Name: primary outcome assessment in a pig model of acute myocardial infarction
Uploaded: 2016-10-14T15:00:00
Description: Watch this Scientific Journal Video about Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction at JoVE.com

The authors gratefully acknowledge Marlijn Jansen, Joyce Visser, Grace Croft, Martijn van Nieuwburg, Danny Elbersen and Evelyn Velema for their excellent technical support during the animal experiments.

All animal experiments were approved by the Ethical Committee on Animal Experimentation of the University Medical Center Utrecht (Utrecht, the Netherlands) and conform to the &#39;Guide for the care and use of laboratory animals&#39;.
NOTE: The protocol to perform a closed-chest balloon occlusion is not part of the current manuscript and is described in detail elsewhere5. In short, pigs (60 - 70 kg) are subjected to 75 min transluminal balloon occlusion of the midportion of the left...

<ol>
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Cardiac remodeling is largely depending on myocardial infarct size and the quality of myocardial infarct repair6,26. To assess the former in a standardized manner, the present manuscript provides an elegant method of in&#160;vivo infusion of Evans blue combined with ex&#160;vivo TTC staining, which has been validated and extensively used8,16,27,28. This method allows for quantification of the area at risk (AAR) and infarct size in relation to AAR16. The current approach ...

Heart failure with reduced ejection fraction (HFrEF) accounts for about 50% of all heart failure cases, affecting an estimated 1 - 2% of people in the western world1. Its most prevalent cause is acute myocardial infarction (AMI). As acute mortality after AMI has declined significantly due to increased awareness and improved treatment options, emphasis has shifted towards its chronic sequelae; the most prominent being HFrEF2,3. Together with increasing health care costs4, the growing epidemic of heart failure stresses the need for novel diagnostics and therapies, which can be studied in a highly translational porcine model of adverse remodeling after AMI as previously described5.
Both, determinants (e.g., infarct size) and functional assessments (e.g., echocardiography) of adverse remodeling are often used for efficacy testing of new therapeutics, indicating the need for reliable and relatively inexpensive methods. The aim of the current paper is to address this need by introducing important and reliable outcome measures for efficacy testing in a pig model of acute myocardial infarction. These include infarct size (IS) in relation to area at risk (AAR), 3D transesophageal echocardiography (3D-TEE) and detailed admittance-based pressure-volume (PV) loop acquisition.
Infarct size is the main determinant of adverse remodeling and survival after AMI6. Although timely reperfusion of ischemic myocardium may salvage reversibly injured cardiomyocytes and limit infarct size, reperfusion itself causes additional damage through the generation of oxidative stress and a disproportionate inflammatory response (ischemia-reperfusion injury (IRI))7. Hence, IRI has been identified as a promising therapeutic target. The ability of novel therapeutics to decrease infarct size is quantified by assessing infarct size in relation to the area at risk (AAR). AAR quantification is mandatory to correct for inter-individual variability in coronary anatomy of animal models, as a larger AAR leads to a larger absolute infarct size. Since infarct size is directly related to cardiac performance and myocardial contractility, variations in AAR can influence study outcome measures irrespective of treatment modalities8.
Three-dimensional transesophageal echocardiography (3D-TEE) is a safe, reliable and, most importantly, clinically applicable inexpensive method to measure cardiac function non-invasively. Whereas transthoracic echocardiography (TTE) images are limited to 2D parasternal long- and short-axis views in pigs9, 3D-TEE can be used to obtain complete 3-dimensional images of the left ventricle. Therefore, it does not require mathematical approximations of left ventricular (LV) volumes such as the modified Simpson&#39;s rule10. The latter falls short of correctly estimating LV volumes after LV remodeling due to the lack of cylindrical geometry11. Moreover, 3D-TEE is preferable over epicardial echocardiography as it does not require surgical interventions, which have been observed to exert cardioprotective effects in the present model12. Although the use of 2D-TEE for the assessment of myocardial function has been described before13,14, limitations regarding ventricular geometry are similar to those observed in 2D-TTE and depend on the extent of LV remodeling. Hence, the larger the infarct (and thus the higher the probability of heart failure), the more likely 2D measurements become flawed by incorrect geometrical assumptions and the higher the need for 3D techniques.
Nonetheless, most imaging modalities are limited in their ability to assess intrinsic functional properties of the myocardium. PV loops provide such relevant additional information and their acquisition is therefore described in detail below.

