Figure 3.

Insertable cardiac monitor electrogram of the syncopal episode proceeding from top to bottom panels in real time. A: Sinus tachycardia with negative polarity followed by abrupt shift to ventricular tachycardia (VT) with positive polarity that was initiated by a premature ventricular contraction (black rectangle). B: Continued VT with noise entering midway through the strip. C: Underlying VT with simultaneous noise detection. The black circle denotes device rejection of the ventricular fibrillation rhythm owing to noise. D: Continued underlying VT with simultaneous noise. E: Continued VT with reduced levels of noise.