Fig. 3.

Intracardiac recordings of ET-GP response reproducibility with synchronised HFS. A and B are from the same patient. C and D are from two different patients. In all the examples, pacing and HFS are delivered from the Map catheter.

A) In the left panel, a second train of HFS produced a PV ectopy which repeated itself after two further HFS. This response was reproducible upon re-testing the same site with HFS in the right panel. The PV ectopy in the right panel has different activation pattern to the left panel PV ectopy. The Map catheter was in the left side of the mid-posterior wall. The PV catheter was in the LIPV.

B) In the same patient as A), a different site was tested with HFS in the left panel. This produced a PV ectopy after the 4th train of HFS, which repeated after 2 further HFS trains. Upon re-testing the same site with HFS, the right panel shows an early PV ectopy in PV 17–18 which initiated rapid PV discharges, causing 3.5 s of AF. The Map catheter was near the base of the LIPV in the posterior wall, 10 mm superior to the Map position from A). The PV catheter was in the LIPV.

C) In a different patient to A/B), a PV ectopy initiated after several trains of HFS which induced 7.6 s of AF. Re-testing this site in the right panel showed repeated PV ectopy which induced 4.5 s of AF. The Map catheter was at the base and ostium of the LIPV in the posterior wall. The PV catheter was in the LIPV.

D) In a different patient to A/B) and C), one negative HFS site was re-tested five times, with no positive response to HFS in each re-test. The Map catheter was medial to the appendage in the anterior wall and the PV catheter was in the left superior PV. This was repeated in 9 other patients which produced the same outcome of negative responses to HFS with up to five re-tests at the same site.

(Same abbreviations as in Fig. 1)