Cardiology

Peripheral Interventions

General description of procedure, equipment, technique

Peripheral artery disease (PAD) revascularization guidelines

  • Standard clinical and functional classification of lower extremity PAD has been previously defined by the Fontaine and Rutherford classification (Table 1).

  • The original Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease (TASC-2000) classification was entirely based on anatomic categories.

    • According to these guidelines, Type-A lesions (defined as short segment stenosis or occlusion) should be offered endovascular therapy (EVT) first whereas surgery was proposed as the treatment of choice for Type-D lesions (long, diffuse, and anatomically complex).

  • The TASC-II (2007) document expanded “endovascular first” option to all Type-B lesions and many Type-C lesions, particularly for patients considered to be at significant surgical risk.

  • TASC-II also incorporated other factors, such as patient comorbidities, patient preference and operator experience and long-term outcomes with both treatment modalities.

  • The American College of Cardiology/American Heart Association (ACC/AHA) guidelines have largely adopted the TASC classification

  • In contemporary practice, however, surgery is commonly reserved for failure of EVT. Preparations to introduce a comprehensive TASC-III consensus guideline are well underway.

Table 1.

Clinical And Functional Classification Of Peripheral Arterial Disease

Indications and patient selection

General fundamental principles of peripheral vascular intervention

  • Procedure planning should start the moment the decision has been made to perform invasive angiography and revascularization of an ischemic territory. Additional imaging studies (arterial Duplex, magnetic resonance angiography [MRA], or CT angiography [CTA]) are often desirable. For aortoiliac disease, CTA is a very useful tool. For superficial femoral artery (SFA) disease, detailed Duplex ultrasound (DUS) mapping is usually adequate, and for tibial disease, MRA often provides superior images compared to CTA.

  • Adequate local anesthesia, proper conscious sedation, and positioning on the angiography table are very important first steps.

  • Ultrasound-guided access (see US-guided access chapter) is associated with lower access site complications and we always employ this technique.

  • Dilute contrast (1/2:1/2 or 2/3:1/3) and consider Visipaque™ (Iodixanol, GE Healthcare Inc., Princeton, NJ) for patients with abnormal renal function.

  • Therapeutic intensity anticoagulation (IV heparin or bivalirudin). Administer first dose prior to positioning the working sheath across the aortic bifurcation; earlier if the sheath is noted to be occlusive. When heparin is used, we aim for a target activated clotting time (ACT) of 200 to 250 seconds.

  • Generally, address any inflow disease during the initial procedure, especially when the indication is claudication. For critical limb ischemia (CLI), both inflow and outflow vessels need to be addressed. (See Table 2 for definitions of CLI.)

  • The goal in the periphery is relieving hemodynamically significant stenosis, not angiographic perfection.

  • Complications are inevitable; therefore, be familiar with the different sheaths, wires, balloons, stents/stent grafts, and niche devices (see below).

  • Be familiar with the “road map” or “smart mask” imaging technique.

Table 2.

Definition of Critical Limb Ischemia

Contraindications

  • For claudicants, we recommend medical management and a walking program for exercise; proceed to revascularization only when the symptoms are severe and refractory to medical therapy or prohibit the successful participation in a meaningful exercise program.

Details of how the procedure is performed

Adopt a systematic approach when obtaining and reviewing the angiographic images

  • Define lesion morphology: Simple versus complex, calcific versus thrombotic, lesions, localized to a “no-stent” flexion zone (groin and knee).

  • Determine need for additional invasive diagnostic evaluation: Such as intravascular ultrasounds (IVUS), and additional angiographic views with specific angulation to better lay out vessels of interest and to determine collateral flow patterns.

  • Look for the presence of chronic total occlusions (CTOs): These are common in patients presenting to the peripheral angiography suite. Treating CTOs is a time, radiation, contrast, effort, and resource intensive endeavor.

  • Assess outflow status: This is particularly important when using endoprosthesis (such as Viabhan, Gore, Flagstaff, AZ) or treating CLI with nonhealing wounds.

  • Evaluate the need for additional access: Such as when treating bilateral aortoiliac disease.

  • Verify the need for adjunctive and niche devices: Such as atherectomy or thrombectomy devices, emboli protection devices (EPD), and reentry devices.

Endovascular therapy for iliac intervention

  • Complex aortoiliac lesions frequently require IVUS evaluation to better assess the anatomy and guide the intervention.

  • When the hemodynamic significance of an angiographic finding is in doubt, perform a translesional pressure gradient assessment (at rest and with induced hyperemia downstream of the lesion).

  • Terminal aortic and proximal iliac lesions are commonly treated with the “kissing stent technique” employing balloon expandable stents (BESs).

