Name: murine echocardiography of left atrium, aorta, and pulmonary artery
Uploaded: 2017-02-20T15:00:00.000+00:00
Duration: 8 min 17 s
Description: Watch this Scientific Journal Video about Murine Echocardiography of Left Atrium, Aorta, and Pulmonary Artery at JoVE.com

This work was supported by the Huffington Center on Aging at Baylor College of Medicine, Geriatrics, CVS DeBakey Heart Center at Houston Methodist Hospital and BCM, NIH RO-1 HL 13870 to ML Entman, as well as a Career Development Award # IK2BX002410 from the United States Department of Veterans Affairs (LMP), Biomedical Laboratory Research and Development Program.
We are immensely grateful to Mark Entman M.D. for sharing his wisdom and supporting this work.

All animals were cared for in accordance with the guidelines of the National Institutes of Health Guide for the Care and Use of Laboratory Animals at Baylor College of Medicine.
1. Set-up
<ol>
	<li>Turn on the echocardiographic system. Start the software by selecting &#34;Cardiac Measurements&#34; from the drop down menu displayed and click &#34;Initialize&#34;.</li>
	<li>To begin a new study click on the &#34;New&#34; button on the upper part of the screen and enter the demographic information of the mouse in study. For example mouse ID, sex, date of birth as well as the name of the operator doing the study.</li>
	<li>Turn on the temperature-controlled EKG board by clicking the &#34;TEMP ON/OFF&#34; button. Set it to a temperature of 39 &#176;C using the up and down arrows.</li>
	<li>To start setting up the anesthesia chamber, first make sure the oxygen and isoflurane levels are appropriate in each of the delivery systems.</li>
	<li>Place the mouse in the anesthesia chamber and induce with isoflurane and oxygen until recumbent and then transfer it to face mask. Confirm that the mouse is properly anesthetized by pinching its paw and checking for lack of movement. Maintain the isoflurane at the lowest possible level that avoids a positive paw withdrawal response.</li>
	<li>Place the mouse in a supine position on the temperature-controlled EKG board and tape each paw to the correspondent transducer element on the board. Optionally, use transducer cream to improve the signal.</li>
	<li>Apply artificial tears ophthalmic lubricant ointment on the mouse&#39;s eyes to prevent dryness.</li>
	<li>Once the mouse is taped to the EKG board, observe an EKG tracing in the lower part of the monitor. Monitor the heart rate throughout the whole study to ensure best results. A heart rate of 400 beats/min is ideal. Heart rates below this range may suggest isoflurane effects.</li>
	<li>Make sure the mouse keeps receiving oxygen and isoflurane by face mask.</li>
	<li>Use an electric razor to shave the body fur from the mouse&#39;s anterior thorax and upper abdominal area. Use depilatory cream if necessary to further ensure fur removal.</li>
	<li>Put a generous amount of transducer gel in the chest of the mouse.</li>
</ol>
2. Image Acquisition
<ol>
	<li>Left Atrium measurement
	<ol>
		<li>Locate the handle beneath the EKG board. Use the handle to adjust the angle of the movable EKG board in which the mouse was placed. Begin by adjusting the EKG board to a 30 - 45&#176; angle along the X axis and 0&#176; angle along the Y axis. Authors refer to it as &#34;supine&#34; position. Use this position for all of the Left Atrium measurements acquisition.</li>
		<li>Place the 25 MHz scan head in the echocardiographic movable arm clamp in a long axis view. Make sure to select the Cardiac Measurement Filter and 2D B-Mode in the echocardiographic system.</li>
		<li>Notice that the echocardiographic set has X and Y axis adjustment torques that can be moved clockwise or counterclockwise. Rotate them to get a long axis view of the heart at the level of the aortic outflow tract and acquire a 5 s movie recording. Acquire the scan by pressing the &#34;Cine Store&#34; button on the keyboard of the echocardiographic system. Use this to calculate the Superior-Inferior measurement of the LA.</li>
