Effects of transcutaneous electrical nerve stimulation (TENS) on arterial stiffness and blood pressure in resistant hypertensive individuals: study protocol for a randomized controlled trial

Background: Resistant hypertension (RH) treatment requires an adequate and intense therapeutic approach. However, the results are not always satisfactory despite intensive treatment. Of the different pathophysiological mechanisms involved in the pathogenesis of RH, sympathetic overstimulation and therapies that block the sympathetic system have been widely studied. These approaches, however, are invasive and expensive. Another possible approach is by transcutaneous electrical nerve stimulation (TENS), a noninvasive method that modulates activity by using low-frequency transcutaneous electrical stimulation to inhibit primary afferent pathways. Thus, the current study will evaluate the effect of applying TENS in the cervicothoracic region of subjects with RH and will seek to develop a new low-cost and readily available therapy to treat this group of hypertensive individuals. Methods/design: This is a randomized, single blind (subject), parallel-assignment study controlled with a sham group and including participants aged 40 to 70 years with resistant hypertension. The trial has two arms: the treatment and control (sham group). The treatment group will be submitted to the stimulation procedure (TENS). The sham group will not be submitted to stimulation. The primary outcomes will be a reduction in the peripheral blood pressure and adverse events. The secondary outcomes will be a reduction the central blood pressure. The study will last 30 days. The sample size was calculated assuming an alpha error of 5 % to reject the null hypothesis with a statistical power of 80 %, thereby resulting in 28 participants per group (intervention versus sham). Discussion: In recent decades, RH has become very common and costly. Adequate control requires several drugs, and in many cases, treatment is not successful. Sympathetic nervous system inhibition by renal denervation and central inhibition have significant effects in reducing BP; however, these treatments are costly and invasive. Another type of sympathetic nervous system inhibition can also be noninvasively achieved by electric current. Therefore, the application of TENS may be a new therapeutic option for treating resistant hypertensive individuals. Trial Registration: Clinical Trials NCT0236597

Effects of acute blood pressure elevation on biochemical-metabolic parameters in individuals with hypertensive crisis

Hypertensive crisis is a common clinical situation that presents a high rate of morbidity and mortality and it is characterized by symptomatic rise of blood pressure (BP), systolic (SBP) ≥ 180 mmHg and/or diastolic (DBP) ≥ 120 mmHg. It is classified as emergency (HE) or hypertensive urgency (HU). There is no description of laboratory findings in patients who present acute BP elevation. Thus, this study had the objective to assess the biochemical-metabolic parameters of patients with HC. We studied 74 normotensive individuals (NT), 74 controlled hypertensive patients (ContrHT), 50 subjects with HU, and 78 with HE for evaluating biochemical-metabolic parameters. HE occurs in older individuals and more frequently in those with known hypertension. More patients with HE had dyslipidemia than those with HU (58% vs. 38%). The diastolic BP and heart rate were higher in the HE group (120 mmHg and 87 bpm) compared to ContrHT (71 mmHg and 71 bpm; p < 0.0001) and NT groups (75 mmHg and 68 bpm; p < 0.0001). Glycemia was higher in HE vs. NT and ContrHT (p < 0.05). HDL cholesterol was lower in HE than NT (p = 0.0088). Potassium was lower in HE vs. NT, ContrHT and HU groups (p < 0.05). Creatinine was higher in the HC group vs. NT and ContrHT (p < 0.05). The GFR was significantly lower in HE group vs. HU, ContrHT and NT (p < 0.001). In conclusion, individuals with HC show biochemical alterations when compared to ContrHT and NT. Acute BP elevations are associated with hyperglycemia, dyslipidemia, and higher potassium and creatinine levels and lower renal function. Abbreviations BMI =body mass index BP =blood pressure CH =hypertensive crisis ContrHT =controlled hypertensive DBP =diastolic blood pressure GFR =glomerular filtration rate HbA1c =glycated hemoglobin HDLc =high-density lipoprotein cholesterol HE =hypertensive emergency HPLC =high-performance liquid chromatography HR =heart rate HU =hypertensive urgency JNC 7 =VII Joint National Committee on the Detection, Evaluation, and Treatment of High Blood Pressure LDLc =low-density lipoprotein cholesterol MDRD =Modification of Diet in Renal Disease NT =normotensive RASB =renin-angiotensin system blockers SBP =systolic blood pressure TC =total cholesterol TG =triglyceride