Symptoms of Left Subclavian Stenosis
Left subclavian artery stenosis typically presents with upper extremity ischemia symptoms and/or posterior cerebral circulatory insufficiency, with the specific symptom pattern depending on the severity of stenosis and presence of vertebral artery involvement. 1, 2
Common Symptoms
Upper Extremity Symptoms
- Arm or hand claudication (exercise-induced pain/fatigue)
- Paresthesia (numbness, tingling)
- Rest pain in severe cases
- Reduced arm strength, especially with exertion
- In extreme cases, digital ischemia or gangrene 1, 3
Neurological Symptoms (Subclavian Steal Syndrome)
When the dominant vertebral artery is affected by subclavian obstruction, reversal of blood flow can cause posterior cerebrovascular insufficiency, resulting in:
- Lightheadedness or syncope
- Vertigo
- Ataxia (impaired coordination)
- Diplopia (double vision)
- Motor deficits
- Tinnitus 1, 4
These neurological symptoms are typically:
- Aggravated by exercising the ipsilateral arm (which amplifies flow reversal)
- Transient and positional
- Quickly resolved when returning to a neutral position 1, 4
Physical Examination Findings
- Asymmetry between left and right arm blood pressure (>10-15 mmHg difference)
- Periclavicular or infraclavicular bruit
- Further drop in blood pressure in the affected limb after arm exercise 2
Special Presentations
Subclavian Steal Syndrome
This occurs when blood flow reverses in the vertebral artery due to proximal subclavian stenosis, causing:
- Posterior circulation symptoms (vertigo, ataxia, visual disturbances)
- Symptoms that worsen with arm exercise 1, 5
Coronary-Subclavian Steal Syndrome
In patients with previous CABG using the left internal mammary artery:
- Angina pectoris
- Myocardial ischemia during upper limb exercise 2
Diagnostic Considerations
It's important to note that:
- Some patients with high-grade stenosis may become asymptomatic as collateral circulation develops 1, 2
- Blood pressure may be symmetrical when bilateral subclavian disease is present 1
- The type of cerebral symptoms may be determined by the location of other extracranial vascular stenoses 6
Clinical Pitfalls to Avoid
Missing the diagnosis: Always consider subclavian stenosis in patients with unexplained arm claudication or vertebrobasilar symptoms, especially with blood pressure asymmetry between arms.
Attributing symptoms to other causes: Vertebrobasilar symptoms may be misdiagnosed as primary vestibular disorders or other neurological conditions.
Focusing only on the subclavian lesion: The presence of other extracranial vascular stenoses may determine the type and severity of symptoms 6.
Overlooking asymptomatic disease: In patients requiring CABG using the ipsilateral internal mammary artery, undiagnosed subclavian stenosis can lead to coronary steal syndrome 2.
The diagnosis should be confirmed with duplex ultrasonography (looking for high-velocity flows and flow reversal in the ipsilateral vertebral artery) and CT or MR angiography of the aortic arch 2.