Percutaneous Revascularization of Peripheral Chronic Total Occlusion — Which Patients, Why, and How?
Recanalization of peripheral arterial total occlusion in lower extremities plays a pivotal role to improve claudication symptoms and limb salvage. Coronary chronic total occlusion (CTO) recanalization has recently gathered controversy with the publication of the occluded artery trial (OAT). However, in peripheral vasculature, specifically in the superficial femoral artery (SFA), occlusion predominates stenosis. The predominance of occlusion is due to limited collaterals, namely the profunda femoris artery and the diffuse nature of the disease.2 The constant endothelial injury, due to twisting, contraction, and kinking of the arteries, results in accelerated atherosclerosis.
Diagnosis of peripheral arterial occlusive disease (PAOD) is by history and physical examination.3 The site of pain in limbs can localize the location of occlusive disease. For example, SFA occlusion manifests as calf pain. Claudication results in the aching, throbbing, or cramping pain in the feet, calves, thighs, or buttocks during ambulation. The pain occurs after walking the same distance each time. The pain should subside in a few minutes, following the cessation of walking. The severity of claudication is best described by Fontaine classification I to IV, ranging from no pain to ulcer or gangrene. The class II is further subdivided into IIa and IIb for the ability to walk > 200 feet and < 200 feet. Physical examination can localize the site of occlusion easily. An absent popliteal artery pulse denotes SFA occlusive disease, while an absent femoral pulse indicates aorto-iliac occlusion. Treatment is warranted for all classes of PAOD, which includes control of hypertension, diabetes mellitus and hypercholesterolemia, cessation of smoking, antiplatlet therapy, and exercise. Revascularization should be considered for persistent claudication despite medical therapy. Revascularization with optimization of medical treatment is needed for patients with rest pain, ulcer, or gangrene.
Ankle brachial index (ABI), especially exercise ABI is helpful in the diagnosis of PAOD. Duplex ultrasound and segmental pressures can be complementary. Angiogram remains the gold standard to define the anatomy. Computerized tomography angiogram and magnetic resonance angiogram can be beneficial in selective cases.
Percutaneous revascularization of CTO in the peripheral arterial tree is unique across iliac, femoral popliteal segments, and tibio-peroneal arteries. Despite TransAtlantic Inter-Society Consensus (TASC),4 recommendations to treat TASC A and B with the percutaneous approach, TASC C and D are being increasingly dealt with using the percutaneous technique. The key is to keep the procedure low risk and safe, as well as to minimize complications. The total occlusions are usually crossed with a 0.035-inch Glidewire®(Terumo, Somerset, New Jersey), with a catheter support from 4 Fr or 5 Fr multipurpose catheters. Alternatives include use of an 0.018-inch wire and the use of Quick-Cross® catheters (Spectranetics, Colorado Springs, Colorado) for support. Difficult cases involve the use of laser (Spectranetics) assistance, reentry catheters, and the use of ultrasound for recanalization of CTO. Additional atherectomy with laser or SilverHawk SXL®(FoxHollow, Redwood City, California) can debulk the lesion. Adjunct balloon angioplasty is needed in a majority of the cases. Cryoplasty (Boston Scientific, Maple Grove, Minnesota) appears to be a promising technology and might prevent the use of stents, especially in arteries across the joints. Regular balloon angioplasty has a high rate of restenosis and reocclusion; hence CTOs are best treated with stents. The success of revascularization depends on the length of occlusion, calcification, and operator experience.
CTO in other vascular beds, such as renal arteries, has a limited role and can be harmful, due to embolization and contrast- induced nephropathy. CTO of the carotid artery has been reported in few case reports; however, embolization can have devastating outcomes.
Revascularization of CTO carries several risks.5 Perforation or rupture of iliac artery carries a high mortality if not treated urgently. SFA recanalization failure can jeopardize collaterals and worsen limb ischemia. Tibio-peroneal vessel perforation can lead to compartment syndrome. If a single tibio-peroneal vessel is compromised, limb loss is imminent. Embolization of iliac and femoro-popliteal vessels can lead to levido reticularis, tissue, intestinal ischemia, and limb loss. Various techniques, such as balloon tamponade, covered stents, coil embolization, and reversal of anticoagulation can treat perforation. Peripheral embolization can be treated with the use of mechanical suction, rheolytic thrombectomy, or thrombolytic infusion.
In summary, CTO of peripheral vasculature is common. Symptomatic occlusions need to be considered for revascularization. Percutaneous revascularization can be safely performed in a majority of the cases. The judicious use of Glidewires, low-profile catheters, and appropriate stents can revascularize peripheral arterial CTO. Adjuvant use of atherectomy, reentry devices, and cryoplasty are complementary. A thorough knowledge of complications, tips, and tricks to handle them are essential.