Peripheral Vascular Stent Insertion 

Updated: Jan 21, 2020
Author: Dale K Mueller, MD; Chief Editor: Karlheinz Peter, MD, PhD 

Overview

Background

Various peripheral arterial occlusive lesions have traditionally been managed with surgical therapy. However, endoluminal intervention with catheter-based techniques has become quite common and, in many cases, is now the treatment of choice. Several interventional products are available for the endovascular specialist, but balloons and stents make up the core of these technologies.

Placement of a metal stent across a stenotic or occluded blood vessel is intended to maintain the patency of the vessel and reestablish flow through it by providing internal structural support. This article discusses the indications, contraindications, anesthesia, necessary equipment, positioning, techniques, and potential complications of endovascular stent placement in peripheral vessels.

Indications

The indications for peripheral vascular stent placement in a patient with known peripheral arterial disease (PAD) are the same as those for open intervention.

Indications for vascular stents in the lower extremities are as follows:

  • Severe, debilitating claudication
  • Lifestyle-limiting claudication refractory to lifestyle modification and exercise regimen
  • Ischemia with rest pain
  • Ischemic nonhealing lower-extremity ulcers

Indications for vascular stents in the upper extremities are as follows:

  • Severe arm claudication with subclavian stenosis
  • Syncope or dizziness with arm use ( subclavian steal syndrome) with evidence of subclavian stenosis and retrograde vertebral flow
  • Ischemic ulcers of the hand

Indications for vascular stents in the visceral arteries are as follows:

  • Difficult-to-control hypertension on three or more medications with or without elevated creatinine levels; greater than 60% renal artery stenosis
  • Mesenteric ischemia (postprandial abdominal pain, weight loss, “food fear”) and more than 70% stenosis in the celiac or superior mesenteric artery

Indications for vascular stents in the carotid arteries are as follows:

  • Most carotid stent procedures are being performed as part of clinical trials
  • Stent therapy for carotid stenosis is reserved for patients at high operative risk (eg, intervention for restenosis following previous surgical repair, prior radiation to the neck, high lesions that are difficult to access surgically, or contralateral carotid occlusion)

Selective stent placement (exclusive of carotid intervention) is indicated as a secondary intervention following balloon angioplasty when the result is residual stenosis greater than 30% or a flow-limiting dissection.

Primary stent placement is generally indicated as initial intervention for iliac, renal, subclavian, and carotid stenosis.

The Trans-Atlantic Inter-Society Consensus II (TASC II)[1] established recommended guidelines for treatment of peripheral vascular disease on the basis of lesion characteristics. An update published in 2015 expanded the TASC classification to include arteries below the knee.[2]

The TASC classification for aortoiliac lesions is as follows:

  • TASC A - Unilateral or bilateral stenosis of the common iliac artery (CIA); unilateral or bilateral single short (≤ 3 cm) stenosis of the external iliac artery (EIA)
  • TASC B - Short (≤ 3 cm) stenosis of the infrarenal aorta; unilateral CIA occlusion; single or multiple stenosis totaling 3-10 cm involving the EIA but not the common femoral artery (CFA); unilateral EIA occlusion not involving the origins of the internal iliac artery (IIA) or CFA
  • TASC C - Bilateral CIA occlusions; bilateral EIA stenosis 3-10 cm long not extending into the CFA; unilateral EIA stenosis extending into the CFA; unilateral EIA occlusion involving the origins of the IIA or CFA; heavily calcified EIA occlusion with or without involvement of the orogins of the CFA or IIA
  • TASC D - Infrarenal aortoiliac occlusion; diffuse disease involving the aorta and both iliac arteries; diffuse multiple stenosis involving the unilateral CIA, EIA, and CFA; unilateral occlusion of both CIA and EIA; bilateral EIA occlusions; iliac stenosis in patients with an abdominal aortic aneurysm (AAA) requiring treatment that is not amenable to endograft placement

The TASC classification for femoropopliteal lesions is as follows:

  • TASC A - Single stenosis ≤ 10 cm long; single occlusion ≤ 5 cm long
  • TASC B - Multiple stenoses or occlusions, each ≤ 5 cm; single stenosis or occlusion ≤ 15 cm not involving the infrageniculate popliteal artery; heavily calcified occlusion ≤ 5 cm long; single popliteal stenosis
  • TASC C - Multiple stenoses or occlusions totaling >15 cm with or without heavy calcification; recurrent stenosis or occlusions after failure of treatment
  • TASC D - Chronic total occlusions of the CFA or the superficial femoral artery (SFA) >20 cm, involving the popliteal artery; chronic total occlusion of the popliteal artery and proximal trifurcation vessels

The TASC classification for infrapopliteal lesions (with the anterior tibial artery as the selected example) is as follows:

