Name: novel percutaneous approach for deployment of 3d printed coronary stenosis implants in swine models of ischemic heart disease
Uploaded: 2020-02-18T16:00:00
Description: Watch this Scientific Journal Video about Novel Percutaneous Approach for Deployment of 3D Printed Coronary Stenosis Implants in Swine Models of Ischemic Heart Disease at JoVE.com

We thank staff members at the UCLA Translational Research Imaging Center and the Department of Laboratory Animal Medicine at University of California, Los Angeles, CA, USA for their assistance. This work is supported in part by the Department of Radiology and Medicine at David Geffen School of Medicine at UCLA, the American Heart Association (18TPA34170049), and by the Clinical Science Research, Development Council of the Veterans Health Administration (VA-MERIT I01CX001901).

We conducted the experiments according to the guidelines by the Animal Welfare Act, the National Institutes of Health, and the American Heart Association on Research Animal Use. Our Institutional Animal Care and Use Committee approved the animal study protocol.
1. Preprocedural preparation of 3D printed coronary stenosis implants
<ol>
	<li>Using tweezers, dip-coat the printed implants in a 25% heparin solution to prevent thrombus formation and allow to air dry for 24 h.</li>
</ol>
<p class="...

<ol>
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In this work, we focused on a novel percutaneous deployment strategy for coronary stenosis-inducing implants and showed that a mother-and-child catheter can be repurposed for effective percutaneous delivery of 3D printed coronary implants. Discrete artificial coronary stenoses of variable severity can be created quickly in swine models with a high success rate and in a minimally invasive manner using standard human percutaneous coronary interventional techniques and equipment. These implants were shown to be safe in the ...

