Mapping and ablation of ventricular tachycardia in coronary artery disease

The different findings during electrophysiology studies may help guide the electrophysiologist in determining whether the mechanism of ventricular tachycardia (VT) is focal or macro-reentry. Additionally, in the patient with ischemic cardiomyopathy, bundle branch reentry VT should always be considered and excluded. This chapter focuses on scar-related macroreentrant VT. The primary goal of mapping in postinfarction reentrant VT is to localize the critical isthmus, where successful ablation may be applied. Pacing from the ablation catheter during VT terminates the tachycardia on the second stimulus without evidence of global capture, presumably by rendering the critical isthmus refractory at a time when it would be needed to conduct the next reentrant wave of depolarization. Recognizing that many VTs in patients with postinfarction cardiomyopathy are unmappable by classic entrain-ment techniques, investigators in the field have long sought alternative substrate-based approaches to allow safe and effective mapping and ablation.