This work was supported and funded under the QREN project 2013/30196, the &#34;la Caixa&#34; Banking Foundation, the Funda&#231;&#227;o para a Ci&#234;ncia e Tecnologia (FCT) project, LCF/PR/HP17/52190002. JS and EB were supported by the European Union&#39;s Horizon 2020 research and innovation program&#160;under the Marie Sklodowska-Curie grant agreement no.&#160;813716. PdCM was supported by the Stichting Life Sciences Health (LSH)-TKI project MEDIATOR (LSHM 21016).

Ascending Aortic Banding for Studying Pressure-Overload Induced Heart Failure

<ol>
	<li>Savarese, 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=Global+burden+of+heart+failure:+a+comprehensive+and+updated+review+of+epidemiology.">Global burden of heart failure: a comprehensive and updated review of epidemiology.</a> Cardiovascular Research. 118 (17), 3272-3287 (2023).</li><li>Hartley, A., 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=Trends+in+mortality+from+aortic+stenosis+in+Europe:+2000-2017.">Trends in mortality from aortic stenosis in Europe: 2000-2017.</a> Frontiers in Cardiovascular Medicine. 8, 748137 (2021).</li><li>Silva, K. A. S., Emter, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+Animal+models+of+heart+failure:+a+translational+bridge+to+clinical+success.">Large Animal models of heart failure: a translational bridge to clinical success.</a> Journal of the American College of Cardiology: Basic to Translational Science. 5 (8), 840-856 (2020).</li><li>Brink, C. B., Lewis, D. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+12+Rs+framework+as+a+comprehensive,+unifying+construct+for+principles+guiding+animal+research+ethics.">The 12 Rs framework as a comprehensive, unifying construct for principles guiding animal research ethics.</a> Animals (Basel). 13 (7), 1128 (2023).</li><li>Choy, J. S., Zhang, Z. D., Pitsillides, K., Sosa, M., Kassab, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Longitudinal+hemodynamic+measurements+in+swine+heart+failure+using+a+fully+implantable+telemetry+system.">Longitudinal hemodynamic measurements in swine heart failure using a fully implantable telemetry system.</a> PLoS One. 9 (8), 103331 (2014).</li><li>Ishikawa, K., 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=Increased+stiffness+is+the+major+early+abnormality+in+a+pig+model+of+severe+aortic+stenosis+and+predisposes+to+congestive+heart+failure+in+the+absence+of+systolic+dysfunction.">Increased stiffness is the major early abnormality in a pig model of severe aortic stenosis and predisposes to congestive heart failure in the absence of systolic dysfunction.</a> Journal of the American Heart Association. 4 (5), 001925 (2015).</li><li>Emter, C. A., Baines, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-intensity+aerobic+interval+training+attenuates+pathological+left+ventricular+remodeling+and+mitochondrial+dysfunction+in+aortic-banded+miniature+swine.">Low-intensity aerobic interval training attenuates pathological left ventricular remodeling and mitochondrial dysfunction in aortic-banded miniature swine.</a> American Journal of Physiology-Heart and Circulatory Physiology. 299 (5), H1348-H1356 (2010).</li><li>Brito, J., Raposo, L., Teles, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Invasive+assessment+of+aortic+stenosis+in+contemporary+practice.">Invasive assessment of aortic stenosis in contemporary practice.</a> Frontiers in Cardiovascular Medicine. 9, 1007139 (2022).</li><li>Tan, W., 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=A+Porcine+model+of+heart+failure+with+preserved+ejection+fraction+induced+by+chronic+pressure+overload+characterized+by+cardiac+fibrosis+and+remodeling.">A Porcine model of heart failure with preserved ejection fraction induced by chronic pressure overload characterized by cardiac fibrosis and remodeling.</a> Frontiers in Cardiovascular Medicine. 8, 677727 (2021).</li><li>Bikou, O., Miyashita, S., Ishikawa, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pig+model+of+increased+cardiac+afterload+induced+by+ascending+aortic+banding.">Pig model of increased cardiac afterload induced by ascending aortic banding.</a> Methods in Molecular Biology. 1816, 337-342 (2018).</li><li>Lelovas, P. P., Kostomitsopoulos, N. G., Xanthos, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparative+anatomic+and+physiologic+overview+of+the+porcine+heart.">A comparative anatomic and physiologic overview of the porcine heart.</a> Journal of the American Association for Laboratory Animal Science. 53 (5), 432-438 (2014).</li><li>Tian, 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=Supra-coronary+aortic+banding+improves+right+ventricular+function+in+experimental+pulmonary+arterial+hypertension+in+rats+by+increasing+systolic+right+coronary+artery+perfusion.">Supra-coronary aortic banding improves right ventricular function in experimental pulmonary arterial hypertension in rats by increasing systolic right coronary artery perfusion.</a> Acta Physiologica (Oxf). 229 (4), 13483 (2020).</li><li>Sorensen, M., Hasenkam, J. M., Jensen, H., Sloth, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subcoronary+versus+supracoronary+aortic+stenosis.+An+experimental+evaluation.">Subcoronary versus supracoronary aortic stenosis. An experimental evaluation.</a> Journal of Cardiothoracic Surgery. 6, 100 (2011).</li><li>Lygate, C. A., 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=Serial+high+resolution+3D-MRI+after+aortic+banding+in+mice:+band+internalization+is+a+source+of+variability+in+the+hypertrophic+response.">Serial high resolution 3D-MRI after aortic banding in mice: band internalization is a source of variability in the hypertrophic response.</a> Basic Research in Cardiology. 101 (1), 8-16 (2006).</li><li>Jalal, Z., 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=Unexpected+Internalization+of+a+Pulmonary+Artery+Band+in+a+Porcine+Model+of+Tetralogy+of+Fallot.">Unexpected Internalization of a Pulmonary Artery Band in a Porcine Model of Tetralogy of Fallot.</a> World Journal for Pediatric and Congenital Heart Surgery. 8 (1), 48-54 (2017).</li></ol>

