Pericardial Space Exploration for Ventricular Tachycardia Mapping:

Ablation of ventricular tachycardia using radiofrequency energy is frequently successful. This includes ablation of right ventricular outflow tract tacbycardia, idiopatbic left ventricular tacbycardia, ventricular tacbycardia due to macroreentry involving tbe bundle brancbes, and ventricular tacbycardia in tbe setting of iscbemic and noniscbemic cardiomyopatbies . ' Mapping of ventricular tacbycardia requires tbe use of one or more of tbe following tecbniques: pace mapping, "P potentials" for some left ventricular tacbycardias, early ventricular activation, concealed entrainment, localization of isolated mid-diastolic potentials, and continuous electrical activity.'•^ Results from surgery suggest tbat ventricular tacbycardia circuits may involve tbe epicardial surface, and tbis involvement may be responsible for unsuccessful localization and cure in some patients.^ Tbese data imply tbat failed attempts at catbeter ablation of ventricular tacbycardia may sometimes be due to inadequate mapping, inadequate lesion size, or to an epicardial circuit and tbe inability of endocardial application of radiofrequency energy to create an epicardial lesion. Perbaps tecbniques are needed to map tbe epicardium to guide radiofrequency ablation of ventricular tacbycardia. In tbis issue of tbe Joumal of Cardiovascular Electrophysioiogy, Sosa et al.'' describe a new tecbnique for mapping tbe epicardium. Sosa et al.'' describe a tecbnique of epicardial mapping of ventricular tacbycardia witb standard electropbysiologic catbeters performed utilizing a pericardial puncture in tbree patients witb Cbagas' disease. Tbis tecbnique is novel and may provide an approacb not only to epicardial mapping, but