Ischemic etiology for adenosine-sensitive fascicular tachycardia

Adenosine-responsive ventricular tachycardias (VTs) typically occur in patients without structural heart disease; and thus, its association with myocardial ischemia is rare. In this case report, we describe a patient who had demonstrable ischemia along the anterolateral wall of the left ventricle and who developed a VT that was clinically terminated with adenosine. Surface electrocardiogram demonstrated a monomorphic VT with a right bundle-branch block morphology and a rightward axis configuration, and electrophysiologic testing showed atrioventricular dissociation upon atrial pacing and retrograde His waves following induction of VT. These findings localized the patient's VT to the left anterior fascicle, an anatomical region that coincided with the patient's territory of ischemia. We describe the electrophysiologic testing involved in elucidating the patient's tachyarrhythmia, and we provide a brief discussion of the pathogenesis and clinical features of adenosine-sensitive VT. Our case demonstrates that heterogeneous mechanisms of VT are operative in patients with ischemic heart disease.