Name: murine echocardiography of left atrium, aorta, and pulmonary artery
Uploaded: 2017-02-20T15:00:00
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 informat...

<ol>
	<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. L., 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=ACCF+/+AHA+Expert+Consensus+Document+Expert+Consensus+Document+ACCF+/+AHA+2009+Expert+Consensus+Document+on+Pulmonary+Hypertension+A+Report+of+the+American+College+of+Cardiology+Foundation+Task+Force+on+Expert+Consensus+Documents+and+the+American+Heart+Association.">ACCF / AHA Expert Consensus Document Expert Consensus Document ACCF / AHA 2009 Expert Consensus Document on Pulmonary Hypertension A Report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents and the American Heart Association.</a> Circulation. , 2250-2294 (2009).</li><li>Cieslik, K. A., Taffet, G. E., Carlson, S., Hermosillo, J., Trial, J., Entman, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immune-inflammatory+dysregulation+modulates+the+incidence+of+progressive+fibrosis+and+diastolic+stiffness+in+the+aging+heart.">Immune-inflammatory dysregulation modulates the incidence of progressive fibrosis and diastolic stiffness in the aging heart.</a> Journal of Molecular and Cellular Cardiology. 50 (1), 248-256 (2011).</li><li>Tate, C. A., Taffet, G. E., Hudson, E. K., Blaylock, S. L., McBride, R. P., Michael, L. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+calcium+uptake+of+cardiac+sarcoplasmic+reticulum+in+exercise-trained+old+rats.">Enhanced calcium uptake of cardiac sarcoplasmic reticulum in exercise-trained old rats.</a> Am J Physiol Heart Circ Physiol. 258 (2), H431-H435 (1990).</li><li>Kitzman, D. W., Daniel, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diastolic+Heart+Failure+in+the+Elderly.">Diastolic Heart Failure in the Elderly.</a> Heart Failure Clinics. 3 (4), 437-453 (2007).</li><li>Sanderson, J. E., Rusconi, C., 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=How+to+diagnose+diastolic+heart+failure+a+consensus+statement+on+the+diagnosis+of+heart+failure+with+normal+left+ventricular+ejection+fraction+by+the+Heart+Failure+and+Echocardiography+Associations+of+the+European+Society+of+Cardiology.">How to diagnose diastolic heart failure a consensus statement on the diagnosis of heart failure with normal left ventricular ejection fraction by the Heart Failure and Echocardiography Associations of the European Society of Cardiology.</a> Eur Heart J. , 2539-2550 (2007).</li><li>Medrano, G., Hermosillo-Rodriguez, J., 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=Left+Atrial+Volume+and+Pulmonary+Artery+Diameter+Are+Noninvasive+Measures+of+Age-Related+Diastolic+Dysfunction+in+Mice.">Left Atrial Volume and Pulmonary Artery Diameter Are Noninvasive Measures of Age-Related Diastolic Dysfunction in Mice.</a> The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. (16), 1-10 (2015).</li><li>Franco, F., Thomas, G. D., 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=Magnetic+Resonance+Imaging+and+Invasive+Evaluation+of+Development+of+Heart+Failure+in+Transgenic+Mice+With+Myocardial+Expression+of+Tumor+Necrosis+Factor-+.">Magnetic Resonance Imaging and Invasive Evaluation of Development of Heart Failure in Transgenic Mice With Myocardial Expression of Tumor Necrosis Factor- .</a> Circulation. 99, 448-454 (1999).</li><li>Jenkins, C., Bricknell, K., Marwick, T. 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. G., 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=ePLAR+-+The+echocardiographic+Pulmonary+to+Left+Atrial+Ratio+-+A+novel+non-invasive+parameter+to+differentiate+pre-capillary+and+post-capillary+pulmonary+hypertension.">ePLAR - The echocardiographic Pulmonary to Left Atrial Ratio - A novel non-invasive parameter to differentiate pre-capillary and post-capillary pulmonary hypertension.</a> International Journal of Cardiology. 212, 379-386 (2016).</li></ol>