  • Self-expanding stents (SESs) are favored for treating markedly tortuous vessels and long lesions, when antegrade approach is used and for the external iliac arteries.

  • Stent grafts are usually reserved for aneurysmal segments, vessel rupture, and selected restenotic lesions.

  • When the aorta is involved and percutaneous transluminal angioplasty (PTA) or IVUS are anticipated, upsizing to a 9 to 12 Fr sheath is necessary.

  • Hybrid (combined open surgical and EVT) approach for complex inflow disease is well established with excellent outcomes.

Endovascular therapy for femoropopliteal disease

  • Occlusion predominates over stenosis in this space and involvement of the distal runoff vessel is common.

  • Factors that may unfavorably influence EVT success in this segment: presence of CLI (vs. intermittent claudication [IC]), longer (vs. shorter), occlusive (vs. stenotic) lesions, poor outflow, and diabetes mellitus.

  • This territory is uniquely subjected to complex mechanical forces. Stent fractures are a consequence of such forces. Stent fractures are commonly associated with in-stent restenosis in this segment.

  • Ostial SFA lesions deserve surgical or hybrid procedure consideration to avoid disrupting the profunda femoris artery (PFA) origin.

  • For lesions that start beyond the SFA origin, with an adequate (0.5 to 1.0 cm) landing “cuff,” crossover technique (from the contralateral CFA), retrograde approach (from the ipsilateral popliteal artery), or a combination of both (using a snare to achieve through-and-through access) can be employed.

  • For popliteal lesions, stenting should be avoided. Options for such lesions include debulking techniques (with or without EPD) or using flexible stent.

  • See Table 3 for TASC II (2007) Classification of Femoral-Popliteal Lesions.

  • Factors adversely associated with successful CTO crossing and subsequent long-term patency are lesion length, severe calcifications, higher TSAC II score, absence of vessel tapering (i.e., flush occlusion), and the presence of collaterals.

  • Decide the crossing strategy: intraluminal (IL) vs. intentional extraluminal. Intraluminal crossing is always preferred but often is not feasible.

    • Several recanalization devices have been introduced in recent years to assist with crossing CTOs:

Table 3.

TASC II (2007) Classification of Femoral-Popliteal Lesions

Intraluminal devices

  • Excimer laser fiberoptic catheters: such as the ClirPath catheter (Spectranetics Corp., Colorado Springs, CO). Delivers bursts of ultraviolet energy in short pulse durations, allowing for a short penetration depth of 50 μm with each burst and eventually break the occlusion.

  • The Safe-Cross RF Crossing Wire (IntraLuminal Therapeutics, Carlsbad, CA) uses optical coherence reflectometry for guidance and radiofrequency energy for microablation of the lesion.

  • The Frontrunner Catheter (Cordis, a Johnson & Johnson Company; Bridgewater, NJ) employs blunt microdissection to create a channel through the occlusion to facilitate wire placement.

  • The FlowCardia Crosser (Peripheral Vascular, Tempe, AZ) uses high-frequency (20,000 Hz) vibration to pulverize the cap and erode the solid surface.

  • The TruePath (Boston Scientific Corp., Natick, MA) is a 0.018-inch wire with a diamond-coated tip that rotates at 13,000 rpm to create microdissection to facilitate access to the distal true lumen.

  • The Wildcat device (Avinger, Inc., Redwood City, CA) is a hydrophilic 0.035-inch catheter with a rotatable tip. The tip may be rotated manually or with a hand-held motorized unit to assume both passive (wedges in) and active (wedges out configurations to traverse the CTO).

Subintimal devices

  • The traditional with a combination of a looped, J-tip hydrophilic guidewire (0.014, 0.018, or 0.035) traversing the subintimal plane cap-to-cap and supported by a hydrophilic microcatheter (to direct the wire to reenter distal to the occlusion).

  • Subintimal (SI) strategy as the primary mode of crossing is preferred when the occlusion is very long, mostly atherosclerotic (no thrombus or heavy calcifications) and, especially, when the distal target vessel is of good quality.

  • Avoid SI crossing when the “reentry” vessel is heavily calcified.

  • In our practice we use a combination of 0.035 angle glide wire and a 4-Fr angle glide catheter and deliberately keep the loop short.

  • Failure to reenter the distal true lumen is encountered in 10% to 20% of cases. Therefore, dedicated reentry devices have been dedicated to address this limitation:

    • The Outback LTD Re-Entry Catheter (Cordis, a Johnson & Johnson Company; Bridgewater, NJ): 6 Fr-compatible, 22-gauge needle to access the distal vessel, uses fluoroscopic markers for guidance to direct the nitinol needle to the lumen.

