Electrophysiological mapping and ablation
Procedures were carried out under general anaesthetic. With the
exception of amiodarone, antiarrhythmic drugs were stopped a minimum of
five days prior to the procedure. Venous access was obtained via
bilateral femoral vein puncture under direct ultrasound guidance.
Heparin boluses were administered prior to trans-septal puncture
followed by continuous heparin infusion to maintain an ACT
>350s. A decapolar catheter (Inquiry, Abbott Medical) was
inserted into the coronary sinus through an AcQRef (Acutus Medical)
sheath which includes a distal electrode used as a unipolar reference.
The first AcQMap catheter was advanced over a 0.032 guide wire into the
RA via an AcQGuide (Acutus Medical) sheath and ultrasound used to
reconstruct the right atrial chamber anatomy as previously described.(7)
The ablation catheter (Tacticath, Abbott Medical) was advanced via an
Agilis sheath into the left atrium across the single transseptal
puncture site. The second AcQGuide sheath was then exchanged for the
transseptal access sheath over the guide wire and a second AcQMap
catheter advanced into the LA (see figure 2). The LA anatomy was then
generated with ultrasound. A circular mapping catheter (Inquiry Optima
or Advisor Variable Loop, Abbott Medical) was used to undertake
electroanatomic voltage mapping and guide pulmonary vein isolation.
In a subset of 9 patients, activation maps were obtained using Supermap
during pacing from up to three atrial sites (left atrial appendage, high
right atrium and proximal coronary sinus) with direct cardioversion used
to restore sinus rhythm where necessary. Pacing consisted of a 4-beat
drive train at 800ms cycle length followed by a single extrastimulus
with coupling interval 20ms above the effective refractory period and
was mapped using the AcQMap Supermap algorithm. Additional details are
provided in the supplementary methods.
In patients attending the procedure in sinus rhythm AF was induced using
burst atrial pacing, otherwise all AF recordings were obtained prior to
DCCV. Once AF was established, recordings of 2 minutes duration were
generated and time alignment between systems facilitated using a below
threshold pacing stimulus from the coronary sinus catheter of 4 beats at
1000, 800 and 600ms intervals and 12 second rest period. Pulmonary vein
isolation was performed using contact force guided radiofrequency
ablation using 40-50 Watts (Tacticath ablation catheter, Abbott
Medical). Simultaneous biatrial AF mapping was repeated following
completion of PVI. Additional ablation and AF mapping was undertaken at
the discretion of the operator.