A 46-year-old African American woman with a history of palpitations presented to the emergency department with right chest discomfort and a racing pulse. A 12-lead electrocardiogram (ECG) was obtained (Figure 1). She had a recent echocardiogram showing a structurally normal heart.
Questions: What are the ECG findings? What is the most likely diagnosis?
The electrophysiology service was consulted to assist with arrhythmia diagnosis and management. The presenting ECG revealed a regular wide complex tachycardia (WCT) with a right bundle branch block (RBBB) and left anterior fascicular block (LAFB) pattern with P waves after the QRS complexes in a 1:1 relationship. The electrophysiology service recommended intravenous adenosine as a diagnostic maneuver. A rhythm strip was recorded during the administration of adenosine (Figure 2).
Schuller JL, Varosy PD, Nguyen DT. Wide Complex Tachycardia and Adenosine. JAMA Intern Med. 2013;173(17):1644-1646. doi:10.1001/jamainternmed.2013.8513