Name: left coronary artery ligation: a surgical murine model of myocardial infarction
Uploaded: 2022-08-09T14:45:00
Description: Watch this Scientific Journal Video about Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction at JoVE.com

This work was supported by National Institute of Health grants (R01HL143967, R01HL142629, R01AG069399, and R01DK129339), AHA Transformational Project Award (19TPA34910142), AHA Innovative Project Award (19IPLOI34760566), and ALA Innovation Project Award (IA-629694) (to PD).

The present study protocol was reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Pittsburgh. Eight (sham n = 4 and MI n = 4) 1-year-old female C57BL/6J mice weighing 24-30 g were used for these experiments. Approximately 100% and at least 80% of mice survived in the first 24 h and 28 days, respectively.
1. Preparation and endotracheal intubation of the mice
<ol>
	<li>Preheat a bead sterilizer (see Table of Materials...

<ol>
	<li>Virani, S. S., 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=Heart+disease+and+stroke+statistics-2021+update:+a+report+from+the+American+Heart+Association.">Heart disease and stroke statistics-2021 update: a report from the American Heart Association.</a> Circulation. 143 (8), 254 (2021).</li><li>Mendis, S., 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=World+Health+Organization+definition+of+myocardial+infarction:+2008-09+revision.">World Health Organization definition of myocardial infarction: 2008-09 revision.</a> International Journal of Epidemiology. 40 (1), 139-146 (2011).</li><li>Frangogiannis, N. 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P., 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=Preclinical+models+of+myocardial+infarction:+from+mechanism+to+translation.">Preclinical models of myocardial infarction: from mechanism to translation.</a> British Journal of Pharmacology. 179 (5), 770-791 (2022).</li><li>De Villiers, C., Riley, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+myocardial+infarction:+comparing+permanent+ligation+and+ischaemia-reperfusion.">Mouse models of myocardial infarction: comparing permanent ligation and ischaemia-reperfusion.</a> Disease Models &amp; Mechanisms. 13 (11), (2020).</li><li>Vasamsetti, S. 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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=General+anesthesia+in+cardiac+surgery:+a+review+of+drugs+and+practices.">General anesthesia in cardiac surgery: a review of drugs and practices.</a> The Journal of Extra-Corporeal Technology. 37 (2), 227-235 (2005).</li><li>Kolk, M. V., 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=LAD-ligation:+a+murine+model+of+myocardial+infarction.">LAD-ligation: a murine model of myocardial infarction.</a> Journal of Visualized Experiments. (32), e1438 (2009).</li><li>Wu, Y., Yin, X., Wijaya, C., Huang, M. -. H., McConnell, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+myocardial+infarction+in+rats.">Acute myocardial infarction in rats.</a> Journal of Visualized Experiments. (48), e2464 (2011).</li><li>Kalogeris, T., Baines, C., Krenz, M., Korthuis, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+six-cell+biology+of+ischemia/reperfusion+injury.">Chapter six-cell biology of ischemia/reperfusion injury.</a> International Review of Cell and Molecular Biology. , 229-317 (2012).</li><li>Scofield, S. 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(178), e63042 (2021).</li></ol>

The murine model of MI is gaining popularity in cardiovascular research laboratories, and this study describes a reproducible and clinically relevant MI model. This protocol improves the LCA ligation process in several ways. To begin with, the use of injectable pre-operative anesthetics such as xylazine/ketamine or sodium pentobarbital14,15 is avoided. Only isoflurane anesthesia was used, which helps enhance animal survival rates (&#62;80% survival 28 days after ...

