Baroreflex Sensitivity Assessment: How Many Sit‐Stand Maneuvers to Evaluate Cardiovascular Disease Risk?

Abstract

OBJECTIVE Although recent evidence suggests that 15 cycles of repeated sit-stand maneuvers may be a useful method for baroreflex sensitivity (BRS) assessment, it remains unclear how many times the maneuver should be performed to estimate BRS for cardiovascular disease (CVD) risk assessment with minimal effort. The purpose of this study was to explore the minimal cycles of sit-stand maneuvers for BRS assessment. We hypothesized that less than 15 cycles of repeated sit-stand maneuvers can evaluate the BRS for CVD risk assessment. METHODS 183individuals (62 ± 12 years, 72% Women) were analyzed cross-sectionally in this study. In the assessment of BRS, the beat-to-beat changes of R-R interval and SBP were measured during 1) 5 minutes of resting seat condition and 2) 5 minutes of the repeated sit-stand maneuvers at 0.05 Hz (i.e. 15 cycles of 10-second sit and 10-second stand). BRS gain, power spectral density (PSD) of R-R interval and SBP were calculated from the 6 conditions: seated rest, 3, 6, 9, 12, 15 cycles of the repeated sit-stand maneuvers using spectral and transfer function analyses. In addition to traditional CVD risk measurements, including hemodynamics and blood biomarker measures, carotid distensibility was calculated from carotid pulse pressure and intra-beat changes of carotid diameter. The associations of age and carotid distensibility with BRS gains calculated from the 6 conditions were tested through partial correlation analysis adjusted for sex. The partial correlation coefficients were compared by Fisher r-to-z transformation analysis. RESULTS The PSDs of R-R interval and SBP were progressively increased as the cycles of repeated sit-stand maneuvers increased. The BRS gains calculated from all the 6 conditions were negatively associated with age and carotid distensibility (all tests were P < 0.001). The BRS gain calculated from the 6 cycles and over of repeated sit-stand maneuvers were strongly associated with age and carotid distensibility compared to the equivalents calculated from the seated rest and 3 cycles of repeated sit-stand maneuvers (P < 0.05). The strength of the correlation did not increase with the greater number of 6 cycles of sit-stand maneuvers. Furthermore, forward stepwise regression analysis showed that age, sex, carotid distensibility, brachial systolic pressure, heart rate, and HDL-cholesterol were selected as the covariates of BRS gains calculated from 6 cycles of the sit-stand maneuvers, and these covariates explained over 60% variance of the BRS gain. CONCLUSION Our results suggest that BRS gain calculated from at least 6 cycles of repeated sit-stand maneuvers is strongly associated with CVD risk factors. We also observed that variabilities of R-R interval and SBP progressively increased as the number of sit-stand cycles increased.