Can uncontrolled Hypertension (HTN) be a symptom of subclavian stenosis?

Uncontrolled Hypertension as a Symptom of Subclavian Stenosis

Uncontrolled hypertension can indeed be a symptom of subclavian stenosis, particularly when there is a significant blood pressure difference between arms, with the higher reading representing the true blood pressure value while the lower reading from the affected arm masks the actual hypertension. 1

Pathophysiology and Clinical Presentation

• Subclavian stenosis occurs when the proximal subclavian artery becomes stenotic or occluded, most commonly due to atherosclerosis, but also potentially from Takayasu arteritis, giant cell arteritis, fibromuscular dysplasia, or radiation-induced arteriopathy 2, 3
• The condition can lead to retrograde blood flow in the ipsilateral vertebral artery (subclavian steal syndrome), potentially causing posterior cerebral circulatory insufficiency 3
• Blood pressure measurements may be falsely low in the arm affected by subclavian stenosis, leading to missed or undertreated hypertension if blood pressure is only measured in the affected arm 1
• A significant inter-arm blood pressure difference (>10-15 mmHg) is a key diagnostic finding, with the side showing lower pressure indicating subclavian artery stenosis 2, 4

Diagnostic Approach

• Bilateral arm blood pressure measurement is recommended for all patients with suspected peripheral arterial disease to identify potential subclavian stenosis 2, 4
• An inter-arm systolic blood pressure difference >15-20 mmHg is considered abnormal and suggestive of subclavian stenosis 4
• More severe differences (>25 mmHg) double prevalence and independently predict mortality 2, 4
• Detection of a periclavicular or infraclavicular bruit may suggest subclavian stenosis 2, 3
• Duplex ultrasonography can identify subclavian stenosis through:
  • Intrastenotic high-velocity flows (50% stenosis: peak systolic velocity ≥230 cm/s) 2
  • Monophasic post-stenotic waveforms 2
  • Flow reversal in the ipsilateral vertebral artery 3, 4

Clinical Significance and Management

• Subclavian stenosis has been associated with increased total and cardiovascular mortality, independent of traditional cardiovascular risk factors 5
• The presence of subclavian stenosis is more common in patients with peripheral vascular disease (11.4% vs 4.5% in general population) 2
• Case reports have documented patients initially thought to be normotensive who were later found to have hypertension masked by subclavian stenosis 1
• Studies have shown that stenting of symptomatic proximal subclavian or vertebral artery stenosis in hypertensive patients can reduce blood pressure measurements 6
• Management options for symptomatic patients include:
  • Endovascular revascularization (angioplasty and stenting) 2, 3
  • Surgical options such as carotid-subclavian bypass 2, 4
• Routine revascularization is not recommended for asymptomatic patients with subclavian stenosis 2

Clinical Pearls and Pitfalls

• Always measure blood pressure in both arms when initially diagnosing hypertension to avoid missing cases due to subclavian stenosis 4, 1
• Using the arm with the highest systolic pressure is required for accurate measurement of blood pressure and ankle-brachial index 4
• Subclavian stenosis should be suspected in patients with:
  • Significant inter-arm blood pressure differences 4
  • Symptoms of posterior cerebral circulation insufficiency (dizziness, vertigo, visual disturbances) 3
  • Upper extremity claudication 2, 4
• The angiographic prevalence of left subclavian stenosis is approximately 3.5% in the general cardiac catheterization population and 5.3% in those with potential surgical coronary disease 7