Does carotid stenosis cause orthostatic hypotension?

From the Guidelines

Carotid stenosis does not typically cause orthostatic hypotension, as orthostatic hypotension is primarily caused by autonomic dysfunction, volume depletion, or medication side effects rather than carotid artery narrowing. Carotid stenosis, which is the narrowing of the carotid arteries that supply blood to the brain, instead causes symptoms related to cerebral hypoperfusion or embolic events, such as transient ischemic attacks (TIAs) or strokes. These symptoms include sudden weakness, numbness, speech difficulties, or visual disturbances. The pathophysiology involves atherosclerotic plaque buildup in the carotid arteries restricting blood flow to the brain or forming emboli that can travel to smaller cerebral vessels.

According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1, orthostatic hypotension is defined as a drop in systolic BP of ≥20 mm Hg or diastolic BP of ≥10 mm Hg with assumption of an upright posture. This guideline also highlights that orthostatic hypotension is often caused by autonomic dysfunction, volume depletion, or medication side effects, rather than carotid artery narrowing.

Key points to consider in the diagnosis and management of orthostatic hypotension include:

• Identifying the underlying cause of orthostatic hypotension, such as autonomic dysfunction, volume depletion, or medication side effects
• Assessing the patient's symptoms and medical history to determine the best course of treatment
• Considering the use of volume expanders, moderate exercise training, or other therapies to manage orthostatic hypotension, as recommended by the European Heart Journal guidelines 1
• Recognizing that carotid stenosis is a distinct condition that causes symptoms related to cerebral hypoperfusion or embolic events, rather than orthostatic hypotension.

In summary, carotid stenosis is not a typical cause of orthostatic hypotension, and the diagnosis and management of orthostatic hypotension should focus on identifying and addressing the underlying cause, rather than carotid artery narrowing.

From the Research

Carotid Stenosis and Orthostatic Hypotension

• The relationship between carotid stenosis and orthostatic hypotension is not directly addressed in the provided studies 2, 3, 4, 5, 6.
• However, study 3 discusses the effects of orthostasis on cerebral hemodynamics in patients with carotid artery disease, suggesting that orthostasis reduces mean flow velocity in cerebral arteries.
• The study 3 also notes that heart rate increases in both controls and patients during orthostasis, while blood pressure shows no change.
• Study 6 investigates the association between asymptomatic carotid artery stenosis and cerebral hypoperfusion, finding that carotid stenosis can restrict blood flow to the brain, leading to cerebral hypoperfusion.
• While these studies provide insight into the effects of carotid stenosis on cerebral hemodynamics and perfusion, they do not directly examine the relationship between carotid stenosis and orthostatic hypotension.

Cerebral Hemodynamics and Carotid Stenosis

• Study 3 suggests that orthostasis induces a decrease in middle cerebral artery flow velocity, which may be related to sympathetic-induced vasoconstriction of cerebral resistance vessels.
• Study 5 investigates changes in intracranial blood flow after stenting in patients with severe carotid artery stenosis, finding improvements in brain perfusion and normalization of collateral flow.
• Study 6 develops a novel approach to quantify interhemispheric cerebral perfusion differences in patients with asymptomatic carotid stenosis, finding associations between carotid stenosis and cerebral hypoperfusion.

Clinical Implications

• The provided studies highlight the importance of considering cerebral hemodynamics and perfusion in patients with carotid stenosis 3, 5, 6.
• While the relationship between carotid stenosis and orthostatic hypotension is not directly addressed, the studies suggest that carotid stenosis can have significant effects on cerebral blood flow and perfusion 3, 5, 6.