Methods
Single operator CF and VISITAG™ Module-guided PVI was performed using a
previously reported standardised protocol6 in
consecutive, unselected adult patients with symptomatic AF undergoing
first-time PVI according to current treatment
indications.7 Briefly, all procedures were undertaken
using GA and IPPV, with respiratory motion “training” undertaken
pre-ablation and applied as required to complete the
CARTO®3 geometry (V.3, Biosense Webster).
Specifically, respiratory motion training was first performed with a
LASSO®Nav catheter (Biosense Webster, 2-5-2mm
inter-electrode spacing) within the right superior PV. If there was
insufficient respiratory motion to trigger its detection, the catheter
was placed within the left inferior PV and respiratory motion training
re-checked. The tidal volume was never deliberately increased, so
respiratory motion detection was negative in some cases. When
respiratory motion detection was triggered, RMA (ACCURESP™) remained
“off”; i.e. RMA was never applied to automated RF annotation during
PVI.
Temperature-controlled RF at 30W (17ml/min irrigation,
48oC) was delivered via a SmartTouch® (Biosense
Webster) catheter using Agilis™ NxT sheath (Abbott, St Paul, MN) support
during proximal pole CS pacing at 600ms. Filter preferences for
automated RF annotation were: Positional stability range 2mm, tag
display duration 3s; force-over-time 100% minimum 1g (the latter
derived from a previous study8 and designed to ensure
on-going RF annotation only in the presence of constant catheter-tissue
contact). RF delivery was guided by automated RF annotation, with the
preferred site of first RF application at the LAPW opposite each
superior PV ~1cm from the PV ostium. The target
annotated RF duration at each first-ablated LAPW site, as well as any
subsequent “RF ON” sites and at the carina (if ablated) was 15s,
whereas ~9-11s was the target for all other sites
consecutively annotated during continuous RF delivery. Following the
required period of first-site annotated RF delivery, target ITD ≤6mm was
achieved predominantly during continuous RF application using
deliberate, rapid movement of the catheter tip initiated via the Agilis
sheath, aided by the distance measurement tool; point-by-point RF was
also applied as necessary. Following completion of circumferential PVI
(entrance and exit block), spontaneous recovery of PV conduction was
assessed and eliminated during a minimum 20-minute wait; dormant
recovery was evaluated and eliminated a minimum of 20 minutes after the
last RF. Neither oesophageal luminal temperature monitoring nor
post-ablation endoscopic evaluation was employed.
All cases where respiratory motion detection occurred were used to
retrospectively assess the effects of RMA on automated RF annotation at
the LAPW. VISITAG™ annotated RF and UE morphology change data were
retrospectively collected; ablation naïve LAPW sites were examined (i.e.
first encirclement during continuous RF delivery, not including touch-up
lesions), with annotated RF duration, mean CF, force time integral (FTI)
and impedance drop data for each site obtained via the VISITAG™ export
function. To examine the effects of RMA, RF data export was performed
separately for ACCURESP™ “on” and “off”: at each setting, ITD was
determined on-line using the proprietary measurement tool. Retrospective
UE analyses were performed using recorded signals (CARTOREPLAY™,
Biosense Webster) as previously described6:
electrograms were automatically deleted at 12-18 hours after case
completion (a CARTO®3 system function), so UE
morphology data was only obtained for the ACCURESP™ “off” setting.
This work received IRB approval for publication as a retrospective
service evaluation. All patients provided written, informed consent.