The Response to Adenosine Tells All: What Is the Mechanism?

CASE PRESENTATION A 19-year-old man was referred to our hospital for the ablation of a narrow QRS complex tachycardia (Figure 1A). The tachycardia was terminated by 10 mg of adenosine-triphosphate (ATP) (Figure 1B). The electrocardiogram during sinus rhythm is also shown (Figure 1C). What is the mechanism of this wide QRS tachycardia?