Sterile Pericarditis in Aachener Minipigs As a Model for Atrial Myopathy and Atrial Fibrillation

Summary

We describe a sterile pericarditis model in minipigs to study atrial myopathy and atrial fibrillation (AF). We present surgical and anesthetic techniques, strategies for vascular access, and a protocol to study the inducibility of AF.

Abstract

Atrial fibrillation (AF) is the most common arrhythmia caused by structural remodeling of the atria, also called atrial myopathy. Current therapies only target the electrical abnormalities and not the underlying atrial myopathy. For the development of novel therapies, a reproducible large animal model of atrial myopathy is necessary. This paper presents a model of sterile pericarditis-induced atrial myopathy in Aachener minipigs. Sterile pericarditis was induced by spraying sterile talcum and leaving a layer of sterile gauze over the atrial epicardial surface. This led to inflammation and fibrosis, two crucial components of the pathophysiology of atrial myopathy, making the atria susceptible to the induction of AF. Two pacemaker electrodes were positioned epicardially on each atrium and connected to two pacemakers from different manufacturers. This strategy allowed for repeated non-invasive atrial programmed stimulation to determine the inducibility of AF at specified time points after surgery. Different protocols to test AF inducibility were used. The advantages of this model are its clinical relevance, with AF inducibility and the rapid induction of inflammation and fibrosis-both present in atrial myopathy-and its reproducibility. The model will be useful in the development of novel therapies targeting atrial myopathy and AF.

Introduction

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia, leading to significant morbidity, mortality, and healthcare expenses¹. In many cases, AF is merely the electrical symptom of the underlying atrial myopathy, which is defined by structural, electrical, autonomic, and contractile remodeling of the atria. This atrial myopathy can lead to AF and stroke^2,3. Most therapies only target the electrical remodeling but do not target the underlying structural changes in the atria (inflammation and fibrosis)^4,5,

Protocol

This protocol has been approved by the University of Antwerp Ethical Committee for Animal Testing (case number 2019-29) and follows the animal care guidelines of the University of Antwerp. Seventeen 6-month-old Aachener minipigs (male, castrated) weighing ~20 kg were selected for this study.

1. Medication and anesthesia

1. Premedication
   1. Ensure that the pigs are fasted for 12 h, but with unlimited access to water.
   2. For sedation, administer the following in one int.......

Discussion

A reliable large animal model is a major asset for the study of atrial myopathy and AF and the development of novel therapies for AF. Implantation of pacemaker leads on the atrial epicardium allowed a longitudinal follow-up and repetitive electrophysiologic testing, which is difficult in small animals. Minipigs are easy to handle, and their hearts are structurally and physiologically similar to the human heart¹⁰.

The sterile pericarditis model is relatively straightforw.......

