ABC | Volume 110, Nº2, February 2018

Original Article Amaral et al Autonomic and vascular control in prehypertensive patients Arq Bras Cardiol. 2018; 110(2):166-174 Table 1 – Demographic and clinical characteristics of the sample Variable Normotensive (n = 14) Prehypertensive (n = 11) p Male gender n (%) 5 (35,7) 6 (54,5) 0,43 a Children of both hypertensive parents n (%) 4 (28,6) 5 (45,5) 0,43 a Age (years) 30 ± 6 29 ± 4 0,57 b BMI (kg/m²) 24 ± 4 25 ± 3 0,28 b Waist circumference (cm) 79 ± 11 82 ± 9 0,51 b Glycemia (mg/dl) 83 [80-93] 89 [83-93] 0,23 c Total Cholesterol (mg/dl) 177,9 ± 39,6 187,3 ± 29,7 0,53 b Triglycerides (mg/dl) 91,5 [57,9-131] 103,5 [63-148] 0,60 c SBP (mmHg) 116 [105-119] 128 [124-132] < 0.01 c DBP (mmHg) 67 [60-71] 75 [71-75] < 0.01 c Cardiac index (L/min/m²) 3,3 ± 0,3 3,7 ± 0,6 0,05 b Total peripheral resistance (mmHg/L) 15,0 [13,8-16,0] 13,8 [12,4-15,7] 0,15 c Cardiac contractility index (mmHg/s) 1113 ± 195 1340 ± 167 < 0,01 b Heart rate (bpm) 67 [ 63-69] 63 [ 62-76] 0,70 c Respiratory rate (ipm) 17 ± 2 17 ± 4 1,00 b Data presented as mean ± standard deviation of mean or median [interquartile range]; absolute value and percentage for males; a : Fisher’s exact test; b : Unpaired Student t test; c : Mann-Whitney U-test; BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure. Discussion The main finding of this study is that peripheral autonomic dysfunction precedes the possible vascular dysfunction in prehypertensive individuals with FHSAH. As expected, the prehypertensive group had higher SBP and DBP. Since blood pressure values are determined by cardiac output and peripheral vascular resistance, in this study, increased cardiac output by increasing systolic volume, possibly modulated by increased cardiac contractility, appears to be related to blood pressure elevation, since both heart rate and peripheral vascular resistance were similar between the groups. Similar results were obtained by Davis et al., 12 who also observed elevation of cardiac index and cardiac contractility, but similar peripheral resistance, in young prehypertensive individuals when compared to normotensive ones. Thus, although the typical hemodynamic finding of hypertension is elevation of peripheral resistance, elevation of cardiac output appears to be responsible for pressure elevation in the early stages of disease development. 25 In addition, studies have shown impairment in the vascular function of prehypertensive patients such as reduction of endothelium-dependent vasodilation, assessed by the infusion of acetylcholine, 10 reduction of the plasma concentration of vasodilatory substances, such as nitric oxide 26 and elevation of vasoconstrictors such as endothelin-1. 10,26 However, in this study, Figure 1 – Vascular function. Data represented as mean ± standard deviation; ANOVA of two factors for repeated measures: *: significant differences in relation to rest; ᵻ : significant differences in relation to the normotensive group. 40 30 20 10 0 * Resting Ɨ * Normotensive Pré-Hipertensos Vascular conductance (units) Ɨ Hyperemia 169