Background: Patients with hypertension have altered autonomic nervous system function,
which are increased sympathetic activity. Transcutaneous Electrical Nerve Stimulation
(TENS) is a useful modality for pain control and has also been shown to be effective in the reduction
of sympathetic activity in healthy subjects and individuals with cardiovascular diseases.
Objective: The aim of this study was to verify the effects of transcutaneous electrical nerve stimulation
by the evaluation of heart rate variability (HRV) in patients with essential hypertension.
Method: Twenty-eight patients received an application of low-frequency TENS(4 Hz) n=8, highfrequency
TENS (100 Hz) n=10 or placebo TENS n=10 in paravertebral ganglionar region during
Results: After 4 Hz TENS, there was a decrease in the low-frequency (LFn.u.) component
(57.71±9.46 vs 45.58±13.51, p<0.026) and an increase in the high-frequency (HFn.u.) component
(33.03±13.83 vs 45.83±20.19, p <0.05) of HRV. After 100 Hz TENS and placebo, there were no
changes in the LF and HF components. No significant differences were found in systolic blood
pressure with low-frequency TENS (129.37± 15.48 vs 126.69 ± 15.21, p<0.490). There was an
increase, although not significant, with high-frequency TENS (131.00 ± 15.97 vs 138.75 ± 25.79,
p<0.121) and placebo (133.80 ± 29.85 vs 134.80 ± 29.72, p< 0.800). No differences were found in
the diastolic blood pressure with low-frequency TENS and placebo, but there was a significant increase
in high-frequency TENS (81.00 ± 11.78 vs 85.65 ± 13.68, p< 0.018).
Conclusion: Low-frequency TENS decreases sympathetic nervous system activity and increases
parasympathetic nervous system activity and high-frequency TENS increases diastolic blood pressure,
when applied on the paravertebral ganglionar region in the hypertensive patients.