<table border="0" cellpadding="0" cellspacing="0" width="875">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">3-dimensional transesophageal echocardiography</td>
			<td style="width:180px;"></td>
			<td style="width:108px;"></td>
			<td style="width:191px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">iE33 ultrasound device</td>
			<td style="width:180px;">Philips</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">X7-2t transducer</td>
			<td style="width:180px;">Philips</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Aquasonic&#174; 100 ultrasound transmission gel</td>
			<td style="width:180px;">Parker Laboratories Inc.</td>
			<td style="width:108px;">01-34</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Battery handle type C (laryngoscope handle)</td>
			<td style="width:180px;">Riester</td>
			<td style="width:108px;">12303</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Ri-Standard Miller blade MIL 4 (laryngoscope blade)</td>
			<td style="width:180px;">Riester</td>
			<td style="width:108px;">12225</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Qlab 10.0 (3DQ Advanced) analysis software</td>
			<td style="width:180px;">Philips</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Pressure-volume loop acquisition</td>
			<td style="width:180px;"></td>
			<td style="width:108px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Cardiac defibrillator</td>
			<td style="width:180px;">Philips</td>
			<td style="width:108px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">0.9% saline</td>
			<td style="width:180px;">Braun</td>
			<td style="width:108px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">8F Percutaneous Sheath Introducer Set</td>
			<td style="width:180px;">Arrow</td>
			<td style="width:108px;">CP-08803</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">9F Radifocus&#174; Introducer II Standard Kit&#160;</td>
			<td style="width:180px;">Terumo</td>
			<td>RS*A90K10SQ</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">8F Fogarty catheter</td>
			<td style="width:180px;">Edward Life Sciences</td>
			<td>62080814F</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">7F Criticath&#8482; SP5107H TD catheter (Swan-Ganz)</td>
			<td style="width:180px;">Becton Dickinson (BD)</td>
			<td>680078</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:397px;">Ultraview SL Patient Monitor and Invasive Command Module (external cardiac output device)</td>
			<td>Spacelabs Healthcare</td>
			<td>91387</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ADVantage system&#8482;</td>
			<td>Transonic SciSense</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">7F tetra-polar admittance catheter (7.0 VSL Pigtail / no lumen)</td>
			<td>Transonic SciSense</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Multi-channel acquisition system (Iworx 404)</td>
			<td>Iworx</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Labscribe V2.0 analysis software</td>
			<td style="width:180px;">Iworx</td>
			<td style="width:108px;">-</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Infarct size / area-at-risk quantification</td>
			<td style="width:180px;"></td>
			<td style="width:108px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Diathermy</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;"></td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Lebsch knife</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;"></td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Hammer</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;"></td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Bone marrow wax</td>
			<td style="width:180px;">Syneture</td>
			<td style="width:108px;"></td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Klinkenberg scissors</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;"></td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Retractor</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;"></td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Surgical scissors</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">7F Percutaneous Sheath Introducer Set&#160;</td>
			<td style="width:180px;">Arrow</td>
			<td>CP-08703</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">8F Percutaneous Sheath Introducer Set&#160;</td>
			<td style="width:180px;">Arrow</td>
			<td style="width:108px;">CP-08803</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">7F JL4 guiding catheter&#160;</td>
			<td style="width:180px;">Boston Scientific</td>
			<td style="width:108px;">H749 34357-662</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">8F JL4 guiding catheter&#160;</td>
			<td style="width:180px;">Boston Scientific</td>
			<td>H749 34358-662&#160;</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">COPILOT Bleedback Control Valves&#160;</td>
			<td>Abbott Vascular</td>
			<td>1003331</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD Connecta&#8482;&#160;</td>
			<td style="width:180px;">Franklin Lakes</td>
			<td>394995</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Contrast agent</td>
			<td style="width:180px;">Telebrix</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:397px;">Persuader 9 Steerable Guidewire 9 (0.014&#34;, 180 cm, straight tip), hydrophilic coating</td>
			<td style="width:180px;">Medtronic Inc.</td>
			<td>9PSDR180HS</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:397px;">SAPPHIRE&#8482; Coronary Dilatation Catheter (PTCA balloon suitable for the size of the particular coronary artery (2.75 - 3.25 mm))</td>
			<td style="width:180px;">OrbusNeich</td>
			<td style="width:108px;">103-3015</td>
			<td>Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Evans Blue&#160;</td>
			<td style="width:180px;">Sigma-Aldrich</td>
			<td>E2129-100G</td>
			<td>Toxic. Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2,3,5-triphenyl-tetrazolium chloride (TTC)</td>
			<td style="width:180px;">Sigma-Aldrich</td>
			<td>T8877-100G</td>
			<td>Irritant. Alternative product can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">9V battery</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Ruler</td>
			<td style="width:180px;">-</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:397px;">Photocamera</td>
			<td style="width:180px;">Sony</td>
			<td style="width:108px;">-</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:397px;">ImageJ</td>
			<td style="width:180px;">National Institutes of Health</td>
			<td style="width:108px;">-</td>
			<td>Alternative product can be used</td>
		</tr>
	</tbody>
</table>