The authors have nothing to disclose.

In recent years, several studies have utilized surgical aortic banding as a model for left ventricular pressure overload and heart failure (descending9 to the ascending aorta10), allowing researchers to obtain various phenotypes tailored to their specific needs. Although using such models requires costly equipment and specialized knowledge, the information they provide is invaluable. Swine, due to its size and similarity to the human heart, serves as an ideal model<sup clas...

Heart failure (HF) is a life-threatening disease that affects millions of people worldwide, causing major social and economic impacts1. One of its significant etiologies is aortic valve disease or aortic stenosis (AS). Aortic stenosis is more prevalent in advanced age and ranks as the second most common valvular lesion in the United States. AS-related mortality has also increased in Europe, particularly in countries without access to recent interventional procedures2. Given the complexity of HF and the scarcity of therapeutic innovations, there is a pressing need for reliable animal models that can replicate the human condition and facilitate the testing of new interventions3. While rodent models outnumber large animal models, the latter offers several advantages due to their size and physiological similarities, allowing the testing of drug doses and medical devices intended for human use.
The aim of this method is to establish a reproducible model of ascending aortic banding (AAB) applicable to most large animal species used in biomedical research. In this study, the procedure is demonstrated in swine using a minimally invasive approach, adhering to the 3Rs principles (replacement, reduction, and refinement4). This approach ensures the creation of an accurate pressure gradient, resulting in high reproducibility (potentially reducing the number of required animals). Additionally, the small surgical incision (2-3 cm) minimizes surgical insult, improving animal well-being compared to more aggressive approaches like sternotomy and larger thoracotomies5 (refinement). Furthermore, providing a video demonstration of the method, along with detailed descriptions in the literature, could potentially reduce the need for animals used solely for training purposes (replacement), further decreasing animal usage. This model can be adapted for different swine strains/breeds with distinct growth rates and induces sustained pressure overload, leading to significant hypertrophy after 1 or 2 months of follow-up.
Current methods employ fixed stenosis6, disregarding animal size variability, or calculate gradient using fluid-filled pressure readings7, which are less reliable than high-fidelity pressure sensors and are susceptible to signal damping8. Another approach uses a single pressure measurement distal to the stenosis5. However, calibrating the stenosis through simultaneous proximal and distal pressure signals using percutaneously delivered high-fidelity pressure sensors represents a substantial optimization of the protocol, resulting in improved group homogeneity. By visually demonstrating this method, other researchers should be able to replicate it without significant obstacles, increasing the availability of this model while promoting the application of the 3Rs principles.

