Endovascular Interventions in Superficial Femoral Artery Disease
Qurat-ul-Aini Jelani, MD
Sasanka Jayasuriya, MBBS, FACC, FASE, RPVI, FSCAI
Carlos Mena, MD, FACC, FSCAI
Key Points
As a result of multiple dynamic stressors, the SFA is the most common site of involvement of atherosclerotic arterial disease in patients with PAD.
Patients presenting with intermittent claudication should be treated with optimal medical therapy, intervention for smoking cessation, and a supervised exercise walking program.
Patients with ongoing symptoms in spite of above therapy and patients presenting with critical limb ischemia are offered endovascular or open surgical revascularization.
Percutaneous transluminal angioplasty with plain or drug-coated balloons and stenting with bare metal stents, drug-eluting stents, or stent grafts are endovascular treatment options in patients with femoropopliteal disease.
I. Introduction
The superficial femoral artery (SFA) is the most common site of involvement of atherosclerotic arterial disease resulting in claudication in patients with peripheral arterial disease (PAD). The SFA and the contiguous popliteal artery constitute the femoropopliteal (FP) segment which is extremely long and exposed to external compression. The SFA is exposed to multiple anatomic and dynamic challenges. There is 13% shortening of the SFA between supine and fetal positions.1 Additionally there are 60 degrees of SFA torsion produced by simultaneous knee and hip flexion.1 While these characteristics make it challenging to treat FP disease, FP involvement occurs in 20%-40% of patients with critical limb ischemia (CLI) and remains the most common location of disease in patients presenting with claudication.2 The severity of symptoms from SFA disease vary considerably, based on the extent of collateralization from the profundal femoral artery. The optimal treatment of SFA disease in patients with intermittent claudication remains a matter of continuing debate. In the last decade, endovascular treatment (EVT) of infrainguinal disease has been readily adopted as an alternative to open bypass surgery. Percutaneous transluminal angioplasty (PTA) and stenting are the most commonly used EVT options for TASC (Trans-Atlantic Inter-Society Consensus) type A and B lesions.3,4 With the advent of advanced techniques such as subintimal angioplasty, advanced devices such as those enabling reentry, availability of mechanical and laser atherectomy, even type C and D lesions are being successfully treated.5 In most cases, endovascular procedures are also well tolerated, requiring short hospital stays, and result in rapid recovery.6 The revised Trans-Atlantic Intersociety Consensus document3 and the American Heart Association7 guidelines recommend the use of EVT as first-line treatment for patients with focal and moderate disease. Open bypass is recommended for diffuse disease or long segment total occlusions. After failure of an exercise program and optimization of medical therapy, EVT
may be considered. As the data for the long-term efficacy of EVT versus open surgical bypass are limited, treatment approach should be individualized and should take into account both patient and procedural risks.
may be considered. As the data for the long-term efficacy of EVT versus open surgical bypass are limited, treatment approach should be individualized and should take into account both patient and procedural risks.
II. Clinical Assessment of Peripheral Arterial Disease in Patients With Superficial Femoral Artery Disease8
Patients at Risk for Peripheral Arterial Disease
Patients at increased risk of PAD including SFA disease include individuals >65 years of age, patient between age 50 and 64 years with risk factors for PAD (ie, diabetes mellitus [DM], history of smoking, hyperlipidemia, and hypertension [HTN]), individuals with known atherosclerotic disease in another vascular territory (eg, coronary, carotid, subclavian, renal etc).
Claudication
The majority of patients with confirmed PAD do not have typical claudication and may either have non-joint-related symptoms(atypical symptoms) or are asymptomatic.9,10
Claudication is a classic manifestation of PAD and is defined as fatigue, discomfort, cramping, or pain of vascular origin in the muscles of the lower extremities that is consistently induced by exercise and consistently relieved by rest (within 10 min).
Critical Limb Ischemia More advanced PAD may manifest as critical limb ischemia (CLI) which is defined as chronic (>2 wk) ischemic rest pain with nonhealing wounds/ulcers or gangrene in one or both legs.
Examination
Examination of patients with PAD include pulse palpation, auscultation for femoral bruits, and inspection of the lower extremities including feet.