Cardiovascular disease is a major public health concern that claims 17.9 million lives each year, accounting for 31 percent of global mortality1. The most prevalent type of cardiovascular anomaly is coronary heart disease, and myocardial infarction (MI) is one of the major manifestations of coronary heart disease2. MI is usually caused by thrombotic occlusion of a coronary artery due to the rupture of a vulnerable plaque3. The resulting ischemia causes profound ionic and metabolic changes in the affected myocardium, as well as a rapid decrease in systolic function. MI results in the death of cardiomyocytes, which can further lead to ventricular dysfunction and heart failure4.
Research on MI in patients is limited due to the scarcity of tissues obtained from patients with MI5. As such, murine models of MI are useful in both studying disease mechanisms as well as developing potential therapeutic targets. Currently available murine models of MI includeirreversible ischemia models (LCA and ablation methods) and reperfusion models (ischemia/reperfusion, I/R)6. Permanent ligation of the left coronary artery (LCA) in mice is the most used method, and it imitates the pathophysiology and immunology of MI in patients7,8,9. Permanent MI can also be induced by ablation methods, which involve electrical damage or cryoinjury. Ablation methods are able to generate uniform-sized infarction at the precise location10. On the other hand, scar formation, infarct morphology, and molecular signaling mechanisms may vary among the ablation methods10,11. The murine I/R method is another important MI model as it represents the clinical scenario of reperfusion therapy12. The I/R model is associated with challenges such as a variable infarct size, difficulty in distinguishing responses of initial injury, and reperfusion6.
Although widely used, LCA ligation methods are associated with low survival rates and post-operative pain13. This protocol demonstrates the murine surgical MI model of LCA ligation that involves the preparation and intubation of mice, LCA ligation, post-operative care, and validation of MI. Rather than using an invasive tracheotomy14, this method employs endotracheal intubation. The animal is intubated by illuminating the oropharynx using a laryngoscope, making the procedure easier, safer, and less traumatic15. The mouse is kept on ventilator support and under isoflurane anesthesia throughout the procedure. Further, echocardiography and Masson&#39;s trichrome staining are performed to evaluate heart function and cardiac fibrosis after MI, respectively. Overall, this method provides a reliable and reproducible surgical murine model of MI that can be used to study pathophysiology and inflammation after MI.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>22 G catheter needle</td>
			<td>Exel INT</td>
			<td>26741</td>
			<td>Thoracentesis</td>
		</tr>
		<tr>
			<td>24 G catheter needle</td>
			<td>Exel INT</td>
			<td>26746</td>
			<td>Endotracheal intubation</td>
		</tr>
		<tr>
			<td>4-0 nylon suture</td>
			<td>Covetrus</td>
			<td>29263</td>
			<td>Suturing of muscles and skin</td>
		</tr>
		<tr>
			<td>8-0 nylon suture</td>