Materials

Name	Company	Catalog Number	Comments
Aachener minipig, 6-months old, male, castrated, weight 15-25 kg	Carfil
Anesthesia and preparation
ECG electrodes
Endotracheal tube 6.5 mm ID	Covidien	115-65OR
External cardioverter-defibrillator	Innomed	Cardio-aid 200B
Heating pad	OK.	OUB 60321
Intravenous catheter 22 GA, 1 Inch	BD	381323
Laryngoscope blade size 4	Miller	SUS426601
Monitor	GE Medical systems	2600040-003
Respirator	Datex-Ohmeda	1009-9000-000
Shaver	Aesculap	GT 104 / REF 985203
Syringe driver pump	Fresenius Kabi	082470
Arterial and central venous line placement
3-lumen central venous catheterization set, 7 French, 16 cm, 0.032 Inch guide	Arrow medical	EU-22703-EN
Arteral catheter 3 French, 8 cm	Vygon	1,15,090
Caresite Luer access device	B. Braun	415122-01
Fluids: IV bags of Plasmalyte, Glucose 5%, NaCl 0.9% (500 mL or 1000 mL)
heparinized saline
Needles: 18 Ga / 40 mm and 22 Ga / 40 mm
Pressure monitoring set, 195 cm	Edwards Lifesciences	T005021M
Pressure tubing 180 cm	Edwards Lifesciences	50P172
suture with needle
Syringes Luerlok: 2 mL, 5 mL, 10 mL, 20 mL, 50 mL
Ultrasound gel	Zealand coating	446-1
Ultrasound with vascular probe	Philips healthcare	EPIQ 7C / REF BZE1723
Surgical set
Blunt-tip surgical scissors	Martin	11-934-25
60 degrees curved Debakey forceps	Aesculap	FB403
Anatomical forceps	AS	13-102-16
Debakey forceps	Geister	10-0634
Electrocautery module	Alsa	Alsatom SU 140/D MPC
Holders for stainless steel wire	COBE	013-123
Mosquito	Leibinger	32-01008
Needledriver, fine	Delacroix-Chevalier	50302-21
Needledriver, normal	Aesculap	BM 77
Rib spreader	Martin	24-178-01
Scalpel	Swann-Morton	0511	no. 24
Scissors for stainless steel wire	Jakobi	411830
Spreaders	AS	16-058-00
Sternum saw	Eure-Power	5000020
Sternum saw blade	MicroAire	ZR-032M
Surgical consumables
Disinfectant: iodine, chlorhexidine
Electrocautery pencil with push button, cable 5 m	Dongguan QueenMed Equipment	ESPB4001LQ
Gastric tube	Vygon	390.12
Mersilene-0, 75 cm	Ethicon	F2505H
Monocryl 3-0, 70 cm	Ethicon	Y423H
Mouth masks, hair nets
Oriflex-4 vacuum flask for surgical draining	Oriplast Krayer	VK00352
Prolene 6-0, 75 cm	Ethicon	8711H
Stainless steel monofilament non-absorbable suture	Ethicon	W995
Sterile drapes	3M	9010
Sterile gauze 20 x 10 cm	Stella	35921
Sterile gloves
Sterile surgical gown
Steritalc PF3	Novatech	16863
Vicryl-0, 75 cm	Ethicon	V324H
Cardiac pacing
Bipolar pacing lead Fineline II Sterox EZ 58 cm	Boston Scientific	4474
Bipolar pacing lead Tendril STS 58 cm	Abbott	2088TC
Ellegaard Göttingen Minipig Frame 3	Lomir	DF H1PU
Ellegaard Göttingen Minipig Sling Cover	Lomir	SS CEG1
Micropace cardiac stimulator	Boston Scientific	EPS 320
Pacemaker for pacing	Medtronic	Azure XT DR MRI SureScan
Pacemaker for sensing	Biotronik	Eluna 8 DR-T
Pacemaker programmer for pacing	Medtronic	CareLink Encore 29901A
Pacemaker programmer for sensing	Biotronik	ICS 3000 DS CD-W US
Medication
Adrenaline 1 mg/mL, 1 mL	Sterop
Atropine 0.5 mg/mL, 1 mL	Sterop
Catapressan 150 µg/mL, 1 ml clonidine	Boehringer Ingelheim	BE021402
Cefazoline 2 g powder	Mylan	BE319794
Cordarone 50 mg/mL, 3 mL amiodarone	Sanofi
Durogesic 50 µg/h fentanyl patches	Janssen-Cilag
Glucose 5%, 500 mL	Baxter	AE0063
Ketalar 50 mg/mL, 10 mL	Pfizer	804101
Lanoxin 0.25 mg/mL, 2 mL digoxine	Aspen
Marcaine 0.5% + adrenaline 1:200,000	Aspen
Midazolam 5 mg/ml, 3 mL	B. Braun	3521740
Morfine 10 mg/mL, 1 mL	Sterop
NaCl 0.9%, 500 mL	Baxter	AKE1323
Nitro Pohl 1 mg/mL, 5 mL nitroglycerine	Pohl Boskamp
Noradrenaline 1 mg/mL, 4 mL	Aguettant
Plasmalyte 1000 mL	Baxter	AKE0324
Propofol 10 mg/mL, 20 mL	B. Braun	3521810
Protamine 1400 IU/mL, 5 mL	Leo pharma
Rapifen 0.5 mg/mL, 2 mL	Janssen-Cilag	95103
Seloken 1 mg/mL, 5 mL metoprolol	AstraZeneca
Sevorane Quick Fill 100% sevoflurane, 250 mL	Abbvie	1283-415
Tracrium 10 mg/mL, 5 mL atracurium	Aspen