Vagal role and pacemaker indication in hypersensitive carotid sinus reflex

Area of Science:

• Cardiology
• Autonomic Nervous System Function

Background:

• The carotid sinus reflex (CSR) plays a role in cardiovascular regulation.
• Hypersensitive carotid sinus reflex (HCSR) is characterized by exaggerated responses to stimuli like carotid sinus pressure (CSP).
• The clinical significance of HCSR, particularly in relation to symptoms like dizziness and syncope, requires further elucidation.

Purpose of the Study:

• To investigate the effect of carotid sinus pressure (CSP) on sinus rate in patients with and without hypersensitive carotid sinus reflex (HCSR).
• To determine if CSP-induced asystole is a reliable diagnostic criterion or an indication for pacemaker implantation.
• To explore the relationship between HCSR, age, and autonomic responses.

Main Methods:

• Carotid sinus pressure (CSP) was applied to 24 control patients and 23 patients with HCSR.
• Intraatrial electrograms were used to record P waves.
• CSP was administered before and after atropine administration to assess autonomic response.

Main Results:

• Patients with HCSR exhibited inconsistent responses to CSP.
• No significant difference in sinoatrial pause duration was observed between symptomatic and asymptomatic HCSR patients.
• Patients with HCSR were older, had slower resting heart rates, and showed diminished atropine response during CSP compared to controls.

Conclusions:

• CSP-induced asystole is not a reliable differential diagnostic criterion or an indication for pacemaker application.
• Hypersensitivity of the carotid sinus reflex may represent physiological augmentation of vagal tone in the elderly.
• Sick sinus syndrome was excluded in all participants through rapid atrial stimulation.