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[Activity of the autonomic nervous system in cardiological syndrome X].

BACKGROUND
The etiology of cardiological syndrome X (CSX) is unknown, however the dysfunction of cardiac autonomic nerves has been reported.


AIM
The aim of the study was to evaluate changes in autonomic nervous system (ANS) activity in CSX patients.


METHODS
Forty-three patients (age 48 +/- 9 yrs) with CSX and forty-three healthy volunteers (age 47 +/- 9 yrs) as a control group were included in the study. The function of ANS was assessed using non-invasive methods: heart rate variability (HRV) and tests based on cardiovascular reflexes.


RESULTS
According to HRV analysis the patients were divided into two groups: A--22 pts with decreased HRV parameters and B--18 pts without significant differences as compared with the controls. At rest there was a difference in the HRV parameters between CSX patients and the controls. The CSX patients had the advantage of sympathetic component (the higher ratio LF/HF and LF value). Additionally an increase in heart rate and rate-pressure product was observed in 58% of CSX patients. In CSX patients the 30/15 ratio was decreased in response to changes in the body position in about 45% of CSX patients. A deep breathing test revealed a drop in the Expiration to Inspiration ratio.


CONCLUSIONS
In patients with cardiological syndrome X selected tests of ANS indicated the presence of disturbances in the sympathetic-parasympathetic balance. In 40% of CSX patients the response to all autonomic tests was diminished. This indicates that the population of CSX patients is heterogeneous with normal and low abnormal ANS activity.