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 border="0" cellpadding="0" cellspacing="0" width="673">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Vevo 770 high-resolution in vivo micro-imaging system</td>
			<td style="width:85px;">Visual Sonics</td>
			<td style="width:119px;">Vevo 770-120</td>
			<td style="width:267px;">Echocardiographic Equipment</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:203px;">707B RMV (Real time MicroVisualization) 30 MHz Scanhead with encapsulated transducer&#160;</td>
			<td style="width:85px;">Visual Sonics</td>
			<td style="width:119px;">707B-256</td>
			<td>Real Time Microvisualization Scanhead</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:203px;">710B RMV (Real time MicroVisualization) 25 MHz Scanhead with encapsulated transducer&#160;</td>
			<td style="width:85px;">Visual Sonics</td>
			<td style="width:119px;">710B-159</td>
			<td>Real Time Microvisualization Scanhead</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:203px;">Vevo integrated rail system including physiological monitoring unit&#160;</td>
			<td style="width:85px;">Visual Sonics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Inhalation Anesthesia System</td>
			<td style="width:85px;">VetEquip</td>
			<td style="width:119px;">VE2627</td>
			<td>Anesthesia System</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Isofluorane</td>
			<td style="width:85px;">Henry Schein</td>
			<td style="width:119px;">50033</td>
			<td style="width:267px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Electric razor&#160;</td>
			<td style="width:85px;">Wahl</td>
			<td style="width:119px;">General supply</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Hair removal cream</td>
			<td style="width:85px;">Nair</td>
			<td style="width:119px;">General supply</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Transductor cream</td>
			<td style="width:85px;">Parker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Transductor gel</td>
			<td style="width:85px;">Parker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Standard Gauze pads&#160;&#160;</td>
			<td style="width:85px;">McKeeson</td>
			<td style="width:119px;">General supply</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Tape</td>
			<td style="width:85px;">Durapore</td>
			<td style="width:119px;">General supply</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Nose cone&#160;</td>
			<td style="width:85px;"></td>
			<td style="width:119px;"></td>
			<td>For anesthesia delivery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Water&#160;</td>
			<td style="width:85px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Vet eye ointment&#160;</td>
			<td style="width:85px;">Puralube</td>
			<td style="width:119px;">General supply&#160;</td>
			<td>To prevent dryness&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Cotton tipped applicators&#160;</td>
			<td style="width:85px;"></td>
			<td style="width:119px;">General supply</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">USB Flash Drive</td>
			<td style="width:85px;"></td>
			<td style="width:119px;">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 ...