Ischemic heart disease continues to be the number one cause of death in the United States1. Large animal models have been used experimentally to understand and characterize mechanisms driving coronary artery disease (CAD) and associated complications (including myocardial infarction, arrhythmic events, and heart failure), as well as for testing of new therapeutics or diagnostic modalities. Results from these studies have helped to broaden the understanding, diagnosis, and monitoring of ischemic heart disease and to advance clinical practice2. Several animal models including rabbits, dogs, and swine have been used. However, coronary stenoses, particularly discrete lesions, occur very rarely in these animals and are difficult to induce reproducibly3. Prior work described the creation of artificial coronary stenoses using ligation, occluders, or external clamps. Recently, we described how to use 3D printing technology to manufacture coronary implants that can be used to percutaneously create discrete artificial coronary narrowing4. Using computer-aided design software, we designed coronary artery implants as hollow tubes with varying inner and outer diameters as well as implant length and then fabricated them using commercially available additive materials. The implants are smooth, hollow, 3D printed tubes with rounded edges. We designed a library of implant sizes with a range of inner diameter, outer diameter, and length. The outer diameter of the implant is based on the size of the coronary guide catheter. The inner diameter is based on the size of a deflated coronary angioplasty balloon. We varied the length of the implant to tailor the desired severity of perfusion. However, safe percutaneous delivery of such devices can be challenging due to the lack of wires and catheters manufactured specifically for large animal use. In contrast, an extensive collection of catheters, wires, and supportive equipment are available for clinical use in human coronary arteries. In this work, we show how to repurpose a clinical grade mother-and-child coronary guide catheter for the delivery of the 3D printed coronary implants.
The GuideLiner catheter (Figure 1A) was developed for percutaneous coronary intervention (PCI) to allow for deep catheter seating and increased support for complex cases5. In our investigation, the GuideLiner catheter was chosen due to familiarity of use and availability, but similar catheters, where available, may also be considered. Considered a &#34;mother-and-child&#34; guide catheter (Figure 1B), the device fits inside a typical coronary guide catheter (&#34;mother&#34;) and is a coaxial flexible tube (&#34;child&#34;). This catheter can be inserted over a guidewire and effectively lengthens the reach of a typical coronary guide catheter by extending beyond the end of the coronary guide. The GuideLiner or a similar mother-and-child catheter can be used as added support for deployment of the 3D printed coronary implants. Because the implants are mounted over angioplasty balloons to be inserted as a unit over a coronary wire into the vessel (Figure 1B,1C), the catheter offers additional support to deliver the implant to the desired site. By positioning the mother-and-child catheter just proximal to the balloon, the implant remains at the desired location during balloon deflation and retraction. Despite having some firmness to its structure, the mother-and-child catheter&#39;s unique ability to be advanced deep into coronary arteries over a guidewire and the radiopaque marker at the catheter tip were essential characteristics for implantation.
Our assembled delivery apparatus consisted of a typical coronary guide catheter, the mother-and-child catheter, and a 3D printed implant fixed onto a deflated coronary angioplasty balloon (Figure 1B). As a functional delivery unit, the mother-and-child catheter not only provided stable additional support for the delivery of the equipment but was also uniquely applied as a shearing device to keep the implants in place during deflation and removal of the balloon. The radiopaque marker at the catheter tip served as a positioning guide for the assembled apparatus and sits proximal to the angioplasty balloon. These characteristics allowed for precise deployment of the flow-limiting implants. The process was designed to be reproducible, efficient, and humane for the animal subjects.
In our application, the mother-and-child percutaneous delivery technique was used to create swine models with focal coronary stenosis for evaluation of contrast-enhanced stress cardiac perfusion magnetic resonance imaging (MRI). However, the technique may be employed in other investigations including vascular systems outside the coronary vessels.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3D-Printed coronary implants</td>
			<td>Study Site Manufactured</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Amiodarone IV solution</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Amplatz Left-2 (AL-2) guide catheter (8F)</td>
			<td>Boston Scientific, Marlborough, Massachusetts, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Balance Middleweight coronary wire (0.014&#34; 300cm)</td>
			<td>Abbott Laboratories, Abbott Park, Illinois, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>COPILOT Bleedback Control valve</td>
			<td>Abbott Laboratories, Abbott Park, Illinois, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Esmolol IV solution (1 mg/kg)</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Formlabs Form 2 3D-printer with a minimum XY feature size of 150 &#181;m</td>
			<td>Formlabs Inc., Somerville, Massachusetts, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Formlabs Grey Resin (implant material)</td>
			<td>Formlabs Inc., Somerville, Massachusetts, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gadobutrol 0.1 mmol/kg</td>
			<td>Gadvist, Bayer Pharmaceuticals, Wayne, NJ</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GuideLiner catheter (6F)</td>
			<td>Vascular Solutions Inc., Minneapolis, Minnesota, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin IV solution</td>
			<td>Surface Solutions Laboratories Inc., Carlisle, Massachusetts, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine IM solution (10 mg/kg)</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lidocaine IV solution</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Male Yorkshire swine (30-45 kg)</td>
			<td>SNS Farms</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Midazolam IV solution</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NC Trek over-the-wire coronary balloon</td>
			<td>Abbott Laboratories, Abbott Park, Illinois, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen-isoflurane 1-2% inhaled mixture</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Rocuronium IV solution</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Pentobarbital IV solution (100mg/kg)</td>
			<td>Study Site Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Triphenyltetrazolium chloride stain</td>
			<td>Institution Pathology Lab</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

After initial optimization of the procedure, the intervention component was completed within 30 min. The implants were successfully delivered in all 11 subjects (100%). The implant was retrieved at the autopsy in all 11 subjects (100%). Using the diagonal branches (along the LAD) or obtuse marginal branches (along the LCX) as positional markers, we found the position of the implant at fluoroscopic-guided deployment and at autopsy to be consistent in 10 of the 11 (91%) subjects where the implant was retrievable. In one su...

Watch this Scientific Journal Video about Novel Percutaneous Approach for Deployment of 3D Printed Coronary Stenosis Implants in Swine Models of Ischemic Heart Disease at JoVE.com

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

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 ...

