EARLY AUTONOMIC CHANGES IN PATIENTS WITH NEWLY DIAGNOSED ARTERIAL HYPERTENSION: PP.25.05

Abstract

Objective: The autonomic nervous system plays a key role in the regulation of blood circulation and its abnormal function is a major factor involved in the early phases of essential arterial hypertension. The objective of the study was to assess the differences between short-term variation in heart rate and blood pressure in healthy individuals and in a group of patients with newly diagnosed mild essential arterial hypertension. Design and Method: Three continuous 5-minute measurements of the ECG and blood pressure in supine position with different breathing patterns (spontaneous breathing, paced breathing 0.1 Hz and 0.33 Hz), were applied at 2 groups of subjects: young healthy (YH, 31 subjects, 13 female) and patients with newly diagnosed mild arterial hypertension (HT, 29 subjects, 12 female). Analyzed parameters: heart rate (HR), heart rate variability spectral power in low frequency (HRVlf) and high frequency (HRVhf) power bands, systolic pressure (SBP), diastolic pressure (DBP) and baroreflex sensitivity (BRS). Results: Mean HR [beat/min] over groups YH/HT at 0.1Hz breathing is 69.9/73.2 (p = NS), during spontaneous breathing 66.1/72.9 (p = NS), and 0.33Hz breathing 67.1/72.8 (p = NS); mean HRVlf [ms2/1000] at 0.1Hz is 17.9/8.5 (p < 0.01), during spontaneous breathing 3.8/2.0 (p = NS) and at 0.33Hz 2.2/0.8 (p < 0.05); mean HRVhf [ms2/1000] at 0.1 Hz is 2.4/1.3 (p = NS), during spontaneous breathing 2.6/1.3 (p = NS) and at 0.33 Hz 2.1/0.7 (p = NS); mean BRS [ms/mmHg] at 0.1 Hz is 17.3/11.2 (p < 0.01), during spontaneous breathing 10.6/8.3 (p = NS) and at 0.33 Hz 9.9/5.9 (p < 0.05). Conclusions: Increased risk of cardiac mortality is closely connected to decreased HRV and BRS as the markers of the short-term circulation control dysfunction. There are no significant differences between both groups in HRVlf, HRVhf and BRS during spontaneous breathing. Group differences in HRVlf and BRS are more significant (p < 0.01) at 0.1Hz breathing than during 0.33Hz breathing (p < 0.05). The 0.1Hz paced breathing is simple and convenient approach to amplify inter-groups differences of the cardiovascular control detected by the HRVlf and BRS in early stages of hypertension.