Differential Diagnosis for High BP in Legs but Low BP in Arms
Single Most Likely Diagnosis
- Aortic Coarctation: This condition, characterized by the narrowing of the aortic isthmus, typically presents with higher blood pressure in the lower extremities compared to the upper extremities due to the increased resistance to blood flow past the coarctation. It is a congenital condition that may not be immediately diagnosed at birth and can present later in life.
Other Likely Diagnoses
- Aortic Dissection: Although more commonly associated with unequal blood pressures between the arms, an aortic dissection can also lead to differential blood pressures between the upper and lower extremities if the dissection involves the descending aorta. The presentation can be acute and dramatic.
- Takayasu Arteritis: This large vessel vasculitis can cause stenosis or occlusion of the aorta and its major branches, potentially leading to differential blood pressures between the upper and lower limbs. It often affects young women and can be associated with systemic symptoms.
- Middle Aortic Syndrome: This condition involves narrowing of the abdominal aorta and can lead to higher blood pressures in the legs compared to the arms due to the increased resistance to blood flow.
Do Not Miss Diagnoses
- Ruptured or Leaking Abdominal Aortic Aneurysm: Although typically presenting with abdominal pain and hypotension, a ruptured abdominal aortic aneurysm can initially cause differential blood pressures due to the partial obstruction of blood flow. This is a medical emergency.
- Aortic Thrombosis: Clot formation in the aorta can obstruct blood flow, potentially causing differential blood pressures. This condition requires immediate attention.
Rare Diagnoses
- Ehlers-Danlos Syndrome with Vascular Involvement: This genetic disorder can lead to vascular fragility and potentially to aortic dissection or aneurysm formation, affecting blood pressure readings.
- Neurofibromatosis Type 1 with Vascular Involvement: This condition can cause vascular abnormalities, including stenosis or aneurysms of major arteries, potentially leading to differential blood pressures.
- Williams Syndrome: A rare genetic disorder that can involve vascular abnormalities, including supravalvular aortic stenosis, which might affect blood pressure in the upper versus lower extremities.