		<li>After the movie acquisition, switch the echocardiographic view to M-Mode by pressing the &#34;M-Mode&#34; button on the keyboard of the echocardiographic system.</li>
		<li>Observe a sagittal view and a cursor. Place the cursor so that it encompasses the whole LA at the level of the aortic outflow tract. Acquire 3 images of this new view. Acquire the scan by pressing the &#34;Frame Store&#34; button on the keyboard of the echocardiographic system. Use this to calculate the Anterior-Posterior measurement of the LA.</li>
		<li>Return to B-Mode by pressing the &#34;B-Mode&#34; button on the keyboard of the echocardiographic system.</li>
		<li>Rotate the movable arm clamp of the set 90&#176; clockwise. This will set the scan head in a short axis view.</li>
		<li>Using the Y axis torque find the intraarticular septum. Make sure to visualize the wall of the atrium. Acquire a 5 s movie recording. Acquire the scan by pressing the &#34;Cine Store&#34; button on the keyboard of the echocardiographic system. Use this to calculate the Medio-Lateral measurement of the LA.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/55214/55214fig1.jpg" /> 
Figure 1: &#34;Supine&#34; Position. Representation of a mouse in the &#34;Supine&#34; Position. Approximately 30 - 45&#176; angle along the X axis and 0&#176; angle along the Y axis. This position is used to acquire all of the Left Atrium measurements. <a href="http://cloudfront.jove.com/files/ftp_upload/55214/55214fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Great Vessels Measurement
	<ol>
		<li>Continue by exchanging the 25 MHz scan head for the 30 MHz scan head. Remove the 25 MHz scan head from the movable arm clamp and place the 30 MHz scan head instead. Make sure to select the Abdominal Measurements Filter and 2D B-Mode in the echocardiographic system.</li>
		<li>Locate the handle beneath the EKG board. Use the handle to adjust the angle of the movable EKG board in which the mouse lies. Begin by adjusting the EKG board to a 5&#176; angle along the X axis and 60&#176; angle along the Y axis. Use this podition for the acquisition of the Aorta and Pulmonary Artery measurements. Refer to this as &#34;standing-up&#34; position.</li>
		<li>Using the X and Y axis adjustment torques in the echocardiographic set, get a long axis view of the heart at the level of the aortic outflow tract and acquire a 5 s movie recording. Acquire the scan by pressing the &#34;Cine Store&#34; button on the keyboard of the echocardiographic system. Use this to calculate the Aortic Diameter.</li>
		<li>After the movie acquisition, rotate the movable arm clamp of the set 90&#176; clockwise. This will set the scan head in a short axis view.</li>
		<li>Using the Y axis torque locate the Pulmonary Artery at the level of its bifurcation and acquire a 5 s movie recording. Acquire the scan by pressing the &#34;Cine Store&#34; button on the keyboard of the echocardiographic system. Use this to calculate the Pulmonary Artery Diameter. 
		NOTE: The researcher may use Doppler imaging as a tool to ensure correct identification of the Pulmonary Artery. If desired, once completing step 2.2.5 press the &#34;PW&#34; button on the keyboard of the echocardiographic system to obtain Doppler imaging. If characteristic pulmonary wave tracings are seen, the researcher can be reassured that the correct location was identified.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/55214/55214fig2.jpg" /> 
Figure 2: &#34;Standing-up&#34; Position. Representation of a mouse in the &#34;Standing-up&#34; Position. Approximately 5&#176; angle along the X axis and a 60&#176; angle along the Y axis. This position is used to acquire the Aorta and Pulmonary Artery diameters. <a href="http://cloudfront.jove.com/files/ftp_upload/55214/55214fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/55214/55214fig3.jpg" /> 
Figure 3: Pulmonary Artery Doppler. Characteristic Pulmonary Artery Doppler imaging. The researcher may use Doppler imaging as a tool to ensure correct identification of the Pulmonary Artery. <a href="http://cloudfront.jove.com/files/ftp_upload/55214/55214fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