<table><tbody><tr><td>3-0 PDS II suture</td><td>Ethicon</td><td>Z683G</td><td>Aorta banding</td></tr><tr><td>5-0 prolene</td><td>Ethicon</td><td>7472H</td><td>Aorta banding</td></tr><tr><td>ACUSON NX2 Ultrasound System</td><td>Siemens</td><td>(240)11284381</td><td>Vascular Access and Echocardiography</td></tr><tr><td>Arterial Extension 200 cm</td><td>PMH</td><td>303.0666</td><td>Anesthesia Maintenance</td></tr><tr><td>Atlan A300 Ventilator</td><td>Draeger</td><td>8621300</td><td>Ventilation</td></tr><tr><td>Bone cutters</td><td>Fehling</td><td>AMP 367.00</td><td>Aorta banding</td></tr><tr><td>Cefazolin 1000 mg</td><td>Labesfal</td><td>100063</td><td>Antibiotic</td></tr><tr><td>Chlorhexidine 4% Wash Solution</td><td>AGA</td><td>19110008</td><td>Cleaning</td></tr><tr><td>Doyen Intestinal Forceps</td><td>Aesculap</td><td>EA121R</td><td>Intubation</td></tr><tr><td>Echogenic Introducer Needle</td><td>Teleflex</td><td>AN-04318</td><td>Vascular Access</td></tr><tr><td>Endotracheal tube</td><td>Intersurgical</td><td>8040070</td><td>Intubation</td></tr><tr><td>ePTFE vascular graft (5 mm x 40 cm)</td><td>GORE-TEX</td><td>S0504</td><td>Aorta banding</td></tr><tr><td>Extension line 100 cm</td><td>PMH</td><td>303.0394</td><td>Anesthesia Induction</td></tr><tr><td>F.O. Laryngoscope</td><td>Luxamed</td><td>E1.317.012</td><td>Intubation</td></tr><tr><td>F.O. Miller Blade 4 204 x 17 mm</td><td>Luxamed</td><td>3</td><td>Intubation</td></tr><tr><td>Fenestrated Sterile Drape</td><td>Bastos Viegas</td><td>4882-256</td><td>Aseptic Technique</td></tr><tr><td>Fentanyl 0.5 mg/10 mL</td><td>B.Braun</td><td>5758883</td><td>Anesthesia / Analgesia</td></tr><tr><td>Guidewire 260 cm J-tip</td><td>B.Braun</td><td>J3 FC-FS 260-035</td><td>Left Ventricle catheterization</td></tr><tr><td>Infusomat Space Infusion Pump</td><td>B.Braun</td><td>24101800</td><td>Fluids / Drug administration</td></tr><tr><td>Intercostal retractor</td><td>Fehling Surgical</td><td>MRP-1</td><td>Thoracotomy</td></tr><tr><td>Introcan Certo IV Catheter 20G</td><td>B.Braun</td><td>4251326</td><td>Fluids / Drug administration</td></tr><tr><td>Isotonic Saline Solution 0.9%</td><td>B.Braun</td><td>5/44929/1/0918</td><td>Fluids / Drug administration</td></tr><tr><td>Ketamidor 100 mg/mL</td><td>Richter pharma</td><td>1121908AB</td><td>Anesthesia Induction</td></tr><tr><td>L10-5v Linear Transducer</td><td>Siemens</td><td>11284481</td><td>Vascular Access</td></tr><tr><td>Midazolam 15 mg/3 mL</td><td>Labesfal</td><td>PLB762-POR/2</td><td>Anesthesia Induction</td></tr><tr><td>Mikro-cath</td><td>Millar</td><td>63405(1)</td><td>Pressure recording</td></tr><tr><td>MP1 guide catheter 6 Fr</td><td>Cordis</td><td>67027000</td><td>Left Ventricle catheterization</td></tr><tr><td>Needle Holder</td><td>Fehling Surgical</td><td>ZYY-5</td><td>Aorta banding</td></tr><tr><td>Non-woven adhesive</td><td>Bastos Viegas</td><td>442-002</td><td>Fluids / Drug administration</td></tr><tr><td>P4-2 Phased Array Transducer</td><td>Siemens</td><td>11284467</td><td>Echocardiography</td></tr><tr><td>Perfusor Compact Syringe Perfusion Pump</td><td>B.Braun</td><td>8717030</td><td>Fluids / Drug administration</td></tr><tr><td>Pressure Signal Conditioner</td><td>ADinstruments</td><td>PCU-2000</td><td>Pressure recording</td></tr><tr><td>Propofol Lipuro 2%</td><td>B.Braun</td><td>357410&amp;nbsp;</td><td>Anesthesia Maintenance</td></tr><tr><td>Radifocus Introducer II Standard Kit B - Introducer Sheath</td><td>Terumo</td><td>RS+B60K10MQ</td><td>Vascular Access</td></tr><tr><td>Radiopaque marker</td><td>Scanlan</td><td>1001-83</td><td>Aorta banding</td></tr><tr><td>Scissors</td><td>Fehling Surgical</td><td></td><td>Thoracotomy</td></tr><tr><td>Skinprep (Chlorhexidine 2% / 70% Isopropyl alcohol)</td><td>Vygon</td><td>SKPC015ES</td><td>Disinfection</td></tr><tr><td>Stopcock manifold (3 ports)</td><td>PMH</td><td>310.0489</td><td>Fluids / Drug administration</td></tr><tr><td>Straight forceps</td><td>Fehling Surgical</td><td>ZYY-1</td><td>Thoracotomy</td></tr><tr><td>Stresnil 40 mg/mL</td><td>ecuphar</td><td>572184.2</td><td>Anesthesia Induction</td></tr><tr><td>Syringe Luer Lock 20 cc</td><td>Omnifix B.Braun</td><td>4617207V</td><td>Anesthesia Induction</td></tr><tr><td>Syringe Luer Lock 50 cc</td><td>Omnifix B.Braun</td><td>4617509F</td><td>Anesthesia Maintenance</td></tr><tr><td>Transdermal fentanyl Patch 50 mcg/h</td><td>Mylan</td><td>5022153</td><td>Analgesia</td></tr><tr><td>Ultravist</td><td>Bayer</td><td>KT0B019</td><td>Angiography</td></tr><tr><td>Universal Hemostasis Valve Adapter</td><td>Merit Medical</td><td>UHVA08</td><td>Left Ventricle catheterization</td></tr><tr><td>Velcro Limb Immobilizer</td><td>PMH</td><td>SU-211</td><td>Animal stabilization</td></tr><tr><td>Venofix A, 21 G</td><td>B.Braun</td><td>4056337</td><td>Anesthesia Induction</td></tr><tr><td>Vista 120S Patient Monitor</td><td>Draeger</td><td>MS32997</td><td>Monitoring</td></tr><tr><td>Weck titanium clip</td><td>Teleflex</td><td>523760</td><td>Aorta banding</td></tr><tr><td>Weck titanium clip applier</td><td>Teleflex</td><td>523166</td><td>Aorta banding</td></tr><tr><td>Zhiem Vision</td><td>Iberdata</td><td>N/A</td><td>Fluoroscopy</td></tr></tbody></table>

