Antonio Michelucci, Chiara Lazzeri, Luigi Padeletti, Giuseppe Bagliani*, Andrea Colella, Alessandra Sabini, Renato Zipoli, Alessandro Costoli, Paolo Pieragnoli, Gianfranco Gensini, Franco Franchi.
Department of Internal Medicine and Cardiology, University of Florence, *Ospedale di Foligno, Italy
|
|
BACKGROUND. Previous experimental studies
showed that chronic atrial fibrillation (CAF) impairs sinus node function and decreases
maximal sinus rate. Moreover it has been reported that electrical shocks attenuates
cardiac sympathetic activity.
METHODS. To evaluate this problem a 24-hour ECG recording (analysis of heart rate
variability: time and frequency indexes) was performed in 30 patients (61±1 yrs, 19
men) with CAF just after electrical cardioversion and in a group of age-sex matched
healthy subjects. CAF was due to essential hypertension in 15, coronary heart disease
in 7, mitral valvulopathy in 8. Diabetes or heart failure were not present. Patients
showed significant lower values of SDANN (the standard deviation of the averages of
NN intervals in all 5-minute segments) and LF (low-frequency components).
RESULTS. No significant differences were found in mean RR interval, HF (high frequency
component), and LF/HF ratio. Moreover, patients lacked the circadian rhythm of LF/HF
ratio.
CONCLUSIONS. A reduced cardiac overall variability and an impairment of cardiac
sympathetic tone were present after CAF cardioversion. An effect of CAF (“remodeling”)
on sinus node function and cardiac autonomic tone can be suggested even if additional
shock effect could not be excluded.
|
