Surgical Implant Procedure and Wiring Configuration for Continuous Long-Term EEG/ECG Monitoring in Rabbits

Summary

The study outlines a protocol for the design, manufacturing, and placement of a novel continuous EEG/ECG recording system in rabbits. This hard-wired system allows for continuous EEG/ECG recordings from nine distinct electrodes on the head and chest, which facilitates comprehensive assessments of electrical activity in the brain and heart.

Abstract

A multi-system approach that includes the continuous collection of electroencephalogram (EEG) and electrocardiogram (ECG) recordings facilitates a comprehensive assessment of electrical activity in the brain and heart, particularly leading up to and surrounding episodic events. Building on our previous protocol that facilitates the collection of intermittent EEG/ECG recordings from conscious restrained rabbits, we developed a protocol for the collection of continuous EEG/ECG recordings from unrestrained rabbits. This new method enables high-quality 24/7 recordings in the housing cage, which captures the normal range of physiological states and enables the rabbits to move, eat, drink, and sleep freely. It enables comprehensive assessments of the prevalence, incidence, and susceptibility to EEG/ECG abnormalities, seizures, arrhythmias, and sudden death. This procedure involves the surgical placement of subdermal electrodes and the design and manufacturing of a robust wiring system that is impervious to damage by the rabbits. The surgical procedure includes two incisions and the sub-dermal tunneling of nine electrodes and wires that exit through a custom-made port. The external connector attaches to a wire harness that includes an electrical swivel, which allows for free range of rabbit motion throughout its cage. Additionally, the wires are enclosed in a metal sheath suspended by a retractor cable from the ceiling of the rabbit's cage. The wires are then connected to an amplifier/digitizer for the acquisition of high-quality continuous EEG/ECG recordings.

Introduction

We previously developed a protocol to collect acute (< 5 h) video/EEG/ECG recordings from rabbits. It involves the use of nine subdermal EEG and ECG pin electrodes, placement of the rabbit in a restrainer, and the investigator closely monitoring the rabbit for the entire duration of the recording¹. While this system provides high-quality video/EEG/ECG recordings, it has several limitations. Arrhythmias, epileptic seizures, and other EEG/ECG abnormalities may be triggered by various physiological and environmental substrates, so these events may be missed when conducting intermittent recordings. Thus, this recording platform does not facilit....

Protocol

The study outlines a protocol for the design, manufacturing, and placement of a novel continuous EEG/ECG recording system in rabbits. The protocol is approved by the Institutional Animal Care and Use Committee (IACUC) at SUNY Upstate Medical University. All IACUC requirements for animal welfare, surgical guidelines, and study endpoints are followed. The investigators and the faculty/staff of the Department of Laboratory Animal Research at SUNY Upstate perform regular welfare checks and general care. Any injuries, discomf.......

Discussion

We present a detailed protocol for the generation of a custom wire harness, the in-house fabrication of an implant, and the procedure for the sterile implantation of the EEG/ECG electrodes, wires, and port. This setup facilitates the collection of continuous, high quality EEG/ECG recordings in an efficient, safe, and financially feasible way. This protocol generates a system in which both EEG and ECG data can be collected in rabbits without the need for restrainers or constant supervision. Continuous long-term EEG a.......