Abnormal physical examination findings may include diminished pulses, vascular bruit, nonhealing wounds/gangrene, and so forth.8
Abnormal physical findings should be confirmed with diagnostic testing.
Ankle brachial index (ABI) is generally the initial test of choice.
The resting ABI is a simple, noninvasive test that is usually obtained by measuring systolic blood pressure at the brachial arteries, dorsalis pedis (DP), and posterior tibial (PT) arteries in the supine position. ABI is calculated for both legs by dividing the higher of the DP or PT pressure by the higher of the right or left arm blood pressure.
Segmental lower extremity blood pressures and pulse volume recordings are often performed along with ABIs which may be used to localize anatomic segments of disease.
A normal ABI is between 1.00 and 1.40.11 An ABI 0.90 demonstrates 90% sensitivity and 95% specificity for PAD and is the accepted threshold for
diagnosis. Values between 0.91 and 1.00 are considered borderline; however, the cardiovascular event rate for an ABI in this range is increased by 10%-20%.
At levels >1.40, the identification of PAD is not accurate because of the presence of arterial calcification and noncompressibility of the blood vessels.
Depending on resting ABI values, additional physiologic testing may be considered including exercise treadmill ABI testing, measurement of toe brachial index (TBI), and perfusion assessment by transcutaneous oxygen pressure (TcPO2) or skin perfusion pressure (SPP).
TBI is used to establish diagnosis of PAD in the setting of noncompressible arteries (ABI >1.40) and may be used in patients with suspected CLI.
An abnormal ABI is consistently related with the presence of coronary and cerebrovascular disease.12,13,14 In addition, it remains a predictor of cardiovascular mortality and morbidity independent of clinical risk prediction scores such as the Framingham risk score, coronary calcium score, and carotid artery intimal medial thickness.15
Revascularization Considerations In patients in whom revascularization is being considered, anatomic imaging may be performed including duplex ultrasound, computed tomography angiography (CTA), or magnetic resonance angiography.16 Duplex ultrasonography is easily accessible, inexpensive, and especially useful in patients with renal failure; however, it has limited sensitivity for multilevel stenosis and in calcified vessels. CTA and MRA both allow rapid acquisition of a high-resolution, three-dimensional roadmap of the peripheral arterial tree. However, the use of CTA is limited by exposure to both iodinated contrast and ionizing radiation. MRA is associated with increased risk of nephrogenic systemic sclerosis in patients with advanced disease receiving gadolinium.
III. Medical Therapy for Patients With Peripheral Arterial Disease
Exercise Programs All patients with PAD should receive guideline-directed medical therapy including a structured exercise program. Treatment should be aimed at limb-related outcomes including improving claudication symptoms and preventing CLI and amputation. One of the goals of medical treatment is to prevent major adverse cardiovascular events including myocardial infarction (MI), stroke, and cardiovascular death. Patients with PAD continue to be undertreated17,18 despite the benefits of multifactorial risk reduction in this patient population.19
Pharmacotherapy Pharmacotherapy for patients with PAD includes antiplatelets and statins and is further tailored to individual risk factors. Exercise training has been a mainstay of treatment for symptomatic PAD,20,21 modifying several pathophysiological mechanisms including improved skeletal muscle metabolism, endothelial function, and gait abnormalities.22 A 12-week intervention of supervised exercise program improves exercise program and quality of life in PAD.20 In trials with follow-up ranging from 18 months to 7 years,23,24,25 a persistent benefit of supervised exercise has been
demonstrated. Supervised exercise program has an excellent safety profile in patients screened for absolute contraindication to exercise such as exercise-limiting cardiovascular disease, amputation or wheelchair confinement.26,27,28
Smoking Cessation Smoking remains a major risk factor for the development and progression of PAD. In a study of 739 patients undergoing lower extremity angiography, 28% were active smokers. Those who quit and continued to abstain had a significantly lower 5-year mortality and improved amputation-free survival.29 Discontinuation of smoking is the most important lifestyle modification in preventing amputation, CLI, and MACE.
