Adenosine sensitive left ventricular summit ventricular tachycardia in a pre-adolescent: case report

Sustained forms of tachycardia especially from the left ventricular summit are rare. Adenosine sensitive outflow tachycardias, especially from the left ventricular summit, are rarer still. These arrhythmias may be exercise or stress induced as they are facilitated by catecholamines and characteristically terminate with adenosine, vagal manoeuvres, and beta-blockers. The surface 12-lead electrocardiogram can be used to localize the anatomic site of origin before catheter ablation; however, prediction of the precise origin may still be challenging due to the intimate and complex anatomy of the outflow tracts.

A 12-year-old female presented to an emergency room with frequent runs of wide complex tachycardia that terminated with adenosine but would spontaneously reinitiate. After three additional temporary terminations with adenosine and because of an inability to completely eliminate tachycardia, she was started on an esmolol infusion that resulted in an abrupt termination of tachycardia. At follow-up, she reported breakthrough episodes of tachycardia with exercise, especially associated with beta-blocker non-compliance. The rest of her cardiac testing was normal apart from an anomalous right coronary artery origin from the left coronary sinus. Given the increased frequency of symptomatic palpitations and medication non-compliance, she underwent an electrophysiology study. During the study, a ventricular tachycardia was successfully mapped to an epicardial focus at the left ventricle summit and was successfully ablated.

The response of this patient's ventricular tachycardia to adenosine suggests a triggered mechanism. To our knowledge, this is the first unambiguous example of left ventricular tachycardia due to cAMP-mediated triggered activity in this age group.