EPISODE 4: SUBCLAVIAN STEAL SYNDROME

INTERESTED IN LEARNING MORE? CHECK OUT OUR SOURCES HERE

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.113.006653

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640015/

https://www.statpearls.com/ArticleLibrary/viewarticle/29613

https://www.kenhub.com/en/library/anatomy/the-subclavian-artery

SUBCLAVIAN STEAL SYNDROME

What is Subclavian Steal Syndrome?

• A vascular phenomenon causing retrograde flow in a vertebral artery when there is stenosis/occlusion of the subclavian artery proximal to the origin of the vertebral artery

Etiology

• Most commonly atherosclerosis

• Other causes: Takayasu Arteritis, thoracic outlet syndrome, cervical ribs, surgical repair/congential anomaly of aortic arch

Pathophysiology

• Significant stenosis of the subclavian artery can affect the distal perfusion in the vertebral artery or axillary artery

• Stenosis in the subclavian will cause the blood pressure distal to the stenosis to fall below the pressure in the contralateral vertebral artery (the one not affected by proximal subclavian stenosis)

• Vigorous use of arm= more need for blood in the distal perfusion site of subclavian artery

• Pressure gradient worsens and causes stenosed subclavian artery to steal retrograde flow of blood from well perfused vertebrobasilar system via the contralateral vertebral artery to supply the ill perfused distal sites ipsilateral to the stenosis.

Review some the relevant anatomy here!!!

IMAGE SOURCE: https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.grepmed.com%2Fimages%2F9302%2Fsteal-subclavian-syndrome-sss-pathophysiology&psig=AOvVaw3E8myVBUFiNcG6k2356VSu&ust=1653936869570000&source=images&cd=vfe&ved=0CA0QjhxqFwoTCMDV0o-xhfgCFQAAAAAdAAAAABAy

Presentation

• Most patients with subclavian artery stenosis is asx in most patients

• Most common symptom= arm claudication (arm pain, fatigue, numbness, parsthesias with exertion)

• Vertebrobasilar insufficiency can occur= dizzy, blurry vision, syncope, vertigo, ataxia, tinnitus, hearing loss

• NOTE: neurological symptoms can be precipitated with head movements involving quick rotation of face toward the affected side

• Physical exam= difference of at least 15mmHg b/w upper extremities on BP testing; decreased amplitude of radial pulse on affected side, bruit may be auscultated in the supraclalvicular fossa

Diagnosis

• Continuous wave doppler and duplex ultrasonography are best first line test

• Magnetic Resonance angiography (MRA) or CTA are the confirmatory diagnostic modality, plus it can help assess intracranial cerebrovascular circulation compared to US

Management

• Open surgical bypass for symptomatic patients

• Management of atherosclerotic disease ( control BP, treat dyslipidemia, control blood glucose if they have diabetes mellitus, stop smoking)