We would like to thank Mrs. Angela Freund for her invaluable technical assistance with embedding and slides production. We would also like to thank Mr. Tadeusz Stopinski at the Institute for Laboratory Animal Science &#38; Experimental Surgery for his insightful help with the veterinary work.

The experiments were performed in accordance with the German animal welfare law (TSchG) and Directive 2010/63/EU pertaining to the protection of animals used for scientific purposes. The official approval for this study was granted by the Governmental Animal Care and Use Committee (Protocol No.: AZ 87-51.04.2010.A065; Landesamt f&#252;r Natur, Umwelt und Verbraucherschutz Nordrhein-Westfalen, Recklinghausen, Germany). The study protocol complied with the Guide for the Care and Use of Laboratory Animals. Postoperative pain treatment is based on the recommendations of the German Society for Laboratory Animal Science (GV-SOLAS) as well as Initiative Veterinary Pain Therapy.
1. Basic techniques and common procedures
<ol>
	<li>Use homozygous apoE-/- Sprague-Dawley rats. Identify the genotype of each animal by using standard methods17.</li>
	<li>Keep the animals under identical conditions (21 &#176;C &#177; 2 &#176;C, 60% &#177; 5% humidity, and a 12 h light/dark cycle) and ensure free access to water and food.</li>
	<li>Carry out all procedures under clean but nonsterile conditions.</li>
	<li>Once the rat is anesthetized, perform all procedures under a surgical microscope at a magnification of 16x.</li>
	<li>Use cotton swabs for compression hemostasis. Gauze swabs (5 cm x 5 cm) soaked with lactated Ringer solution are helpful to keep the groin moist.</li>
	<li>Follow waste disposal regulations to dispose used materials.</li>
</ol>
2. Preparations before surgery
<ol>
	<li>Prepare the veterinary drugs before starting the operation. Keep all solutions at room temperature, unless otherwise indicated.</li>
	<li>Thirty minutes before the procedure, administer 0.03-0.05 mg/kg&#160;buprenorphine subcutaneously.</li>
	<li>Anesthetize the rat with an intraperitoneal injection of 100 mg/kg body weight (BW) (S)-ketamine and 8 mg/kg BW xylazine.</li>
	<li>Assess the rat&#8217;s weight using a weighing scale.</li>
	<li>Place the rat on a heating pad and fix the upper and lower limbs using medical tape. Position the rat with its left hind limb fully extended and as much in line with its spine as possible so as to create a straight line between femoral artery and aorta. This will facilitate advancing the balloon-mounted stent through the aortic bifurcation.</li>
	<li>Maintain anesthesia with inhalation of 1.5 vol% isoflurane in 97.5% oxygen at a flow rate of 2 L/min. 
	NOTE: Allow the rat to breathe spontaneously, without intubation.</li>
	<li>Apply eye ointment to prevent eye damage during unconsciousness.</li>
	<li>Shave the fur from the groin and lower abdomen area of the rat and sterilize the corresponding skin with a povidone-iodine solution.</li>
	<li>Before starting the surgery, verify adequate depth of anesthesia by pinching the tail tip and the interdigital tissue.&#160;</li>
</ol>
3. Surgery
<ol>
	<li>Make a medial incision of ~0.5&#8210;1 cm in the left groin to open the skin and the underlying fascia.</li>
	<li>Bluntly dissect and probe in the depths until the pulsating left femoral artery can be identified.</li>
	<li>Using very fine forceps, prepare the femoral artery by gently removing the surrounding connective tissue. Be careful to harm neither the femoral nerve nor the femoral vein, which is medial to the artery.</li>
	<li>Prepare about 1 cm of the femoral artery. Carefully put the tip of the forceps under the vessel to gently lift it.</li>
	<li>Thread pieces of 4-0 silk suture under the distal and proximal parts of the artery and form slings. Clamp the ends of each of the two thread slings between the branches of a surgical clamp. Use the surgical clamps to control the artery. Gently stretch and lift the slings in order to temporarily interrupt blood flow. 
	NOTE: Work fast to avoid a prolonged tourniquet which may lead to tissue damage.</li>
	<li>Using sharp micro scissors, perform an arteriotomy in the middle of the femoral artery.</li>
	<li>Introduce a guide wire through the arteriotomy. When reaching the proximal thread sling, release the tension of the thread by moving the surgical clamp and advance the guide wire further towards the abdominal aorta. 
	NOTE: Cut the guide wire using a wire cutter to facilitate handling.</li>
