P91 THE EFFECTS OF DEVICE-GUIDED PACED BREATHING ON ARTERIAL STIFFNESS: IMPACT OF THE AUTONOMIC NERVOUS SYSTEM

Abstract

Objective: The autonomic nervous system (ANS) plays an important role in regulating blood pressure (BP), but its action on arterial stiffness (AS) is still debated. Here we examine if device-guided paced breathing (DGB) 1, via its action on ANS, can affect AS beyond its BP-lowering effect in hypertensive (HT) subjects. Design and Methods: Central mean arterial pressure (MAP) (pulse-wave analysis of the radial artery, SphygmoCor, AtCor Medical, Australia), AS (carotid-femoral pulse wave velocity (cfPWV), SphygmoCor) and ANS activity (as high resolution heart rate variability (HRV) of low-frequency/high-frequency range (LF/HF)), (Schiller Medilog AR12plus, United States) were determined in HT subjects. All measurements were performed in supine position after 15 min of rest and subsequently repeated during supervised DGB therapy. Results: 33 HT patients (18 male); age (mean ±SD) 46 ± 13 years; BP 144 ± 19/86 ± 9 mmHg; cfPWV 9.9 ± 2.1 m/s were recruited. DGB decreased (mean [95% CI]) LF/HF by 0.15 [0.08, 0.22] as well as MAP (−6.7 [−8.4,−5.1] mmHg) and cfPWV (−1.1 [−0.8,−1.3] m/s), all P < 0.01. Bivariate analysis showed a positive correlation between decrease in HRV activity and reduction of cfPWV and MAP (ß = 0.476 and ß = 0.402 respectively, both P < 0.05). The relationship between cfPWV and HRV activity was also still significant in multi-regression models adjusted for confounders (baseline PWV value and change in BP), P < 0.05. Conclusions: DGB, via its action on ANS, affected both BP and AS in HT subjects. Reduction of cfPWV was not fully explained by the BP-lowering effect suggesting that the ANS may play an independent role in modulating AS.