    • The Pioneer (Medtronic CardioVascular; Santa Rosa, CA): 6 Fr catheter with two wire ports, each 0.014-inch compatible. One port houses a hollow-core nitinol needle and an integrated 64-element phase-array IVUS device, which is connected to the Volcano s5i Imaging System console (Volcano Corp.; Rancho Cordova, CA). Reentry is guided by IVUS images.

  • Avoid ipsilateral antegrade CFA access when using reentry devices.

Endovascular Therapy for Below-the-Knee (Tibial) Disease

Principles of EVT in tibial disease

The wide variation in vessel sizes is difficult to match with available EPD inventory.

  • The current evidence does not support routine stenting as the primary EVT for short Fem-Pop disease. It is reasonable to primarily stent long lesions as the risk of restenosis is high.

  • Bailout stenting: when PTA is complicated by extensive dissection, suboptimal result is noted, recurrent intense recoil despite prolonged balloon inflation, and perforation.

  • In our practice we adopted a PTA first strategy and generally resort to stenting when necessary ("bailout strategy").

  • We are awaiting the results of several large trials currently evaluating drug-eluting balloons and stents for longer de novo and restenotic lesions. The move towards more uniform definitions and endpoints in the peripheral space is certainly an important step in the right direction

  • Extensive occlusive tibial disease is almost always present in CLI patients.

  • Successful endovascular therapy (EVT) of CLI requires addressing inflow as well as outflow vessels to establish in-line pulsatile flow to the ischemic wound.

  • Primary patency is less important in this space unless extensive tissue loss is present (average time to healing lower extremity ischemic wounds is 6 to 10 months).

  • Besides revascularization, management of CLI patients, particularly those presenting with ischemic wounds requires multidisciplinary team of wound care specialists, podiatrists, orthotists, prosthetists, and infectious and vascular experts.

  • Bypass surgery is advocated for patients with tibial disease presenting with CLI and who are deemed a good surgical risk, expected to live >2 years, and have acceptable vein conduits and good target vessels.

  • The success rate of tibial interventions has improved over the past few years and is quickly becoming the initial treatment strategy in most CLI patients. Two major factors contributed to this:

    • The availability of dedicated below-the-knee (BK) interventional tools, including wires and balloons (longer, hydrophilic-coated with improved pushability and trackability and lower crossing profiles), BK drug-eluting balloons, BK stents, and low-profile atherectomy devices

  • The routine use of an EPD in patients undergoing routine lower extremity EVT is not warranted.

  • Thrombotic lesions and using excisional atherectomy are associated with a high incidence of distal embolization.

  • Distal emboli may in these situations shut down distal outflow and cause acute limb ischemia, particularly when the runoff vessels are deemed poor.

  • Several challenges continue to hinder applying EPD to the lower extremities.

    • The diffuse nature of PAD and the common involvement of distal vessels leaves fewer segments appropriate to use as a landing zone.

    • Traversing the device through calcific stenotic lesions and tortuous vessels imposes the risk of damage or entrapment during delivery and retrieval, especially after it had been filled with liberated debris.

  • Antegrade access (direct entry to the SFA) is advocated in tibial intervention. It has the following advantages:

    • Allows high-quality imaging.

    • Less contrast expenditure (average <100 cc per procedure)

    • Excellent support and control of interventional devices, including smaller profile (4F) systems.

    • Obviates the need for closure devices and its associated complications

  • Obtaining high-quality informative angiographic images is critical when treating the tibial space.

    • Usual views to include anteroposterior and ipsilateral oblique

    • Angulated projections (cranial and caudal) should be obtained to layout the vessels, particularly bifurcation points, and to accurately determine target lesions

  • Endoluminal crossing is always preferred over SI crossing and PTA in the tibial vessels:

    • To avoid damaging the outflow in case EVT fails and surgery is sought

    • SI PTA in the tibial vessels is associated with high restenosis rate

  • To avoid vessel dissection, which can turn the case from CKLI to acute limb ischemia:

    • Accurately size the long balloons

    • Start with smaller diameter (2 mm) and gradually progress to the target diameter balloon (3 mm then 4 mm, sequentially).

    • Apply prolonged (3 to 5 minutes), high-pressures (8 to 12 ATM) inflations (as long as the balloon is properly sized).

    • Administer spasmolytics liberally throughout the case to avoid intense spasm in these small and diseased vessels

  • Fortunately, vessel closure is uncommon unless a complication (distal emboli or dissection) has occurred.

  • See our algorithm for EVT of tibial disease in CLI patients.

  • See Table 4.

Table 4.

Algorithmic Approach for BK Interventions

The use of emboli protection devices (EPD) in lower extremity interventions

  • Improved skill set of contemporary endovascular specialists, including the ability to successfully and safely achieve several vascular access options (from the ankle, ipsilateral antegrade, etc).

Outcomes (applies only to therapeutic procedures)

Iliac intervention

  • The overall technical success rate of iliac artery angioplasty (weighted averages from 2,222 limbs) was 96% with primary patency of 86%, 82%, and 71% at 1, 3, and 5 years, respectively. In contrast, aorto-bifemoral bypass surgery carries a mortality rate as high as 3% and 5-year patency rate of 88%.

  • Hybrid (combined open surgical and EVT) approach for complex inflow disease, demonstrated excellent primary and secondary patency rates (60% and 98%, respectively).

  • Primary patency rates in this space are further improved when covered stent grafts were used (87% versus 53% with bare stents).

Femoropopliteal interventions

  • Outcomes are related to lesion parameters (length, complexity, calcifications, inflow and outflow status), patient-related risk factors, and compliance (complete smoking cessation, presence of diabetes, walking exercise program, atherosclerotic risk factor control)

  • PTA, especially when an excellent result is achieved, has acceptable patency rates and remains the initial procedure for most patients

  • Stenting improves outcomes when revascularizing chronic total occlusions or when flow-limiting dissections or suboptimal luminal gain secondary to recoil or calcification are noted

  • Atherectomy strategies may improve the vessel response to angioplasty and increase allow successful stenting when necessary

Tibial (below-the-knee) interventions:

  • Limb salvage outcomes with EVT to this space are comparable to those provided by bypass surgery.

  • EVT has significantly lower 30-day morbidity and mortality compared to bypass surgery.

Complications and their management

1. Complications of EVT to the aortoiliac space include perforation, dissection (that might propagate into the distal aorta or the femoral artery), pseudoaneurysm formation, and distal embolization.

  • Heavy and bulky calcifications may be related to rupture risk

  • The actual risk of aortic rupture in practice is much lower than feared: Based on Laplace’s law [Wall stress = (pressure x radius) / (2 x wall thickness)], dilating a larger-diameter vessel may cause overstretching of the wall at lower pressure compared to small-diameter vessel. Given this, and the low compliance of large diameter balloons, it is recommended that only low inflation pressure (<4 ATM) be employed in the aortoiliac arteries.

  • Pain is a sign of adventitial stretching and may herald arterial rupture.

  • Prompt balloon deflation is mandatory once the patient reports pain during aortoiliac PTA.

  • Meticulous postdilatation radiographic evaluation, low index of suspicion, and immediate recognition and management are important for a safe and successful procedure free from potentially devastating complications.

  • These complications can also apply to the femoropopliteal and tibial space.

  • Access site complications (particularly bleeding, less frequently thrombosis and vessel dissection) are of major importance in peripheral interventions:

    • The incidence of access site interventions can be minimized by using US-guided access for femoral, popliteal, and tibial sites.

    • Brachial access is also associated with increased risk of complications and may require cut down at the completion of the intervention.

    • Timely administration of anticoagulation decreases the risk of thrombotic access site complications, particularly when the sheath is occlusive or near occlusive.

  • Frequent ACT assessment is necessary, particularly in long procedures.

2. Complications seen with crossing CTOs include perforation, distal embolization (particularly with thrombotic lesions), and loss of collateral vessels.

  • These are seen with either technique (IL and SI)

  • They rarely require emergent open surgery, as they can be managed with prolonged balloon inflation and, occasionally, require covered stents.

What’s the evidence?

Mayfield, JA, Reiber, GE, Maynard, C. "Trends in lower limb amputation in the Veterans Health Administration, 1989-1998". J Rehabil Res Dev. vol. 37. 2000. pp. 23-30.

(Between 1989-1998, there were 60,324 amputations in VA facilities (10% of total U.S. amputations) and 24% of these were secondary to PAD. VA rates of major and minor amputation declined an average of 5% each year, while the number of diabetes-associated amputations remained the same.)

Allie, DE, Hebert, CJ, Lirtzman, MD. "Critical limb ischemia: a global epidemic. A critical analysis of current treatment unmasks the clinical and economic costs of CLI". EuroIntervention. vol. 1. 2005. pp. 60-9.

(This paper highlights the lack of systematically approaching patients with severe PAD before amputation. It showed that only 35% of the 417 reference-amputation population treated with primary amputation for infrainguinal disease between 1999 and 2001 had an ankle brachial index (ABI) and only 16% had angiography before amputation.)