Materials

Name	Company	Catalog Number	Comments
3:1 heat shrink wrap with adhesive	N/A	Wirefly	Adhesive lined polyolefin tubing designed to shrink 1/3 diameter when heated. Isolate electrodes when connecting wires and plugs, connecting pieces of the wire harness together
Absorbent Pads	-	any	Absorbent pads for Fluid collection
BD E-Z Scrub 116 Surgical Scrub Brush/Sponge	371163	BD E-Z Scrub	3% PCMX Surgical Scrub Brush/Sponge To scrub prior to operating for aseptic technique
Biopsy Punches	1315	ARGENT, McKesson	6 mm circular cutting blade for circular incision for port
Buprenorphine	-	-	0.3 mg/mL Buprenorphine For post-operative pain control
Butt connectors	X003C7S38P	SVAAR	Tinned copper butt splice 26-22 AWG non-insulated butt connectors Connecting carbon fiber wires from the electrodes to the plug
Cautery Pen	https://jorvet.com/product/cautery-kit-accessories/	Jorgensen Laboratories, Inc.	Hand-held Bovie Cautery Pen For controlling bleeding
Coaxial cable through-wall bushing	COAX BUSH WH	Commercial Electric	Plastic bushing with 6.9mm inner diameter opening and 1cm+ post Wire port
Cohesiant Wrap	https://healthypets.com/vetone-cohesiant-wrap-blue-2x5yd/	AmerisourceBergen	4in x 5yd self-adherent wrap For post-operative wound protection
Disposable Scalpel with Handle	https://www.securos.com/	Securos Surgical AmerisourceBergen	Sterile disposable scalpels For making incisions
Electrical Slip Ring		Taidacent	High Speed Ball Conductive Slip Ring 12 way 2A Collector ring rotary joint rotary connector, Electrical slip ring to allow free movement of animal without binding up the wire harness
Eye lube pro	https://domespharma.us/eye-lube-pro-detailer-final-v6/	Sentrx	Lubricating Gel Prevents eye drying/damage during anesthesia
GLUture	503763	World Precision Instrument	Topical Tissue Adhesive For closure of incision sites
Isoflurane	ANADA # 200-129	Isospire	Isoflurane For anesthesia
Isopropyl alcohol	500205	VETone	70% isopropyl alcohol Topical antiseptic
Jet Liquid	1403	Lang Dental Mfg. Co., Inc.	Fast curing acrylic resin liquid Dental acrylic resin liquid for sealing the bushing and the wires for the wire exit port.  Also used to seal the port to the skin.
Jet Tooth Shade Powder	1420	Lang Dental Mfg. Co., Inc.	Fast curing provisional crown and bridge acrylic resin powder. Dental acrylic powder for sealing the bushing and the wires for the wire exit port.  Also used to seal the port to the skin.
Ketamine	-	-	100 mg/mL Ketamine For sedation
Metal shower sheathing	HOS-960M	Waterpik	Ultra-Flexible Replacement Metal Shower Hose, Extra Long for Handheld Shower Heads, 96-inch, Chrome Metal sheathing for wire harness
MR Conditional/CT Electrodes Array and Extension Set	MRQW32415	RhythmLink	Quick connect system with male-female plugs and 8 leads. Plugs used for port-wire harness connection.  Wires and DIN connectors used for the wire harness
Polypropylene Blue Monofilament Sutures	P8665	SECUROPRO	3-0, FS-2, 18” reverse cutting suture. Close any surgical incisions
Retractor cable	‎0487-013	West Coast Manufacturing Company	Industrial Retractable Reel with 48" Stainless Steel Cable, Steel Bracket Back, Chrome Front, 8 oz. Retraction, Plastic Hose Clamp. Pulls excess wire harness up and away from animal
Rubber gasket	E-3603 NSF-51	Saint Gobain	Clear rubber tubing cut to 1.5 cm width. Gasket for protection/maintaining a seal.
Small Webb Electrodes	SWEBB1215	RhythmLink	6mm, flat disc [WEBB*] electrode, silver-chloride, wire, Subdermal electrodes
Sterile Latex Surgical Gloves	10122	AmerisourceBergen	Sterile Latex Gloves, Powder-Free, Donned for sterile surgical technique
Sterile marker	DYNJSM01	Medline	Sterile Marker, Mark incision/electrode sites
Sterile surgical drapes with adhesive	-	any	Sterile surgical drapes with adhesive strip on one side, Create a fixed sterile field
Veterinary anesthesia masks	-	any	Plastic cones with rubber gaskets to seal over rabbit’s face. Various sizes. Delivery of inhaled anesthesia
Veterinary Betadine Surgical Scrub	NDC 67618-154-16	Betadine	Povidone-iodine, 7.5%, Antiseptic Sudsing Skin Cleanser
Xylazine	-	-	100 mg/mL Xylazine, For sedation