Differential Diagnosis for Differing Upper Extremity Blood Pressures

Single Most Likely Diagnosis

• Atherosclerotic Subclavian Artery Stenosis: This condition is a common cause of differing upper extremity blood pressures due to the narrowing of the subclavian artery, which supplies blood to the arms. It can lead to reduced blood pressure in the affected arm.

Other Likely Diagnoses

• Subclavian Artery Thrombosis: A blood clot in the subclavian artery can reduce blood flow to the arm, resulting in lower blood pressure.
• Thoracic Outlet Syndrome: Compression of the subclavian artery or vein between the clavicle and first rib can lead to decreased blood pressure in the affected arm.
• Arterial Embolism: A blockage in one of the arteries supplying the arm can cause a difference in blood pressure between the two arms.

Do Not Miss Diagnoses

• Aortic Dissection: Although less common, a tear in the aorta's inner layer can lead to differing blood pressures in the arms and is a medical emergency.
• Takayasu Arteritis: A rare form of large vessel vasculitis that can cause stenosis or occlusion of the subclavian arteries, leading to differing arm blood pressures.
• Giant Cell Arteritis: Inflammation of the arteries can lead to stenosis or occlusion, affecting blood pressure in the arms.

Rare Diagnoses

• Subclavian Steal Syndrome: A rare condition where there is reversal of blood flow in the vertebral artery due to significant stenosis or occlusion of the subclavian artery, which can lead to symptoms including differing arm blood pressures.
• Coarctation of the Aorta: A congenital condition characterized by the narrowing of the aortic isthmus, which can result in differing blood pressures in the arms, although it typically presents with hypertension in the arms and hypotension in the lower limbs.
• Pseudocoarctation of the Aorta: A condition similar to coarctation but without the actual narrowing of the aorta, which can still lead to differing arm blood pressures due to kinking or buckling of the aorta.