What does Unequal blood pressure in the left and the right upper arms mean?

Atherosclerosis: Plaque buildup in the arteries can lead to narrowing or obstruction, causing unequal blood flow and pressure.

Subclavian Artery Stenosis: Narrowing of the subclavian artery, usually on one side, leads to reduced blood pressure in the affected arm.

Aortic Dissection: A tear in the wall of the aorta can create a false channel, disrupting blood flow and causing pressure differences.

Coarctation of the Aorta: A congenital condition causing narrowing of the aorta, which can lead to pressure differences.

Thoracic Outlet Syndrome: Compression of blood vessels (or nerves) as they pass through the thoracic outlet can affect blood pressure.

Takayasu Arteritis: An inflammatory disease that can cause narrowing of large arteries, including the subclavian arteries.

Giant Cell Arteritis: Inflammation of blood vessels, typically in older adults, can affect blood flow.

Obstruction or narrowing of peripheral arteries can lead to unequal pressures.

Conditions like subclavian steal syndrome, where blood is “stolen” from the brain to supply the arm due to an obstruction, can cause differences.

Blood Clots: In the subclavian or brachial arteries can reduce blood pressure in one arm.

Measurement Error: Incorrect cuff size, positioning, or technique can falsely create a pressure difference.

If the difference in systolic blood pressure is greater than 20 mmHg, or if you have symptoms like dizziness, arm pain, or fainting, it’s essential to consult a healthcare provider. This may require further investigation using imaging techniques like Doppler ultrasound, CT angiography, or MRI.

Early detection and management of the underlying cause are crucial to preventing complications such as stroke or cardiovascular events.

Source: Uptodate , Medscape