a minimally invasive model of aortic stenosis in swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological similarities to humans. Efforts have been dedicated to creating a model of pressure-overload induced heart failure, and ascending aortic banding while still supra-coronary and not a perfect mimic of aortic stenosis in humans, closely resembling the human condition.
The purpose of this study is to demonstrate a minimally invasive approach to induce left ventricular pressure overload by placing an aortic band, precisely calibrated with percutaneously introduced high-fidelity pressure sensors. This method represents a refinement of the surgical procedure (3Rs), resulting in homogenous trans-stenotic gradients and reduced intragroup variability. Additionally, it enables swift and uneventful animal recovery, leading to minimal mortality rates. Throughout the study, animals were followed for up to 2 months after surgery, employing transthoracic echocardiography and pressure-volume loop analysis. However, longer follow-up periods can be achieved if desired. This large animal model proves valuable for testing new drugs, particularly those targeting hypertrophy and the structural and functional alterations associated with left ventricular pressure overload.

During the initial development of the model, the mortality rate was approximately 30%, with animals dying from acute heart failure after banding and surgical complications. However, after the model was established, surgical complications became less common, and the mortality rate dropped to around 15%. The two deaths that occurred were due to aortic rupture during dissection.
The use of high-fidelity pressure sensors enables obtaining high-quality pressure signals (Figure ...