  • TASC A - Single focal stenosis ≤ 5 cm long in the target tibial artery with occlusion or stenosis of similar or worse severity in the other tibial arteries
  • TASC B - Multiple stenoses, each ≤ 5 cm long or total length ≤ 10 cm, or a single occlusion ≤ 3 cm long in the target tibial artery with occlusion or stenosis of similar or worse severity in the other tibial arteries
  • TASC C - Multiple stenoses in the target tibial artery and/or a single occlusion with total lesion length >10 cm with occlusion or stenosis of similar or worse severity in the other tibial arteries
  • TASC D - Multiple occlusions involving the target tibial artery with a total lesion length >10 cm or dense lesion calcification or nonvisualization of collaterals; the other tibial arteries are occluded or have dense lesion calcification

Preferred treatment is as follows:

  • TASC A lesions - Endovascular therapy is the treatment of choice
  • TASC B lesions - Endovascular therapy is the preferred treatment, but this depends on patient comorbidities, fully informed patient preference, and the operator’s long-term success rate
  • TASC C lesions - Surgery is the preferred treatment for good-risk patients, but this depends on patient comorbidities, fully informed patient preference, and the operator’s long-term success rate
  • TASC D lesions - Surgery is the treatment of choice

There has been an increase in the adoption of an endovascular-first approach for even complex (TASC C/D) lesions. However, more and better-quality data comparing open with endovascular therapy are needed is needed, particular with regard to meaningful outcomes (eg, limb viability, wound healing, quality of life, and survival) besides anatomic patency.[2]

Contraindications

No absolute contraindications for using stents in the peripheral vessels exist. Recommendations against the use of stents for peripheral intervention are outlined in the general guidelines for high-category TASC lesions listed above (see Indications).

Other limiting factors may relate more to those that would be considered in any angiographic procedure, such as renal insufficiency, which may limit the ability to use iodinated contrast for the procedure, or pregnancy, which would contraindicate the use of radiation.

It generally is not recommended to place stents across areas of extreme flexion or compression points that could lead to stent crushing and fracture—for instance, across the inguinal ligament (CFA) or across the knee flexion point in the popliteal artery (which is actually proximal to the knee joint itself). Again, most limitations are based on guidelines only and must be assessed on a case-to-case basis.

Technical Considerations

Self-expanding stents are preferred for long lesions, tortuous vessels, or areas where concern for external forces or compression exists. Such stents are more flexible, more trackable, and available in much longer lengths (currently in the range of 2-17 cm for a single stent); these are ideal for femoral-popliteal lesions.

Balloon-expandable stents are recommended for ostial lesions, calcified lesions, and short-segment lesions because they can be deployed precisely and exert a stronger radial force; these are ideal for treatment of renal, mesenteric, iliac, and subclavian lesions.

If stent insertion is considered a likely possibility, a minimum sheath diameter of 6 French should be considered.

In the treatment of contralateral femoral-popliteal lesions, a long sheath extending to the contralateral CFA gives a more stable position through which to work.  A meta-analysis by Antoniou et al demonstrated that drug-eluting stents yielded better short-term results than bare-metal stents, with increased patency and freedom from target lesion revascularization; the influence on end points such as limb salvage remains unknown.[3]

In treating subclavian, mesenteric, and renal lesions, a guide catheter is useful to help track a balloon-expandable stent to the desired vessel; this requires a larger-diameter sheath to accommodate the guide catheter of the required diameter.

Treatment of aortic lesions can be done with Palmaz stents (large-diameter balloon-expandable stents that must be manually mounted onto a large balloon)[4] ; alternatively, one can consider covered stent grafts such as those used for aortic aneurysmal disease.

Venous stenting has also shown benefit in certain cases[5] ; this is mostly seen in iliac vein stenosis (eg, May-Thurner syndrome) and can be performed with larger-diameter Wallstents with much more significant oversizing (≥25%) because veins have much higher capacitance.

Decision-making should always take into consideration the possibility that an endovascular intervention might limit future surgical options. For example, placement of a stent in the CFA or the below-the-knee popliteal artery could limit the option of a bypass in the future and thus should probably be avoided.[6]

Outcomes

A retrospective analysis by Haine et al compared interwoven nitinol stents (INS) with drug-eluting stents (DES) in patients with femoropopliteal lesions.[7] The primary endpoint was time to clinically driven target lesion revascularisation (CD-TLR) within 12 months. Secondary endpoints were time to death, amputation and composite of death, amputation and CD-TLR. At 12 months, the cumulative incidence of CD-TLR did not differ in the two groups. One stent was not determined to be rpeferable to the other, even for calcified or popliteal artery lesions.

A retrospective cohort analysis by Phair et al evaluated paclitaxel drug-eluting stent implantation (DES) and angioplasty with drug (paclitaxel)-coated balloons (DCB) in the treatment of 97 patients with long-segment (>100 mm) femoropopliteal disease (Rutherford III-VI).[8]  After the initial procedure, patients were followed for target lesion restenosis (>50% reduction in lumen diameter on duplex ultrasonography). Cumulative primary patency was 87% at at 6 months and 71% at 12 months. The corresponding figures for DES were 88% and 80%, respectively, and those for DCB were 81% and 49%.

