In accordance with the concepts of autonomic heart control system functioning listed above, it provoked an direct interest, in particular, to studying of a dynamic of 0,1 Hz oscillations of the HRV in subjects with different EF of the left ventricle. The aim of the present study was investigation of dynamic stability of 0,1 Hz component of the HRV spectrum in patients with coronary artery disease (CAD) and different EF during veloergometric tests under controlled breathing with 10 seconds period. Methods: 45 male patients with CAD aged of 50±3 years with left ventricle EF<50% and 35 male patients with CAD aged of 52±6 years with left ventricle EF>60% were involved in the study. Veloergometric test was performed. Registration of R-R intervals was performed in relaxed probationer’s condition (sedentary posture) and in 90 seconds after the beginning of 25 Wt load stage of veloergometric test. The duration of R-R chain registration was 5 minutes. Frequency assessments of HRV obtained with the help of R-R chain spectrum construction on the basis of autoregressive model. Results: In process of studying of 0,1 Hz component of the HRV spectrum absence of any reliable differences in its spectral power in patients with normal and damaged EF was shown (Table 1 [Tab. 1]). Under the load rising till 25 Wt in subjects with EF<50% consequent depression of 0,1 Hz component spectral power in 2-3 times in comparison with the relaxed condition was observed (table). At the same time, there was no similar reliable expressed dynamic in the group with EF>60%. It possible to say that the activity level of the 0,1 Hz oscillations in the autonomic heart control system in subjects with EF>60% is characterized by relative tolerance to low-intensive loads, while in patients with EF<50% the activity of 0,1 Hz oscillations is very unstable to the same loads. Conclusions: The stability of 0,1 Hz component of the HRV spectrum to low intensity loads associates with the severity of myocardial contractility damage. The power dynamic of 0,1 Hz component of the HRV spectrum may be considered an independent index of dynamic stability of the heart autonomic control.
Abstract book of 33rd International Congress on Electrocardiology, Cologne, Germany, June 28th - July 1st, 2006; PS88: p 36