Watch this Scientific Journal Video about Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research at JoVE.com

Author Spotlight: Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research 

This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

A Minimally Invasive Model of Aortic Stenosis in Swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological ...

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932 Views.  University of Porto. This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

Video: Author Spotlight: Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research 

Imaging In-Stent Restenosis: An Inexpensive, Reliable, and Rapid Preclinical Model

Preclinical models of restenosis are essential to unravel the pathophysiological processes that lead to in-stent restenosis and to optimize existing and future drug-eluting stents.
A variety of antibodies and transgenic and knockout strains are available in rats. Consequently, a model for in-stent restenosis in the rat would be convenient for pathobiological and pathophysiological studies. 
In this video, we present the full procedure and pit-falls of a rat stent model suitable for high throughput stent research. We will show the surgical procedure of stent deployment, and the assessment of in-stent restenosis using the most elegant technique of OCT (Optical Coherence Tomography). This technique provides high accuracy in assessing plaque CSAs (cross section areas) and correlates well with histological sections, which require special and time consuming embedding and sectioning techniques. OCT imaging further allows longitudinal monitoring of the development of in-stent restenosis within the same animal compared to one-time snapshots using histology.

This video demonstrates how to use a preclinical inexpensive and reliable model to study pathobiological and pathophysiological processes of in-stent restenosis development. Longitudinal in vivo monitoring using OCT (Optical Coherence Tomography) and analysis of OCT images are also demonstrated.

Preclinical models of restenosis are essential to unravel the pathophysiological processes that lead to in-stent restenosis and to optimize existing and ...

Biology

Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early cardiopulmonary dysfunction is difficult to diagnose, particularly in animal models, as cardiopulmonary function is often measured invasively, requiring anesthesia. As many anesthetic agents are cardiodepressive, subtle changes in cardiovascular function may be masked. In contrast, chronic instrumentation allows for measurement of cardiopulmonary function in the awake state, so that measurements can be obtained under quiet resting conditions, without the effects of anesthesia and acute surgical trauma. Furthermore, when animals are properly trained, measurements can also be obtained during graded treadmill exercise.
Flow probes are placed around the aorta or pulmonary artery for measurement of cardiac output and around the left anterior descending coronary artery for measurement of coronary blood flow. Fluid-filled catheters are implanted in the aorta, pulmonary artery, left atrium, left ventricle and right ventricle for pressure measurement and blood sampling. In addition, a 20 G&#160;catheter is positioned in the anterior interventricular vein to allow coronary venous blood sampling.
After a week of recovery, swine are placed on a motor-driven treadmill, the catheters are connected to pressure and flow meters, and swine are subjected to a five-stage progressive exercise protocol, with each stage lasting 3 min. Hemodynamic signals are continuously recorded and blood samples are taken during the last 30 sec of each exercise stage.
The major advantage of studying chronically instrumented animals is that it allows serial assessment of cardiopulmonary function, not only at rest but also during physical stress such as exercise. Moreover, cardiopulmonary function can be assessed repeatedly during disease development and during chronic treatment, thereby increasing statistical power and hence limiting the number of animals required for a study.

Here we present a protocol to assess cardiopulmonary function in awake swine, at rest and during graded treadmill exercise. Chronic instrumentation allows for repeated hemodynamic measurements uninfluenced by cardiodepressive anesthetic agents.

This protocol describes the surgical procedure to chronically instrument swine and the procedure to exercise swine on a motor-driven treadmill. Early ...

A Chronic Cardiac Ischemia Model in Swine Using an Ameroid Constrictor

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but regardless of the approach, an in vivo model is needed to test each treatment. The pig is one of the most used large animal models for cardiovascular disease. Its heart is very similar in anatomy and function to that of a human. The ameroid placement technique creates an ischemic area of the heart, which has many useful applications in studying myocardial infarction. This model has been used for surgical research, pharmaceutical studies, imaging techniques, and cell therapies.
There are several ways of inducing an ischemic area in the heart. Each has its advantages and disadvantages, but the placement of an ameroid constrictor remains the most widely used technique. The main advantages to using the ameroid are its prevalence in existing research, its availability in various sizes to accommodate the anatomy and size of the vessel to be constricted, the surgery is a relatively simple procedure, and the post-operative monitoring is minimal, since there are no external devices to maintain. This paper provides a detailed overview of the proper technique for the placement of the ameroid constrictor.