 

Periprocedural Care

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:

  • Guide wires
  • Sheaths for access
  • Various diagnostic catheters
  • Contrast material
  • Occasionally, an intravascular ultrasound device
  • 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).[4] 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.[9]

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[4] :

  • Usually made of metal alloy
  • Flexible, but exerting less radial force (though stents capable of greater outward force are being studied [10] )
  • More crush-resistant
  • Easier to track
  • Available in longer lengths
  • Ideal for long lesions, tortuous vessels, and vessels with varying diameter

Balloon-expandable stents typically have the following characteristics[4] :

  • Usually made of stainless steel
  • Exerting a strong radial force but crushable
  • More radiopaque
  • Capable of being deployed more precisely
  • 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.

 

Technique

Stenting of Peripheral Vessels

Vessel access is achieved with an 18-gauge needle or a micropuncture kit that utilizes a smaller-caliber needle and wire. Use of a micropuncture kit under ultrasonographic guidance is recommended for brachial arterial access.

A wire of appropriate diameter and length is used to cross the lesion of concern. It must be long enough to accommodate the shaft length of the stent device (which is usually 80 or 135 cm). The access sheath must also be of a diameter sufficient to accommodate the balloon or stent device. Generally, a 5-French sheath is adequate for most balloons less than 8 mm in diameter, but a 6-French sheath is generally the minimum for stents 5 mm or more in diameter. It is critical that the wire always be under direct control outside the body when catheters are exchanged or balloons or stents are advanced.

If angioplasty is to be attempted first, then an appropriately sized balloon (diameter and length vary) is placed across the lesion and inflated to the desired diameter and pressure for 1-2 minutes, with care taken not to exceed the vessel diameter. If a residual stenosis greater than 30-40% or a flow-limiting intimal dissection exists, then placement of a stent is recommended.

Balloon-expandable stents should be matched to the vessel diameter, whereas self-expanding stents may be upsized about 10-15% to maintain enough radial force to appose the vessel wall. After deployment of a self-expanding stent, a balloon may be reinserted and inflated to help with vessel wall apposition. Again, the balloon should not be oversized.

Angioplasty has generally been recommended as first-line therapy for femoral-popliteal disease and tibial disease. However, primary stenting for femoral-popliteal disease is also acceptable.[11]  Especially in the case of occlusions, predilatation with a smaller-diameter balloon may be required to pass the stent device across the lesion. Primary stenting without initial angioplasty (with a balloon-expandable stent) is preferred for iliac, renal, subclavian, and mesenteric lesions.

Predilation can facilitate passage of the stent device, especially because balloon-expandable stents are more rigid and less trackable than self-expanding stents. The stent length should be chosen to cover the entire extent of the area harboring disease of concern. If multiple stents are required for sufficient coverage, there should be 1-2 cm of overlap between adjacent stents, and stent placement should generally begin most distally and then proceed proximally.

Finally, angiography should be performed to assess the final result. Distal imaging is recommended to rule out embolization following the intervention.

Complications

Potential complications of peripheral vascular stent insertion include the following:

  • Bleeding (hematoma or pseudoaneurysm)
  • Infection
  • Contrast nephropathy
  • Dissection
  • Distal embolization
  • Stent fracture
  • In-stent restenosis or thrombosis - Cilostazol may lower the rate of this complication [12] ; flow-modification stents have also been suggested as a possible means of minimizing this problem [13] ; mechanical [14] and laser-based [15] approaches to atherothrombectomy have been used to treat this condition as well
  • Arterial rupture
  • Arterial spasm
 

Medication

Medication Summary

The goals of pharmacotherapy are to sedate and reduce morbidity.

Anxiolytics, Benzodiazepines

Class Summary

In the operating room, intravenous (IV) administration of a small dose of midazolam before arterial line insertion can reduce anxiety, tachycardia, and hypertension.

Midazolam

Midazolam is a short-acting benzodiazepine with a rapid onset of action.

Opioid Analgesics

Class Summary

Induction of anesthesia is accomplished by using high doses of an opioid (usually fentanyl or remifentanil).

Fentanyl citrate (Duragesic, Abstral, Actiq, Fentora, Onsolis)

Fentanyl citrate is a synthetic opioid that has 75-200 times more potency and a much shorter half-life than morphine sulfate. It has fewer hypotensive effects than morphine and is safer in patients with hyperactive airway disease because of minimal or no associated histamine release. By itself, fentanyl citrate causes little cardiovascular compromise, although the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Fentanyl citrate is highly lipophilic and protein-bound. Prolonged exposure to it leads to accumulation of the drug in fat and delays the weaning process. Consider continuous infusion because of the medication's short half-life.