Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

Summary

Here we describe and compare two positions for obtaining the apical four-chamber view in mice. These positions enable the quantification of the right ventricular function, provide comparable results, and can be used interchangeably.

Abstract

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV diastolic function is rarely quantified in experimental studies. This might be due to technical difficulties in the visualization of the RV in the apical four-chamber view in rodents. Here we describe two positions facilitating the visualization of the apical four-chamber view in mice to assess the RV diastolic function.

The apical four-chamber view is enabled by tilting the mouse fixation platform to the left and caudally (LeCa) or to the right and cranially (RiCr). Both positions provide images of comparable quality. The results of the RV diastolic function obtained from two positions are not significantly different. Both positions are comparably easy to perform. This protocol can be incorporated into published protocols and enables detailed investigations of the RV function.

Introduction

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling¹ and is associated with pressure-overload conditions². Echocardiography (EchoCG) can be used for the characterization of RV diastolic dysfunction^3,4. Despite recent developments in small animal echocardiography, measurements of diastolic parameters are rarely reported. In contrast, measurements of the systolic function are widely used for the characterization of transgenic mice⁵, as well as for the evaluation of a treatment response⁶.<....

Protocol

The study was performed according to national regulations for animal experimentation and EU Directive 2010/63. Prepare equipment as described previously by Brittain et al.⁸.

1. Mouse Preparation

1. Obtain 12 to 13 week-old male C57Bl6/J mice and house them with a 12 h light/dark cycle, at a constant room temperature, and with ad libitum access to standard laboratory chow and water, until the start of the experiment.
2. Anesthetize the mouse using general anesthesia approved by the Institute and check for the lack of response to the toe pinch. Under mild anesthesia with isoflurane 0.....

Results

The apical four-chamber view is difficult to obtain in mice. Therefore, manipulations of the platform position can help to visualize the heart by changing its position in the thorax. The tilting of the platform to the left and to the right improved the acoustic window and provided images of comparable quality in B-mode (Figure 1). After obtaining the correct positions, measurements in PW-, M-, and TDI-modes provided images of comparable quality (

Discussion

The echocardiographic RV function and dimension assessment from parasternal positions have been well described. In contrast, the apical position in mouse echocardiography has been neglected partly due to technical difficulties. Using a horizontal platform position, it is difficult to obtain a sufficient acoustic window for four-chamber view imaging. To facilitate the imaging of this position, the platform can be tilted to the left, a manipulation similar to the left-sided positioning of patients. This should result in a .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
RMV-707B scan head 30 MHz	Visual Sonics	P/N 11459	mouse scan head
VisualSonics Vevo 770® High-Resolution Imaging System	Visual Sonics	770-230	ultrasound machine
Veet depilation creme for sensitive skin	Veet	07768307
Surgical tape Durapore 3M	3M Deutschland GmbH	1538-1	for fixation
Askina Brauncel cellulose swabs	B.Braun	9051015
Aquasonic ultrasound gel	Parker Laboratories Inc.	BT025-0037L
Electrode Gel	GE medical systems information technologies Inc.	2034731-002	apply to extremities for countinous ECG and heart rate monitoring
Thermasonic gel warmer	Parker Laboratories Inc.	82-04-20	to reduce heat loss warm up the ultrasound gel before use