3. Post Procedure Animal Recovery
<ol>
	<li>To safely remove the mouse from the EKG board, remove the gel from the chest of mouse and remove the tape from the extremities.</li>
	<li>Turn off the anesthesia and oxygen delivery systems. Return the mouse to its cage and do not leave the mouse unattended until it has regained sufficient consciousness to maintain sternal recumbency.</li>
</ol>
4. Image Analysis
<ol>
	<li>Image Transferring
	<ol>
		<li>Use a USB flash drive to transfer the images collected in the echocardiographic system into a computer. Insert the USB flash drive into a USB port in the echocardiographic system.</li>
		<li>Select the study or studies to transfer by clicking on the study name(s).</li>
		<li>Click on the &#34;Copy To&#34; button located on the upper part of the screen. A new window showing files and directories will appear. Select the directory corresponding to the USB flash drive just inserted and click &#34;OK&#34;.</li>
		<li>Remove the USB flash drive from the echocardiographic system and insert it into a USB port in the computer to be used for analysis.</li>
		<li>Launch the echocardiographic software. Click on the &#34;Copy From&#34; button located on the upper part of the screen. Observe a new window showing files and directories. Select the studies to be copied from the directory corresponding to the USB flash drive just inserted and click &#34;OK&#34;.</li>
		<li>After copying the files, observe them in the study list. To begin analyzing a study, double click on its name and select the name of the operator analyzing.</li>
	</ol>
	</li>
	<li>Left Atrium Analysis 
	NOTE: For all the following atrial measurements use the EKG as a guide to select the P-wave as the point where the researcher wants to measure the LA. This corresponds to the pre-atrial contraction time when the LA is at its largest capacity.
	<ol>
		<li>Select the movie clip corresponding to the Superior-Inferior dimension of the Left Atrium (Step 2.1.3). Determine the pre-atrial contraction time using the EKG as a guide. This way the cavity is measured at its largest capacity.</li>
		<li>From the tool bar on the top of the screen, click on &#34;Tools&#34; and then &#34;Measurements&#34;. A new window will appear. Click on the &#34;Linear distance Measurement Tool&#34; icon (it corresponds to the first icon on the left upper corner of the window). Measure the cavity at its largest diameter.</li>
		<li>Select the image corresponding to the Anterior-Posterior dimension of the Left Atrium (Step 2.1.5). Determine the pre-atrial contraction time using the EKG as a guide. This way the cavity is measured at its largest capacity. To measure it repeat step 4.2.2.</li>
		<li>Select the image corresponding to the Medio-Lateral dimension of the Left Atrium (Step 2.1.8). Determine the pre-atrial contraction time using the EKG as a guide. This way the cavity is measured at its largest capacity. Measure the cavity from the interatrial septum to the opposing wall in a diagonal fashion. To measure it repeat step 4.2.2. 
		NOTE: Repeat steps 4.2.1 thru 4.2.4 at least 3 times and acquire the average values to minimize error.</li>
	</ol>
	</li>
	<li>Great Vessels Analysis 
	NOTE: For all the following great vessels measurements use the EKG as a guide to select a time after the QRS complex as the point where the researcher wants to measure. This corresponds to the point where the great vessels are at their largest capacity.
	<ol>
		<li>Select the movie clip corresponding to the Aorta (Step 2.2.3). Determine a point after the QRS using the EKG. Measure the diameter at a 90&#176; angle using the vessel wall as a reference. To measure it repeat step 4.2.2</li>
		<li>Select the movie clip corresponding to the Pulmonary Artery (Step 2.2.5). Determine a point after the QRS using the EKG. Measure the diameter at a 90&#176; angle using the vessel wall as a reference. Select a plane above the pulmonary artery bifurcation. To measure it repeat step 4.2.2.</li>
	</ol>
	</li>
</ol>

