A Pulmonary Trunk Banding Model of Pressure Overload Induced Right Ventricular Hypertrophy and Failure

Summary

We present a surgical method to induce right ventricular hypertrophy and failure in rats.

Abstract

Right ventricular (RV) failure induced by sustained pressure overload is a major contributor to morbidity and mortality in several cardiopulmonary disorders. Reliable and reproducible animal models of RV failure are therefore warranted in order to investigate disease mechanisms and effects of potential therapeutic strategies. Banding of the pulmonary trunk is a common method to induce isolated RV hypertrophy but in general, previously described models have not succeeded in creating a stable model of RV hypertrophy and failure.

We present a rat model of pressure overload induced RV hypertrophy caused by pulmonary trunk banding (PTB) that enables different phenotypes of RV hypertrophy with and without RV failure. We use a modified ligating clip applier to compress a titanium clip around the pulmonary trunk to a pre-set inner diameter. We use different clip diameters to induce different stages of disease progression from mild RV hypertrophy to decompensated RV failure.

RV hypertrophy develops consistently in rats subjected to the PTB procedure and depending on the diameter of the applied banding clip, we can accurately reproduce different disease severities ranging from compensated hypertrophy to severe decompensated RV failure with extra-cardiac manifestations.

The presented PTB model is a valid and robust model of pressure overload induced RV hypertrophy and failure that has several advantages to other banding models including high reproducibility and the possibility of inducing severe and decompensated RV failure.

Introduction

The right ventricle (RV) can adapt to a persistent pressure overload. In time, however, adaptive mechanisms fail to sustain cardiac output, the RV dilates and eventually the RV fails. RV function is the main prognostic factor of several cardiopulmonary disorders including pulmonary arterial hypertension (PAH), thromboembolic pulmonary hypertension (CTEPH), and various forms of congenital heart disease with a pressure (or volume) overload of the RV. Despite intense treatment, RV failure remains a predominant cause of death in these conditions.

As a consequence of the unique properties^1,2

Protocol

All rats were treated according to Danish national guidelines described in the Danish law on animal experiments and Ministerial order on animal experiments. All experiments were approved by the Institutional Ethics Review Board and conducted in accordance with the Danish law for animal research (authorization number 2012-15-2934-00384, Danish Ministry of Justice).

1. Adjustment of the Ligating Clip Applier

NOTE: The banding of the pulmonary trunk is performed with a modified open ligating clip applier with an angled jaw. The applier is modified with an adjustable stop mechanism to stop the compress....

Results

Using the described PTB procedure in previous studies from our group^12,13, we induced RV hypertrophy (PTB mild) by banding with a 1.0 mm clip, a moderate degree of RV failure (PTB moderate) by banding with a 0.6 mm clip and a severe degree of RV failure (PTB severe) by banding with a 0.5 mm clip. The rats subjected to the severe banding developed extra-cardiac manifestations of RV failure including liver failure and ascites (

Discussion

We describe an accessible and highly reproducible method of pulmonary trunk banding using a modified ligating clip applier to compress a titanium clip around the pulmonary trunk. By adjusting the applier to compress the clip to different inner diameters, distinct phenotypes of RV hypertrophy and failure can be induced including severe RV failure with extra-cardiac manifestation of decompensation.

Although simple, the protocol contains a few critical steps. Importantly, the rats cannot be too b.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
17 G IV Venflon Cannula	Becton Dickinson, US	393228	Distal 2 mm of the needle have been cut off
1 mL syringe + 26 G needle	Becton Dickinson, US	303172 & 303800
4-0 absorbable multifilament suture	Covidien, US	GL-46-MG	Polysorb, violet, 5x18"
4-0 multifilament ligature	Covidien, US	LL-221	Polysorb, violet, 98"
Buprenorphine	Indivior UK Limited		Local procurement, Temgesic 0.3 mg/mL
Carprofene	ScanVet, DK	27693	Norodyl 50 mg/mL
Chlorhexidine	Faaborg Pharma, DK		Local procurement
Contractor	Aesculap, Germany	BV010R	Blunt, self retaining, 70 mm
Ear Hooklet	Lawton, Germany	66-0261	Small, 14 cm, tip modified to an angle of 85°
Eye gel	Decra, UK		Lubrithal, Local procurement
Forceps, Delicate Tissue	Lawton, Germany	09-0020
Forceps, Dissecting	Lawton, Germany	09-0013	1 regular, 1 with tip modified to an angle of 100°
Gas Anesthesia System	Penlon Limited, UK	SD0217SL	Sigma Delta Vaporizer
Hair trimmer	Oster	76998-320-051
Horizon Open Ligating Clip Applier	Teleflex, US	137085	Modified with adjustable stop mechanism
Horizon Titanium Clips	Teleflex, US	001200	Small
Induction chamber	N/A
Iris Scissor	Lawton, Germany	05-1450
Iris Scissor	Aesculap, Germany	BC060R
Mechanical ventilator	Ugo Basile, Italy	7025
Microscissor	Lawton, Germany	63-1406
Microscope	Carl Zeiss, Germany	303294-9903
Needle Holder	Lawton, Germany	08-0011	TITEGRIP
Pean	Lawton, Germany	06-0100	Halsted-Mosquito, straight
Pro-Optha	Lohmann & Rauscher, Germany	16515	Tampon
Saline 9 mg/mL	Fresenius Kabi, DK	209319
Sevoflurane	AbbVie, US		Sevorane, Local procurement
Surgical hook	Lawton, Germany	51-0665	Cushing, 19 cm, tip modified to an angle of 90°
Surgical Tape	3M, US	1530-0	Micropore
Temperature Controller	CMA Microdialysis; Sweden	8003760	CMA 450
Weighing machine	VWR, US
Wistar rat weanlings	Janvier Labs, France		RjHan:WI, 100-120 g