Dear Dave, thank you for your question. The only published study that I could find regarding the influence of sleep patterns on AV node function is attached to this response. This study was done in patients with sleep apnea which is a condition that is usually found in obese people who transiently close their airway during sleep due to excess tissue in the throat. Vagal tone is usually at the highest level during sleep and it's not uncommon to have pauses like you mentioned. The significance of the pauses seen on your Holter Monitor is unclear, but I doubt that these pauses are anything to worry about. Mobitz I AV block is considered to be a benign rhythm disorder, but the significance of this and the pauses found on your Holter monitor will have to be determined by your own physician.
I hope this information is useful. Information provided in the heart forum is for general purposes only. Only your physician can provided specific diagnoses and therapies. Feel free to write back with further questions. Good luck!
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Koehler U. Fus E. Grimm W. Pankow W. Schafer H. Stammnitz A. Peter JH.
Dept of Internal Medicine, Schlafmedizinisches Labor, Philipps-University Marburg, Germany.
Heart block in patients with obstructive sleep apnoea: pathogenetic factors and effects of treatment.
European Respiratory Journal. 11(2):434-9, 1998 Feb.
Heart block during sleep has been described in up to 10% of patients with obstructive sleep apnoea. The aim of this study was to determine the relationship between sleep stage, oxygen desaturation and apnoea-associated bradyarrhythmias as well as the effect of nasal continuous positive airway pressure (nCPAP)/nasal bi-level positive airway pressure (nBiPAP) therapy on these arrhythmias in patients without electrophysiological abnormalities. Sixteen patients (14 males and two females, mean age 49.6+/-10.4 yrs) with sleep apnoea and nocturnal heart block underwent polysomnography after exclusion of electrophysiological abnormalities of the sinus node function and atrioventricular (AV) conduction system by invasive electrophysiological evaluation. During sleep, 651 episodes of heart block were recorded, 572 (87.9%) occurred during rapid eye movement (REM) sleep and 79 (12.1%) during nonrapid eye movement (NREM) sleep stages 1 and 2. During REM sleep, the frequency of heart block was significantly higher than during NREM sleep: 0.69+/-0.99 versus 0.02+/-0.04 episodes of heart block x min(-1) of the respective sleep stage (p<0.001). During apnoeas or hypopnoeas, 609 bradyarrhythmias (93.5%) occurred with a desaturation of at least 4%. With nCPAP/ nBiPAP therapy, apnoea/hypopnoea index (AHI) decreased from 75.5+/-39.6 x h(-1) to 3.0+/-6.6 x h(-1) (p<0.01) and the number of arrhythmias from 651 to 72 (p<0.01). We conclude that: 1) 87.9% of apnoea-associated bradyarrhythmias occur during rapid eye movement sleep; 2) the vast majority of heart block episodes occur during a desaturation of at least 4% without a previously described threshold value of 72%; and 3) nasal continuous positive airway pressure or nasal bi-level positive airway pressure is the therapy of choice in patients with apnoea-associated bradyarrhythmias.