	<li>Place the proximal end of the guide wire between the diaphragm and the renal arteries. 
	NOTE: Advancing the guide wire too far bears the risk of aortic or cardiac injury. We recommend opening the abdomen to ensure adequate positioning of the guide wire and the stent at least for the first several animals.</li>
	<li>Introduce a crimped and balloon-mounted coronary stent measuring 2.25 mm x 8 mm (max. 2.5 mm x 8 mm) over the guide wire into the femoral artery and advance it to the abdominal aorta.</li>
	<li>Place the stent just above the aortic bifurcation but below the renal arteries. Deploy the stent by inflating the balloon catheter to 12 atm for 15 s by using an inflation syringe system.</li>
	<li>Deflate the balloon catheter and maintain negative pressure according to the manufacturer&#8217;s recommendations for the stent in use.</li>
	<li>Slowly withdraw the deflated catheter while leaving the stent in place.</li>
	<li>Just before taking out the catheter, create tension on the thread loop above the incision with the surgical clamp to interrupt blood flow again. Then remove the balloon catheter and directly ligate the vessel proximally.</li>
	<li>Tie the proximal and the distal thread loops to ligate the femoral artery and confirm adequate hemostasis of the arteriotomy. Collateral arteries will ensure further perfusion to the limb.</li>
	<li>Close the muscle overlying the artery, as well as the skin incision by using 10-0 non-resorbable sutures.</li>
</ol>
4. Animal care after stent implantation
<ol>
	<li>Immediately after the operation, allow the rat to recover for 60 min in a special intensive care unit cage with warmed air (30&#8210;35 &#176;C) and an oxygen supply.</li>
	<li>Watch the animals carefully until fully recovered. Afterwards, move the rats into a normal cage. Provide ad libitum access to water and food.</li>
	<li>Administer postoperative analgesia every 6-12 hours with 0.03-0.05 mg/kg buprenorphine (s.c., in 500&#181;l NaCl)&#160;for a total of 72 hours under clinical assessment.</li>
	<li>Have the food mixed with clopidogrel (15 mg/kg) to avoid thrombosis of the implanted stent.</li>
	<li>To enhance hypercholesterolemic conditions and plaque formation, start western diet feeding at 6&#8210;8 weeks after birth and continue until euthanasia. If desired, a cohort of animals fed normal rat chow can serve as control.</li>
</ol>
5. Tissue collection and processing
<ol>
	<li>Before starting the tissue explantation at the designated time point, euthanize the animal according to IACUC guidelines. Harvest the stented aorta for histological analysis at the end of the observation period.</li>
	<li>Open the abdomen by a midline incision and remove the stented segment of the aorta as well as adjacent non-stented parts of the aorta, measuring 0.5 cm each.</li>
	<li>Place the tissue into a solution of 4% buffered formalin for 24 h for fixation.</li>
	<li>Embed the stented arterial tissue in plastic and perform histological and immunohistochemical staining according to standard protocols18,19.</li>
</ol>
6. Histomorphometric analysis
<ol>
	<li>Perform histomorphometric analysis of sequential sections of the proximal, middle, and distal part of the stented aorta by means of a microscope linked to a computer with an appropriate image analysis software.</li>
	<li>Trace the contours of the external elastic lamina (EEL, between adventitia and media), internal elastic lamina (IEL, between media and neointima), and lumen with a graphic drawing tablet. From these values, calculate EEL area, IEL area, and lumen area with the software.</li>
	<li>Calculate the percent cross-sectional area in-stent restenosis (ISR): 
	<img alt="Equation 1" src="/files/ftp_upload/61442/61442equ01.jpg" /></li>
	<li>Calculate the total neointimal area (Ai): 
	<img alt="Equation 2" src="/files/ftp_upload/61442/61442equ02.jpg" /></li>
	<li>Measure the neointimal thickness (NIT) over each stent strut as the distance between strut and lumen. Measure the NIT between the stent struts as the distance between IEL and lumen. 
	NOTE: Alternatively, calculate NIT as 
	<img alt="Equation 3" src="/files/ftp_upload/61442/61442equ03.jpg" /> 
	where PL and PIEL are the lumen and internal elastic lamina perimeter, respectively20.</li>
	<li>Perform additional analyses according to the requirements of the study.</li>
</ol>

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The authors have nothing to disclose.

