Blunted Chronotropic Response to Hypotension in Cough Syncope

Area of Science:

• Cardiology
• Neurology
• Physiology

Background:

• Cough syncope (CS) is an uncommon fainting condition.
• Its causes are debated, involving reflex and mechanical factors.
• Baroreflex responses may contribute to CS, potentially causing hypotension and cardioinhibition.

Purpose of the Study:

• To compare hemodynamic and chronotropic responses to cough in CS patients versus control groups.
• To investigate the role of baroreflex responses in the pathophysiology of cough syncope.

Main Methods:

• The study included 8 CS patients, 21 vasovagal syncope patients, and 6 patients with nonvertiginous lightheadedness.
• Participants underwent volitional coughing while seated, achieving a systolic blood pressure of ≥200 mm Hg.
• Beat-to-beat blood pressure, heart rate, and recovery time after cough-induced hypotension were recorded.

Main Results:

• CS patients exhibited a significantly greater drop in systolic blood pressure post-cough compared to controls.
• Recovery time from cough-induced hypotension was longer in CS patients.
• Despite greater hypotension, CS patients showed a blunted post-cough heart rate increase compared to controls.

Conclusions:

• The blunted chronotropic response in CS patients, despite significant hypotension, supports the contribution of baroreflex cardioinhibition to cough syncope.
• These findings highlight the complex interplay of hemodynamic and autonomic responses in CS pathophysiology.