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Education in Heart
Clinical relevance of arrhythmias during sleep: guidance for clinicians
  1. L J Gula,
  2. A D Krahn,
  3. A C Skanes,
  4. R Yee,
  5. G J Klein
  1. Department of Medicine, University of Western Ontario, London, Ontario, Canada
  1. Correspondence to:
    Dr Andrew Krahn
    London Health Sciences Centre, University Campus, 339 Windermere Road, London, Ontario, Canada N6A 5A5; akrahnuwo.ca

https://doi.org/10.1136/hrt.2003.019323

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    Cardiac rhythm during sleep is influenced by the autonomic nervous system and various pathologic states. Most arrhythmias that occur during sleep are detected incidentally on Holter recordings, and are in fact benign. Although such findings may not necessitate further investigation, they may be an important clue to an underlying disorder in need of investigation and treatment. It is important to recognise predisposing factors to sleep related arrhythmia in order to prevent and treat potentially dangerous cardiac rhythms. It is also important to establish a threshold for referral to a cardiologist or electrophysiologist once such arrhythmias are detected.

    NORMAL CARDIAC RHYTHM DURING SLEEP

    Sleep is a dynamic and complex process. The stages of sleep, conventionally divided into rapid eye movement (REM) and non-rapid eye movement (non-REM), are characterised by unique autonomic influences over cardiac rhythm and haemodynamics. Non-REM sleep is graded 1–4 according to electroencephalogram (EEG) characteristics and diminished arousability. REM sleep occurs at approximately 90 minute intervals, encompasses most dream activity, and is characterised by rapid eye movements and reduced voluntary muscle activity. Studies of individuals free of cardiac disease show that sinus bradycardia, sinus pauses, and type 1 second degree atrioventricular (AV) block are common during sleep (table 1⇓).1 Sinus pauses up to two seconds in duration occur commonly in young people in association with sinus arrhythmia (fig 1⇓).1 This is seen more frequently in athletes,w1 and less frequently in those over 80 years of age.w2 These arrhythmias are, for the most part, both asymptomatic and benign. They are a reflection of changes in autonomic tone that occur during sleep and require no intervention unless accompanied by symptoms.2

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    Table 1

    Normal rhythm changes during sleep in healthy subjects1,2

    Figure 1

    Typical arrhythmias demonstrated in a healthy male during sleep. Upper panel: pronounced sinus arrhythmia. Lower panel: type …

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