primary outcome assessment in a pig model of acute myocardial infarction

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are therefore required to confine cardiac damage, promote survival and reduce the disease burden of heart failure. Large animal experiments are an essential part in the translational process from experimental to clinical therapies. To optimize clinical translation, robust and representative outcome measures are mandatory. The present manuscript aims to address this need by describing the assessment of three clinically relevant outcome modalities in a pig acute myocardial infarction (AMI) model: infarct size in relation to area at risk (IS/AAR) staining, 3-dimensional transesophageal echocardiography (TEE) and admittance-based pressure-volume (PV) loops. Infarct size is the main determinant driving the transition from AMI to heart failure and can be quantified by IS/AAR staining. Echocardiography is a reliable and robust tool in the assessment of global and regional cardiac function in clinical cardiology. Here, a method for three-dimensional transesophageal echocardiography (3D-TEE) in pigs is provided. Extensive insight into cardiac performance can be obtained by admittance-based pressure-volume (PV) loops, including intrinsic parameters of myocardial function that are pre- and afterload independent. Combined with a clinically feasible experimental study protocol, these outcome measures provide researchers with essential information to determine whether novel therapeutic strategies could yield promising targets for future testing in clinical studies.

3D Transesophageal Echocardiography
3D transesophageal echocardiography (3D-TEE) can be used for the assessment of global cardiac function. After AMI, global cardiac function differs from healthy baseline values. In particular, left ventricular ejection fraction (LVEF) decreases from 59 &#177; 4% to 37 &#177; 6% after one week of reperfusion (n = 10) (GPJ van Hout, 2015). An increase in end-systolic volume (51 &...

Watch this Scientific Journal Video about Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction at JoVE.com

Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction

Reliable and accurate outcome assessment is the key for translation of preclinical therapies into clinical treatment. The current paper describes how to assess three clinically relevant primary outcome parameters of cardiac performance and damage in a pig acute myocardial infarction model.

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are ...

