[Sympathetic response in primary hypertension]

High blood pressure (BP) is a major cause of cardiovascular disease and primary hypertension is a frequent pathological condition. Sympathetic hyperactivity may be involved in primary hypertension. The purpose of this study was mainly to evaluate sympathetic activity when performing cardiovascular autonomic profile examination in patients with primary hypertension in comparison with normotensive subjects.

This prospective study included one group of hypertensive patients (n=120, mean age 54 years) compared with a control group (n=120, mean age 52 years) of normotensive subjects. Autonomic tests included deep-breathing (DB), hand-grip (HG) and echostress test (ES). Comparison tests between the two groups, similar in age, were expressed as mean+/-SE and made using the t Student test, p<0.05 was considered significant.

Alpha-adrenergic sympathetic response using ES method produced a BP response of 20,0%+/-9,8 in hypertensive patients group and 15,2%+/-8,6 in the control group (p<0.001). Alpha-adrenergic sympathetic response using three minutes HG test was of 16,7%+/-7,5 in hypertensive patients group and 13,3%+/-6,5 in the control group (p<0.001). Vagal stimulation in hypertensive group after DB showed that electrocardiographic: ECG (EKG) waves R (RR) interval variation was of 30,2%+/-8,1 meanwhile in the control group this RR variation was of 46,1%+/-21,1 p<0.001, and the one of HG of 15 seconds was 17,6%+/-10,2 versus 32,5%+/-12,7 p<0.001.

Hypertensive patients had a significantly higher sympathetic response to central and peripheral stimulations and a significantly lower parasympathetic response when compared to normotensive controls.