IV. Interventions for Patients With Peripheral Arterial Disease
Principles of Catheter-Based Interventions
The main treatment aim of EVT intervention in the SFA/FP circulation is to restore unobstructed flow to the tibial trifurcation. There are standard definitions for success and patency. Angiographic success refers to a residual diameter stenosis not more than 30% and subsequent patency with less than 50% recurrent stenosis.30 Hemodynamically, the success of an intervention is indicated by an increase in ABI of at least 0.15 and an improvement in Rutherford class.30 Restenosis occurs frequently and correlates directly with lesion length.31
Intermittent claudication (IC) may be caused by occlusive lesions in the aortoiliac segment, common femoral artery, SFA, and profundal femoral and popliteal arteries. In patients with multisegment disease, the more proximal disease should be treated first. This usually results in symptomatic improvement without extending treatment to distal arteries.6 There are multiple EVT options for SFA/FP occlusive disease (FPOD),6 including PTA alone,32 angioplasty with self-expanding stents,33 angioplasty with balloon-expandable stents,34 angioplasty with covered stent grafts,35,36 atherectomy,8 antimyoproliferative drug-coated balloons (DCBs),37,38,39 and drug-eluting stents (DESs).40 Other modalities include thrombolysis that uses lytic agents acting on fibrin and thrombectomy that uses direct techniques to remove clot.
Overview of Guidelines6
According to the Society for Vascular Surgery (SVS) guidelines for atherosclerotic disease of the lower extremities, EVT is recommended over open surgery for focal occlusive disease of the SFA not involving the origin (class IC). For focal lesions (<5 cm), with unsatisfactory results with balloon angioplasty, selective stenting is suggested (2C). The use of self-expanding nitinol stents (with or without paclitaxel) is recommended for intermediate length lesions (1B). Surgical bypass is recommended as the initial revascularization strategy for diffuse femoropoliteal disease, small caliber (<5 mm), or extensive calcification of the SFA. According to the American College of Cardiology/American Heart Association (ACC/AHA) guidelines, revascularization of the FP segment is recommended for patients with CLI or for patients who have had a suboptimal response to a trial of exercise.41 An endovascular
first approach is recommended for TASC A through C lesions and is a reasonable approach for TASC D lesions (Table 10.1) as determined by the experience of the operator, and the patient’s comorbidities.
The morphological classification for SFA/FP lesions and thereby treatment is also guided by the recommendations made by the Trans-Atlantic Inter-Society Consensus document II (TASC II) (Table 10.2).42 TASC-A and B are managed with endovascular techniques; TASC-C are treated by either endovascular revascularization or bypass based on individual risk stratification. TASC-D lesions are generally surgically managed.
In general the outcomes of PTA and stenting depend on both anatomic and clinical characteristics.7 Patency after PTA is greatest for lesions in the common iliac artery, decreasing distally. Patency also decreases with increasing length, multiple and diffuse lesions, presence of comorbidities including diabetes, smoking and renal
failure.43,44,45,46,47,48,49 Although there is no consensus on a diagnostic transstenotic pressure gradient, intravascular pressure measurements have been recommended to determine whether lesions are significant—for example a stenoses of 50%-75% may or may not be hemodynamically significant. Multiple criteria have been suggested including a mean gradient of 10 mm Hg before or after vasodilators or a peak systolic pressure gradient of 15% after administration of a vasodilator.50,51
TABLE 10.1. ACC/AHA Recommendations for Femoropoliteal Intervention in Stable Limb Ischemia
Class I, Level of Evidence: A
Endovascular procedures are indicated for patients with a vocational or lifestyle-limiting disability
Due to intermittent claudication when clinical features suggest a reasonable likelihood of symptomatic improvement with endovascular intervention and: (1) there has been an inadequate response to exercise or pharmacological therapy, and/or (2) there is a very favorable risk-benefit ratio (eg, focal stenosis)
Class IIa, Level of Evidence: C
Stents (and other adjunctive techniques such as lasers, cutting balloons, atherectomy devices, and thermal devices) can be useful in the femoral, popliteal, and tibial arteries as salvage therapy for a suboptimal or failed result from balloon dilation (eg, persistent translesional gradient, residual diameter stenosis >50%, or flow-limiting dissection)
Class IIb, Level of Evidence: A
The effectiveness of stents, atherectomy, cutting balloons, thermal devices, and lasers for the treatment of femoral-popliteal arterial lesions is not well established (except to salvage a suboptimal result from balloon dilation)
Class III, Level of Evidence: C
Primary stent placement is not recommended in the femoral, popliteal, or tibial arteries
Class III, Level of Evidence: C
Endovascular intervention is not indicated as prophylactic therapy in an asymptomatic patient with lower extremity peripheral arterial disease (PAD)
Data from Anderson JL, Halperin JL, Albert NM, et al. Management of patients with peripheral artery disease (compilation of 2005 and 2011 ACCF/AHA guideline recommendations): A report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation. 2013;127(13):1425-1442.
