Excerpt

A 67-year-old woman with prior pulmonary vein (PV) isolation for paroxysmal atrial fibrillation presented with persistent atrial tachycardia (AT). The clinical AT had a cycle length (CL) of 202 ms. The PV-left atrium (LA) disconnection was confirmed. The AT was mapped with the Orion™ catheter and Rhythmia™ system (Boston Scientific, Marlborough, MA); 26,515 points were obtained over 11 min, with standard beat-acceptance-criteria. The map suggested that 3 ATs were simultaneously rotating as shown in Fig. 1; AT1 used the roof, posterior LA wall, mitral isthmus (MI), and lateral LA wall, as the circuit. AT 2 had a localized circuit around a small posterior LA wall scar next to the left PVs sharing AT1’s circuit at the roof and posterior LA wall. AT3 was a counter-clockwise perimitral flutter sharing AT1’s circuit on the mitral isthmus and lateral LA wall. As shown in the figure, the difference between the total CL and post-pacing-interval (PPI) was <20 ms on the roof, posterior LA, site posterior to the left PVs, MI, lateral LA, and several sites around the mitral valve, which proved those circuits rotated simultaneously but not passively. The first application was delivered at the posterior wall close to the PV (yellow dots), with assumed scar from a previous PV isolation (black dots). That was the AT2 circuit’s slow conduction zone, and the CL changed to 210 ms within 180 s. A second map was created with 31,206 points in 10 min, which demonstrated that AT1 and AT3 were simultaneously rotating. A MI line was created (purple dots) terminating the AT within 10 min. Other ATs were not induced and the patient has been free from AT for 6 months.

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