The overall goal of this methodology is to acquire reliable and reproducible outcome measurements for the evaluation of new therapies in a pig model of acute myocardial infarction. This method can help answer key questions in the cardiovascular field, such as the effect of therapeutic interventions on the schema of a fusion injury and for modeling also an acute myocardial infarction. The main advantage of these techniques is that they allow for an accurate and a clinically relevant assessment of ischemia reperfusion injury and cardiac remodeling.Through this method, can provide insight into myocardial ischemia reperfusion injury. It can also be applied to other studies involving the evaluation of cardiac function. The current protocol allows for the acquisition of primary outcome measurements prior to, or after an acute myocardial infarction.The infarction is made using a 75-minute transluminal balloon occlusion of the left anterior descending artery, which is detailed by the cited video. This video demonstrates how to perform three dimensional transesophageal echocardiography, and the pressure of volume loop measurements for baseline, short-term, and long-term follow up measurements. The video also demonstrates how to measure infarct size and area at risk staining after termination.Prepare the pig with anesthesia as described in the text protocol, and connect the animal to the echocardiography machine using the EKG leads. Now, prepare the echo probe. Put some ultrasound gel on the tip and unlock it so that it is flexible.Adjust the imaging angle to 90 degrees using the handheld operating piece. With the pig in a right lateral position, open the mouth and carefully insert the probe into the esophagus. Be careful not to apply too much pressure, and to avoid the normal anatomic pharyngeal pouch, which resembles a Zenker's diverticulum.Then, insert the probe 50 to 60 centimeters, measure from the tip of the snout, and slowly rotate and flex the head to a left anterolateral position to visualize the heart. Make sure all of the heart's walls are clearly visible. If necessary, lock the echo probe tip to stabilize the image acquisitions.On the display, toggle the 3D Full Volume option to produce to perpendicular images of the left ventricle. Then, maximize the sector width that is being acquired by selecting FV Opt Volume. Now, pause the ventilation and press Acquire to obtain full volume measurements.After obtaining a complete measurement, switch on the mechanical ventilation. After the echo acquisition, unlock the probe and slowly remove it from the animal. Then, monitor the pig until it has recovered from the surgery.In preparation, soak the sensing tips of the catheter in 0.9%saline for at least 20 minutes. After preparing the pig for surgery, infuse 100 international units of heparin per kilogram, and place an 8F introducer sheath in the carotid, and a 9F sheath in the jugular vain. Next, insert a Swan Ganz catheter thought the 9F sheath, inflate the balloon at the tip of the catheter, and wedge it in a small pulmonary artery.Once adequately placed in there peripheral part of the lung, deflate the balloon and connect the Swan Ganz catheter to an external cardiac output device. Upon connection, view the cardiac output menu on the external cardiac output device. Enter the weight of the animal into the system and calculate the length so the BMI is 22.5.Proceed by loading a 20 milliliter syringe with room temperate 0.9%saline and attaching it to the injection port connected to the lumin with the most proximal debouchment. Switch off the ventilation and wait for five heartbeats. First, press Manual, then press Start on the output device.Then, rapidly infuse five milliliters of saline to measure the cardiac output. Within 15 seconds, the device measurements will be shown. Then, switch on the ventilation.Repeat this procedure three times and calculate the average stroke volume. Between infusions, wait a minute or two to allow the end-tidal carbon dioxide to return to preexisting values. Now, remove the Swan Ganz catheter and insert an 8F Fogarty catheter through the 9F sheath in the jugular vein, and position it in the inferior vena cava.While the tip remains in 0.9%saline, calibrate the pressure signal of the PV loop catheter as close to 0 as possible, using the course and fine buttons. Then, input the measured stroke volume into the system. The next step is to advance the PV loop catheter through the 8F sheath in the carotid artery, and, while using fluoroscopy, advance and center the tip into the left ventricle.Now, plot the raw conductance signal against the pressure signal, which should make a rectangular loop. Using this graph, select the largest adequately placed segment. Then, pause the mechanical ventilation and press enter on the pressure volume loop module to take a baseline scan to convert conductance to volume.When the module shows the heart rate, systolic and diastolic conductance, turn the respiration back on. Before proceeding, the measured heart rate must be equal to the EKG, or pressure derived heart rate. There cannot be any arrhythmia, and the systolic and diastolic conductance must be adequately sensed.If the baseline data is determined to be adequate, accept it by pressing enter and write down the heart rate and systolic and diastolic conductance shown on the PV loop module. Then, plot the volume signal against the pressure signal. The loops must still be rectangular.Now, pause the ventilation and acquire baseline pressure volume by recording 10 to 12 consecutive heartbeats. Then, switch on the ventilation again and allow the end-tidal carbon dioxide level to return to preexisting values. Next, under fluoroscopic guidance, inflate the Fogarty catheter to reduce the preload.Then, record 10 to 12 consecutive beats without ventilation as before. The systolic blood