Introduction

Subclavian steal syndrome (SSS), first described in 1961, is a type of peripheral artery disease in which reduction or absence of flow in the proximal subclavian artery reverses the normal direction of blood flow in the vertebral artery. Blood is drawn from the contralateral vertebral, basilar or carotid artery to provide flow in the affected subclavian artery distal to the stenosis.

For most patients, subclavian steal is well tolerated with conservative medical therapy. In patients who have failed conservative therapy or in significantly symptomatic patients, endovascular intervention has become the primary treatment modality. Stent supported angioplasty for SSS has been performed for patients with symptomatic subclavian steal syndrome. Surgical options, such as carotid-subclavian bypass, are generally reserved for patients who have failed endovascular treatment. In a small subset of patients, standard intraluminal antegrade and/or retrograde access are unsuccessful. Typically, these patients have to undergo open surgical procedures to relieve their symptoms.

 

Case 1

A 61-year-old left-handed female with past medical history significant for hypertension, grand mal seizures, tobacco dependence, substance abuse and obesity presented to an outside hospital with slurred speech and left-sided weakness 3 days prior to admission; and 2 days of incoordination and unsteadiness when standing. Magnetic resonance imaging (MRI) did not demonstrate any acute infarction and contrast-enhanced magnetic resonance angiography (MRA) of the head and neck demonstrated an absence of flow in the proximal left subclavian artery.

Final angiography through the left subclavian artery showed a significant improvement in the antegrade flow through subclavian artery. There was no longer any antegrade flow from the proximal subclavian artery through to the vertebral artery; however, given the patient’s initial angiogram showing only retrograde flow, this likely only improved flow to the posterior circulation. Examination of her left hand demonstrated significantly improved capillary refill; and the patient's left arm blood pressure had significantly improved, with near equalization when compared to the contralateral side. The patient had an uncomplicated subsequent hospital course, with remarkable improvement of her symptoms by the 6-month clinical follow-up.

 

 

Case 2

A 55-year-old female with a history of heavy smoking presented with intermittent dizziness when standing, as well as loss of consciousness when lifting her arms above her shoulders. Additionally, she complained of intermittent left upper extremity pain, paresthesias to the elbow and right upper extremity pain, and paresthesias to the finger tips with exertion. She reported new, worsening blurred vision in the right eye over the prior 6 weeks. Past medical history was significant for hypertension. On physical examination, she had an unobtainable radial pulse in her right arm, with weakness and a cool right upper extremity and mild left upper extremity dysmetria.

Final angiography from the right radial approach through the stent demonstrated excellent position of the stent, good wall apposition, and confirmed the right common and right vertebral artery origins were patent. Final arch angiography demonstrated antegrade flow in the innominate, right common, right subclavian, right vertebral and left common carotid arteries. The left vertebral artery still had retrograde flow and steal supplying the left subclavian artery. Immediately post procedure, the patient had normal radial and ulnar pulses with complete resolution of her right arm pain and paresthesias.

 

Discussion

SSS, also referred to as subclavian steal phenomenon or subclavian steal steno-occlusive disease, represents a combination of signs and symptoms related to the reduction or absence of blood flow in the proximal subclavian artery, typically due to atherosclerotic disease involving the proximal subclavian or innominate arteries. Other etiologies include: arteritis such as Takayasu’s arteritis, post-radiation changes, compression syndromes, fibromuscular dysplasia or neurofibromatosis. Regardless of the cause, the impeded flow through the subclavian vessels results in reversal of the normal direction of blood flow in the vertebral artery or internal thoracic artery; as blood is drawn from the contralateral vertebral, basilar or carotid artery to provide flow in the affected subclavian artery, distal to the stenosis.

This altered physiology may result in a combination of signs and symptoms, depending on the vessels affected. Vascular insufficiency symptoms related to decreased subclavian or innominate artery flow may include: claudication, muscle fatigue and paresthesias of the ipsilateral upper extremity. Vertebrobasilar insufficiency from the reversal of flow in the ipsilateral vertebral artery may manifest as headaches, dizziness or vertigo, vision abnormalities, syncope, ataxia, impaired consciousness, or facial sensory or motor deficits. In select patients with internal mammary artery grafts status post-coronary artery bypass grafting (CABG), symptoms of ischemic heart disease may manifest, including angina pectoris due to coronary-subclavian steal.

 

Conclusions

Endovascular treatment is considered the first-line intervention in medically refractory patients with symptomatic SSS. In the setting of chronic total occlusions, a retrograde radial subintimal approach using a heavy tip wire for controlled subintimal dissection is a novel technique that may be considered when an antegrade approach and standard wires have failed.

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Source

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4984364/