Case report
A 77-year-old woman with ischemic cardiomyopathy was referred for
radiofrequency catheter ablation (RFCA) for recurrent ventricular
tachycardia (VT). Mapping was performed during atrial fibrillation paced
at 60 per minute by the implanted cardioverter defibrillator because of
hemodynamically unstable VT. RFCA was performed by targeting local
abnormal ventricular activity (LAVA)1 using a
3.5-mm-tip open-irrigated catheter equipped with three microelectrodes
(MEs: Qdot MicroTM; Biosense Webster, Diamond Bar,
California). While mapping the left ventricle, the standard bipolar
electrode detected LAVA, whereas the MEs did not detect the
corresponding signals (Figure 1). What is the mechanism underlying these
apparently paradoxical electrograms?