underscores the importance of recognizing vagally mediated atrioventricular (AV) block in procedural settings, as misinterpretation of these transient events may lead to unnecessary evaluations or inappropriate permanent pacemaker implantation. Increased awareness of this benign, reflex-mediated phenomenon may help clinicians avoid overdiagnosis of intrinsic conduction disease.