Our MRI-compatible minimally invasive closed chest swine model. It facilitates a more rapid translational study of ischemic heart disease. We've shown that a mother-and-child catheter can be used to precisely deploy coronary implants in a safe and quick manner, limiting adverse effects to the animal subjects.Our method can be used to develop new diagnostic imaging techniques in ischemic heart disease. With some slight modifications, it can also be applied to other vascular disease states. Although it can be difficult to selectively cannulate the left main coronary artery in smaller pigs, using a mother-and-child catheter allows excellent quality angiograms to be obtained.Our method allows us to induce a focal coronary lesion in the vessel of our choice and to conduct an MRI study on the same day. Visual demonstration of the technique will help reduce trial and error in future investigations, resulting in more reproducible results. The day before the procedure, use tweezers to dip coat printed implants in a 25%Heparin solution.And allow the implants to dry for 24 hours. On the day of the procedure confirm an appropriate level of sedation in a 30 to 45 kilogram Yorkshire swine, and use the Seldinger technique to insert the arterial and venous sheaths into the bilateral femoral arteries and veins of the animal. Then flush all of the catheter ports continuously with Heparinized normal saline.After vascular access has been obtained, administer 5, 000 to 10, 000 units of Heparin to maintain an activated clotting time of greater than 300 hundred seconds. For hemodynamic monitoring, use electrocardiography chest feeds for recording changes in the ST segment, T waves, and heart rate during the entire experimental period. Use a pressure transducer to record the continuous femoral arterial pressure throughout the procedure.Attach a pulse oximeter to the animal's ear for continuous pulse oximetry recordings. Insert a deflated NC TREK over the wire coronary balloon through a mother-and-child catheter of the desired size such that the balloon tip extends beyond the tip of the catheter. Mount the 3D printed implant onto the deflated angioplasty balloon such that the implant is positioned between the markers of the balloon and close to the proximal marker.Then use an Instaflator to inflate the balloon to two to three atmospheres to fix the implant onto the balloon and verify that the implant is positioned closer to the proximal half of the balloon so it'll be closest to the mother-and-child catheter when ready for removal. To induce a coronary angiography with a fluoroscopic C-arm in the antero posterior projection, attach a control valve to a left or right coronary guide catheter. Introduce the guide catheter over a J tipped wire through the right femoral artery sheath.And under fluoroscopic guidance advance the catheter to the aortic root. Selectively engage the catheter into the left main coronary artery, and inject five milliliters of iodinated contrast under fluoroscopy to visualize the left coronary system. Position the guide catheter toward the left main coronary artery for the second angiogram.Once engaged within or position near the left main coronary artery, advance a 0.014 inch 300 centimeter coronary wire into the left main coronary artery and further advance the wire to the distal left anterior descending artery. Insert the previously assembled mother-and-child catheter with the inflated coronary angioplasty balloon and implant over the coronary wire and advance the assembly to the desired location along the coronary vessel. Inject five milliliters of iodinated contrast to visualize a discreet narrowing at the desired location where the coronary implant should be deployed.Once the implant is in position, advance the mother-and-child catheter to the proximal marker of the inflated balloon. The geometric constraints of the delivery system allow the stenosis to be positioned within the proximal to mid portion of the pig coronary artery. Deflate the balloon and retract it through the mother-and-child catheter to shear the implant off the balloon as it is retracted, fixing the position of the implant within the designated segment of the vessel.Then perform final angiograms to document the location of the new artificial stenosis within the vessel and two orthogonal views as possible to acquire visual estimation of the stenosis severity. After harvest, dissect the ex-vivo heart to expose the coronary vessels. Note the location of the implant in relation to the branches it was positioned next to to retrieve the implants and inspect the vessel for gross injury.Then photograph the heart tissue for gross pathology and stain with TTC to exclude myocardial infarction. In these stress cardiac profusion magnetic resonance images of a coronary implant deployed in the proximal to mid left anterior descending artery, the implanted vessel can be observed at rest and at peak adenosine vasodilator stress. Note the inducible perfusion defects in the segments subtended by the left anterior descending artery.Remember to ensure that the mother-and-child catheter is flush against the implant in a stable position prior to deflation of the coronary balloon to allow for shearing of the balloon upon withdrawal. We can now deploy an implant and conduct an entire MR imaging study start to finish in a single day, drastically cutting down on the timing and logistical challenges for these experiments.

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