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	<li>Upadhya, B., Taffet, G. E., Ping, C., Kitzman, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+failure+with+preserved+ejection+fraction+in+the+elderly:+scope+of+the+problem.">Heart failure with preserved ejection fraction in the elderly: scope of the problem.</a> Journal of Molecular and Cellular Cardiology. 83, 73-87 (2015).</li><li>Mclaughlin, V. V., Archer, S. 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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+real-time+three-dimensional+echocardiography+to+measure+left+atrial+volume:+Comparison+with+other+echocardiographic+techniques.">Use of real-time three-dimensional echocardiography to measure left atrial volume: Comparison with other echocardiographic techniques.</a> Journal of the American Society of Echocardiography. 18 (9), 991-997 (2005).</li><li>Ujino, K., Barnes, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-dimensional+echocardiographic+methods+for+assessment+of+left+atrial+volume.">Two-dimensional echocardiographic methods for assessment of left atrial volume.</a> The American journal of cardiology. 98 (9), 1185-1188 (2006).</li><li>Scalia, G. M., Scalia, I. 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The authors have nothing to disclose.

There are three critical steps to successfully measure the LAV, Aorta and PA diameters. During the Set-up it is important to completely remove the fur on the chest; failure to do so will result in interference with image quality. During the Image Acquisition steps it is important to obtain each image with their corresponding probe and filter as the frames per second vary from probe to probe: that is 25 MHz and Cardiac Filter for the assessment of the LAV and 30 MHz and Abdominal Filter for assessment of the Aorta and PA ...

The present methodology teaches the investigator how to measure and use the LAV, Aorta diameter and PA diameter with 2D echocardiography in mice under isoflurane. Heart Failure with preserved Ejection Fraction (HFpEF) in elderly people affects up to 10% in those 80 years and older1 and results in significant morbidity and mortality. Significant mortality also occur from Pulmonary Hypertension (PH), an insidious disease process presenting with similar symptoms as HFpEF, in which elevated pulmonary artery pressures lead to exertional dyspnea, progressive right heart failure, and often death.2 The increasing prevalence of both HFpEF and PH signify the need for developing a method that allows for accurate evaluation and monitoring of interventions in murine models in a non-invasive, non-terminal approach.
Aging leads to a deterioration of diastolic function via alterations in ventricular-arterial stiffening, vascular dysfunction, inflammation3, impaired calcium regulation4, decreased &#946;-adrenergic responsiveness, and physical deconditioning producing slowed active relaxation and increased passive stiffness. Over time this leads to increased LV filling pressure and compensatory enlargement of the LA.5
Though other etiologies such as valvular dysfunction (mitral regurgitation or stenosis) and infiltrative processes cause elevations in pressure and volume in the LA1, the European Society of Cardiology supports the addition of LA size as a noninvasive reflection of LV function.6
Correlations between LA volume and invasive measures of diastolic function have been studied in mice. LA volume correlated with differences in function determined invasively within age groups for both 14- and 31-months-old mice. In the 14-months-old mice, LA volume correlated with three standard invasive measures of diastolic function &#8722;dP/dtmin (r2 = .5, p &#60;0.05), Tau (time constant of relaxation, (r2 = .6, p &#60;0.05), and left ventricular end diastolic pressure (r2 = .25, p &#60;0.05). For the 31 months-old mice, the correlations between LA volume and -dP/ dtmin (r2 = .92, p &#60;0.05) and LVEDP (r2 = .61, p &#60;0.05) were apparent though the relationship with Tau was less clear. Therefore, LA volume increased with diastolic impairment not only across groups but within age groups.7
Studies of cardiac function in murine models using catheter techniques to evaluate cardiac performance, although rigorous and reliable, are limited due to their incompatibility with repeated assessments.8 Alternatives to invasive measures such as MRI and 3D echocardiography may also be more accurate than 2D echocardiographic techniques, but they are more expensive; 2D echocardiography is considered adequate for LA volume evaluation. 9,10
Assessment of the LA volume and PA diameter with echocardiography allows the discrimination between models that produce primary increases in pulmonary artery resistance resulting in an increase in PA diameter with no change in LA pressure or LAV from those where the Pulmonary Artery and Left Atrium both enlarge as a result of elevated filling pressures on the left side of the heart. This approach was taken by Scalia et al. who showed that in people, the echocardiographic Pulmonary Artery to Left Atrial Ratio (ePLAR) is a parameter to accurately differentiate between patients with pre-pulmonary capillary hypertension and post-capillaryhypertension.11

