Subclavian, innominate and vertebral artery atherosclerosis is a frequently underdiagnosed but important manifestation of peripheral artery disease. Although it is less closely associated with coronary artery disease than lower extremity PAD (1), it is more highly associated with TIA’s and strokes. Proximal subclavian stenosis can result in subclavian steal phenomenon which reverses flow in the vertebral artery (usually the left) resulting in a variety of vague and often under appreciated neurologic symptoms such as vertigo, ataxia, diplopia, and nausea and vomitting. It can also result in coronary steal phenomenon in patients with prior LIMA bypass grafts which can ultimately lead to cardiac ischemia and infarction in these already tenuous patients (1).
Endovascular treatment of symptomatic atherosclerotic disease of the innominate, subclavian, vertebral and common carotid arteries with angioplasty and/or stenting has been shown to be superior to surgical intervention due to lower complication rates and comparable efficacy (1).
- Clinical Subclavian steal is distinguished from angiographic steal which is often asymtomatic (1).
- Clinical steal results in left arm ischemia and vertebrobasilar insufficiency which is worse with left arm exercise (1).
- Arm ischemia manifests as arm claudication, paresis and atheroemboli (1).
- Vertebrobasilar insufficiency manifests as ataxia, diplopia, vertigo, syncope, dizziness, nausea and vomitting (1)
- Bilateral upper extremity blood pressures reveal a difference of at least 20 points systolic(1).
- CTA or MRA are initial tests of choice. Allowing assessment of the Aortic Arch and the circle of willis(1).
- Doppler may show reversal of flow within the vertebral artery and can be used in lieu of MRA or CTA in patients with renal insufficiency. Although less comprehensive than CTA or MRA, it can serve as justification to proceed to angiography.
- Angiography is the gold standard and permits visual interpretation of location and degree of disease as well as differential diagnosis which includes atherosclerosis, FMD, dissection and vasculitis.
- Anticoagulation is mandatory and should persist for life.
- ASA 81mg po daily.
- Lipid lowering agents.
- Diet and Exercise
- Tobacco cessation
- Second antiplatelet such as Plavix, Ticlid or Aggrenox should be added in symptomatic patients who are not good candidates for revascularization.
- PTA and Stenting are the mainstay of interventional therapy.
- Surgery is difficult and dangerous in these distributions.
- For proximal subclavian, innominate and vertebral stenoses, primary stenting with balloon expandable stent is believed to be better than PTA alone or PTA followed by stenting due to the reduced risk of atheroemboli(1).
- For mid to distal subclavian stenoses (beyond the vertebral and internal mammary arteries), PTA alone is preferred, with self-expanding stents as bail-out choice for dissection or inadequate PTA(1).
- ASA 81 mg po q day and loading dose of Plavix, 300mg po x1 then 75mg po q day beginning 48 hours in advance if possible(1).
- Access is best via femoral artery.
- Brachial artery may be used when angle of subclavian or innominate is too steep, no definable nipple of vessel ostium is present, or if there is severe aortoiliac disease that raises risk of atheroemboli(1). Brachial puncture should be low, at level of olecranon fossa(1). Brachial punctures carry real risk of brachial nerve injury which can be quite debilitating and prolonged.
- Short 5F sheath is later exchanged for 90cm 6F sheath from femoral approach or 45cm 6F sheath from brachial approach(1).
- Pigtail arch shot in LAO projection
Cross the Lesion
- Anticoagulate. 5000U of Heparin given IV is a reasonable choice, or Heparin can be given as 80-100U per Kg IV. Continue full anticoagulation for 24 hours post procedure.
- Cross the lesion with 125cm catheter (from Femoral approach) and 0.014 or 0.018 soft tip wire such as Spartacore, or 0.035 hydrophilic wire.(1).
- Advance long sheath to the proximal margin of the stenosis.
- Good angiographic visualization of internal mammary and vertebral arteries is critical for subclavian interventions.
- Consider placing an 0.014 safety wire in the vertebral artery for subclavian lesions which are close to this artery(1).
- Predilation may increase the risk of embolic complications, but may be necessary in cases of very severe stenosis, and can be performed with low profile balloons.
- For proximal subclavian and vertebral arteries, balloon expandable stents are mandatory. Monorail is convenient. Low profile coronary stents are good choices.
- For subclavian disease distal to the vertebral arteries, self-expanding stents are a bail-out option for unsuccessful PTA.
- Choose a stent just long enough to cover the lesion. Typically a short stent (15-20mm) approximately 7-8mm in diameter for subclavian stenoses(1), or short 3.5 – 5 mm diameter stent for vertebral stenoses.
- Inflate stent rapidly(1).
- Do not overdilate the origin of the subclavian artery which is notoriously fragile and more succeptible to rupture than other vascular beds(1).
- Limited data for DES in this circulation but appear promising. 2 drug antiplatelet therapy as is commonly administered for DES in coronary circulation is mandatory for 1 year to prevent acute thrombosis.
- Cutting balloons and Embolic protection devices are not routinely used(1).
- Clinical assessment and color doppler US at 3 months, 6 months, 12 months, and annually thereafter(1).
- MRI is not recommended in stented patients due to signal void(1).
1. Muller-Hulsbeck, S. Subclavian and Vertebral Arterial Interventions. Seminars in Interventional Radiology; 24:2. 2007.
Jason E. Himmel, M.D.
Disclaimer: The information above is not intended to represent a thorough or exhaustive reference of any topic. There are nuances to every clinical situation which may render this information irrelevant, impractical or inappropriate and it is the sole responsibility of the practitioner to interpret the information provided on this website with utmost caution. There is simply no substitute for good clinical judgement.