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 Figure 2 – LF SBP-iRR gain and LF SBP-iRR delay time; Data represented in Box plot (minimum value, first quartile, median, third quartile and maximum value); iRR: RR interval; SBP: systolic blood pressure; LF: low frequency; Unpaired Student t test: *: significant difference in relation to the normotensive group (p = 0.03). 35 30 25 20 15 10 5 0 Normotensive Prehypertensive Normotensive Prehypertensive .00 –1.00 –2.00 –4.00 –3.00 LF SBP-iRR gain (mms/mmHg) LF SBP-iRR delay time (s) * Table 2 – Cardiac and peripheral autonomic modulation Variable Normotensive (n = 13) Prehypertensive (n = 11) p Cardiac Modulation Variance IRR (ms²) 2050 [985-3264] 1718 [1067-3806] 0,50 b VLF iRR (ms²) 905 ± 699 1178 ± 625 0,33 a LF iRR (ms²) 565 [277-1067] 413 [263-1360] 0,98 b HF iRR (ms²) 481 [212-897] 340 [195-606] 0,54 b LF iRR (un) 51 ± 19 57 ± 17 0,46 a HFi RR (un) 49 ± 19 43 ± 17 0,46 a LF/HF 0,90 [0,58-1,87] 1,52 [0,98-1,91] 0,50 b Peripheral modulation Variance SBP (mmHg²) 9,4 [ 4,9-12,7] 18,3 [ 14,8-26,7] < 0,01 b VLF SBP (mmHg²) 6,9 [2,0-11,1] 13,5 [10,7-22,4] 0,01 b LF SBP (mmHg²) 1,7 [1,0-3,0] 3,0 [2,0-4,0] 0,04 b HF SBP (mmHg²) 2,0 [1,0-2,0] 1,0[1,0-2,5] 0,77 b Breathing LF (un) 0 [ 0-6] 0 [ 0-12] 0,92 b HF (un) 100 [94-100] 100 [88-100] 0,92 b Data presented as mean ± standard deviation of mean or median [interquartile range]; a unpaired Student t test; b - Mann-Whitney U-test; iRR: RR interval; SBP: systolic blood pressure; VLF : very low frequency; LF: low frequency; HF: high frequency; un: standard units. we observed greater forearm vascular conductance in both the rest and the peak of reactive hyperemia in the prehypertensive patients when compared to the normotensive ones. Other studies, also using the venous occlusion plethysmography technique, obtained controversial results regarding the vascular function of prehypertensive patients. For example, Schwartz et al. 27 evaluated the resting forearm vascular conductance of normotensive and prehypertensive young men and did not observe differences between groups. Beck et al. 28 evaluated youngsters of both sexes and observed lower vascular conductance in prehypertensive patients in relation to the normotensive ones. Already during the maneuver of reactive hyperemia, Beck et al. 26 and Beck et al., 28 in contrast to the results of this study, observed a lower peak flow in prehypertensive patients using, respectively, venous occlusion plethysmography and high‑resolution ultrasound. The differences between the results of this study and the others may be related to the 170