Alterations in reflex function contributing to syncope: orthostatic hypotension, carotid sinus hypersensitivity and...

Area of Science:

• Cardiology
• Neurology
• Internal Medicine

Background:

• Orthostatic hypotension (OH) and associated neurological symptoms are common clinical issues.
• Maintaining blood pressure and heart rate upon standing relies on intact mechanical, neural, and neurohormonal systems.
• Dysfunction in these systems can lead to OH and syncope.

Purpose of the Study:

• To categorize the mechanisms of orthostatic hypotension.
• To discuss the contributing factors and potential treatments for OH.
• To introduce carotid sinus syndrome (CSS) as a related condition.

Main Methods:

• Review of physiological mechanisms underlying blood pressure regulation.
• Categorization of OH causes into three main types: impaired compensatory responses, overwhelming orthostatic stimulus, and drug interference.
• Discussion of carotid sinus hypersensitivity (CSH) and its subtypes.

Main Results:

• OH mechanisms include autonomic changes, neuropathy, CNS disease, hemorrhage, and medication side effects.
• Treatment focuses on addressing underlying causes, with options like head-up tilting and mineralocorticoids.
• Carotid sinus syndrome (CSS), particularly cardioinhibitory CSH, involves exaggerated responses to carotid sinus stimulation.

Conclusions:

• Effective management of OH requires identifying and correcting underlying causes or contributing factors.
• While some treatments exist, many have limited efficacy or problematic side effects.
• Carotid sinus hypersensitivity requires specific management, with cardiac pacing being highly effective for severe symptoms.