TABLE 10.2. Morphological Stratification of Femoropopliteal Lesions42
Lesion Type
Stenosis or Occlusion Pattern
Procedure
A
1. Single stenosis less than 3 cm of the superficial femoral artery or popliteal artery
Endovascular
B
Single stenosis 3-10 cm in length, not involving the distal popliteal artery
Heavily calcified stenoses up to 3 cm in length
Multiple lesions, each less than 3 cm (stenoses or occlusions)
Single or multiple lesions in the absence of continuous tibial runoff to improve inflow for distal surgical bypass
Endovascular
C
Single stenosis or occlusion longer than 5 cm
Multiple stenoses or occlusions, each 3-5 cm in length, with or without heavy calcification
Endovascular or surgical bypass
D
Complete common femoral artery or superficial femoral artery occlusions or complete popliteal and proximal trifurcation occlusions
Surgical bypass
Vascular Access
Vascular access is the most important part of any endovascular intervention (Table 10.3). The most common access vessel is common femoral artery (CFA). The brachial artery may be used in some cases; left brachial access is usually preferred, as the risk of cerebral embolization is less than access via right brachial approach. Safest approach to obtaining access is by using ultrasound guidance and using a micropuncture needle. The puncture site for CFA must be below the inguinal ligament and above the femoral bifurcation in the region overlying the femoral head. The puncture site should be confirmed fluoroscopically/angiographically. By angiography, the puncture site/needle entry site should be between the origin of the inferior epigastric artery/lateral circumflex artery and femoral bifurcation. Contralateral and ipsilateral arterial access can both be used. Generally contralateral access site is preferred which requires an up-and-over technique to cross the bifurcation. Contralateral approach may not be used in case of tortuous iliac arteries, hostile aortic bifurcations, Y-prosthesis, or abdominal stent grafts.53 In cases of failed antegrade approach or flush SFA occlusion, ipsilateral retrograde popliteal approach may be used. Left brachial access is reserved for cases of CFA and SFA lesions in the presence of bilateral iliac artery occlusions. It is associated with the risk of vertebrobasilar stroke. Research has recently been published evaluating transradial and transulnar access in combination with transpedal access for femoral artery angioplasty.52
Once access is obtained, the micropuncture sheath is exchanged for an appropriate sized sheath (ranging from 4 to 7 French). Digital subtraction angiography of the distal aorta and iliac arteries followed by angiography of the target extremity is performed using a 5 French flush catheter.
TABLE 10.3. Access Sites Used for Superficial Femoral Artery Intervention
Access Site
Contralateral common femoral artery (CFA)
Most commonly used. Technically feasible
Ipsilateral CFA/antegrade
In patients with significant iliac disease.
Unsuitable for ostial or proximal superficial femoral artery (SFA) disease
Retrograde transpopliteal
Patients with contraindication to both contralateral and ipsilateral approach.
In patients with chronic total occlusions when failure to cross proximal cap
Retrograde brachial
In patients with iliac disease or other contraindications to contralateral or ipsilateral approach.
Mostly in patients with proximal or mid-SFA disease
Retrograde transpedal
Maybe combined with contralateral or ipsilateral approach. Mainly used when failure to cross proximal cap of chronic occlusions
Retrograde transradial
Maybe combined with contralateral or ipsilateral approach. Combined with transpedal approach52
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