Available online 6 December 2023

A 31-year-old woman reported dizziness in the early postpartum period after receiving dexmedetomidine. The ECG was misinterpreted as complete heart block; however, more careful analysis revealed an atypical Wenckebach pattern with dual AV nodal conduction and termination of nonconducted P waves with junctional escape beats. The patient's rhythm returned to sinus after stopping dexmedetomidine.

Atypical Wenckebach patterns account for greater than 50% of patients with Mobitz Type I AV block and can be misinterpreted as high degree AV block. This case highlights causes of atypical Wenckebach patterns and how careful analysis of intervals can help clinicians avoid misdiagnosis.

A 31-year-old woman without any prior history of cardiac disease with an intrauterine pregnancy at 37 weeks was admitted to the hospital in labor. She received dexmedetomidine for analgesia during labor. Three hours after delivery, the patient reported dizziness. Vital signs included a heart rate of 48 beats per minute, respiratory rate of 20 beats per minute, blood pressure of 135/65 mmHg, and room air oxygen saturation of 98%. Her only medications included a prenatal vitamin. Her

Two key features of typical Wenckebach periodicity are grouped beating and RP-PR reciprocity. [1] In “typical” Wenckebach, the prolongation of the PR interval occurs in decreasing increments; the PR interval may increase by 100 ms, then 50 ms, and so forth until there is a nonconducted P wave and subsequent pause. [1] The pause results in grouped beating, which clinicians quickly recognize as a clue pointing towards 2nd degree AV block. [1,2] However, 50% or more of patients with Mobitz Type I

Written consent has been obtained from the patient for publication of their medical case and ECG images.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

John M. Cunningham: Conceptualization, Supervision, Writing – original draft, Writing – review & editing. Ann Mackey: Conceptualization, Writing – original draft, Writing – review & editing. Charles Tharp: Conceptualization, Supervision, Writing – original draft, Writing – review & editing.

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