AF Septal Pacing (Clinical Investigation Plan)

The purpose of this non-randomized, non-controlled, acute, single-arm research study is to evaluate the feasibility to obtain a stable position of a ring of stimulation electrodes on the interatrial septum. The possibility to terminate atrial arrythmias will also be evaluated.

The evidence of treating AF by pacing is limited, although these algorithms are of interest, since they appear to be safe and usually add little additional cost. Using a computer model, a new dual-stage septal pacing has been developed.The proposed septal pacing algorithm could suppress AF reentries in a more robust way than classical single site rapid pacing. The feasibility of pacing both atria simultaneously from a single lead placed in the interatrial septum has been previously demonstrated clinically. The septal pacing concept has also been successfully tested in a computer model of AF and in a pig model . Experimental studies are now needed to determine whether similar termination mechanisms and efficacies can be observed in humans. The purpose of this non-randomized, non-controlled, acute, single-arm research study is to evaluate the feasibility to obtain a stable position of a ring of stimulation electrodes on the interatrial septum

Approximately 15 subjects with AF indicated for ablation of the pulmonary vein will be enrolled in the study. Participants will attend the Baseline visit and the Procedure visit. The baseline visit can be on the same day as the ablation procedure. Since it is an acute study, no follow-up visit will occur. The research procedure will be performed during an already scheduled ablation procedure. Subjects will be enrolled over a period of approximately 18 months

Patients with either paroxymal or persistent AF already referred to the center for Pulmonary Vein Ablation will be stimulated delivering a novel dual-stage pacing protocol to terminate atrial fibrillation usinf a ring of electrodes positioned on the septum.

After pulmonary vein isolation, during the routine waiting time of half an hour to confirm efficacy of the ablation, the septal catheter, already in place in right atrium, will be positioned on the interatrial septum. If the patient will not be in sinus rhythm, he/she will be externally cardioverted in order to determine pacing thresholds and impedances on all septal catheter electrodes. Next, atrial fibrillation will be induced by rapid atrial pacing.AF cycle length will be determined in the left atrial appendage, during 1 minute of atrial fibrillation using ablation catheter electrodes. Subsequently, a pacing scheme will be applied and capture on decapolar recording catheters, already in place for the standard ablation procedure will be assessed as well as AF termination.

To assess Pacing Site Stability, the number of interatrial septal pacing electrodes which are successfully placed in a stable position, will be counted. A stable position in this study is defined as a location where the pacing threshold will be < 10 mA at a pacing pulse width of 1 msec. Stable pacing further requires that no ventricular capture will be induced during atrial stimulation at twice the atrial capture threshold.

To assess Localized Atrial Capture the following endpoints will be considered: - the number of AF episodes in which local capture is recorded during atrial septal stimulation in at least one of the electrode positions

Inclusion Criteria: Patient referred to the center to undergo ablation of the pulmonary vein using radiofrequency (initial AF ablation, or redo procedure). In case of paroxysmal AF the right atrium should be dilated as indicated by > 29 ml mm2 or the left atrium should be dilated as indicated by > 34 ml mm2. Patient is willing and able to cooperate with the study procedure. Patient is willing to provide the Informed Consent for their participation in the study. Exclusion Criteria: Patients under 18 years or over 80 years old. Women who are currently pregnant or have a positive pregnancy test. Patients with an implantable cardiac device. Patients who already underwent an AF septal ablation procedure.