Perioperative Medicine  |   June 2017
Effect of Thoracic Epidural Anesthesia on Ventricular Excitability in a Porcine Model
Author Notes
  • From the Department of Anesthesiology and Perioperative Medicine (K.H.-Q., T.T., E.A.D., K.Y., W.Z., A.M.), UCLA Cardiac Arrhythmia Center (U.B., A.M.), and UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine (K.H.-Q., U.B., A.M.), University of California, Los Angeles (UCLA), Los Angeles, California.
  • This article is featured in “This Month in Anesthesiology,” page 1A.
    This article is featured in “This Month in Anesthesiology,” page 1A.×
  • This article has a video abstract.
    This article has a video abstract.×
  • Submitted for publication September 20, 2016. Accepted for publication January 31, 2017.
    Submitted for publication September 20, 2016. Accepted for publication January 31, 2017.×
  • Address correspondence to Dr. Mahajan: Department of Anesthesiology and Perioperative Medicine, David Geffen School of Medicine at UCLA, 757 Westwood Blvd., Suite 3325, Los Angeles, California 90095. amahajan@mednet.ucla.edu. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.
Article Information
Perioperative Medicine / Basic Science / Cardiovascular Anesthesia / Regional Anesthesia
Perioperative Medicine   |   June 2017
Effect of Thoracic Epidural Anesthesia on Ventricular Excitability in a Porcine Model
Anesthesiology 6 2017, Vol.126, 1096-1106. doi:10.1097/ALN.0000000000001613
Anesthesiology 6 2017, Vol.126, 1096-1106. doi:10.1097/ALN.0000000000001613
Abstract

Background: Imbalances in the autonomic nervous system, namely, excessive sympathoexcitation, contribute to ventricular tachyarrhythmias. While thoracic epidural anesthesia clinically suppresses ventricular tachyarrhythmias, its effects on global and regional ventricular electrophysiology and electrical wave stability have not been fully characterized. The authors hypothesized that thoracic epidural anesthesia attenuates myocardial excitability and the proarrhythmic effects of sympathetic hyperactivity.

Methods: Yorkshire pigs (n = 15) had an epidural catheter inserted (T1 to T4) and a 56-electrode sock placed on the heart. Myocardial excitability was measured by activation recovery interval, dispersion of repolarization, and action potential duration restitution at baseline and during programed ventricular extrastimulation or left stellate ganglion stimulation, before and 30 min after thoracic epidural anesthesia (0.25% bupivacaine).

Results: After thoracic epidural anesthesia infusion, there was no change in baseline activation recovery interval or dispersion of repolarization. During programmed ventricular extrastimulation, thoracic epidural anesthesia decreased the maximum slope of ventricular electrical restitution (0.70 ± 0.24 vs. 0.89 ± 0.24; P = 0.021) reflecting improved electrical wave stability. Thoracic epidural anesthesia also reduced myocardial excitability during left stellate ganglion stimulation–induced sympathoexcitation through attenuated shortening of activation recovery interval (−7 ± 4% vs. −4 ± 3%; P = 0.001), suppression of the increase in dispersion of repolarization (313 ± 293% vs. 185 ± 234%; P = 0.029), and reduction in sympathovagal imbalance as measured by heart rate variability.

Conclusions: Our study describes the electrophysiologic mechanisms underlying antiarrhythmic effects of thoracic epidural anesthesia during sympathetic hyperactivity. Thoracic epidural anesthesia attenuates ventricular myocardial excitability and induces electrical wave stability through its effects on activation recovery interval, dispersion of repolarization, and the action potential duration restitution slope.