This protocol describes the implantation of human-sized coronary stents into the abdominal aorta of apoE-/- rats. Several technical points are worth emphasizing. First, a mismatch between the stent size and the size of the aorta should be avoided. Placing too small a stent can lead to stent malapposition, whereas implantation of a stent that is too large for the aorta can cause overstretch, tearing, and injury of the vessel. Therefore, we recommend using stents between 2.0 and 2.5 mm in diameter, and to keep i...

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of coronary artery disease1. The long-term success of stents, however, can be limited by the occurrence of in-stent restenosis (ISR) that is determined by an excessive proliferation of neointimal tissue within the stent2,3. ISR may require a re-intervention either with coronary artery bypass or re-PCI. A variety of animal models have been suggested for the study of ISR, each of them featuring advantages and shortcomings. The major drawbacks of the most commonly used porcine coronary and rabbit iliac artery models, albeit developing lesions markedly similar to humans after stent implantation4,5, are large animal and housing costs which brings up logistical difficulties especially in long-term studies, as well as limitations in handling and equipment. Furthermore, availability of antibodies to cellular proteins of swine and rabbits is limited. On the other hand, murine models provide the major advantages of high throughput and reproducibility, as well as ease of handling, housing, and therefore cost-effectiveness. Furthermore, a higher number of antibodies are available. However, while apolipoprotein E-deficient (apoE-/-) mice have been broadly used for the study of atherosclerosis6,7,8, they are unsuitable for the study of ISR as stents have to be miniaturized to be implanted into mice, potentially changing the stents&#8217; mechanical properties. Moreover, the aortic wall of mice measures between 50 &#181;m in young mice and 85 &#181;m in old mice9, and stents have to be deployed using pressure levels as low as 2 atm, which might lead to malapposition of the stent10. Rats, however, allow for the implantation of commercially available human coronary stents, and demonstrate a vascular healing course similar to larger animals after aortic stent implantation, first reported by Langeveld et al.11. This technique originally required a trans-abdominal access, which necessitated a physical constriction of the aorta to achieve a temporary interruption of blood flow. To avoid the potentially associated vessel injury and inflammatory reactions, the technique was later refined by the introduction of a trans-iliac access, which additionally resulted in a higher survival rate of the animals12.
Because wildtype rats do not develop atherosclerotic lesions13, apoE-/- rats have been generated using nuclease techniques such as Transcription Activator-Like Effector Nuclease (TALEN)14, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9)15, and Zinc Finger (ZF)16. ApoE-/- rats have been commercially available since 2011. Providing an atherogenic background, apoE-/- rats allow for a more realistic evaluation of human-sized coronary stents, especially with regards to ISR.
Herein, we describe the method via the transfemoral access route and using a commercially available thin-strut cobalt-chromium drug-eluting stent (DES), however, it can also be applied for the study of other stent types, such as bare metal stents (BMS) or biodegradable stents.

