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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

Using simultaneous video-EEG-ECG-oximetry-capnography, we developed a methodology to evaluate the susceptibility of rabbit models to develop provoked arrhythmias and seizures. This novel recording system establishes a platform to test the efficacy and safety of therapeutics and can capture the complex cascade of multi-system events that culminate in sudden death.

Abstract

Patients with ion channelopathies are at a high risk of developing seizures and fatal cardiac arrhythmias. There is a higher prevalence of heart disease and arrhythmias in people with epilepsy (i.e., epileptic heart.) Additionally, cardiac and autonomic disturbances have been reported surrounding seizures. 1:1,000 epilepsy patients/year die of sudden unexpected death in epilepsy (SUDEP). The mechanisms for SUDEP remain incompletely understood. Electroencephalograms (EEG) and electrocardiograms (ECG) are two techniques routinely used in the clinical setting to detect and study the substrates/triggers for seizures and arrhythmias. While many studies and descriptions of this methodology are in rodents, their cardiac electrical activity differs significantly from humans. This article provides a description of a non-invasive method for recording simultaneous video-EEG-ECG-oximetry-capnography in conscious rabbits. As cardiac electrical function is similar in rabbits and humans, rabbits provide an excellent model of translational diagnostic and therapeutic studies. In addition to outlining the methodology for data acquisition, we discuss the analytical approaches for examining neuro-cardiac electrical function and pathology in rabbits. This includes arrhythmia detection, spectral analysis of EEG and a seizure scale developed for restrained rabbits.

Introduction

Electrocardiography (ECG) is routinely used in the clinical setting to assess the dynamics of cardiac electrical conduction and the electrical activation-recovery process. ECG is important for detecting, localizing, and assessing the risk of arrhythmias, ischemia, and infarctions. Typically, electrodes are affixed to the patient's chest, arms, and legs in order to provide a three-dimensional view of the heart. A positive deflection is produced when the direction of myocardial depolarization is toward the electrode and a negative deflection is produced when the direction of myocardial depolarization is away from the electrode. Electrographic components of the cardi....

Protocol

All experiments were carried out in accordance with the National Institutes of Health (NIH) guidelines and Upstate Medical University Institutional Animal Care and Use Committee (IACUC). In addition, an outline of this protocol is provided in Figure 1.

1. Preparing recording equipment

  1. Connect the computer to an amplifier with a 64-pin headbox.
    NOTE: Each animal has four straight subdermal scalp pin electrodes (7 or 13 mm) for EE.......

Representative Results

The method described above is capable of detecting abnormalities in the electrical conduction system of the brain and the heart as well as respiratory disturbances. A data acquisition software is used to assess the ECG morphology and detect any abnormal heart rates, conduction disturbances, or ECG rhythms (atrial/ventricular ectopic beats, and brady-/tachy-arrhythmias) (Figure 6). In addition to visualizing the ECG morphology, the traces are analyzed to quant.......

Discussion

This experimental setup facilitates detailed simultaneous video-EEG-ECG-oximetry-capnography recordings and analyses in rabbits, particularly in models of cardiac and/or neuronal diseases. The results of this article show that this method is capable of detecting seizures and arrhythmias and differentiating them from electrographic artifacts. Expected results were obtained when giving rabbits a proconvulsant, which induced seizures. The data obtained from the video-EEG recordings were able to be further analyzed to differ.......

Acknowledgements

Authors acknowledge this study was supported by grants from the American Heart Association, American Epilepsy Society, and SUNY Upstate Department of Pharmacology.

....

Materials

NameCompanyCatalog NumberComments
0.9% Sodium Chloride Irrigation, USP - Flexible ContainerPFIZER (HOSPIRA)7983-09Dilutant
10cc Luer Lock syringe with 20G x 1" NeedleSur-VetSS-10L2025Used as a flush after drug injection
4x4 gauze spongesFisher Scientific22-415-469Rolled in a tube to splint ear with angiocatheter
Apple SauceKirkland897971Vehicle for oral medications
ComputerDellOptiplex 5040Acquisition computer
E-4031Tocris1808Agent known to prolong the QT interval
ECG ElectrodeRhythmLinkRLSND116-2.513mm 35-degree bent (0.4 mm diameter) subdermal pin electrodes
EEG ElectrodeRhythmLinkRLSP5135-twist 13mm straight (0.4mm diameter) subdermal pin electrodes
EEGLAB (2020)Swartz Center for Computational NeuroscienceOpen AccessCan perform spectral analysis of EEG
Ethernet-to-ethernet adapterLinksysUSB3G16Adapter for connecting the camera to the computer
Euthanasia-III SolutionMed-PharmexANADA 200-280Contains pentobarbital sodium and phenytoin sodium, controlled substance
Foam paddingGenericN/AReduces pressure applied to the neck of small rabbits by the restrainer in order to prevent the adverse cardiorespiratory effects of neck compression
Heparin Lock FlushMedlineEMZ50051240To maintain patency of angiocatheter
IR LightBoschEX12LED-3BD-8WFacilitates recordings in the dark
LabChart Pro (2019, Version 8.1.16)ADInstrumentsN/AECG Analysis
JELCO PROTECTIV Safety I.V. Catheters, 25 gaugeSmiths Medical3060Used to catherize marginal ear vein
MATLAB (R2019b, Update 5)MathWorksN/ARequired to run EEGLAB
MicrophoneSony StereoECM-D570PRecording of audible manifestions of seizures
Micropore Medical Tape, Paper, White3M1530-1Used to secure wires and create ear splint
Natus NeuroWorksNatusLC101-8Acquisition and review software
Pentylenetetrazol (1 - 10 mg/kg always in 1mL volume)Sigma-Aldrich88580Dilutions prepared in saline
Photic StimulatorGrassPS22Stimulator to control frequency, delay, duration, intensity of the light pulses
Plastic wire organizer / bundler12Vwire.comLM-12-100-BLKBundle wires to cut down on noise
PS 22 Photic StimulatorGrass InstrumentsBZA641035Strobe light with adjustable flash frequency, delay, and intensity
PVC pipeGenericN/APrevents small rabbits from kicking their hind legs and causing spinal injury
Quantum AmplifierNatus13926Amplifier / digitizer
Quantum HeadBox AmplifierNatus2213464-pin breakout box
Rabbit RestrainerPlas-Labs501-TCVarious size rabbit restrainers are available. 6" x 18" x 6" in this study.
Rubber pad (booster)GenericN/ARaises small rabbits up in the restrainer to prevent neck compression
SpO2 ear clipNONIN61000PureSAT/SpO2
SpO2 sensor adapterNONIN13931XPOD PureSAT/SpO2
SRG-X120 1080p PTZ Camera with HDMI, IP & 3G-SDI OutputSonySRG-X120Impela Camera
Terumo Sur-Vet Tuberculin Syringe 1cc 25G X 5/8" Regular LuerSur-Vet13882Used to inject intravenous medications
Veterinary Injection Plug Luer LockSur-VetSRIP2VInjection plug for inserting the needle for intravenous medication
Webcol Alcohol Prep, Sterile, Large, 2-plyCovidien5110To prepare ear vein before catheterization

References

  1. Kaese, S., et al. The ECG in cardiovascular-relevant animal models of electrophysiology. Herzschrittmacherther Elektrophysiology. 24 (2), 84-91 (2013).
  2. Pogwizd, S. M., Bers, D. M. Rabbit models of heart disease. Drug ....

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