			<td>S&#38;T</td>
			<td>3192</td>
			<td>Ligation of LAD</td>
		</tr>
		<tr>
			<td>Anesthetic Vaporizers</td>
			<td>Vet equip</td>
			<td>VE-6047</td>
			<td>Anesthetic support</td>
		</tr>
		<tr>
			<td>Animal physiology monitor</td>
			<td>Fujifilm</td>
			<td>VEVO 3100</td>
			<td>Monitor heart rate,respiration rate and body temperature</td>
		</tr>
		<tr>
			<td>Betadine solution</td>
			<td>PBS animal health</td>
			<td>11205</td>
			<td>Antispetic</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Covetrus</td>
			<td>55175</td>
			<td>Analgesic</td>
		</tr>
		<tr>
			<td>Disecting microscope</td>
			<td>OMANO</td>
			<td>OM2300S-V7</td>
			<td>Binocular</td>
		</tr>
		<tr>
			<td>Electric razor</td>
			<td>Wahl</td>
			<td>79300-1001M</td>
			<td>Shaving</td>
		</tr>
		<tr>
			<td>Electrode gel</td>
			<td>Parker Laboratories</td>
			<td>W60698L</td>
			<td>Electrically conductive gel</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Decon Laboratories</td>
			<td>22-032-601</td>
			<td>Disinfectant</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>FST</td>
			<td>11065-07</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Gauze</td>
			<td>Curity</td>
			<td>CAR-6339-PK</td>
			<td>Sterile</td>
		</tr>
		<tr>
			<td>Heat lamp</td>
			<td>Satco</td>
			<td>S4998</td>
			<td>Post surgery care</td>
		</tr>
		<tr>
			<td>Heating pad</td>
			<td>Kent scientific</td>
			<td>Surgi-M</td>
			<td>Temperature control</td>
		</tr>
		<tr>
			<td>Hot Bead sterilizer</td>
			<td>Germinator 500</td>
			<td>11503</td>
			<td>Sterilization of surgical instrument</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Covetrus</td>
			<td>29405</td>
			<td>Anesthesia</td>
		</tr>
		<tr>
			<td>Masson&#8217;s trichrome staining kit</td>
			<td>Thermoscientific</td>
			<td>87019</td>
			<td>Measurement of cardiac Fibrosis</td>
		</tr>
		<tr>
			<td>Micro Needle Holder</td>
			<td>FST</td>
			<td>12500-12</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Micro scissors</td>
			<td>FST</td>
			<td>15000-02</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Ophthalmic ointment</td>
			<td>Dechra</td>
			<td>Puralube Vet</td>
			<td>Sterile occular lubricant</td>
		</tr>
		<tr>
			<td>Scanning Gel</td>
			<td>Parker Laboratories</td>
			<td>Aquasonic 100</td>
			<td>Aqueous ultrasound transmission gel</td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>FST</td>
			<td>14060-11</td>
			<td>Stainless Steel</td>
		</tr>
		<tr>
			<td>Small Animal Laryngoscope</td>
			<td>Penn-Century</td>
			<td>Model LS-2-M</td>
			<td>Illuminating the oropharynx</td>
		</tr>
		<tr>
			<td>Small animal ventilator</td>
			<td>Harvard apparatus</td>
			<td>557058</td>
			<td>Ventilator support</td>
		</tr>
		<tr>
			<td>Surgical light</td>
			<td>Cole parmer</td>
			<td>41723</td>
			<td>Illuminator Width (in): 7</td>
		</tr>
		<tr>
			<td>Vevo 3100 preclinical imaging platform</td>
			<td>Fujifilm</td>
			<td>VEVO 3100</td>
			<td>Echocardiography</td>
		</tr>
		<tr>
			<td>VevoLAB software</td>
			<td>Fujifilm</td>
			<td>VevoLAB 3.2.6</td>
			<td>Echocardiography data analysis</td>
		</tr>
	</tbody>
</table>

