EXPLORING POSTINFARCTION REENTRANT VENTRICULAR-TACHYCARDIA WITH ENTRAINMENT MAPPING

Ventricular tachycardia late after myocardial infarction is usually du e to reentry in the infarct region. These reentry circuits can be larg e, complex and difficult to define, impeding study in the electrophysi ology laboratory and making catheter ablation difficult. Pacing throug h the electrodes of the mapping catheter provides a nea approach to ma pping. When pacing stimuli capture the effects on the tachycardia depe nd on the location of the pacing site relative to the reentry circuit, The effects observed allow identification of various portions of the reentry circuit, without the need for locating the entire circuit. Ist hmuses where relatively small lesions produced by radiofrequency cathe ter ablation can interrupt reentry can often be identified. A classifi cation that divides reentry circuits into one or more functional compo nents helps to conceptualize the reentry circuit and predicts the like lihood that heating with radiofrequency current will terminate tachyca rdia. These methods are helping to define human reentry circuits.