In a patient with carotid sinus syndrome, what is typically the result of mechanical pressure on the carotid sinus?

In a patient with carotid sinus syndrome, applying mechanical pressure to the carotid sinus leads to a reflexive response that results in sinus bradycardia and hypotension.

The carotid sinus is a baroreceptor that is sensitive to changes in blood pressure. When pressure is applied to it, the increased stimulation of the baroreceptors sends signals to the brain via the glossopharyngeal nerve, leading to increased parasympathetic (vagal) tone and decreased sympathetic output. This heightened vagal influence slows down the heart rate (resulting in bradycardia) and, due to reduced cardiac output, can also cause a drop in blood pressure (hypotension).

This physiological response demonstrates the baroreceptor reflex in action, where the body attempts to regulate blood pressure in response to perceived increases. In the context of carotid sinus syndrome, which may be characterized by exaggerated responses to carotid sinus pressure, patients can experience significant fluctuations in heart rate and blood pressure with minimal stimuli, corroborating the response of bradycardia and hypotension upon mechanical pressure.