Murine Echocardiography and Ultrasound Imaging

MU in cardiac function could be viewed using echocardiography. Here, heart function is assessed in normal mice and representative images are shown from ultrasound. Assessment of cardiac function.

In a surgical mouse model of heart failure using a visual sonic's vivo 2100, the heart is visualized in two dimensions. Images and video are captured for analysis using B mode, color and pulse wave doppler imaging, three dimensional reconstruction and M mode. The videos are then analyzed and changes in cardiac function and morpho over time are revealed.

Hi, I'm an pisser from the laboratory of Burns Blackwell in the Department of Medicine at the AB Cardiovascular Research Institute at the University of Rochester Medical Center. I'm Steven Belmont, also from the Black Salt Laboratory. I'm Tonya Cohor from Visual Sonics and I'm Bris Black Salt.

Today we'll be showing you a procedure for high resolution mouse echocardiography. We use this procedure in our laboratory to study cardiac function and morph informatory. So let's get started.

Begin by securing a isof fluorine anesthetized mouse into an animal handling platform. In the supine position, place a nose cone over the animal's nose and mouth to deliver 0.5 to 1%isof fluorine. To maintain the anesthesia, secure the pause of the mouse to the electrode pads with conducting gel.

Ensure appropriate ECG body temperature at 37 degrees Celsius and check respiratory rate for physiological assessment. During imaging applied depilatory cream to the chest and upper abdomen of the mouse, after two minutes, use wet gauze to remove the cream. Once the mouse has been prepared for imaging, tilt the left side of the platform to rotate the animal handling platform 30 degrees about the anterior posterior axis.

Orient the transducer in the vertical position and rotate 10 degrees counterclockwise with the notch pointed towards the posterior of the mouse. Next, while in two dimensional viewing video B mode, lower the transducer over the left para sternal line until the heart comes into view. Once the P mony artery comes into view, collect images and store them still in B mode, move the transducer left or right until the aortic outflow and apex come into view.

Some rotation of the probe may be necessary to ensure proper alignment with the long axis of the heart. Use video capture to obtain data for subsequent analysis. Minimize the field of view to ensure the highest frame rate possible.

For downstream regional strain analysis. Each time a video is captured, the prior 100 frames are saved. Switch to the color Doppler mode by selecting color Doppler.

Although color doppler has been available for over 30 years in humans, this technology has only recently been possible in rodent ultrasound. To quickly monitor the direction and velocity of blood flow, the doppler window overlay digitizes the flow from red indicating flow toward the probe to blue, indicating flow away from the probe. Acquire necessary images by image capture.

Once all color Doppler data has been obtained, switch the instrument to pulse wave Doppler mode. The one dimensional view used to digitally assess blood flow, direction and velocity over time. Move the probes slightly toward the head of the mouse until the pary artery comes into view.

In the context of heart failure, PW color doppler measurements of the pary artery can be used as a surrogate for right heart function. Capture images as desired short axis. Echocardiography provides a view of the entire left ventricle contracting in a concentric fashion and allows for accurate b and m mode based assessment of cardiac function and morph geometry in B mode.

From the parasternal lung axis view, rotate the transducer orthogonal to the left para sternal lung axis view at the level of the papillary muscle. Ensure proper location along the length of the left ventricle. Both papillary muscles should be clearly visible and separated, giving a horizontal cross-sectional view with the M mode, place the sample volume through the center of the ventricle and acquire data if desired.

Attach, initiate and utilize the three-dimensional motor to obtain the images necessary for complete three-dimensional reconstruction. Physiology settings, including respiratory rate and ECG are set for gating 3D image capture in end diastole. Once the end diastole 3D capture is complete.

Physiology settings for respiratory rate and ECG are set for gating the 3D image capture in end systole. The subcostal view is the best approach for measuring competency and pressure gradients across the mitral valve. Tilt the upper left corner of the platform all the way down.

Orient the transducer towards the right shoulder of the mouse, maintaining the short axis rotation of the probe in B mode, lower the transducer over the upper abdomen so that it rests below the diaphragm. Visualize the mitral valve using color doppler as described before. Rotate the animal handling platform into the left lateral decubitus position.

The left side of the platform should be tilted as far as possible. Next, orient the transducer tilted as far up as possible along the length of the mouse at the level of the scapula. Lower the transducer inferior to the right shoulder along the anterior axillary line.

Visualize the aortic arch and acquire images. Raise the head of the mouse and lower the transducer into the suprasternal notch of the mouse. Visualize blood flow using color doppler and acquire images.

This is a long axis view of the heart in B mode showing both the left ventricle and a small portion of the right ventricle here. A left sho axs view of another heart was taken in M mode. The upper image shows the position of the sample volume line in yellow through the center of the chamber.

The bottom image is a one dimensional trace of the above line over time, as well as calculations of morpho in cyan. This is a view of the aortic arch in B mode. The closed aortic valve can be seen on the left and the blood vessel supplying the head and upper limbs of the mouse can be seen on the right.

Radial strain analysis was performed on a mouse prior to developing heart dysfunction shown in the top image and a mouse with global hypokinesis and regional dyssynchrony shown in the bottom image. Both phenotypes were induced through transverse aortic constriction. A mouse model of increased after load in the figure.

The time is displayed on the X axis and the radial strain as a percentage is shown on the y axis. Strain analysis allows for regional assessment of cardiac function that may otherwise go unnoticed. In conventional techniques such as M mode, which only directly measures function of the anterior free wall and the posterior wall, the anterior free wall is shown in green.

The lateral wall is shown in pink. The posterior wall is shown in cyan. The inferior free wall is shown in blue.

The posterior septal wall is shown in yellow. The anterior septum is shown in magenta and the average is shown in black. We've just shown you how to perform echocardiography on mice When doing this procedure.

It's important to remember to properly orient the ultrasound probe using the same landmarks to ensure reliable data. So that's it. Thanks for watching and good luck with your experiments.