Heart rate and blood pressure variability and baroreflex sensitivity in hypercholesterolaemia

To evaluate cardiovascular autonomic function in hypercholesterolaemia, we studied 16 age-matched pairs of healthy males with elevated serum cholesterol and normocholesterolaemic control subjects (altogether 37 men, aged 27-56 years). We used power spectral analysis to measure short-term heart rate and blood pressure variability, and the phenylephrine method to determine baroreceptor reflex sensitivity. The mean (SD) serum cholesterol concentration was 6.43 (1.22) among the hypercholesterolaemic subjects and 4.30 (0.44) mmol/l among the control men (P < 0.001). The respective low density lipoprotein (LDL) cholesterol concentrations were 4.44 (1.22) and 2.46 (0.38) mmol/l (P < 0.001). The total power (0.0-0.5 Hz) of heart rate and blood pressure variability did not differ between the groups, and neither did the high-frequency (0.15-0.5 Hz) and medium-frequency components (0.07-0.15 Hz). Mean (SD) baroreceptor reflex sensitivity was 18.1 (7.9) in hypercholesterolaemic and 19.4 (6.3) ms mmHg-1 in normocholesterolaemic subjects (P = 0.352). when all the subjects were analysed together, we observed a slight inverse trend between serum LDL cholesterol and baroreceptor reflex sensitivity (r = -0.235, P = 0.161). In conclusion, hypercholesterolaemia does not alter autonomic neural regulation of the cardiovascular system as assessed heart rate and blood pressure variability and baroreflex sensitivity.