title: A challenging EP tracing.
abstract: A 69-year-old male patient with prolonged PR interval presented with narrow QRS complex tachycardia for electrophysiological study. A discussion on different possibilities is made During tachycardia, diagnosis was made as atrioventricular nodal reentrant tachycardia, trial to ablate the slow pathway was not successful to cure the tachycardia along with a high degree atrioventricular block occurs made it more challenging for diagnosis, by studying the sequence of atrial, His and ventricular potentials diagnosis was supposed to be an accessory pathway connecting the atria with ventricle.
authors.affiliation: Department of Cardiology, The Second Xiangya Hospital of Central South University, Middle Ren-Min Road, No. 139, Changsha, Hunan 410011, China.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Salah
authors.forename: Shenghua
authors.initials: S
authors.lastname: Zhou
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
mesh_terms: D000368:Aged; D002036:Bundle of His / Q000503:physiopathology; D003937:Diagnosis, Differential; D004562:Electrocardiography; D006327:Heart Block / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis* / Q000503:physiopathology
keywords: AV nodal reentrant; Accessory pathway; High degree atrioventricular block; Prolonged PR interval