Editor’s Perspective: Reentry, Pseudo-Reentry, and Pseudo-Pseudo-Reentry
A dichotomy exists as to the ease and success of ablation for focal origin when compared with macroreentrant tachyarrhythmias, and inexact diagnosis of the arrhythmia mechanism is often a factor. In this installment of Teaching Rounds in Electrophysiology, Selvaraj et al1 present findings in a patient with previous tetralogy of Fallot repair and ventricular tachycardia. They use this case to teach us how the visual interpretation of electroanatomic maps can be misleading, and most importantly, they underscore the value of defining arrhythmia mechanism.
Article see p 553
Color-coded electroanatomic maps are meant to facilitate our ability to recognize activation sequences. We learn what is early and where the circuits are located… Or do we?
When “Early” Site Ablation Is Ill-Advised
Once a reference point, which for ventricular tachycardia is often a recognizable portion of the QRS, is established and a window of interest, typically spanning the cycle length of the tachycardia, is chosen, one can readily recognize sites of early activation coded red on the activation map display. For focal source tachycardias, ablation at such sites is likely to be successful. However, caution is required when targeting these sites in some instances.
Automatic or localized reentrant fascicular tachycardia may have exits from the Purkinje system to the ventricular myocardium at potentially distant and multiple sites away from the true tachycardia origin. Early ventricular electrograms, when compared with the QRS, simply identify the breakout sites of the tachycardia, as well as sinus rhythm.
Supravalvar and Thoracic Vein Arrhythmia
Tachycardia that originates in one of the cul-de-sacs of the heart (atria or ventricle) may similarly enter the myocardium of the cardiac chamber at one or multiple locations that may be relatively distant from the true origin. Unless the true origin outside …