<table>
	<tbody>
		<tr>
			<td>Diet</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SNIFF High Fat diet + Clopidogrel (15 mg/kg)</td>
			<td>SNIFF Spezialdi&#228;ten GmbH, Soest</td>
			<td>custom prepared</td>
			<td>Western Diet</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Drugs and Anesthetics</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Essex Pharma</td>
			<td>997.00.00</td>
			<td></td>
		</tr>
		<tr>
			<td>ISOFLO (Isoflurane Vapor) vaporiser</td>
			<td>Eickemeyer</td>
			<td>4802885</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Forene Abbott</td>
			<td>B 506</td>
			<td></td>
		</tr>
		<tr>
			<td>Isotonic (0.9%) NaCl solution</td>
			<td>DeltaSelect GmbH</td>
			<td>PZN 00765145</td>
			<td></td>
		</tr>
		<tr>
			<td>Ringer&#39;s lactate solution</td>
			<td>Baxter Deutschland GmbH</td>
			<td>3775380</td>
			<td></td>
		</tr>
		<tr>
			<td>(S)-ketamine</td>
			<td>CEVA Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Medistar Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Consumable supplies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL syringes</td>
			<td>BD Plastipak</td>
			<td>4606108V</td>
			<td></td>
		</tr>
		<tr>
			<td>2 mL syringes</td>
			<td>BD Plastipak</td>
			<td>4606027V</td>
			<td></td>
		</tr>
		<tr>
			<td>6-0 prolene suture</td>
			<td>ETHICON</td>
			<td>N-2719K</td>
			<td></td>
		</tr>
		<tr>
			<td>4-0 silk suture</td>
			<td>Seraflex</td>
			<td>IC 158000</td>
			<td></td>
		</tr>
		<tr>
			<td>Bepanthen Eye and Nose Ointment</td>
			<td>Bayer Vital GmbH</td>
			<td>6029009.00.00</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton Gauze swabs</td>
			<td>Fuhrmann GmbH</td>
			<td>32014</td>
			<td></td>
		</tr>
		<tr>
			<td>Durapore silk tape</td>
			<td>3M</td>
			<td>1538-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-Alcohol Skin Desinfection Solution</td>
			<td>Antiseptica GmbH</td>
			<td>72PAH200</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterican needle 18 G</td>
			<td>B. Braun</td>
			<td>304622</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterican needle 27 3/4 G</td>
			<td>B.Braun</td>
			<td>4657705</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Paper</td>
			<td>commercially available</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical instruments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe forceps curved x1</td>
			<td>Fine Science Tools Inc.</td>
			<td>11151-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe forceps straight</td>
			<td>Fine Science Tools Inc.</td>
			<td>11050-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle holder Mathieu</td>
			<td>Fine Science Tools Inc.</td>
			<td>12010-14</td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>Fine Science Tools Inc.</td>
			<td>14074-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Semken forceps</td>
			<td>Fine Science Tools Inc.</td>
			<td>11008-13</td>
			<td></td>
		</tr>
		<tr>
			<td>Small surgical scissors curved</td>
			<td>Fine Science Tools Inc.</td>
			<td>14029-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Small surgical scissors straight</td>
			<td>Fine Science Tools Inc.</td>
			<td>14028-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Standard pattern forceps</td>
			<td>Fine Science Tools Inc.</td>
			<td>11000-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Vannas spring scissors</td>
			<td>Fine Science Tools Inc.</td>
			<td>15000-08</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting microscope</td>
			<td>Leica MZ9</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Temperature controlled heating pad</td>
			<td>Sygonix</td>
			<td>26857617</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment for stent implantation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Drug-eluting stent Xience 2,25mm x 8mm</td>
			<td>Abbott Vascular USA</td>
			<td>1009544-18</td>
			<td></td>
		</tr>
		<tr>
			<td>Guide wire Fielder XT PTCA guide wire: 0.014&#34; x 300cm</td>
			<td>ASAHI INTECC CO., LTD Japan</td>
			<td>AGP140302</td>
			<td></td>
		</tr>
		<tr>
			<td>Inflation syringe system</td>
			<td>Abbott 20/30 Priority Pack</td>
			<td>1000186</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue processing and analysis</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>30% H2O2</td>
			<td>Roth</td>
			<td>9681</td>
			<td>Histology</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Roth</td>
			<td>K928.1</td>
			<td>Histology</td>
		</tr>
		<tr>
			<td>Giemsas Azur-Eosin-Methylenblau</td>
			<td>Merck</td>
			<td>109204</td>
			<td>Histology</td>
		</tr>
		<tr>
			<td>Graphic Drawing Tablet</td>
			<td>WACOM Europe GmbH</td>
			<td>CTL-6100WLK-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Roti Histofix, Formaldehyd 4% buffered</td>
			<td>Roth</td>
			<td>P087</td>
			<td>Histology</td>
		</tr>
		<tr>
			<td>Technovit 9100</td>
			<td>Morphisto</td>
			<td>12225.K1000</td>
			<td>Histology</td>
		</tr>
	</tbody>
</table>

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 stent implantation in the abdominal aorta of rats using a trans-femoral access route (Figure 1). The first central point of this animal model is that it allows for the deployment of human-sized coronary stents. A commercially available crimped and balloon-mounted coronary stent can be placed into the abdominal aorta of rats. Thus, in addition, the same principle of stent deployment as in humans can be applied. Another advantage of the use of rats is the availability o...

