This tracing demonstrates unidirectional conduction during a PV isolation procedure. At onset, there is conduction from the left atrium (LA) into the left superior PV [LSPV; †, far-field atrium (A) followed by PV potentials (PVPs)] interspersed with paced beats demonstrating local PV capture (*) without conduction to the LA. Following the fourth paced impulse, a spontaneous discharge lasting 2.4 s is observed within the PV, dissociated from sinus rhythm (‡). Mechanistically, the small density PV current fails to excite the LA (exit block); however, the larger LA electrical mass is able to activate the injured but viable LA–PV junction (entrance conduction).
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: [email protected].