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.

Figure 1 demonstrates the representative active ECG and respiration signals during the echocardiographic evaluation of sham (Figure 1A) and MI (Figure 1B) mice. Verification of active ECG and respiration signals are important before acquiring the echocardiographic data. Figure 2 shows echocardiographic measurement of cardiac functional parameters following 28 days after LCA ligation. <s...

Watch this Scientific Journal Video about Left Coronary Artery Ligation: A Surgical Murine Model of Myocardial Infarction at JoVE.com

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

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 ...

The surgical model permanent ligation of left artery in mice can be used to investigate the pathophysiology and associated inflammatory response after myocardial infarction. This method provides a reliable and producible mouse model of MI, which is easy, safe, and less invasive. To begin, preheat a bead sterilizer to 250 degrees Celsius and place autoclaved surgical instruments in it for a few minutes.Ensure the depth of anesthesia in the mouse by checking the response to a firm toe pinch. Weigh the mouse to estimate the dosage of the pre-operative analgesic drug buprenorphine and inject the drug intraperitoneally. Trim the fur on the left side of the thorax using an electric razor.After disinfecting the surgical site, place the mouse in the supine position on an inclined board. Secure the head and limbs of the mouse using an elastic band attached to the upper incisors and adhesive tape respectively. Apply sterile ophthalmic lubricant to the eyes to prevent dryness while under anesthesia.Open the jaw and gently pull the tongue out of the oral cavity. Identify the opening of the larynx by illuminating the oral pharynx using a laryngoscope. Cut off about 0.5 centimeters from a 24 gauge catheter needle and insert the blunt needle into the plastic shield.Direct the blunt needle with the plastic shield into the trachea. Take out the needle, leaving the plastic shield in the trachea. Set the ventilator to a respiratory rate of 137 beats per minute, optimized for the mice used in this study and tidal volume 0.18 closing capacity.Connect the respirator tubes to the catheter shield and confirm correct intubation by looking for a synchronized chest movement with the ventilator. Disconnect the respirator tube from the catheter shield and place the animal in the supine position on a preheated temperature controlled surgical board. Reconnect the mouse to the ventilator.After disinfecting the surgical site gently lift the skin using a pair of forceps and make a small cutaneous transverse incision along the line between the left pectoralis major and minor muscles using a pair of surgical scissors. Separate the underlying pectoralis muscles with forceps and dissecting scissors. After making an incision in the third intercostal space gently stretch the ribs apart using retractors to expose the left ventricle.Move the pericardial fat aside and locate the left coronary artery, which runs from the edge of the left atrium toward the apex of the heart. Pass an 8-0 nylon suture under the left coronary artery with the help of a needle holder. Legate the left coronary artery with a double knot followed by a second knot.Remove the retractors and insert a 22 gauge catheter needle into the chest cavity. Remove the needle, leaving the tip of the plastic shield in the thoracic cavity. Close the ribcage using a 4-0 nylon suture.Connect a syringe to the 22 gauge plastic shield and slowly remove excess air trapped in the thoracic cavity by gently pressing the chest to establish a negative air pressure. Remove the plastic shield. Switch off the isoflurane supply and place the mouse on the ventilator supplying oxygen.One spontaneous breathing of the mouse starts, switch off the ventilator. Keep the mouse under a heat lamp and monitor until it is awake. The animal should not be left unattended until it has recovered enough consciousness to maintain sternal recumbency.Monitor the mouse daily for any sign of pain or discomfort. Continue intraperitoneal injection of buprenorphine every 6 to 8 hours for an additional two days following the surgery. Active ECG and respiration signals were verified before acquiring the echocardiographic data.The echocardiographic measurement of cardiac functional parameters was noted 28 days after left coronary artery ligation. The M-mode images of the peroneal short axis view of SHAM and MI hearts were observed. The MI images showed defective heart wall movement following left coronary artery ligation.Indicators of heart failure, such as increased left ventricular mass, decreased ejection fraction, and decreased cardiac output were observed in the MI group as compared to the SHAM group. Masson's trichrome staining of the lower, middle, and upper ventricle sections showed increased collagen staining in the infarcted heart, indicating augmented fibrosis. In most cases, the artery is not feasible.However, ligating the myocardial tissue 2 to 4 millimeters below the edge of the left atrium results in efficient ligation of the artery.

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Research

JoVE Journal

Medicine

Coronary Artery Ligation and Intramyocardial Injection in a Murine Model of Infarction

