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An Underrecognized Cause of Recurrent Nocturnal Syncope with a Pacemaker: Sleep Rate Mode
Jonathan D Woo1, James V Quinn2
1Department of Emergency Medicine, Stanford University School of Medicine, Palo Alto, California.
The Journal of Emergency Medicine
|June 10, 2023
Summary
Nocturnal syncope in pacemaker patients can be caused by Sleep Rate Mode (SRM), a feature not recognized by emergency physicians. Turning off SRM resolved recurrent syncope in a case study, highlighting its importance for diagnosing bradycardia.
Area of Science:
- Cardiology
- Emergency Medicine
Background:
- Nocturnal syncope is a common emergency department presentation, often linked to orthostatic hypotension.
- Pacemaker evaluations typically focus on non-perfusing rhythms, overlooking newer features like Sleep Rate Mode (SRM).
- SRM is designed for heart rate fluctuations during REM sleep but lacks clinical benefit evidence and documented complications.
Observation:
- A 92-year-old woman with a Medtronic Avisa pacemaker experienced recurrent nocturnal syncope and bradycardia.
- These episodes led to multiple emergency department visits.
- Syncope resolved after disabling the SRM feature on her pacemaker.
Findings:
- Recurrent nocturnal syncope in a pacemaker patient was attributed to the Sleep Rate Mode (SRM).
- SRM is not typically identified on pacemaker interrogation reports for emergency physicians.
- Disabling SRM successfully treated the patient's syncope and bradycardia.
Implications:
- Emergency physicians must be aware of SRM as a potential cause of nocturnal syncope in pacemaker patients.
- Recognizing SRM is crucial for diagnosing chronotropic incompetence related to pacemakers.
- Further research is needed on SRM's clinical utility and potential adverse events.
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