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Updated: Jun 19, 2026
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Minimally Invasive Murine Laryngoscopy for Close-Up Imaging of Laryngeal Motion During Breathing and Swallowing
Published on: December 1, 2023
Swallowing-induced cardio-respiratory responses in man
1Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Summary
Swallowing can rapidly reverse pronounced bradycardia (slow heart rate) by increasing heart rate and restoring P waves, even during breath-holding. This suggests swallowing can quickly counteract high vagal tone.
Area of Science:
- Cardiology
- Autonomic Nervous System Physiology
Background:
- Swallowing is known to transiently increase heart rate.
- One author experienced significant bradycardia during breath-holding, particularly post-expiration.
Purpose of the Study:
- To investigate cardiac responses during swallowing in the context of pronounced bradycardia.
- To explore the effect of swallowing on heart rate and pacemaker activity during breath-holding.
Main Methods:
- Monitoring cardiac responses, including heart rate and P waves (lead II and I), during breath-holding and swallowing.
- Inducing bradycardia through maximal inspiration and prolonged breath-holding.
- Administering swallowing commands to observe immediate cardiac changes.
Main Results:
- Heart rate increased immediately after swallowing (from <50 bpm to 68±1 bpm), with P waves reappearing.
- P waves reappeared 0.7±0.1s after the first swallow, indicating a rapid response.
- Despite continued breath-holding, P waves disappeared again at faster rates (57±1 bpm), and reappeared at even lower rates (30-40 bpm) after subsequent swallows.
- P wave persistence in lead I when absent in lead II suggested a sinoatrial (SA) node pacemaker shift, not to the atrioventricular (AV) node.
Conclusions:
- Swallowing can rapidly reverse pronounced bradycardia and restore normal pacemaker activity.
- The findings suggest that increased vagal tone can be quickly counteracted by the act of swallowing.
- Autonomic nerves can shift the dominant pacemaker within the SA node, a phenomenon potentially influenced by swallowing.
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