Influence of left ventricular hypertrophy on heart period variability in patients with essential hypertension.

Abstract

To evaluate whether left ventricular hypertrophy in hypertensive patients is associated with a greater impairment of sympathovagal balance assessed by means of heart period variability. Forty hypertensive patients, 20 with echocardiographic evidence of left ventricular hypertrophy and 20 without, and 20 control subjects, were subjected to 24 h blood pressure monitoring and Holter recording on 2 consecutive days. Power spectrum analyses of heart period variability were performed utilizing the fast Fourier transform algorithm. No difference was detectable in 24 h, daytime and night-time blood pressure values between hypertensive patients with and without left ventricular hypertrophy. Low- and high-frequency powers were higher in controls than in hypertensives; in particular, low-frequency power showed a progressive decrease through control subjects and hypertensives without and with left ventricular hypertrophy. Furthermore, significant negative correlations were found between left ventricular mass index and low- and high-frequency power. No difference was detectable in ultra-low- and very low-frequency power. During daytime low- and high-frequency power were higher in controls than in hypertensives; during night-time, low- and high-frequency power increased significantly in all groups and low-frequency power was still higher in control subjects. Considering that, when analysed over 24 h Holter recording, low- and high-frequency power both reflected the parasympathetic modulation of heart rate, the present results demonstrate a parasympathetic withdrawal in hypertension; this sympathovagal imbalance is greater in patients with cardiac hypertrophy and is related to the increase in left ventricular mass.