Heart rate autonomic regulation in hypertensive patients with obstructive sleep apnea syndrome

Abstract

Objective. To analyze peculiarities of heart rate autonomic regulation in patients with hypertension and obstructive sleep apnea (OSA) at rest and during active orthostatic test (AOT). Design and methods. The study involved 65 patients, average age — 53,7 ± 10,1 years. The complex examination included anthropometric parameters measurement, cardiopulmonary monitoring (CPM), and analysis of heart rate variability (HRV) at rest and during the AOT. Results. The group 1 included 26 people with mild-to-moderate OSA, the group 2 consisted of 39 patients with severe OSA. In group 1 sympathetic influences on the heart rate regulation were predominant, and very low frequency (VLF) waves made a significant contribution in the overall spectrum. Key indicators of the CPM had no effects on HRV in group 1. In group 2, the severity of respiratory disorders directly affected the heart rate: low frequency (LF) waves and the LF/HF index, while high frequency (HF) waves reduced along with the increase in OSA severity. In group 1, the total capacity of the spectrum increased due to a larger contribution of LF-waves and VLF-waves during the AOT. The LF/HF index increased during the AOT. In group 2, there was a paradoxical increase in HF-waves, and a decrease in LF/HF index. Conclusions. The autonomic regulation of the heart rate is disturbed in hypertensive patients with OSA. Excessive sympathetic activation occurs as OSA severity increases, manifesting as the rise of VLF and LF-waves proportion and being the most profound in patients with severe OSA.