The purpose of this protocol is to demonstrate the placement of a delayed constricting device (an ameroid constrictor) around a coronary artery in a swine model. This device creates an ischemic area of the heart that is useful for studying new diagnostic imaging techniques and new methods of treatment.

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but ...

Surgical Swine Model of Chronic Cardiac Ischemia Treated by Off-Pump Coronary Artery Bypass Graft Surgery

Chronic cardiac ischemia that impairs cardiac function, but does not result in infarct, is termed hibernating myocardium (HM). A large clinical subset of coronary artery disease (CAD) patients have HM, which in addition to causing impaired function, puts them at higher risk for arrhythmia and future cardiac events. The standard treatment for this condition is revascularization, but this has been shown to be an imperfect therapy. The majority of pre-clinical cardiac research focuses on infarct models of cardiac ischemia, leaving this subset of chronic ischemia patients largely underserved. To address this gap in research, we have developed a well-characterized and highly reproducible model of hibernating myocardium in swine, as swine are ideal translational models for human heart disease. In addition to creating this unique disease model, we have optimized a clinically relevant treatment model of coronary artery bypass surgery in swine. This allows us to accurately study the effects of bypass surgery on heart disease, as well as investigate additional or alternate therapies. This model surgically induces single vessel stenosis by implanting a constrictor on the left anterior descending (LAD) artery in a young pig. As the pig grows, the constrictor creates a gradual stenosis, resulting in chronic ischemia with impaired regional function, but preserving tissue viability. Following the establishment of the hibernating myocardium phenotype, we perform off-pump coronary artery bypass graft surgery to revascularize the ischemic region, mimicking the gold-standard treatment for patients in the clinic.

This protocol presents a surgical large animal model of chronic, single vessel ischemia that results in regional abnormalities but does not create infarct, known as hibernating myocardium. Following establishment of chronic ischemia, animals are treated with off-pump LIMA-LAD coronary artery bypass graft surgery to revascularize the ischemic tissue.

Chronic cardiac ischemia that impairs cardiac function, but does not result in infarct, is termed hibernating myocardium (HM). A large clinical subset of ...

Complete and Partial Aortic Occlusion for the Treatment of Hemorrhagic Shock in Swine

Hemorrhage remains the leading cause of preventable deaths in trauma. Endovascular management of non-compressible torso hemorrhage has been at the forefront of trauma care in recent years. Since complete aortic occlusion presents serious concerns, the concept of partial aortic occlusion has gained a growing attention. Here, we present a large animal model of hemorrhagic shock to investigate the effects of a novel partial aortic balloon occlusion catheter and compare it with a catheter that works on the principles of complete aortic occlusion. Swine are anesthetized and instrumented in order to conduct controlled fixed-volume hemorrhage, and hemodynamic and physiological parameters are monitored. Following hemorrhage, aortic balloon occlusion catheters are inserted and inflated in the supraceliac aorta for 60 min, during which the animals receive whole-blood resuscitation as 20% of the total blood volume (TBV). Following balloon deflation, the animals are monitored in a critical care setting for 4 h, during which they receive fluid resuscitation and vasopressors as needed. The partial aortic balloon occlusion demonstrated improved distal mean arterial pressures (MAPs) during the balloon inflation, decreased markers of ischemia, and decreased fluid resuscitation and vasopressor use. As swine physiology and homeostatic responses following hemorrhage have been well-documented and are like those in humans, a swine hemorrhagic shock model can be used to test various treatment strategies. In addition to treating hemorrhage, aortic balloon occlusion catheters have become popular for their role in cardiac arrest, cardiac and vascular surgery, and other high-risk elective surgical procedures.

Here, we present a protocol demonstrating a hemorrhagic shock model in swine that uses aortic occlusion as a bridge to definitive care in trauma. This model has application in testing a wide range of surgical and pharmacological therapeutic strategies.

Hemorrhage remains the leading cause of preventable deaths in trauma. Endovascular management of non-compressible torso hemorrhage has been at the ...