The overall goal of this procedure is to acquire and analyze echocardiographic images for the determination of the left atrial volume and the aorta, and pulmonary artery diameters in mice. This technique can discriminate between increases in the pulmonary artery resistance and diameter with no changes in the left atrial volume from models in which the PA and the LA are both enlarged. The main advantage of this technique, is that it is a non-terminal, non invasive approach that allows for serial assessment of the same animal.This technique has the potential to further our ability to monitor interventions and to initiate other studies in the field of cardiopulmonary science. Demonstration of this technique is critical as the proper probe and mouse positioning are necessary for optimal image acquisitioning. Before beginning the procedure, turn on the echocardiographic system and select cardiac measurements from the drop down menu.Click initialize to start the software. Then, click the new button to begin a new study, and enter the demographic information of the experimental animal. Click temp on and off to turn on the temperature controlled EKG board, and use the up and down arrows to set the temperature to 39 degrees Celsius.Next, turn on the oxygen delivery system and anesthesia chamber and confirm that the mouse is properly anesthetized by lack of response to paw pinch. Place the animal in the supine position on the temperature controlled EKG board. Apply lubricant ointment to the animal's eyes, and then tape each paw to the correspondent EKG electrode on the board.Observe the EKG tracing in the lower part of the monitor. Then, use an electric razor to shave the fur from the anterior thorax and upper abdominal area, and cover the chest with a generous amount of transducer gel. To measure the left atrium, use the handle beneath the EKG board to adjust the angle of the board to 30 to 45 degrees along the X axis, and 0 degrees along the Y axis.Next, place the 25 MHz scan head in the echocardiographic movable arm clamp in the long axis view, and select the cardiac measurement filter, and the 2-D B-Mode in the echocardiographic system. Rotate the X and Y adjustment torques to obtain a long axis view of the heart at the level of the aortic outflow tract and press the Cine Store button to acquire a five second movie recording. Now, switch the echocardiographic view to M-Mode, a sagittal view of the heart and a cursor will appear.Move the cursor so that it encompasses the whole left atrium at the level of the aortic outflow tract. And press the Frame Store button on the keyboard to acquire three images on this view. In B-Mode, rotate the movable arm clamp 90 degrees clockwise to set the scan head in the short axis view.Then, use the Y axis torque to find the intra-articular septum, and acquire a five second recording that includes the wall of the atrium. We're measuring the left atrium diameters using EKG tracing as a timing guide to select the image corresponding to the P wave time point. This corresponds to the pre-atrial contraction time, when the left atrium is at its largest capacity.To measure the great vessels, replace the 25 MHz scan head with a 30 MHz scan head, and select the abdominal measurements filter, and the 2-D B-Mode. Use the handle under the EKG board to adjust the angle of the board to a 5 degree angle along the X axis and 60 degrees along the Y axis. Use the X and Y axis adjustment torques to obtain a long axis view of the heart at the level of the aortic outflow tract, and acquire a five second movie recording.Rotate the movable arm clamp of the set 90 degrees clockwise to set the scan head in the short axis view. Then, use the Y axis torque to locate the pulmonary artery at the level of its bifurcation, and acquire a five second movie recording. To ensure the correct location of the pulmonary artery, you can also acquire the pulmonary artery doppler tracing by pressing the PW button.Observe the normal respiratory variation in the tracing. For the great vessels measurements, use the EKG tracing as a timing guide to select a time point after a QRS complex. This corresponds to the point where the great vessels are at the largest capacity.Echocardiographic assessment of the left atrium volume and the pulmonary artery diameter permits the discrimination between models, where an increased pulmonary artery resistance results in an increased pulmonary artery diameter with no change in the left atrium volume from instances when the pulmonary artery and left atrial enlargement are both a result of elevated filling pressures on the left side of the heart when the mitral valve is normal. By comparison, older animals develop an increase in both their pulmonary artery diameter, and left atrium volume, suggesting that the backward propagation of pressure drives the increase in the pulmonary artery diameter observed in this group. Using the demonstrated technique to measure the left atrium and great vessels allows the acquisition of both reproducible and consistent data between the experimental animals, as evidenced by these measurements obtained from a group of 19-month-old mice that underwent two subsequent echocardiographic assessments.Further, these results are easily reproduced between researchers, as apparent in the similarities observed between these four images obtained for the measurement of the left atrium super inferior diameter, and the pulmonary artery diameter acquired by two different researchers. Once this technique has been mastered, the images can be acquired in 15 minutes if it is performed properly. While attempting this procedure, it's important to monitor the heart rate throughout the whole study.A heart rate of 400 beats per minute is ideal. Following this procedure, other methods like dopplers can be performed to answer additional questions about systolic and diastolic cardiac functions. We hope that this technique will pave the way for researchers in the field of cardiopulmonary science to explore age-associated left ventricular diastolic dysfunction and pulmonary hypertension in mice, as well as therapeutic interventions for these and other pathologies.

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

Research

JoVE Journal

Medicine

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 ...

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, ...

A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms at work during MI and developing effective therapeutic approaches requires methodology to reproducibly simulate the clinical incidence and reflect the pathophysiological changes associated with MI. Here, we describe a surgical method to induce MI in mouse models that can be used for short-term ischemia-reperfusion (I/R) injury as well as permanent ligation. The major advantage of this method is to facilitate location of the left anterior descending artery (LAD) to allow for accurate ligation of this artery to induce ischemia in the left ventricle of the mouse heart. Accurate positioning of the ligature on the LAD increases reproducibility of infarct size and thus produces more reliable results. Greater precision in placement of the ligature will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies and improving our understanding of the mechanisms producing cardiac dysfunction following MI. This mouse model of MI is also useful for the preclinical testing of treatments targeting myocardial damage following MI.

We introduce a surgical method to induce experimental ischemia/reperfusion (I/R) injury to simulate myocardial infarction (MI) in mouse models that allows for more clarity in positioning of the ligation on the left anterior descending artery (LAD) to increase the reproducibility of MI experiments in mice.

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms ...