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo. With the advent of genetic modifications to the whole organism or the myocardium and an array of biological and/or synthetic materials, there is great potential for any combination of these to assuage the extent of acute ischemic injury and impede the onset of heart failure pursuant to myocardial remodeling. 
Here we present the methods and materials used to reliably perform this microsurgery and the modifications involved for temporary (with reperfusion) or permanent coronary artery occlusion studies as well as intramyocardial injections. The effects on the heart that can be seen during the procedure and at the termination of the experiment in addition to histological evaluation will verify efficacy. 
Briefly, surgical preparation involves anesthetizing the mice, removing the fur on the chest, and then disinfecting the surgical area. Intratracheal intubation is achieved by transesophageal illumination using a fiber optic light. The tubing is then connected to a ventilator. An incision made on the chest exposes the pectoral muscles which will be cut to view the ribs. For ischemia/reperfusion studies, a 1 cm piece of PE tubing placed over the heart is used to tie the ligature to so that occlusion/reperfusion can be customized. For intramyocardial injections, a Hamilton syringe with sterile 30gauge beveled needle is used. When the myocardial manipulations are complete, the rib cage, the pectoral muscles, and the skin are closed sequentially. Line block analgesia is effected by 0.25% marcaine in sterile saline which is applied to muscle layer prior to closure of the skin. The mice are given a subcutaneous injection of saline and placed in a warming chamber until they are sternally recumbent. They are then returned to the vivarium and housed under standard conditions until the time of tissue collection. At the time of sacrifice, the mice are anesthetized, the heart is arrested in diastole with KCl or BDM, rinsed with saline, and immersed in fixative. Subsequently, routine procedures for processing, embedding, sectioning, and histological staining are performed. 
Nonsurgical intubation of a mouse and the microsurgical manipulations described make this a technically challenging model to learn and achieve reproducibility. These procedures, combined with the difficulty in performing consistent manipulations of the ligature for timed occlusion(s) and reperfusion or intramyocardial injections, can also affect the survival rate so optimization and consistency are critical.

Numerous genetic manipulations and/or intramyocardial injections of genes, proteins, cells, and/or biomaterials are superimposed upon the dimension of time in studies of acute ischemia/ reperfusion injury and chronic remodeling in mice. This video illustrates the microsurgical procedures for ischemia/reperfusion, permanent coronary artery ligation, and intramyocardial injection studies.

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo.  With the advent of genetic modifications to ...

Modified Technique for Coronary Artery Ligation in Mice

Myocardial infarction (MI) is one of the most important causes of mortality in humans1-3. In order to improve morbidity and mortality in patients with MI we need better knowledge about pathophysiology of myocardial ischemia. This knowledge may be valuable to define new therapeutic targets for innovative cardiovascular therapies4. Experimental MI model in mice is an increasingly popular small-animal model in preclinical research in which MI is induced by means of permanent or temporary ligation of left coronary artery (LCA)5. In this video, we describe the step-by-step method of how to induce experimental MI in mice.
The animal is first anesthetized with 2% isoflurane. The unconscious mouse is then intubated and connected to a ventilator for artificial ventilation. The left chest is shaved and 1.5 cm incision along mid-axillary line is made in the skin. The left pectoralis major muscle is bluntly dissociated until the ribs are exposed. The muscle layers are pulled aside and fixed with an eyelid-retractor. After these preparations, left thoracotomy is performed between the third and fourth ribs in order to visualize the anterior surface of the heart and left lung. The proximal segment of LCA artery is then ligated with a 7-0 ethilon suture which typically induces an infarct size ~40% of left ventricle. At the end, the chest is closed and the animals receive postoperative analgesia (Temgesic, 0.3 mg/50 ml, ip). The animals are kept in a warm cage until spontaneous recovery.

The surgical procedure used to induce experimental myocardial infarction in mice begins with left thoracotomy between the third and the fourth ribs in order to visualize the anterior surface of the heart and left lung. The left coronary artery is ligated, the chest is closed and the mouse is allowed to recover spontaneously.

Myocardial infarction (MI) is one of the most important causes of mortality in humans1-3. In order to improve morbidity and mortality in patients with MI ...

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 ...

Minimal Invasive Surgical Procedure of Inducing Myocardial Infarction in Mice

Myocardial infarction still remains the main cause of death in western countries, despite considerable progress in the stent development area in the last decades. For clarification of the underlying mechanisms and the development of new therapeutic strategies, the availability of valid animal models are mandatory. Since we need new insights into pathomechanisms of cardiovascular diseases under in vivo conditions to combat myocardial infarction, the validity of the animal model is a crucial aspect. However, protection of animals are highly relevant in this context. Therefore, we establish a minimally invasive and simple model of myocardial infarction in mice, which assures a high reproducibility and survival rate of animals. Thus, this models fulfils the requirements of the 3R principle (Replacement, Refinement and Reduction) for animal experiments and assure the scientific information needed for further developing of therapeutical strategies for cardiovascular diseases.

