A Closed-chest Model to Induce Transverse Aortic Constriction in Mice

Summary

Here, we present a protocol of Transverse Aortic constriction (TAC) via a lateral thoracotomy. This technique is a minimally invasive, closed chest surgical procedure aiming to simulate pressure overload and heart failure in mice utilizing standard TAC laboratory settings.

Abstract

Research on cardiac hypertrophy and heart failure is frequently based on pressure overload mouse models induced by TAC. The standard procedure is to perform a partial thoracotomy to visualize the transverse aortic arch. However, the surgical trauma caused by the thoracotomy in open-chest models changes the respiratory physiology as the ribs are dissected and left unattached after chest closure. To prevent this, we established a minimally invasive, closed chest approach via lateral thoracotomy. Herein we approach the aortic arch via the 2^nd intercostal space without entering the chest cavities, leaving the mouse with a less traumatic injury to recover from. We perform this operation using standard laboratory settings for open chest TAC procedures with equal survival rates. Apart from maintaining physiological breathing patterns due to the closed chest approach, the mice seem to benefit by showing rapid recovery, as the less invasive technique appears to facilitate a fast healing process and to reduce immune response after trauma.

Introduction

Mouse models are often used to mimic human diseases¹. Transverse aortic constriction (TAC) is used to induce pressure overload and left ventricular hypertrophy². The open-chest TAC model in mice was validated by Rockman et al.³ and the surgical procedure is described in detail by DeAlmeida et al.⁴. Banding of the transverse aorta is more favorable in comparison to abdominal aortic constriction because a larger portion of the circulation can compensate negative effects of this latter procedure².

The bandin....

Protocol

This protocol was approved by the Ethics Committee for Animal Experimentation LANUV Recklinghausen (#84-02.04.2016.A374). Generally, this procedure is performed on adult mice >10 weeks of age. However, it is possible to perform this surgery on younger animals as well. Surgical tools must be sterilized before use and all steps are to be performed under aseptic conditions.

1. Induction of Anesthesia and Intubation

1. Inject buprenorphine 0.1 µg/g body weight intraperitoneally for pain relief. Repeat the intraperitoneal injections of 0.1 mg/kg buprenorphine every 8 h for the next three days after surgery.
2. For induct....

Results

A successful TAC guarantees the induction of pressure overload and left ventricular hypertrophy. An ad hoc validation of pressure overload can be achieved using Doppler flow velocity measurement as shown in Figure 2. While preoperative blood flow velocity is equal in both carotid arteries, TAC causes an augmented blood velocity in the right carotid artery due to elevated pressure in the left ventricle and aorta while causing post-stenotic attenuated blood flo.......

Discussion

The rapid onset of hypertension due to TAC differs from clinically relevant hypertrophy caused by aortic stenosis or hypertension. Nevertheless, the use of small animal models to induce heart failure has many advantages and is, therefore, chosen by many investigators¹¹. This closed chest-model improves the already existing models of the surgical technique to induce transverse aortic constriction in mice⁴.

The most critical step is the passage und.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Pressure-volume catheter	Millar Instruments, USA	SPR-839
Mouse ventilator	Harvard Apparatus GmbH, Germany	Minivent - TYPE 845
Mouse ventilator	Harvard Apparatus GmbH, Germany	Y-connection with intubation cannula OD 1.2mm 73-2844
Vaporizer	Dräger Medical AG&CO.KG, Germany	19.3 Isofluran-Vaporizer (a newer version is available under catalog number  D-877-2010)
Microscope	Leica Microsystems, Germany	MZ 7.5
Light source	Schott AG, Germany	KL 1500 LCD
6-0 Prolene	Ethicon, USA	Polypropylene suture BV-1 9.3 mm 3/8c	suture for surgery
Seraflex	Serag Wiessner, Germany	USP 5/0 schwarz;  IC108000	suture for constriction
Homoeothermic Controlled Operating Tables	Harvard Apparatus GmbH, Germany	Typ 872/3 HT with tripod stand and homoeothermic controller Type 874; 73-4233
Flexible Rectal Probe	Harvard Apparatus GmbH, Germany	1.6 mm OD; 55-7021
Doppler Signal Visualisation Instrument	Indus Instruments, USA	Doppler Signal Processing Workstation (DSWP) with 20MHz Pulsed Doppler Module
Arruga Intracapsular Forceps	Altomed, UK	A5400
Doppler Probe	Indus Instruments, USA	20MHz Tubing-mounted Probe
Jaffe Lid Retractor	Altomed, UK	A3513