Cardiac dysautonomia and arterial distensibility in essential hypertensives

INTRODUCTION: The central nervous system plays an important role in the regulation of blood pressure: the sympathetic nervous system may be a primary contributor to the development of some forms of essential hypertension. Hypertension is also associated with reduced distensibility of large arteries. The aim of our study is the evaluation of a correlation between cardiac dysautonomia (evaluated by means of heart rate variability [HRV]) and altered artery distensibility (evaluated by means of measurement of the time interval from the onset of the QRS wave and the detection of the last Korotkoff sound [QKD interval]). MATERIALS AND METHODS: HRV and QKD interval were evaluated in 23 patients (60.9+/-8.7 years) with untreated hypertension and in 20 control subjects (53.2+/-16.8 years). QKD interval and QKD(100-60) (that is QKD for a 100 mm Hg systolic blood pressure and 60 bpm heart rate) were measured during a 24-hours blood pressure monitoring. HRV was evaluated by means of a spectral method. Three main spectral components were distinguished: very low frequency (VLF), low frequency (LF) and high frequency (HF) component. RESULTS: Patients with reduced QKD(100-60) interval show reduced total power and spectral components values, with higher LF/HF ratio in basal conditions in comparison with control group. In patients with hypertension, QKD(100-60) values correlated significantly with LF/HF ratio (Spearman r=-0.551; p=0.006), HF spectral component (Spearman r=0.630; p=0.001) and total power (Spearman r=0.426; p=0.004). CONCLUSIONS: Our results suggest that sympathetic overactivity may be the contributor of reduced arterial distensibility observed in patients with essential hypertension