Evaluation of Hydrodynamic Properties in Mounted Porcine Aortic Valves

An Ex Vivo Porcine Model for Hydrodynamic Testing of Experimental Aortic Valve Procedures and Novel Medical Devices

The options for testing new cardiac procedures and investigative medical devices prior to use in an animal model are limited. In this study, we present a method for mounting a porcine aortic valve in a pulse duplicator to evaluate its hydrodynamic properties. These properties can then be evaluated before and after the procedure under investigation is performed and/or the investigative medical device is applied. Securing the inflow segment presents some difficulty owing to the lack of circumferential myocardium in the left ventricular outflow tract. This method addresses that issue by securing the inflow segment using the anterior leaflet of the mitral valve and then suturing the left ventricular free wall around the inflow fixture. The outflow segment is secured simply by inserting the fixture into an incision in the superior aspect of the aortic arch. We found that specimens had significantly different hydrodynamic properties before and after tissue fixation. This finding induced us to use fresh specimens in our testing and should be considered when using this method. In our work, we used this method to test novel intracardiac patch materials for use in the valvular position by performing an aortic valve neocuspidization procedure (Ozaki procedure) on the mounted porcine aortic valves. These valves were tested before and after the procedure to assess the change in hydrodynamic properties in comparison to the native valve. Herein, we report a platform for hydrodynamic testing of experimental aortic valve procedures that enables comparison with the native valve and between different devices and techniques used for the procedure under investigation.

Author Spotlight: Advancing Cardiac Procedure Testing Prior to Embarking on Large Animal Studies 

We present a method for mounting a porcine aortic valve on a pulse duplicator to test its hydrodynamic properties. This method can be used to determine the change in hydrodynamics after the application of an experimental procedure or novel medical device prior to use in a large animal model.

The options for testing new cardiac procedures and investigative medical devices prior to use in an animal model are limited. In this study, we present a ...

Bioengineering

Porcine Model of Infrarenal Abdominal Aortic Aneurysm

Large animal models to study abdominal aortic aneurysms are sparse. The purpose of this model is to create reproducible, clinically significant infrarenal abdominal aortic aneurysms (AAA) in swine. To achieve this, we use a combination of balloon angioplasty, elastase and collagenase, and a lysyl oxidase inhibitor, called &#946;-aminopropionitrile (BAPN), to create clinically significant infrarenal aortic aneurysms, analogous to human disease.
Noncastrated male swine are fed BAPN for 7 days prior to surgery to achieve a steady state in the blood. A midline laparotomy is performed and the infrarenal aorta is circumferentially dissected. An initial measurement is recorded prior to aneurysm induction with a combination of balloon angioplasty, elastase (500 units)/collagenase (8000 units) perfusion, and topical elastase application. Swine are fed BAPN daily until terminal procedure on either postoperative day 7, 14, or 28, at which time the aneurysm is measured, and tissue procured. BAPN + surgery pigs are compared to pigs that underwent surgery alone.
Swine treated with BAPN and surgery had a mean aortic dilation of 89.9% &#177; 47.4% at day 7, 105.4% &#177; 58.1% at day 14, and 113.5% &#177; 30.2% at day 28. Pigs treated with surgery alone had significantly smaller aneurysms compared to BAPN + surgery animals at day 28 (p &#60; 0.0003). The BAPN + surgery group had macroscopic and immunohistochemical evidence of end stage aneurysmal disease.
Clinically significant infrarenal AAA can be induced using balloon angioplasty, elastase/collagenase perfusion and topical application, supplemented with oral BAPN. This model creates large, clinically significant AAA with hallmarks of human disease. This has important implications for the elucidation of AAA pathogenesis and testing of novel therapies and devices for the treatment of AAA. Limitations of the model include variation in BAPN ingested by swine, quality of elastase perfusion, and cost of BAPN.&#160;

This novel model creates robust infrarenal abdominal aortic aneurysms in swine using a combination of balloon angioplasty, elastase/collagenase perfusion, topical elastase application, and oral compound &#946;-aminopropionitrile administration, which interferes with collagen cross-linking.

Large animal models to study abdominal aortic aneurysms are sparse. The purpose of this model is to create reproducible, clinically significant infrarenal ...

