Changes in the Power of the Low- and High-Frequency Bands of the Heart Rate Variability Spectrum in Coronary Heart Disease Patients with Different Severities of Coronary Atherosclerosis in the Course of Load Tests

The specific features of the changes in the low-frequency (LF) and high-frequency (HF) bands of the heart rate variability (HRV) spectrum were studied in coronary heart disease (CHD) patients with different numbers of coronary arteries affected by hemodynamically significant stenosis in the course of a bicycle exercise test. Male patients (143) with CHD aged 49±8 years participated in the study. Subgroups with hemodynamically significant stenosis in one, two, or three coronary arteries; with no stenosis; and with a varying degree of total coronary bed lesion were distinguished. Tachograms were recorded in the course of bicycle exercise tests with loads of 25 and 50 W with spontaneous respiration for 3 min at each stage of a test. The frequency estimates of HRV in the LF and HF bands of the spectrum were obtained using the parametric method for constructing the spectrum based on the autoregressive model. It was shown that hemodynamically significant coronary stenoses significantly influenced the state of the mechanisms of autonomic regulation of the heart, which, in CHD patients with a three-vessel coronary lesion, is characterized by an extremely low adaptability.