<table><tbody><tr><td>Vevo 770 high-resolution in vivo micro-imaging system</td><td>Visual Sonics</td><td>Vevo 770-120</td><td>Echocardiographic Equipment</td></tr><tr><td>707B RMV (Real time MicroVisualization) 30 MHz Scanhead with encapsulated transducer&amp;nbsp;</td><td>Visual Sonics</td><td>707B-256</td><td>Real Time Microvisualization Scanhead</td></tr><tr><td>710B RMV (Real time MicroVisualization) 25 MHz Scanhead with encapsulated transducer&amp;nbsp;</td><td>Visual Sonics</td><td>710B-159</td><td>Real Time Microvisualization Scanhead</td></tr><tr><td>Vevo integrated rail system including physiological monitoring unit&amp;nbsp;</td><td>Visual Sonics</td><td></td><td></td></tr><tr><td>Inhalation Anesthesia System</td><td>VetEquip</td><td>VE2627</td><td>Anesthesia System</td></tr><tr><td>Isofluorane</td><td>Henry Schein</td><td>50033</td><td></td></tr><tr><td>Electric razor&amp;nbsp;</td><td>Wahl</td><td>General supply</td><td></td></tr><tr><td>Hair removal cream</td><td>Nair</td><td>General supply</td><td></td></tr><tr><td>Transductor cream</td><td>Parker</td><td></td><td></td></tr><tr><td>Transductor gel</td><td>Parker</td><td></td><td></td></tr><tr><td>Standard Gauze pads&amp;nbsp;&amp;nbsp;</td><td>McKeeson</td><td>General supply</td><td></td></tr><tr><td>Tape</td><td>Durapore</td><td>General supply</td><td></td></tr><tr><td>Nose cone&amp;nbsp;</td><td></td><td></td><td>For anesthesia delivery</td></tr><tr><td>Water&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Vet eye ointment&amp;nbsp;</td><td>Puralube</td><td>General supply&amp;nbsp;</td><td>To prevent dryness&amp;nbsp;</td></tr><tr><td>Cotton tipped applicators&amp;nbsp;</td><td></td><td>General supply</td><td></td></tr><tr><td>USB Flash Drive</td><td></td><td>General supply</td><td></td></tr></tbody></table>

murine echocardiography of left atrium, aorta, and pulmonary artery

The present methodology teaches the investigator how to measure and use the LAV as a surrogate of chronic elevations in Left Ventricular diastolic pressure through echocardiography, as well as to obtain measurements of the Aorta and PA diameter in mice.
Mice older than 10 d of age can be analyzed using the present technique. The technique is composed of 3 main steps: set-up, image acquisition, and image analysis. The set-up step consists of getting the mouse anesthetized with 1% isoflurane, shaving it, and taping it in a supine position to a heated EKG board where the image acquisition will take place. The image acquisition step consists of learning to identify the cardiac structures and obtaining all the required images with its correspondent probe and axis in order to be able to calculate volumes and diameters. The image analysis step consists of measuring the previously acquired images with the aid of computer software.
Advantages of the proposed technique include a fast (15 min) procedure that would allow the researcher to evaluate interventions in a non-invasive, non-terminal approach and therefore follow the same mouse over time; each mouse can be used as its own control. This fact plus having the same operator perform all the acquisition and analysis for the entire experiment minimizes the limitation of operator-dependency. The present methodology is useful for mouse researchers in cardiovascular and pulmonary medicine.

Assessment of the LA volume and PA diameter with echocardiography allows the discrimination between models where increased pulmonary artery resistance results in increased PA diameter with no change in LAV from those where the Pulmonary Artery and Left Atrial enlargement are both a result of elevated filling pressures on the left side of the heart. Images displaying the differences in the two pathophysiologies are shown in Figure 4. Images of the LA and PA are from young,...

Watch this Scientific Journal Video about Murine Echocardiography of Left Atrium, Aorta, and Pulmonary Artery at JoVE.com

Murine Echocardiography of Left Atrium, Aorta, and Pulmonary Artery

The following protocol describes the methodology for the acquisition and analysis of echocardiographic images used to obtain the Left Atrial Volume (LAV), Aorta (Ao) diameter, and Pulmonary Artery (PA) diameter in mice. This technique is a non-invasive, non-terminal procedure that allows assessment of the cardiopulmonary function.