Novel Percutaneous Approach for Deployment of 3D Printed Coronary Stenosis Implants in Swine Models of Ischemic Heart Disease

Minimally invasive methods for creating models of focal coronary narrowing in large animals are challenging. Rapid prototyping using three-dimensionally (3D) printed coronary implants can be employed to percutaneously create a focal coronary stenosis. However, reliable delivery of the implants can be difficult without the use of ancillary equipment. We describe the use of a mother-and-child coronary guide catheter for stabilization of the implant and for effective delivery of the 3D printed implant to any desired location along the length of the coronary vessel. The focal coronary narrowing was confirmed under coronary cineangiography and the functional significance of the coronary stenosis was assessed using gadolinium-enhanced first-pass cardiac perfusion MRI. We showed that reliable delivery of 3D printed coronary implants in swine models (n = 11) of ischemic heart disease can be achieved through repurposing mother-and-child coronary guide catheters. Our technique simplifies the percutaneous delivery of coronary implants to create closed-chest swine models of focal coronary artery stenosis and can be performed expeditiously, with a low procedural failure rate.

We describe a novel, cost-effective, and efficient technique for percutaneous delivery of three-dimensionally printed coronary implants to create closed-chest swine models of ischemic heart disease. The implants were fixed in place using a mother-and-child extension catheter with high success rate.

Minimally invasive methods for creating models of focal coronary narrowing in large animals are challenging. Rapid prototyping using three-dimensionally ...

Implantation of Human-Sized Coronary Stents into Rat Abdominal Aorta Using a Trans-Femoral Access

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of coronary artery disease. In-stent restenosis (ISR) is determined by an excessive proliferation of neointimal tissue within the stent and limits the long-term success of stents. A variety of animal models have been used to elucidate pathophysiological processes underlying in-stent restenosis (ISR), with the porcine coronary and the rabbit iliac artery models being the most frequently used. Murine models provide the advantages of high throughput, ease of handling and housing, reproducibility, and a broad availability of molecular markers. The apolipoprotein E deficient (apoE-/- ) mouse model has been widely used to study cardiovascular diseases. However, stents must be miniaturized to be implanted into mice, involving important changes of their mechanical and (potentially) biological properties. The use of apoE-/- rats can overcome these shortcomings as apoE-/- rats allow for the evaluation of human-sized coronary stents while at the same time providing an atherogenic phenotype. This makes them an excellent and reliable model to investigate ISR after stent implantation. Here, we describe, in detail, the implantation of commercially available human coronary stents into the abdominal aorta of rats with an apoE-/- background using a trans-femoral access.

This protocol describes the implantation of human coronary stents into the abdominal aorta of rats with an apoE-/- background using a trans-femoral access. Compared with other animal models, murine models carry the advantages of high throughput, reproducibility, ease of handling and housing, and a broad availability of molecular markers.

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of ...

A Surgical Model of Heart Failure with Preserved Ejection Fraction in Tibetan Minipigs

More than half of heart failure (HF) cases are classified as heart failure with preserved ejection fraction (HFpEF) worldwide. Large animal models are limited for investigating the fundamental mechanisms of HFpEF and identifying potential therapeutic targets. This work provides a detailed description of the surgical procedure of descending aortic constriction (DAC) in Tibetan minipigs to establish a large animal model of HFpEF. This model used a precisely controlled constriction of the descending aorta to induce chronic pressure overload in the left ventricle. Echocardiography was used to evaluate the morphological and functional changes in the heart. After 12 weeks of DAC stress, the ventricular septum was hypertrophic, but the thickness of the posterior wall was significantly reduced, accompanied by dilation of the left ventricle. However, the LV ejection fraction of the model hearts was maintained at &gt;50% during the 12-week period. Furthermore, the DAC model displayed cardiac damage, including fibrosis, inflammation, and cardiomyocyte hypertrophy. Heart failure marker levels were significantly elevated in the DAC group. This DAC-induced HFpEF in minipigs is a powerful tool for investigating molecular mechanisms of this disease and for preclinical testing.

The present protocol describes a step-by-step procedure to establish a minipig model of heart failure with preserved ejection fraction using descending aortic constriction. The methods for evaluating cardiac morphology, histology, and function of this disease model are also presented.

More than half of heart failure (HF) cases are classified as heart failure with preserved ejection fraction (HFpEF) worldwide. Large animal models are ...