Impaired parasympathetic control of heart rate after myocardial infarction.
We measured the variation in heart rate during deep breathing, a sensitive non-invasive measure of cardiac parasympathetic activity, in 95 patients 3 weeks after myocardial infarction and in 40 asymptomatic healthy controls. The variation in rate was significantly lower (11.6 +/- 6.1 vs 17.6 +/- 7.3 beats/min, P less than 0.001) in patients with myocardial infarction than in controls. Forty-nine patients (52%) and 5 controls (13%) were considered to have diminished (less than or equal to 10 beats/min) variation of rate. The diminution in this variation was not related to the type or location of myocardial infarction, to maximum release of CK-MB or to cardiovascular medication. Our results suggest that impairment of vagal control of heart rate is common after myocardial infarction. The impairment cannot be predicted by any specific feature of the disease.
Niemelä
M J
MJ
Department of Medicine, Oulu University Central Hospital, Finland.
Airaksinen
K E
KE
Ikäheimo
M J
MJ
Groundstroem
K
K
Linnaluoto
M K
MK
Takkunen
J T
JT
D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D001794:Blood Pressure; D005260:Female; D006321:Heart / Q000294:innervation; D006339:Heart Rate; D006801:Humans; D008297:Male; D008451:Maximal Voluntary Ventilation; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology