Autonomic Nervous System Activity in Patients with Lower Urinary Tract Symptoms Secondary to Benign Prostatic Hyperplasia Estimated by Heart Rate Variability

Introduction: Aging induces autonomic nervous system (ANS) dysfunction with increased sympathetic drive. Benign Prostatic Hyperplasia (BPH) is responsible for lower urinary tract symptoms (LUTS), and its pathogenesis is com- plex. Exemplified by previous studies, the probably cause of BPH and secondary LUTS is due to the overly active sympa- thetic ANS resulting from aging. Objectives: The aim of our study was to estimate the ANS activity in BPH patients with LUTS using frequency domain analysis parameters of heart rate variability (HRV). Additionally, the relationship of ANS activity to the subjective meas- ures of LUTS, and the objective measures of BPH, as well as the biochemical and biometrical variables, were investi- gated. Material & methods: The study was performed on 30 men with LUTS secondary to BPH. The cohort of patients was asked to complete IPSS and quality of life questionnaires. We performed biometrical, biochemical measurements and urological estimations. Additionally, a serum sample was obtained for Prostate Specific Antigen and its derivatives analy- sis. ANS activity was assessed by HRV measurements in resting conditions, after simulation with deep breathing and by the tilt up test. In the HRV recording, frequency domain analysis parameters were calculated according to fast Fourier transformation and the correlation for ANS activity parameters vs BPH variables were analyzed. The following HRV pa- rameters were taken into consideration: VLF (power of very low frequency), LF (power of low frequency), LFnu (LF power in normalized units), HF (power of high frequency), HFnu (HF power in normalized), LF/HFnu (normalized ratio of LF power to HF power), PSD (total power of spectrum of the RR variability). Results: All participants (mean age 65 ± 7 years) presented moderate LUTS (IPSS = 14 pts.; QofL = 3 pts.) with Qave.= 7,4 ml/sec. and PVR = 48 ± 45 ml. Normalized values of LF and HF were 60.86 ± 18.96 (%) and 39.14 ± 18.96 (%), respec- tively. VLF - 238.75 ± 214.96 (ms 2 ). LF/HF ratio and its normalized value were 2.97 ± 3.04 (1) and 1.57 ± 1.40 (1), re- spectively. In response to deep breathing, significant increases of LF, LFnu, LF/HF, LF/HFnu and total power of HRV spectrum and a decrease of HFnu were observed. The E/I ratio was 1,12 ± 0,08. During the tilt up test, VLF, LFnu, LF/HF, and LF/HFnu were increased, while HFnu decreased. The 30/15 ratio was 0,98 ± 0,05. The observed strong corre- lations are as follows: 1) between prostate enlargement and HFnu and LFnu power; 2) between total PSA level and LFnu, HF, HFnu; 3) between free/total PSA ratio and LF/HFnu; 4) between PSA density of the transition zone and HF; 5) be- tween plasma noradrenalin level and HF; 6) between age and LFnu, HFnu, LF/HF and LF/HFnu; 7) between plasma adrenaline level and prostate enlargement: prostate length and transition zone height. Conclusions: These results demonstrate the sympathetic overactivity of ANS at rest in patients with BPH and LUTS. It is also suggested that in the pathophysiology of BPH, the heighten activity of the sympathetic ANS, and parasympathetic drive are important.