pressure must remain above 60 millimeters of mercury, and no arrhythmia can interfere with the measurements. After acquiring the data, deflate the Fogarty catheter, switch on the ventilation, and wait for the end-tidal carbon dioxide to return to preexisting levels.Now, remove the Fogarty and PV loop catheters while continuing to record arterial pressure to correct for pressure drift. Finally, monitor the animal until it has recovered before returning it to the other animals. After preparing the animal for surgery, access both carotid arteries using a surgical exploration of the neck.Then, insert a 7F and an 8F introducer sheath in the respective carotid artery. Now, administer heparin at 100 units per kilo. In order to perform a sternotomy, make a medium 30 to 40 centimeter incision from just below the suprasternal notch to a point just below the xiphoid process.Then, advance through the linea alba down to the sternum. Use diathermy to carefully split the xiphoid and use Klinkenberg scissors to separate the posterior sternum from the pericardium. Continue the separation bluntly, moving cranially.Make sure to point the scissor tips upwards towards the sternum to avoid cardiac damage. Perform a sternotomy by using a hammer and Lebsche knife. Bone marrow bleeding can be minimized by rubbing bone marrow wax on the marrow.Open the thorax with a retractor. Now, open the pericardium using surgical scissors. Connect standard Y catheters to the guiding catheters.Then, connect a three-way tap with a 10 centimeter extension to both Y connectors. Then, position one of the guiding catheters in the ostium of the left main coronary artery via one of the sheaths. Next, using a guide wire inserted into the left anterior descending artery, advance a coronary dilatation catheter through the left main coronary artery catheter, and position the balloon where the coronary occlusion was performed during the myocardial infarction induction.Do not inflate yet. Continue by positioning the other guiding catheter in the ostium of the right coronary artery using the other sheath. Now, perform a coronary angiography.Infuse contrast agent under fluoroscopy. First, confirm correct positioning of the guiding catheter in the left main coronary artery with an anteroposterior view. Thereafter, visualize the right coronary artery.The contrast infusion may propel the balloon further into the coronary artery. Reposition it if necessary. Then, attach syringes with freshly made 2%Evans Blue dye to the three-way taps.Next, using a coronary angiography, inflate the balloon and confirm that it completely occludes part of the coronary artery. The occlusion is critical. While the balloon is inflated, inject the dye through both guiding catheters at 5 milliliters per second.The heart should not turn blue, except for the part of the left ventricle that is deprived of blood flow. If the heart does not go into ventricular fibrillation spontaneously, touch a nine volt battery to the non-infarcted part of the heart five beats after dye infusion. Then, incise the cable vein to release pressure and use suction to drain out the blood.Now, deflate the balloon. Retract it along with both guiding catheters. Then, explant the heart by dissecting the surrounding membranes, and making a transverse cut through the large vessels.Make sure to wash off all the blood and dye with 0.9%saline, both on the outside and on the inside. Then, carefully dissect the left ventricle. Then, make five equal 10 millimeter thick sections from apex to base, in a plane parallel to the atrial ventricular groove.Photograph both sides of all five slices under ambient light conditions using a ruler in the image for calibration. Then, stain the slices in TTC and photograph them again. 3D transesophageal echocardiography was used for the assessment of global cardiac function.One week after an acute myocardial infarction, global cardiac function deteriorated when compared to healthy baseline values, based on results from 10 animals. This was accounted for by reduced contraction of the anteroseptal wall. Pressure volume loops were also used, both to assess global cardiac function, and to calculate intrinsic myocardial muscle properties.Outcome measurements of the former were easily calculated, and include EDV int he lower right corner, and ESV in the upper left corner. These values provide important information on left ventricular geometry. From these measures, the left ventricular rejection fraction, an important measure of left ventricular pump function, was calculated, along with several other parameters.For intrinsic cardiac performance, different measurements were derived from the PV loops, such as the end systolic and end diastolic pressure volume relationship. After myocardial infarction, the end systolic volume pressure relationship slope may decrease, indicating decreased contractility. Ultimately, stains were used to identify the remote myocardium from the area at risk, and the infarcted myocardium.About 22%of the left ventricle made up the area at risk, most of which was infarcted. After watching this video, you should have a good understanding of how to perform 3D transesophageal echocardiography, pressure volume loop data acquisition, and infarct size to area at risk staining. Once mastered, transesophageal echocardiography can be performed in 20 minutes.Pressure volume loop data acquisition in 30 minutes. And infarct size and area at risk staining in 60 minutes. While attempting PV loops and infarct size area at risk staining, it is important to remember to be cautious not to induce and arrhythmias.The techniques shown in this video can help researchers in the field of cardiovascular disease to explore ischemia and reperfusion injury in large animal models.

Research

JoVE Journal

Medicine

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