Subclavian Artery Stenosis/Interventions
Atul Singla, MD
Imaad Razzaque, MD
Chiranjiv S. Virk, MD
Key Points
Subclavian stenosis is four times more common in the left subclavian in comparison to the right.
Symptoms of subclavian stenosis include upper limb claudication, vertebrobasilar steal, and, in case of mammary artery graft to coronary arteries, symptoms of coronary ischemia and cardiomyopathy.
Endovascular revascularization is undertaken by femoral, brachial, or radial access.
Balloon expandable stents with intravascular ultrasound (IVUS) guidance is recommended for proximal lesions.
5 year patency rates of subclavian stent placement have been showed to be greater than 80% in different series.
I. Introduction
Subclavian artery stenosis is uncommon but is associated with significant morbidity and mortality.1,2 It is usually focal, and the left side is four times more commonly affected than right in the majority of lesions.3,4,5 It is most frequently due to atherosclerosis but may also be caused by fibromuscular dysplasia, Takayasu arteritis, thoracic outlet compression, radiation induced, or trauma.
Anatomically, the left subclavian artery originates as the most distal branch of the aortic arch whereas right subclavian artery is a branch of brachiocephalic artery. The subclavian artery gives rise to the vertebral artery, the internal mammary artery, and the thyrocervical trunk, before terminating as the axillary artery (Fig. 4.1).
II. Subclavian Artery Lesions
A. Asymptomatic Patients with isolated subclavian artery lesions are often asymptomatic because of the presence of a rich collateral supply.
FIGURE 4.1: Anatomy of subclavian artery.
B. Symptomatic
1. Upper limb ischemia/arm claudication and fatigue.
2. Subclavian steal syndrome: Owing to severe proximal obstruction, blood flow reverses along the vertebral artery to supply the respective arm (vertebral-subclavian steal) resulting in disorientation, loss of balance, dizziness, diplopia, nystagmus, tinnitus, or hearing loss, consistent with vertebrobasilar insufficiency.
3. Coronary steal phenomenon: Severe proximal stenosis can also cause reversal of flow in the coronary artery bypass graft (either left or right internal mammillary artery) to supply the arm leading to angina, myocardial infarction, and ischemic cardiomyopathy if the degree of steal is significant (Fig. 4.2).
III. Evaluation
A. Clinical evaluation of suspected significant subclavian artery stenosis should begin with measuring blood pressure of both arms. A difference >15 mm Hg suggests significant stenosis.6,7 This may not hold true in the presence of bilateral disease, which, fortunately, is an infrequent finding.
FIGURE 4.2: Subclavian artery stenosis depicting reversal of flow across left vertebral artery depicting steal physiology.
B. Decreased amplitude of the pulse, atrophic changes with the skin and/or nails of the affected arm, and auscultation of a bruit in the supraclavicular fossa suggest subclavian artery stenosis.
C. Noninvasive imaging such as duplex ultrasound with color flow can provide anatomical and functional assessment of a significant subclavian stenotic lesion. Findings such as waveform dampening, monophasic waveform, flow reversal, color aliasing suggestive of turbulent flow, or increased velocities at the suspected site of stenosis are suggestive of significant obstruction.
D. Other noninvasive imaging modalities include magnetic resonance angiogram (MRA) and computer tomographic angiography (CTA), the latter providing excellent resolution of the lesion as well as surrounding structures, helpful in planning endovascular treatment.
IV. Angiography
A. Invasive Digital Subtraction Angiography Invasive digital subtraction angiography remains the gold standard imaging modality for assessing significant subclavian artery stenosis. Technique: For diagnostic angiography most commonly, common femoral artery access is utilized. Ipsilateral brachial or radial can be accessed if necessary (eg, aortoiliac occlusions). Introducer sheaths between 4 Fr and 6 Fr sheath can be used.
B. Arch Aortography Arch aortography is performed utilizing nonangled pigtail catheter positioned in the ascending aorta in left anterior oblique (LAO) 30-45° projection (Fig. 4.3). Usually power injection with 15-20 mL/s for a total of 30-40 mL contrast can be used depending on renal function of the patient. We commonly dilute contrast with 50% contrast and 50% heparinized saline to reduce the total contrast volume.
C. Subclavian or Innominate Angiography
1. Selective subclavian or innominate angiography can be performed using one of the several catheters available (Judkins right (JR) 4, angled glide, multipurpose, vertebral, Simmons, Vitek, IM etc. [Fig. 4.4]). We commonly use the JR4 catheter. The catheter is advanced over a 0.035″ glidewire advanced to the distal subclavian artery to obtain a selective angiogram. Care should be taken when engaging or
manipulating catheters to avoid dislodgement of aortic atheroma to minimize the risk of stroke. In cases when thoracic outlet syndrome is suspected, angiograms are repeated with the arm abducted and internally rotated.
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