Abnormal heart rate variability in a subject with second degree atrioventricular blocks during sleep.
OBJECTIVE
We compare the profiles of heart rate variability (HRV) during sleep stages in 9 healthy controls and one subject with second degree atrioventricular blocks (AVB), investigating the role of sympathovagal balance in such pathology.


METHODS
Sleep and cardiac records were taken for one night in 9 male subjects from 21:00 to 07:00 h and for two nights in a male subject with AVB. Time and frequency domain indexes of HRV were calculated over 5 min-periods.


RESULTS
In one subject without any daytime heart disease, 253 and 318 AVB of type 2 (Mobitz 2) were observed during the two experimental nights, predominantly during rapid eye movement (REM) sleep and the surrounding sleep stage 2 in the second half of the night. In the 9 control subjects, absolute HRV indexes and low frequency (LF)/(LF+high frequency, HF) (where LF and HF are low frequency and high frequency power) were low during slow wave sleep, and significantly increased during REM sleep and the preceding sleep stage 2. In the subject with AVB, these HRV indexes were abnormally low during all sleep stages, with a predominant increase in parasympathetic activity as inferred from low LF/(LF+HF). During wake, however, LF/(LF+HF) normally increased, and the tachycardia observed with the arousal that terminates SWS was preserved in the subject with AVB.


CONCLUSIONS
These results suggest that in the subject with second degree atrioventricular blocks, sleep processes, particularly during REM sleep, create a specific neurological background that prevents an increase in sympathetic tone and triggers cardiac pauses.
Institut de Physiologie, Laboratoire des Régulations Physiologiques et des Rythmes Biologiques chez l'Homme, 4 rue Kirschleger, 67085 Strasbourg Cedex, France. antoine.viola@medecine.u-strasbg.fr
A U
AU
Viola
C
C
Simon
S
S
Doutreleau
J
J
Ehrhart
B
B
Geny
F
F
Piquard
G
G
Brandenberger
D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D006327:Heart Block / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D020923:REM Sleep Parasomnias / Q000503:physiopathology*; D012895:Sleep, REM / Q000502:physiology*