Low-Level EMF Stimulation for Paroxysmal Atrial Fibrillation
Condition: Atrial Fibrillation; Catheter Ablation; Autonomic Imbalance
MeSH terms: Atrial Fibrillation
Study type: Interventional

Summary: 
      This research has two main specific aims. First, a commercially-available stimulator will be
      utilized to assess the effect of low-level electromagnetic field (EMF) stimulation on atrial
      fibrillation (AF) inducibility in patients with paroxysmal AF presenting for catheter
      ablation as compared to sham stimulation. We hypothesize a reduction in AF inducibility in
      patients treated with EMF stimulation. Second, we aim to assess for the effect of low-level
      EMF on level of systemic inflammatory mediators. We hypothesize a reduction in the level of
      the inflammatory mediator tissue necrosis factor (TNF)-α in patients treated with EMF
      stimulation as compared to sham stimulation. The long-term objective of this research is to
      develop low-level EMF as a therapeutic alternative for patients with AF, and this research
      will help to determine the efficacy of low-level pulsed EMF in this regard.
    

Detailed description: 
      This is a prospective, randomized, sham-controlled trial. Patients will be enrolled upon
      presentation to our electrophysiology (EP) lab for ablation of paroxysmal AF. After informed
      consent is obtained, the patient will be randomized to one of two protocols that have been
      pre-programmed into the magnetic field stimulator. As described below, one of the protocols
      will be an active stimulation protocol, and one will be sham (i.e. no stimulation delivered).
      These will be named "Stim 1" and "Stim 2" in the computer. Because the specifics of the
      protocol are programmed into the stimulator by the device manufacturer, investigators will
      not know which of these two protocols is active vs. sham. The patient will then be brought to
      the EP lab for the procedure and will be placed on the lab table with their head positioned
      in the magnetic coil. Vascular access will then be obtained and diagnostic catheters placed
      as is standard practice for AF ablation.

      Because the study is limited to patients with paroxysmal AF, patients will begin the study in
      normal sinus rhythm (NSR). Before the experimental protocol is begun, baseline
      electrophysiologic intervals will be recorded as is standard practice for all patients
      presenting for EP study. This will include measurement of the atrio-ventricular nodal
      effective refractory period (AVNERP) using programmed stimulation from the right atrial (RA)
      appendage, atrio-his (AH) interval, and his-ventricular (HV) interval per standard practice.
      Burst atrial pacing will then be utilized to induce AF. Measurements of the number of burst
      pacing attempts required to induce AF, as well as the AF cycle length, and duration of
      pacing-induced AF will be recorded. Attempts at AF induction will occur for 15 minutes. Prior
      to induction of AF, 5ml of venous blood will be drawn from the central venous sheaths to
      measure baseline levels of the inflammatory mediator (TNF)-α. These samples will be stored
      for analysis.

      After baseline measurements are obtained, the coil will be turned on and whichever protocol
      the patient has been assigned to will be run. The system to be used contains a
      signal-generator coupled to a Helmholtz coil capable of producing a magnetic field in
      response to an electric current. The Helmholtz coil itself is has 9 inches of separation in
      between the two coils that allows for placement of the coil around the participant's head and
      upper neck. The choice of the head and neck as the site of stimulation is intended to target
      the vagus nerve as it exits the jugular foramen to course caudally in the carotid sheath. The
      system is designed to create a homogenous, isotropic magnetic field with a field strength
      from 1 to 99 pico-Tesla (pT) with a frequency range of 0.01 Hz to 50 Hz.

      Active Stimulation will involve application of a pulsed-EMF with the parameters 0.032
      micro-gauss (µG) at 0.89 Hz for 60 minutes. In participants randomized to sham stimulation,
      the coil will be positioned around the neck as previously described, but no current will be
      applied to the stimulator.

      During the 60 minute stimulation time, trans-septal puncture and mapping of the left atrium
      will be performed as is standard practice for this procedure, but no ablation will be
      performed. After the 60 minute protocol is complete, venous blood samples will again be drawn
      (within 5 minutes of protocol completion), stored, and analyzed as previously described. If
      the patient remains in AF after the end of the 60 minute session, they will be electrically
      cardioverted to sinus rhythm. The same stimulation protocol as described previously will
      again be employed, again noting number of attempts required to induce AF, duration of
      pacing-induced AF, AF cycle length, and measurements of AVNERP, AH, HV intervals and levels
      of TNF-α.
    

Intervention name(s): Low-level Pulsed EMF; Sham Stimulation
Intervention type(s): Device; Device
Intervention description(s): Low-level pulsed electromagnetic field stimulator delivered through a Helmholtz coil positioned around the participant's head and neck. Stimulation parameters are 0.032 µG at 0.89 Hz for 60 minutes.; The stimulator will be placed around the participant's head and neck, but no EMF will be delivered.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment