ABC | Volume 113, Nº6, December 2019

Original Article Elias Neto et al. Great arteries behavior during orthostasis Arq Bras Cardiol. 2019; 113(6):1072-1081 during the tilt test at 70° (0–2 min, 10 min and 20 min), and in the recovery phase (0–2 min). The correlation between PWV obtained during the protocol and all parameters was determined using Pearson’s correlation coefficient in the entire sample. Then, multiple linear regression was used to assess the influence of the different hemodynamic parameters on the PWV during the tree phase. All assumptions required for regression analysis were verified. The partial linear correlation coefficients between PWV and age controlled for the blood pressure effect were calculated for each phase of the protocol. Similarly, the influence of age on the correlation of PWV and blood pressure was determined. Then, multivariate analysis of variance (MANOVA) and analysis of covariance (ANCOVA) were performed to assess the independent effects of age and SBP on PWV in the different phases of the protocol. Considering that the 2 major modulating factors of PWV level are age and SBP, the clinical results were assessed after adjustment for these 2 variables. Aiming at assessing the variables that interfere with heart rate behavior in orthostatic position, multiple linear regression was performed. A normality assessment of the data was performed for all variables. The significance level for all tests was established as α = 0.05. The statistical analyses were performed using the SPSS for Windows software (version 18.0, SPSS Inc., 2010). Results Effects of the tilt test at 70 on the hemodynamic characteristics of the participants Figure 1 shows the dynamic behavior of the hemodynamic variables during the protocol. Table 2 shows the mean values of the variables studied at baseline, during the tilt test, and in the recovery phase. Based on the analysis of these data, the response of the individuals to postural changes was associated with a 6% increase in DBP, which was maintained during the entire phase of orthostatic position. The same was observed for the MBP value in orthostatic position. On the other hand, PP in orthostatic position decreased by 10.6%. An 11.5%-increase in PWV in orthostatic position (PWVp) was observed as compared with the baseline PWV value. Association between PWV in the supine position and anthropometric and hemodynamic characteristics of the participants The results of the linear correlation analysis between carotid-femoral PWV in the supine position and the anthropometric and hemodynamic parameters are shown in Table 3. Multiple linear regression showed that age (p < 0.001) and SBP (p < 0.001) were the only independent predictive variables of baseline PWV. These 2 factors accounted for approximately 50% of the variability observed in baseline PWV (r 2  = 0.505, p < 0.001). Association between mean PWV during the tilt test at 70° and the anthropometric and hemodynamic characteristics of the participants Analysis of the correlation between PWV measurements taken in the supine position (baseline PWV) and PWV during the tilt test (PWVp) showed a significant influence of baseline PWV on the response obtained in orthostatic position (Figure 2A). Results of the linear correlation analysis between carotid-femoral PWVp obtained during the tilt test and the anthropometric and hemodynamic parameters of the study participants are shown in Table 4. Figure 1 – Chart showing the dynamic behavior of hemodynamic parameters monitored during the protocol. 151x155 mm (96 x 96 DPI) 140 135 125 115 95 90 90 90 95 100 100 110 110 105 105 95 80 70 12,0 11,0 10,0 9,0 Basal 2m 4m 6m 8m 10m 12m 14m 16m 18m 20m Rec. min. 85 75 130 120 SBP.mmHg DBP.mmHg PWV.m/s MBP.mmHg MBP.mmHg 1074