Studies on cardiac sympathovagal balance and large artery distensibility in patients with untreated essential hypertension

Background: Power spectral analysis of heart rate variability and arterial distensibility are non-invasive measures of cardiac autonomic modulation an d mechanical vessel wall properties, respectively. The aim of the present s tudy was to assess cardiac sympathovagal balance, carotid and brachial arte ry distensibility and a possible relation between these parameters in mildl y hypertensive patients as compared to normotensive controls. Methods: Total power (TP, 0.01 to 0.5 Hz) and spectral components (low freq uency 0.04-0.15 Hz, mainly sympathetic cardiac modulation; high frequency 0 .15-0.4 Hz, mainly vagal cardiac modulation) and cardiac sympathovagal bala nce (LF/LH ratio) of short term heart rate variability (ECG-recording) were calculated in 15 untreated essential hypertensive patients (HYP) and 15 ag e- and sex-matched healthy controls (CON). Brachial and carotid artery dist ensibility coefficient (DC) was measured with a multigate doppler system (e cho-tracking). Results: TP (ms(2) x 10(-3)) (11.2 +/- 0.8 vs 13.6 +/- 0.9, P < 0.03), LF/H F ratio (1.07 +/- 0.08 vs 0.75 +/- 0.07, P < 0.01) and HF (ms(2) x 10(-3)/% ) (0.7 +/- 0.1/49 +/- 2 vs 1.3 +/- 0.2/58 +/- 2, P < 0.01/P < 0.01) were si gnificantly reduced in HYP compared to CON subjects. LF (ms(2) x 10(-3)/%) was 0.7 +/- 0.1/50 +/- 2 vs 0.9 +/- 0.1/41 +/- 2, P = 0.16/P < 0.01. Caroti d artery DC (15 +/- 2 vs 26 +/- 2 P < 0.001) and brachial artery DC (4.7 +/ - 0.6 vs 9 +/- 1.0, P < 0.001) were significantly reduced in HYP. There was a significant correlation between carotid DC and LF/HF (rho = -0.41, P < 0 .03). Conclusion: The data shows reduced heart rate variability and altered cardi ac sympathovagal balance as well as impaired arterial distensibility in unt reated mildly hypertensive patients. The relative increase in sympathetic m odulation and decreased carotid distensibility appear to be related.