The present methodology teaches the investigator how to measure and use the LAV as a surrogate of chronic elevations in Left Ventricular diastolic ...

murine-echocardiography-of-left-atrium-aorta-and-pulmonary-artery

Research

JoVE Journal

Medicine

14.3K Views.  Baylor College of Medicine. The following protocol describes the methodology for the acquisition and analysis of echocardiographic images used to obtain the Left Atrial Volume (LAV), Aorta (Ao) diameter, and Pulmonary Artery (PA) diameter in mice. This technique is a non-invasive, non-terminal procedure that allows assessment of the cardiopulmonary function.

Video: Murine Echocardiography of Left Atrium, Aorta, and Pulmonary Artery

Transthoracic Echocardiography in Mice

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene targeting methods can be used to generate mice with altered cardiac size and function,1-3 and as a result, in vivo techniques are needed to evaluate their cardiac phenotype. Transthoracic echocardiography, pulse wave Doppler (PWD), and tissue Doppler imaging (TDI) can be used to provide dimensional measurements of the mouse heart and to quantify the degree of cardiac systolic and diastolic performance. Two-dimensional imaging is used to detect abnormal anatomy or movements of the left ventricle, whereas M-mode echo is used for quantification of cardiac dimensions and contractility.4,5 In addition, PWD is used to quantify localized velocity of turbulent flow,6 whereas TDI is used to measure the velocity of myocardial motion.7 Thus, transthoracic echocardiography offers a comprehensive method for the noninvasive evaluation of cardiac function in mice.

Transthoracic echocardiography offers a noninvasive method for the evaluation of cardiac function in mice. A combination of ultrasound and Doppler imaging modalities can be used to obtain dimensional measurements of the heart and intracardiac blood flow, which together provide an assessment of cardiac systolic and diastolic performance.

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene ...

Murine Echocardiography and Ultrasound Imaging

Rodent models of cardiac pathophysiology represent a valuable research tool to investigate mechanism of disease as well as test new therapeutics.1 Echocardiography provides a powerful, non-invasive tool to serially assess cardiac morphometry and function in a living animal.2 However, using this technique on mice poses unique challenges owing to the small size and rapid heart rate of these animals.3 Until recently, few ultrasound systems were capable of performing quality echocardiography on mice, and those generally lacked the image resolution and frame rate necessary to obtain truly quantitative measurements. Newly released systems such as the VisualSonics Vevo2100 provide new tools for researchers to carefully and non-invasively investigate cardiac function in mice. This system generates high resolution images and provides analysis capabilities similar to those used with human patients. Although color Doppler has been available for over 30 years in humans, this valuable technology has only recently been possible in rodent ultrasound.4,5 Color Doppler has broad applications for echocardiography, including the ability to quickly assess flow directionality in vessels and through valves, and to rapidly identify valve regurgitation. Strain analysis is a critical advance that is utilized to quantitatively measure regional myocardial function.6 This technique has the potential to detect changes in pathology, or resolution of pathology, earlier than conventional techniques. Coupled with the addition of three-dimensional image reconstruction, volumetric assessment of whole-organs is possible, including visualization and assessment of cardiac and vascular structures. Murine-compatible contrast imaging can also allow for volumetric measurements and tissue perfusion assessment.

This video demonstrates use of a rail-mounted high-frequency ultrasound probe to perform echocardiography on an anesthetized mouse. The methods describe both conventional two-dimensional and M-mode measurements of cardiac function in addition to newer, more powerful tools such as color Doppler, strain analysis, as well as general and targeted contrast imaging.

Rodent models of cardiac pathophysiology represent a valuable research tool to investigate mechanism of disease as well as test new therapeutics.1  ...

Murine Fetal Echocardiography

Transgenic mice displaying abnormalities in cardiac development and function represent a powerful tool for the understanding the molecular mechanisms underlying both normal cardiovascular function and the pathophysiological basis of human cardiovascular disease. Fetal and perinatal death is a common feature when studying genetic alterations affecting cardiac development 1-3. In order to study the role of genetic or pharmacologic alterations in the early development of cardiac function, ultrasound imaging of the live fetus has become an important tool for early recognition of abnormalities and longitudinal follow-up. Noninvasive ultrasound imaging is an ideal method for detecting and studying congenital malformations and the impact on cardiac function prior to death 4. It allows early recognition of abnormalities in the living fetus and the progression of disease can be followed in utero with longitudinal studies 5,6. Until recently, imaging of fetal mouse hearts frequently involved invasive methods. The fetus had to be sacrificed to perform magnetic resonance microscopy and electron microscopy or surgically delivered for transillumination microscopy. An application of high-frequency probes with conventional 2-D and pulsed-wave Doppler imaging has been shown to provide measurements of cardiac contraction and heart rates during embryonic development with databases of normal developmental changes now available 6-10. M-mode imaging further provides important functional data, although, the proper imaging planes are often difficult to obtain. High-frequency ultrasound imaging of the fetus has improved 2-D resolution and can provide excellent information on the early development of cardiac structures 11.

Fetal and perinatal death is a common feature when studying genetic alterations affecting cardiac development. High-frequency ultrasound imaging has improved 2-D resolution and can provide excellent information on early cardiac development and is an ideal method to detect the impact on cardiac structure and function prior to death.

Transgenic mice displaying abnormalities in  cardiac development and function represent a powerful tool for the understanding  the molecular mechanisms ...

Echocardiographic Assessment of the Right Heart in Mice

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential therapies. Given the expense and time involved in creating animal models of disease, it is critical that researchers have tools to accurately assess phenotypic expression of disease. Right ventricular dysfunction is the major manifestation of pulmonary hypertension. Echocardiography is the mainstay of the noninvasive assessment of right ventricular function in rodent models and has the advantage of clear translation to humans in whom the same tool is used. Published echocardiography protocols in murine models of PAH are lacking.
In this article, we describe a protocol for assessing RV and pulmonary vascular function in a mouse model of PAH with a dominant negative BMPRII mutation; however, this protocol is applicable to any diseases affecting the pulmonary vasculature or right heart. We provide a detailed description of animal preparation, image acquisition and hemodynamic calculation of stroke volume, cardiac output and an estimate of pulmonary artery pressure.

This article provides a protocol for the echocardiographic assessment of right ventricular size and pulmonary hypertension in mice. Applications include phenotype determination and serial assessment in transgenic and toxin-induced mouse models of cardiomyopathy and pulmonary vascular disease.

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential ...

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction4. To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential.
A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software.
Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic&#160;and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC.
Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

Right ventricle (RV) dysfunction is critical to the pathogenesis of cardiovascular disease, yet limited methodologies are available for its evaluation. Recent advances in ultrasound imaging provide a noninvasive and accurate option for longitudinal RV study. Herein, we detail a step-by-step echocardiographic method using a murine model of RV pressure overload.

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, ...

Echocardiographic Approaches and Protocols for Comprehensive Phenotypic Characterization of Valvular Heart Disease in Mice

The aim of this manuscript and accompanying video is to provide an overview of the methods and approaches used for imaging heart valve function in rodents, with detailed descriptions of the appropriate methods for anesthesia, the echocardiographic windows used, the imaging planes and probe orientations for image acquisition, the methods for data analysis, and the limitations of emerging technologies for the evaluation of cardiac and valvular function. Importantly, we also highlight several future areas of research in cardiac and heart valve imaging that may be leveraged to gain insights into the pathogenesis of valve disease in preclinical animal models. We propose that using a systematic approach to evaluating cardiac and heart valve function in mice can result in more robust and reproducible data, as well as facilitate the discovery of previously underappreciated phenotypes in genetically-altered and/or physiologically-stressed mice.

This protocol provides a detailed description of the echocardiographic approach for comprehensive phenotyping of heart and heart valve function in mice.

The aim of this manuscript and accompanying video is to provide an overview of the methods and approaches used for imaging heart valve function in ...

Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

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.

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.

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV ...

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional imaging to study the cardiac anatomy of the left ventricle and M-mode echo to assess its dimensions. However, this could limit a comprehensive study. Herein, we describe a protocol that allows an assessment of the heart chamber size, left ventricular function (systolic and diastolic) and valvular function. A conventional medical ultrasound machine was used in this protocol and different echo views were obtained through left parasternal, apical and suprasternal windows. In the left parasternal window, the long and short axis were acquired to analyze left chamber dimensions, right ventricle and pulmonary artery dimensions, and mitral, pulmonary and aortic valve function. The apical window allows the measurement of heart chamber dimensions and evaluation of systolic and diastolic parameters. It also allows Doppler assessment with detection and quantification of heart valve disturbances (regurgitation or stenosis). Different segments and walls of the left ventricle are visualized throughout all views. Finally, the ascending aorta, aortic arch, and descending aorta can be imaged through the suprasternal window. A combination of ultrasound imaging, Doppler flow and tissue Doppler assessment have been obtained to study cardiac morphology and function. This represents an important contribution to improve the assessment of cardiac function in adult rats with impact for research using these animal models.