A highly reproducible model for myocardial infarction in mice with minimal invasive manipulations is described. The model can be easily performed, resulting in a high reproducibility and survival rate. Thus, the described model will reduce the number of required animals as requested by the 3R principle (Replacement, Refinement and Reduction).

Myocardial infarction still remains the main cause of death in western countries, despite considerable progress in the stent development area in the last ...

Permanent Ligation of the Left Anterior Descending Coronary Artery in Mice: A Model of Post-myocardial Infarction Remodelling and Heart Failure

Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It is characterized by fluid retention, shortness of breath, and fatigue, in particular on exertion. Heart failure is a growing public health problem, the leading cause of hospitalization, and a major cause of mortality. Ischemic heart disease is the main cause of heart failure.
Ventricular remodelling refers to changes in structure, size, and shape of the left ventricle. This architectural remodelling of the left ventricle is induced by injury (e.g., myocardial infarction), by pressure overload (e.g., systemic arterial hypertension or aortic stenosis), or by volume overload. Since ventricular remodelling affects wall stress, it has a profound impact on cardiac function and on the development of heart failure. A model of permanent ligation of the left anterior descending coronary artery in mice is used to investigate ventricular remodelling and cardiac function post-myocardial infarction. This model is fundamentally different in terms of objectives and pathophysiological relevance compared to the model of transient ligation of the left anterior descending coronary artery. In this latter model of ischemia/reperfusion injury, the initial extent of the infarct may be modulated by factors that affect myocardial salvage following reperfusion. In contrast, the infarct area at 24 hr after permanent ligation of the left anterior descending coronary artery is fixed. Cardiac function in this model will be affected by 1) the process of infarct expansion, infarct healing, and scar formation; and 2) the concomitant development of left ventricular dilatation, cardiac hypertrophy, and ventricular remodelling.
Besides the model of permanent ligation of the left anterior descending coronary artery, the technique of invasive hemodynamic measurements in mice is presented in detail.

Heart failure is the leading cause of hospitalization and a major cause of mortality. A model of permanent ligation of the left anterior descending coronary artery in mice is applied to investigate ventricular remodelling and cardiac dysfunction post-myocardial infarction. The technique of invasive hemodynamic measurements in mice is presented.

Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It ...

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.

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 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 ...

Intramyocardial Transplantation of MSC-Loading Injectable Hydrogels after Myocardial Infarction in a Murine Model

One of the major issues facing current cardiac stem cell therapies for preventing postinfarct heart failure is the low retention and survival rates of transplanted cells within the injured myocardium, limiting their therapeutic efficacy. Recently, the use of scaffolding biomaterials has gained attention for improving and maximizing stem cell therapy. The objective of this protocol is to introduce a simple and straightforward technique to transplant bone marrow-derived mesenchymal stem cells (MSCs) using injectable hydroxyphenyl propionic acid (GH) hydrogels; the hydrogels are favorable as a cell delivery platform for cardiac tissue engineering applications due to their ability to be cross-linked in situ and high biocompatibility. We present a simple method to fabricate MSC-loading GH hydrogels (MSC/hydrogels) and evaluate their survival and proliferation in three-dimensional (3D) in vitro culture. In addition, we demonstrate a technique for intramyocardial transplantation of MSC/hydrogels in mice, describing a surgical procedure to induce myocardial infarction (MI) via left anterior descending (LAD) coronary artery ligation and subsequent MSC/hydrogels transplantation.

Stem cell-based therapy has emerged as an efficient strategy to repair injured cardiac tissues after myocardial infarction. We provide an optimal in vivo application for stem cell transplantation using gelatin hydrogels that are able to be enzymatically cross-linked.

One of the major issues facing current cardiac stem cell therapies for preventing postinfarct heart failure is the low retention and survival rates of ...