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. Author manuscript; available in PMC: 2010 Sep 30.
Published in final edited form as: Circulation. 2007 Nov 12;116(22):2535–2543. doi: 10.1161/CIRCULATIONAHA.107.696583

Figure 4.

Figure 4

Class II mutants exhibited intermittent use of bypass tracts. A, Surface ECG of a class II mutant showed normal AV conduction. B, vECG of the same heart after isolation and Langendorff perfusion clearly demonstrated conduction through a bypass tract. C and D, Activation maps showed bypass conduction (C) followed by a collision beat (D) where signals were coming both from the apex and the base of the ventricle in a single heart. E, vECG data from the same heart demonstrated intermittent use of the bypass during pacing. First 2 beats had a short PR interval, which indicates accessory pathway conduction, whereas the next 3 beats were conducted through the AV node. P indicates atrial depolarization; QRS, ventricular depolarization; LV, left ventricle; RV, right ventricle; A, apex; and Stim, stimulus.