Ablation Settings and Endpoints
Radiofrequency current should be applied in a point-by-point fashion in
power-controlled mode with an open irrigated-tip catheter.
Radiofrequency energy is limited to 35 watts along the left atrial
posterior wall and roof, and to 40 watts in the remaining areas for
duration of at least 30 seconds at each site. The ablation endpoint for
each GP is defined as the complete elimination of all targeted EGMs and
elimination of positive VR following ablation at any site that
demonstrated positive response in the previous ablation attempt(s).
In patients with VVS, achievement of 75% of the sinus rate that was
detected during pre-ablation atropine response test may be accepted as
clinical endpoint. In patients with functional atrioventricular block,
the clinical endpoints should be as follows: in patients with persistent
atrioventricular block,
achievement of 1:1 atrioventricular conduction; in patients with
paroxysmal atrioventricular block, achievement of at least one of the
following: 75% of the final PR interval that was recorded during
pre-ablation atropine response test, a reduction in PR interval of
greater than 25%, or achievement of final sinus rate of <75%
of that was recorded during the pre-ablation atropine response test.
Pachon et al (34) used extracardiac vagal stimulation (ECVS) to evaluate
procedural endpoints. As a main advantage of the technique, denervation
effect of sinus and atrioventricular nodes can be evaluated in
real-time. Furthermore, response to ECVS might be more specific to
quantify the vagal denervation than simple increase in the heart rate
(34). However, this technique requires the ECVS hardware whose
availability is limited.