Leville, CD, Kashyap, VS, Clair, DG. "Endovascular management of iliac artery occlusions: extending treatment to TransAtlantic Inter-Society Consensus class C and D patients". J Vasc Surg. vol. 43. 2006. pp. 32-39.

(One of the earlier single center reviews that showed that complex long-segment and bilateral iliac occlusions can be safely treated via endovascular means with high rates of symptom resolution and comparable initial technical success, low morbidity, and mid-term durability to results with open reconstruction.)

Sidhu, R, Pigott, J, Pigott, M, Comerota, A. "Subintimal angioplasty for advanced lower extremity ischemia due to TASC II C and D lesions of the superficial femoral artery". Vasc Endovasc Surg. vol. 44. 2010. pp. 633-37.

(Single center review that showed that subintimal angioplasty for TASC C/D lesions is a safe procedure and may be considered an alternative to bypass, especially in high-risk patients.)

Baril, DT, Chaer, RA, Rhee, RY, Makaroun, MS, Marone, LK. "Endovascular interventions for TASC II D femoropopliteal lesions". J Vasc Surg. vol. 51. 2010. pp. 1406-12.

(Endovascular interventions for TASC II D lesions were performed on 585 limbs between July 2004 and July 2009 and were safe with excellent hemodynamic improvement and limb salvage rates.)

Mouanoutoua, M, Maddikunta, R, Allaqaband, S. "Endovascular intervention of aortoiliac occlusive disease in high-risk patients using the kissing stents technique: long-term results". Catheter Cardiovasc Interv,. vol. 60. 2003. pp. 320-6.

(One of the earlier studies that provided favorable 20-month follow-up data for kissing stent technique.)

Chang, RW, Goodney, PP, Baek, JH, Nolan, BW, Rzucidlo, EM, Powell, RJ. "Long-term results of combined common femoral endarterectomy and iliac stenting/stent grafting for occlusive disease". J Vasc Surg. vol. 48. 2008. pp. 362-7.

(This is a landmark paper that provided initial data to support a hybrid strategy where combined common femoral endarterectomy with iliac stenting yielded acceptable long-term results. It also showed that the use of stent grafts versus bare stents is associated with improved primary patency.)

Berger, T, Sorensen, R, Konrad, J. "Aortic rupture: A complication of transluminal angioplasty". AJR. vol. 146. 1986. pp. 373-4.

(Classic paper that goes over the mechanics of aortic rupture during endovascular therapy.)

Colapinto, AF, Hames-Jones, EP, Johnston, KW. "Percutaneous transluminal dilatation and recanalization in the treatment of peripheral vascular disease". Radiology. vol. i35. 1980. pp. 583-7.

(One of the earliest papers that documented the viability of transluminal angioplasty as an alternative to bypass surgery for iliac and femoropopliteal occlusive disease.)

Bolia, A, Miles, KA, Brennan, J, Bell, PR. "Percutaneous transluminal angioplasty of occlusions of the femoral and popliteal arteries by subintimal dissection". Cardiovasc Intervent Radiol. vol. 13. 1990. pp. 357-63.

(The first description of recanalization of femoral and popliteal arterial occlusions by intentional subintimal dissection.)

Suri, R, Wholey, MH, Postoak, D, Hagino, RT, Toursarkissian, B. "Distal embolic protection during femoropopliteal atherectomy". Catheter Cardiovasc Interv. vol. 67. 2006. pp. 417.

(Early report that documented the retrieval of significant debris released during SilverHawk atherectomy and advocates routine use of distal embolic devices when using this device.)

Wholey, MH, Toursarkissian, B, Postoak, D, Natarajan, B, Joiner, D. "Early experience in the application of distal protection devices in treatment of peripheral vascular disease of the lower extremities". Catheter Cardiovasc Interv. vol. 64. 2005. pp. 227-35.

(An early paper that used different distal emboli protection devices in five cases that required different endovascular techniques, from PTA to stenting to catheter-directed thrombolysis. The results were favorable for the use of distal protection devices in these cases.)

Conte, MS. "Bypass versus angioplasty in severe ischaemia of the leg (BASIL) and the (hoped for) dawn of evidence-based treatment for advanced limb ischemia". JVS. vol. 51. 2010. pp. 69S-75S.

(This paper provides the final analysis of the long-term outcomes from BASIL (The Bypass versus Angioplasty in Severe Ischemia of the Leg) trial, which is the only randomized controlled trial (RCT) comparing open surgical bypass with endovascular therapy for severe limb ischemia. This analysis supports the primacy of open surgical bypass using the vein for most patients with SLI and raises questions about the sequelae of failed endovascular interventions.)
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