Watch this Scientific Journal Video about Implantation of Human-Sized Coronary Stents into Rat Abdominal Aorta Using a Trans-Femoral Access at JoVE.com

Implantation of Human-Sized Coronary Stents into Rat Abdominal Aorta 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 ...

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Medicine

4.1K Views.  University Hospital RWTH Aachen. 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.

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

The C-seal: A Biofragmentable Drain Protecting the Stapled Colorectal Anastomosis from Leakage

Colorectal anastomotic leakage (AL) is a serious complication in colorectal surgery leading to high morbidity and mortality rates1. The incidence of AL varies between 2.5 and 20% 2-5. Over the years, many strategies aimed at lowering the incidence of anastomotic leakage have been examined6, 7. 
The cause of AL is probably multifactorial. Etiological factors include insufficient arterial blood supply, tension on the anastomosis, hematoma and/or infection at the anastomotic site, and co-morbid factors of the patient as diabetes and atherosclerosis8. Furthermore, some anastomoses may be insufficient from the start due to technical failure.
Currently a new device is developed in our institute aimed at protecting the colorectal anastomosis and lowering the incidence of AL. This so called C-seal is a biofragmentable drain, which is stapled to the anastomosis with the circular stapler. It covers the luminal side of the colorectal anastomosis thereby preventing leakage.
The C-seal is a thin-walled tube-like drain, with an approximate diameter of 4 cm and an approximate length of 25 cm (figure 1). It is a tubular device composed of biodegradable polyurethane. Two flaps with adhesive tape are found at one end of the tube. These flaps are used to attach the C-seal to the anvil of the circular stapler, so that after the anastomosis is made the C-seal can be pulled through the anus. The C-seal remains in situ for at least 10 days. Thereafter it will lose strength and will degrade to be secreted from the body together with the gastrointestinal natural contents.
The C-seal does not prevent the formation of dehiscences. However, it prevents extravasation of faeces into the peritoneal cavity. This means that a gap at the anastomotic site does not lead to leakage.
Currently, a phase II study testing the C-seal in 35 patients undergoing (colo-)rectal resection with stapled anastomosis is recruiting. The C-seal can be used in both open procedures as well as laparoscopic procedures. The C-seal is only applied in stapled anastomoses within 15cm from the anal verge. In the video, application of the C-seal is shown in an open extended sigmoid resection in a patient suffering from diverticular disease with a stenotic colon.

The C-seal is a biofragmentable drain protecting the stapled colorectal anastomosis. In this video, details of the manufacturing, deployment and use are shown.

Colorectal anastomotic leakage (AL) is a serious complication in colorectal surgery leading to high morbidity and mortality rates1. The incidence of AL ...

Rat Heterotopic Abdominal Heart/Single-lung Transplantation in a Volume-loaded Configuration

Herein, we describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The configuration of the transplant graft involves anastomosis of donor inferior vena cava (IVC) to recipient IVC, and donor ascending aorta (Ao) to recipient abdominal Ao. The right upper and middle lung lobes are preserved and function as conduits for blood flow from right heart to left heart.
There are several advantages to using this technique, and it lends itself to a broad range of applications. Because the graft is transplanted in a configuration that allows for dyamic volume-loading, cardiac function may be directly assessed in vivo. The use of pressure-volume conductance catheters permits characterization of load-dependent and load-independent hemodynamic parameters. The graft may be converted to a loaded configuration by applying a clamp to the recipient&#8217;s infra-hepatic IVC. We describe modified surgical techniques for both donor and recipient operations, and an ideal myocardial protection strategy. Depending on the experimental aim, this model may be adapted for use in both acute and chronic studies of graft function, immunologic status, and variable ventricular loading conditions. The conducting airways to the transplanted lung are preserved, and allow for acute lung re-ventilation. This facilitates analysis of the effects of the mixed venous and arterial blood providing coronary perfusion to the graft.
A limitation of this model is its technical complexity. There is a significant learning curve for new operators, who should ideally be mentored in the technique. A surgical training background is advantageous for those wishing to apply this model. Despite its complexity, we aim to present the model in a clear and easily applicable format. Because of the physiologic similarity of this model to orthotopic transplantation, and its broad range of study applications, the effort invested in learning the technique is likely to be worthwhile.

We describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The transplant configuration results in a partially loaded graft circulation, allowing direct functional assessment. This model may be employed for acute or chronic studies of function and immunologic status of the transplanted graft.

Herein, we describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The configuration of the transplant graft ...

Ultrasound Based Assessment of Coronary Artery Flow and Coronary Flow Reserve Using the Pressure Overload Model in Mice

Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow reserve (CFR) in humans. Reduced CFR is accompanied by marked intramyocardial and pericoronary fibrosis and is used as an indication of the severity of dysfunction. This study explores, step-by-step, the real-time changes measured in the coronary flow velocity, CFR and systolic to diastolic peak velocity (S/D) ratio in the setting of an aortic banding model in mice. By using a Doppler transthoracic imaging technique that yields reproducible and reliable data, the method assesses changes in flow in the septal coronary artery (SCA), for a period of over two weeks in mice, that previously either underwent aortic banding or thoracotomy. 
During imaging, hyperemia in all mice was induced by isoflurane, an anesthetic that increased coronary flow velocity when compared with resting flow. All images were acquired by a single imager. Two ratios, (1) CFR, the ratio between hyperemic and baseline flow velocities, and (2) systolic (S) to diastolic (D) flow were determined, using a proprietary software and by two independent observers. Importantly, the observed changes in coronary flow preceded LV dysfunction as evidenced by normal LV mass and fractional shortening (FS). 
The method was benchmarked against the current gold standard of coronary assessment, histopathology. The latter technique showed clear pathologic changes in the coronary artery in the form of peri-coronary fibrosis that correlated to the flow changes as assessed by echocardiography. 
The study underscores the value of using a non-invasive technique to monitor coronary circulation in mouse hearts. The method minimizes redundant use of research animals and demonstrates that advanced ultrasound-based indices, such as CFR and S/D ratios, can serve as viable diagnostic tools in a variety of investigational protocols including drug studies and the study of genetically modified strains.

Coronary flow reserve (CFR) is useful for assessment of myocardial oxygen demand and evaluation of cardiovascular risk. This study establishes a step-by-step transthoracic Doppler echocardiographic (TTDE) method for longitudinal monitoring of the changes in CFR, as measured from coronary artery in mice, under the experimental pressure overload of aortic banding.

Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow ...

Creation of Abdominal Adhesions in Mice

Abdominal adhesions consist of fibrotic tissue that forms in the peritoneal space in response to an inflammatory insult, typically surgery or intraabdominal infection. The precise mechanisms underlying adhesion formation are poorly understood. Many compounds and physical barriers have been tested for their ability to prevent adhesions after surgery with varying levels of success. The mouse and rat are important models for the study of abdominal adhesions. Several different techniques for the creation of adhesions in the mouse and rat exist in the literature. Here we describe a protocol utilizing abrasion of the cecum with sandpaper and sutures placed in the right abdominal sidewall. The mouse is anesthetized and the abdomen is prepped. A midline laparotomy is created and the cecum is identified. Sandpaper is used to gently abrade the surface of the cecum. Next, several figure-of-eight sutures are placed into the peritoneum of the right abdominal sidewall. The abdominal cavity is irrigated, a small amount of starch is applied, and the incision is closed. We have found that this technique produces the most consistent adhesions with the lowest mortality rate.

Abdominal adhesions that form after surgery are a major cause of pain, infertility, and hospitalization and reoperation for small bowel obstruction. Our surgical procedure for creating abdominal adhesions in mice is a reliable tool to study the mechanisms underlying the formation of adhesions.

Abdominal adhesions consist of fibrotic tissue that forms in the peritoneal space in response to an inflammatory insult, typically surgery or ...