Murine Left Anterior Descending (LAD) Coronary Artery Ligation: An Improved and Simplified Model for Myocardial Infarction

Ischemic heart disease (IHD), or acute coronary syndrome (ACS), is one of the leading causes of death in the United States. IHD is characterized by reduced blood supply to the heart, resulting in the loss of oxygen to and the ensuing necrosis of the heart muscle. The MI model has gained popularity for its use as a short-term ischemia-reperfusion model and a long-term permanent ligation model. Below, we describe a reliable method for the permanent ligation of the LAD. With mouse genetic engineering technology becoming more advanced, and with an increasing availability of quality murine surgical instruments, the mouse has become a popular model for MI surgeries. Our surgical model incorporates the use of an easily reversible anesthetic for the rapid recovery of the mouse; a minimally invasive endotracheal intubation without involving a tracheotomy; and a thoracentesis through the original thoracotomy site without creating an additional incision in the chest, as is done in some other methods, to effectively remove excess blood and air from the chest cavity. This method is comparatively less invasive than other methods, which dramatically reduces surgical and post-surgical complications and mortality and improves reproducibility.

Murine Left Anterior Descending LAD Coronary Artery Ligation: An Improved and Simplified Model for Myocardial Infarction

We provide a reliable method for left anterior descending artery (LAD) ligation in a mouse model. This method is comparatively less invasive than other methods, involving endotracheal intubation, a left-sided thoracotomy approach, and thoracentesis. This method can be used as a model for both acute and chronic myocardial infarction (MI).

Ischemic heart disease (IHD), or acute coronary syndrome (ACS), is one of the leading causes of death in the United States. IHD is characterized by ...

Direct Re-implantation of Left Coronary Artery into the Aorta in Adults with Anomalous Origin of Left Coronary Artery from the Pulmonary Artery (ALCAPA)

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly which is one of leading causes of myocardial ischemia and infarction in children. If left untreated, it results in a 90% mortality rate in the first year of life. In patients who survive to the adulthood, the coronary steal phenomenon and retrograde left-sided coronary flow provide a substrate for chronic subendocardial ischemia, which may lead to left ventricular dysfunction, ischemic mitral regurgitation, malignant ventricular arrhythmias, and sudden cardiac death. The average age of life-threatening presentation is 33 years and of sudden cardiac death 31 years. Therefore, surgical correction is highly recommended as soon as the diagnosis is made, regardless of age. In adult-type ALCAPA originating from the right-facing sinus of the pulmonary artery, direct re-implantation of the ALCAPA into the aorta is the more physiologically sound repair technique to re-establish the dual-coronary perfusion system and is recommended. This protocol describes the technique of direct re-implantation of adult-type ALCAPA into the aorta.

Direct Re-implantation of Left Coronary Artery into the Aorta in Adults with Anomalous Origin of Left Coronary Artery from the Pulmonary Artery ALCAPA

Surgical correction of ALCAPA is highly recommended, regardless of age or the degree of intercoronary collateralization. This protocol presents a technique for the direct re-implantation of adult-type ALCAPA into the aorta to re-establish the dual-coronary perfusion. Whenever feasible, direct re-implantation is preferred to other surgical correction techniques.

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly which is one of leading causes of myocardial ...

Murine Myocardial Infarction Model using Permanent Ligation of Left Anterior Descending Coronary Artery

Myocardial infarction (MI) and acute coronary diseases are among the most prominent causes of death in population with western lifestyle. The murine models of MI with permanent ligation of left-anterior descending (LAD) coronary artery closely mimics MI in humans. Murine models benefit from the extensive genetic engineering available nowadays. Here we propose a reproducible murine surgical model of myocardial infarction by permanent LAD coronary ligation. Our technique comprises anesthesia with ketamine/xylazine that can be rapidly reversed by administration of an antagonist, intubation without tracheotomy for mechanical-assisted ventilation, ventilation with application of extrinsic positive end-expiratory pressure (PEEP) to avoid alveolar collapse, a thoracotomy method limiting to the minimum surgical lesions made to skeletal muscles, and lung inflation without thoracentesis. This method is sparsely invasive, reproducible and reduces post-surgery mortality and complications.

Herein we describe a surgical procedure showing how to achieve permanent ligation of the left-anterior descending coronary artery in mice. This model is of high relevance to investigate the pathophysiology of myocardial infarction and the concomitant biological processes.

Myocardial infarction (MI) and acute coronary diseases are among the most prominent causes of death in population with western lifestyle. The murine ...

Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the left ventricle by draining blood from the left atrium (LA) and returning it to the systemic arterial circulation via the femoral artery. It can provide flows ranging from 2.5-5 L/min depending on the size of the cannula. Here, we discuss the mechanism of action of LAFAB, available clinical data, indications for its use in cardiogenic shock, steps of implantation, post-procedural care, and complications associated with the use of this device and their management.
We also provide a brief video of the procedural component of device therapy, including the pre-placement preparation, percutaneous placement of the device via transseptal puncture under echocardiographic guidance and the post-operative management of device parameters.

The following article describes the stepwise procedure for placement of a device (e.g., Tandemheart) in cardiogenic shock (CS) that is a percutaneous left ventricular assist device (pLVAD) and a left atrial to femoral artery bypass (LAFAB) system that bypasses and supports the left ventricle (LV) in CS.

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the ...

Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction

Ischemic heart disease and subsequent myocardial infarction (MI) is one of the leading causes of mortality in the United States and around the world. In order to explore the pathophysiological changes after myocardial infarction and design future treatments, research models of MI are required. Permanent ligation of the left coronary artery (LCA) in mice is a popular model to investigate cardiac function and ventricular remodeling post MI. Here we describe a less invasive, reliable, and reproducible surgical murine MI model by permanent ligation of the LCA. Our surgical model comprises of an easily reversible general anesthesia, endotracheal intubation that does not require a tracheotomy, and a thoracotomy. Electrocardiography and troponin measurement should be performed to ensure MI. Echocardiography at day 28 after MI will discern heart function and heart failure parameters. The degree of cardiac fibrosis can be evaluated by Masson's trichrome staining and cardiac MRI. This MI model is useful for studying the pathophysiological and immunological alterations after MI.

Presented here is a surgical procedure for permanent ligation of the left coronary artery in mice. This model can be used to investigate the pathophysiology and associated inflammatory response after myocardial infarction.

Ischemic heart disease and subsequent myocardial infarction (MI) is one of the leading causes of mortality in the United States and around the world. In ...

ICE-Based 3D Remodeling for the Left Atrium and Pulmonary Vein

Three-Dimensional Modeling of the Left Atrium and Pulmonary Veins with a Precise Intracardiac Echocardiography Approach

Intracardiac echocardiography (ICE) is a novel tool for estimating cardiac anatomy during pulmonary vein isolation procedures, particularly the left atrium (LA) anatomy and pulmonary vein structures. ICE is widely used to establish a three-dimensional (3D) left atrial structural model during ablation procedures. However, it is unclear whether using ICE in a precise 3D modeling method can provide a more accurate left atrial 3D model and the transseptal approach. This study proposes a protocol to model the left atrium and pulmonary veins with ICE and fast anatomical mapping (FAM) catheter remodeling. It evaluates the accuracy of the models produced using the two methods through observer scoring. We included 50 patients who underwent ICE-based 3D remodeling and 45 who underwent FAM 3D remodeling based on pulmonary vein isolation procedures. The pulmonary vein antrum remodeling is estimated by comparing the antrum area acquired by remodeling and left atrial computed tomography angiography (CTA). The observer scores for the modeling in the ICE and FAM groups were 3.40 &#177; 0.81 and 3.02 &#177; 0.72 (P &#60; 0.05), respectively. The pulmonary vein antrum area obtained using the ICE- and FAM-based methods showed a correlation with the area acquired by left atrium CT. However, the 95% confidence interval bias was narrower in ICE-acquired models than in FAM-acquired models (-238 cm2 to 323 cm2 Vs. -363 cm2 to 386 cm2, respectively) using Bland-Altman analysis. Therefore, precise ICE possesses high accuracy in estimating the left atrial structure, becoming a promising approach for future cardiac structure estimation.

Author Spotlight: Advancements in Intracardiac Echocardiography for Atrial Anatomy Assessment 

Accurate intracardiac echocardiography (ICE) shows significant accuracy in estimating the left atrial structure, a prospective and promising cardiac structure estimation method. Here we propose a protocol for three-dimensional modeling of the left atrium and pulmonary veins with ICE and fast anatomical mapping (FAM) catheter remodeling.

Intracardiac echocardiography (ICE) is a novel tool for estimating cardiac anatomy during pulmonary vein isolation procedures, particularly the left ...