Effects of pulsed field ablation on the parasympathetic nervous system: a mechanistic approach
Authors: Kowalewski Christopher , Bouyer Benjamin , Ascione Ciro , Vlachos Konstantinos , Benali Karim , Yokoyama Masaaki , Kneizeh Kinan , Spittler Raphael , Popa Miruna , Benabou Léa , Tixier Romain , Arnaud Marine , Pambrun Thomas , Derval Nicolas , Hocini Mélèze , Haïssaguerre Michel , Cochet Hubert , jais pierre , Sacher Frederic , Duchateau Josselin 
Published: March 2024

Background: Pulsed field ablation (PFA) is a novel technique
for pulmonary vein isolation in atrial fibrillation management. Notably,
asystole episodes of varying durations have been observed during
electroporation, but the underlying mechanisms remain unclear.
Objective: This study hypothesizes that asystole during PFA is
attributable to the activation of parasympathetic ganglia on the left
atrium’s surface. Methods: We conducted a study with 24
patients (67% male, 62.8 ± 11.0 years, BMI: 25.3 ± 5.6) suffering from
paroxysmal atrial fibrillation. The order of pulmonary veins chosen for
electroporation was randomized to avoid cumulative electroporation
effects. PFA was performed and the duration of cardiac pauses
post-electroporation was recorded for each application. To examine the
impact of electroporation on the parasympathetic nervous system,
transjugular vagal stimulation (TJVS) was performed from the right
internal jugular before and after isolation of each vein, during sinus
rhythm and atrial pacing. Continuous data were analyzed with Student’s
t-tests or Mann-Whitney U tests as appropriate; nominal data were
evaluated using chi-square or Fisher exact tests. Results:
Pre-PFA TJVS induced sinus pauses of 10.1 ± 2.74 seconds. A sinus block
of over 3 seconds was present in 23 out of 24 patients. Post-PFA, the
Right Superior Pulmonary Vein (RSPV) showed the highest decrease of
TJVS-induced sinus pauses (RSPV: before 8.41 ± 4.53 vs after 3.27 ± 3.53
sec, p<0.001, RIPV: before 6.76 ± 4.54 sec vs. 6.89 ± 5.07
sec, p=0.90; LSPV: before 6.76 ± 5.25 sec vs. after 6.93 ± 4.29 sec,
p=0.61; LIPV: before 7.80 ± 4.06 sec vs. after 7.88 ± 3.84 sec, p=0.91).
Notably, sinus blocks over 3 seconds decreased significantly after RSPV
ablation (19 before PFA, 10 after PFA, p<0.01), with less
dramatic changes in other veins (RIPV: before 19, after 16, p=0.33;
LSPV: before 14, after 19, p=0.11; LIPV: before 21, after 21, p=1.00).
RSPV PFA also had the strongest impact on TJVS-induced AV block duration
compared to the remaining veins (RSPV: before 6.49 ± 3.48 vs after 4.07
± 3.27 sec, p<0.01, RIPV: before 6.00 ± 3.29 sec vs. 4.58 ±
3.99 sec, p=0.08; LSPV: before 5.15 ± 3.94 sec vs. after 5.14 ± 3.48
sec, p=0.93; LIPV: before 6.06 ± 3.98 sec vs. after 5.83 ± 3.44 sec,
p=0.38). The incidence of AV blocks over 3 seconds was markedly reduced
post-RSPV and post RIPV ablation (RSPV: before:19 vs. after: 14, p=0.11,
RIPV: before:19 vs. after: 14, p=0.11), with minor changes in other
veins (LSPV: before 14, after 16, p=0.55; LIPV: before 17, after 18,
p=0.77). Conclusions: PFA applications during pulmonary vein
isolation have acute effect on the autonomic nervous system, as
evidenced by the decrease in TJVS-induced sinus and atrioventricular
block at the level of the right superior pulmonary vein. PFA-induced
pauses are more frequent during applications on the LSPV, and less
frequent when prior isolation of the RSPV has been performed, suggesting
a vagally-mediated mechanism involving the right superior and/or right
posterior ganglionated plexi.