A Model of Cardiac Remodeling Through Constriction of the Abdominal Aorta in Rats

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and fluid retention. Changes in myocardial structure, electrical conduction, and energy metabolism develop with heart failure, leading to contractile dysfunction, increased risk of arrhythmias, and sudden death. Hypertensive heart disease is one of the key contributing factors of cardiac remodeling associated with heart failure. The most commonly-used animal model mimicking hypertensive heart disease is created via surgical interventions, such as by narrowing the aorta. Abdominal aortic constriction is a useful experimental technique to induce a pressure overload, which leads to heart failure. The surgery can be easily performed, without the need for chest opening or mechanical ventilation. Abdominal aortic constriction-induced cardiac pathology progresses gradually, making this model relevant to clinical hypertensive heart failure. Cardiac injury and remodeling can be observed 10 weeks after the surgery. The method described here provides a simple and effective approach to produce a hypertensive heart disease animal model that is suitable for studying disease mechanisms and for testing novel therapeutics.

A rat model of abdominal aortic constriction that induces cardiac hypertrophy and remodeling is described. An efficient, highly-reproducible, and minimally-invasive method is used to provide a simple yet useful platform for research in myocardial hypertrophy and dysfunction.

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and ...

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 ...

Patch Angioplasty in the Rat Aorta or Inferior Vena Cava

Pericardial patches are commonly used in vascular surgery to close vessels. To facilitate studies of the neointimal hyperplasia that forms on the patch, we developed a rat model of patch angioplasty that can be used in either a vein or an artery, creating a patch venoplasty or a patch arterioplasty, respectively. Technical aspects of this model are discussed. The infra-renal IVC or aorta are dissected and then clamped proximally and distally. A 3 mm venotomy or arteriotomy is performed in the infrarenal inferior vena cava or aorta of 6 to 8 week-old Wistar rats. A bovine pericardial patch (3 mm x 1.5 mm x 0.6 mm) is then used to close the site using a 10-0 nylon suture. Compared to arterial patches, venous patches show increased neointimal thickness on postoperative day 7. This novel model of pericardial patch angioplasty can be used to examine neointimal hyperplasia on vascular biomaterials, as well as to compare the differences between the arterial and venous environments.

We have established a model of pericardial patch angioplasty that can be used in either small-diameter veins or arteries. This model can be used to compare venous and arterial neointimal hyperplasia formation.

Pericardial patches are commonly used in vascular surgery to close vessels. To facilitate studies of the neointimal hyperplasia that forms on the patch, ...

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 ...

Balloon-based Injury to Induce Myointimal Hyperplasia in the Mouse Abdominal Aorta

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine balloon denudation model, which is comparable with established vessel injury models in large animals. The aorta denudation model with balloon catheters mimics the clinical setting and leads to comparable pathobiological and physiological changes. Briefly, after performing a horizontal incision in the aorta abdominalis, a balloon catheter will be inserted into the vessel, inflated, and introduced retrogradely. Inflation of the balloon will lead to intima injury and overdistension of the vessel. After removing the catheter, the aortic incision will be closed with single stiches. The model shown in this article is reproducible, easy to perform, and can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, which can be applied in an economical fashion. By using different knockout-mouse strains, the impact of different genes on MH development can be assessed.

This article demonstrates a murine model to study the development of myointimal hyperplasia (MH) after aortic balloon injury.

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine ...

Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans

Coronary artery calcification (CAC) provides an objective measure of coronary artery disease and can readily be identified on non-gated computed tomography (CT) scans with a high correlation with gated cardiac CT scans. This standardized protocol takes a step-wise approach to not only optimizing an image for the identification of calcification but also to distinguishing CAC from other common causes of calcification in the cardiac silhouette. Recognition of CAC on non-gated CT scans helps to identify a very powerful prognostic factor that can influence therapeutic interventions or downstream diagnostic testing without requiring a gated cardiac scan. These non-gated CT scans are often acquired as part of the routine care of the patient, and this data is readily available without another dose of&#160;ionizing radiation. This protocol allows for the precise and accurate extraction of this data for the purposes of retrospective data analysis in clinical research studies, but also in the clinical evaluation and management of patients.

Here, we present a protocol to reliably and systematically identify coronary artery calcification (CAC) on non-gated computed tomography (CT) scans of the chest or abdomen. CAC provides an objective measure of coronary artery disease for both research and clinical purposes.