A non-invasive protocol for transthoracic echocardiography assessment of cardiac anatomy and function for adult rats is presented in the current study. The heart valves, all four cardiac chambers and the ascending aorta, aortic arch and descending aorta are studied in detail.

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional ...

Echocardiographic Characterization of Left Ventricular Structure, Function, and Coronary Flow in Neonate Mice

Echocardiography is a non-invasive procedure that enables the evaluation of structural and functional parameters in animal models of cardiovascular disease and is used to assess the impact of potential treatments in preclinical studies. Echocardiographic studies are usually conducted in young adult mice (i.e., 4-6 weeks of age). The evaluation of early neonatal cardiovascular function is not usually performed because of the small size of the mouse pups and the associated technical difficulties. One of the most important challenges is that the short length of the pups&#39; limbs prevents them from reaching the electrodes in the echocardiography platform. Body temperature is the other challenge, as pups are very susceptible to changes in temperature. Therefore, it is important to establish a practical guide for performing echocardiographic studies in small mouse pups to help researchers detect early pathological changes and study the progression of cardiovascular disease over time. The current work describes a protocol for performing echocardiography in mouse pups at the early age of 7 days old. The echocardiographic characterization of cardiac morphology, function, and coronary flow in neonatal mice is also described.

The present protocol describes the echocardiographic assessment of left ventricular morphology, function, and coronary blood flow in 7-day old neonate mice.

Echocardiography is a non-invasive procedure that enables the evaluation of structural and functional parameters in animal models of cardiovascular ...

Transthoracic Echocardiography to Assess Post-Resuscitation Left Ventricular Dysfunction After Acute Myocardial Infarction and Cardiac Arrest in Pigs

One of the main causes of out-of-hospital cardiac arrest is acute myocardial infarction (AMI). After successful resuscitation from cardiac arrest, approximately 70% of patients die before hospital discharge due to post-resuscitation myocardial and cerebral dysfunction. In experimental models, myocardial dysfunction after cardiac arrest, characterized by an impairment in both left ventricular (LV) systolic and diastolic function, has been described as reversible but very little data are available in cardiac arrest models associated with AMI in pigs. Transthoracic echocardiography is the first-line diagnostic test for the assessment of myocardial dysfunction, structural changes and/or AMI extension. In this pig model of ischemic cardiac arrest, echocardiography was done at baseline and 2-4 and 96 hours after resuscitation. In the acute phase, the examinations are done in anesthetized, mechanically ventilated pigs (weight 39.8 &#177; 0.6 kg) and ECG is recorded continuously. Mono- and bi-dimensional, Doppler and tissue Doppler recordings are acquired. Aortic and left atrium diameter, end-systolic and end-diastolic left ventricular wall thicknesses, end-diastolic and end-systolic diameters and shortening fraction (SF) are measured. Apical 2-, 3-, 4-, and 5-chamber views are acquired, LV volumes and ejection fraction are calculated. Segmental wall motion analysis is done to detect the localization and estimate the extent of myocardial infarction. Pulsed Wave Doppler echocardiography is used to record trans-mitral flow velocities from a 4-apical chamber view and trans-aortic flow from a 5-chamber view to calculate LV cardiac output (CO) and stroke volume (SV). Tissue Doppler Imaging (TDI) of LV lateral and septal mitral anulus is recorded (TDI septal and lateral s&#39;, e&#39;, a&#39; velocities). All the recordings and measurements are done according to the recommendations of the American and European Societies of Echocardiography Guidelines.

Transthoracic echocardiography is the first-line diagnostic test for post-resuscitation left ventricular dysfunction and structural changes in a pig model of cardiac arrest.