Equipment
Because angiographically guided stent implantation is a highly specialized procedure, proper equipment is necessary for imaging and for the procedure itself. Fluoroscopy units can be either mobile (transportable C-arm) or fixed (ceiling- or floor-mounted). Mobile units can be transported to an operating room (OR), an intensive care unit (ICU), or other areas for use. Fixed units are mounted in specialized endovascular laboratories or suites and generally have superior imaging quality. High-quality display monitors come in various sizes and configurations.
Equipment employed in the procedure may include, but is not limited to, the following:
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Guide wires
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Sheaths for access
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Various diagnostic catheters
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Contrast material
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Occasionally, an intravascular ultrasound device
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Interventional tools, including angioplasty balloons, stents, atherectomy devices, reentry devices, and so forth
Having protective lead wear for anyone who will be at risk of exposure to radiation during the procedure and education in radiation safety is also important.
Stents used for peripheral intervention differ with regard to size, material, and deployment mechanism, and their varying properties make them desirable or undesirable for particular lesion types. They may be primarily differentiated as being either self-expanding or balloon-expandable, and they are generally composed of stainless steel or a metal alloy (eg, nitinol). [5] Both self-expanding and balloon-expandable stents are available in bare metal or fabric-covered types (“stent graft”).
Biodegradable stents are being assessed for application to peripheral arterial disease (PAD), but more study is required before changes are made to current treatment guidelines. [10]
Platforms are generally for the 0.035-in. wire system, but they can also be on the 0.014- or 0.018-in. systems. The minimum sheath size for most commercially available stents is at least 5 or 6 French. Large sheaths or guide catheters are required for larger-diameter stents. The most important properties are radial force, flexibility, radiopacity, and precision of deployment.
Self-expanding stents typically have the following characteristics [5] :
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Usually made of metal alloy
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More crush-resistant
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Easier to track
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Available in longer lengths
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Ideal for long lesions, tortuous vessels, and vessels with varying diameter
Balloon-expandable stents typically have the following characteristics [5] :
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Usually made of stainless steel
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Exerting a strong radial force but crushable
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More radiopaque
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Capable of being deployed more precisely
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Ideal for short lesions, vessels with uniform diameter, calcified lesions, and vessels that are deep and resistant to crushing forces
Patient Preparation
Anesthesia
Most endovascular procedures, whether diagnostic or interventional, can be performed with moderate intravenous (IV) sedation and local anesthesia at the puncture site. A common combination for sedation is 1-2 mg of midazolam with 25-50 μg of fentanyl, depending on the patient’s size and response. Hemodynamic monitoring with pulse oximetry and familiarity with advanced cardiac life support are critical whenever moderate sedation is being administered.
Positioning
The vast majority of peripheral stent placement procedures are performed with the patient in the supine position with arms at the sides. The legs can be taped together at the ankles to keep them in proximity; this becomes important in performing simultaneous imaging of the two lower extremities to ensure that both can be visualized during the image capture.
If brachial access is necessary, the arm can be abducted 45-90º from the patient’s side to afford better access to the brachial site. When jugular venous access is necessary, the head is turned to the contralateral side for exposure. Finally, if popliteal or tibial venous access is required, the patient can be placed in a prone position; access will be in the posterior leg.
The site to be accessed should be prepared and appropriately draped with the usual sterile precautions used for invasive procedures.
