title: Effects of transcutaneous electrical nerve stimulation (TENS) on arterial stiffness and blood pressure in resistant hypertensive individuals: study protocol for a randomized controlled trial.
abstract: 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
  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).
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  Clinical Trials NCT02365974.
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil. vilelamartin@uol.com.br.
authors.forename: José Fernando
authors.initials: JF
authors.lastname: Vilela-Martin
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Luiz Tadeu
authors.initials: LT
authors.lastname: Giollo-Junior
authors.affiliation: Cardiology Division, Federal University of Rio Grande do Sul (UFRS), Porto Alegre, Brazil.
authors.forename: Gaspar Rogério
authors.initials: GR
authors.lastname: Chiappa
authors.affiliation: Physical Therapy Division, University of Brasilia (UNB), Brasilia, Brazil.
authors.forename: Gerson
authors.initials: G
authors.lastname: Cipriano-Junior
authors.affiliation: Cardiology Division, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Paulo José Cardoso
authors.initials: PJ
authors.lastname: Vieira
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Fábio
authors.initials: F
authors.lastname: dos Santos Ricardi
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Manoel Ildefonso
authors.initials: MI
authors.lastname: Paz-Landim
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Days Oliveira
authors.initials: DO
authors.lastname: de Andrade
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Elizabeth do Espírito Santo
authors.initials: Edo E
authors.lastname: Cestário
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Luciana Neves
authors.initials: LN
authors.lastname: Cosenso-Martin
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Yugar-Toledo
authors.affiliation: Internal Medicine Department and Hospital de Base, Hypertension Clinic, Medical School in São José do Rio Preto (FAMERP), Av Anísio Haddad 7700 casa 129, Jd das Palmeiras, 15093-000, São José do Rio Preto, SP, Brazil.
authors.forename: José Paulo
authors.initials: JP
authors.lastname: Cipullo
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D062186:Arterial Pressure / Q000187:drug effects; D001938:Brazil; D002985:Clinical Protocols; D004351:Drug Resistance; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012107:Research Design; D016037:Single-Blind Method; D013997:Time Factors; D004561:Transcutaneous Electric Nerve Stimulation / Q000009:adverse effects; D016896:Treatment Outcome; D059289:Vascular Stiffness / Q000187:drug effects
chemical_list: D000959:Antihypertensive Agents
keywords: Arterial stiffness; Blood pressure; Resistant hypertension; Sympathetic system; Transcutaneous electrical nerve stimulation