Ambulatory daytime blood pressure versus tonometric blood pressure measurements in the laboratory: effect of posture.

OBJECTIVE: To compare blood pressure (BP) in tonometric radial artery recordings during passive head-up tilt with ambulatory recordings and evaluate possible laboratory cutoff values for hypertension. METHODS: Laboratory BP and ambulatory BP were recorded in normotensive (n = 69), unmedicated hypertensive (n = 190), and medicated hypertensive (n = 151) subjects. RESULTS: Mean age was 50.2 years, BMI 27.7 kg/m 2 , ambulatory daytime BP 139/87 mmHg, and 276 were male (65%). As supine-to-upright changes in SBP ranged from -52 to +30 mmHg, and in DBP from -21 to +32 mmHg, the mean values of BP supine and upright measurements were compared with ambulatory BP. The mean(supine+upright) systolic laboratory BP was corresponding to ambulatory level (difference +1 mmHg), while mean(supine+upright) DBP was 4 mmHg lower ( P  < 0.05) than ambulatory value. Correlograms indicated that laboratory 136/82 mmHg corresponded to ambulatory 135/85 mmHg. When compared with ambulatory 135/85 mmHg, the sensitivity and specificity of laboratory 136/82 mmHg to define hypertension were 71.5% and 77.3% for SBP, and 71.7% and 72.8%, for DBP, respectively. The laboratory cutoff 136/82 mmHg classified 311/410 subjects similarly to ambulatory BP as normotensive or hypertensive, 68 were hypertensive only in ambulatory, while 31 were hypertensive only in laboratory measurements. CONCLUSION: BP responses to upright posture were variable. When compared with ambulatory BP, mean(supine+upright) laboratory cutoff 136/82 mmHg classified 76% of subjects similarly as normotensive or hypertensive. In the remaining 24% the discordant results may be attributed to white-coat or masked hypertension, or higher physical activity during out-of-office recordings.

Individual changes of central blood pressure in response to upright posture: different hemodynamic phenotypes.

OBJECTIVES: Most studies about upright regulation of blood pressure have focused on orthostatic hypotension despite the diverse hemodynamic changes induced by orthostatic challenge. We investigated the effect of passive head-up tilt on aortic blood pressure. METHODS: Noninvasive peripheral and central hemodynamics in 613 volunteers without cardiovascular morbidities or medications were examined using pulse wave analysis, whole-body impedance cardiography and heart rate variability analysis. RESULTS: In all participants, mean aortic SBP decreased by -4 (-5 to -3) mmHg [mean (95% confidence intervals)] and DBP increased by 6 (5--6) mmHg in response to upright posture. When divided into tertiles according to the supine-to-upright change in aortic SBP, two tertiles presented with a decrease [-15 (-14 to -16) and -4 (-3 to -4) mmHg, respectively] whereas one tertile presented with an increase [+7 (7-- 8) mmHg] in aortic SBP. There were no major differences in demographic characteristics between the tertiles. In regression analysis, the strongest explanatory factors for upright changes in aortic SBP were the supine values of, and upright changes in systemic vascular resistance and cardiac output, and supine aortic SBP. CONCLUSION: In participants without cardiovascular disease, the changes in central SBP during orthostatic challenge are not uniform. One-third presented with higher upright than supine aortic SBP with underlying differences in the regulation of systemic vascular resistance and cardiac output. These findings emphasize that resting blood pressure measurements give only limited information about the blood pressure status.

Adverse influence of bisoprolol on central blood pressure in the upright position: a double-blind placebo-controlled cross-over study.

Treatment with beta-blockers is characterized by inferior reduction of central versus peripheral blood pressure. We examined changes in blood pressure, cardiac function, and vascular resistance after 3 weeks of bisoprolol treatment (5 mg/day) during passive head-up tilt in 16 never-treated Caucasian males with grade I-II primary hypertension. A double-blind, randomized, placebo-controlled cross-over design was applied, and hemodynamics were recorded using continuous tonometric pulse wave analysis and whole-body impedance cardiography. Bisoprolol decreased blood pressure in the aorta (~8/10 mmHg, p ≤ 0.032) and radial artery (~10/9 mmHg, p ≤ 0.037), but upright aortic systolic blood pressure was not significantly reduced (p = 0.085). Bisoprolol reduced heart rate and left cardiac work, and increased subendocardial viability index in supine and upright positions (p ≤ 0.044 for all). Bisoprolol increased stroke volume in the supine (~11 ml, p = 0.02) but not in the upright position, while only upright (~1 l/min, p = 0.007) but not supine cardiac output was reduced. Upright elevation in systemic vascular resistance was increased 2.7-fold (p = 0.002), while upright pulse pressure amplification was decreased by ~20% (p = 0.002) after bisoprolol. Aortic augmentation index, augmentation pressure, and pulse pressure were not changed in the supine position but were increased in the upright position (from 9% to 17%, 3-6 mmHg, and 30-34 mmHg, respectively, p ≤ 0.016 for all). In conclusion, although bisoprolol treatment reduced peripheral blood pressure, central systolic blood pressure in the upright position was not decreased. Importantly, the harmful influences of bisoprolol on central pulse pressure and pressure wave reflection were manifested in the upright position.

Salbutamol-induced Decrease in Augmentation Index is Related to the Parallel Increase in Heart Rate.

The change in augmentation index following salbutamol inhalation has been applied to evaluate endothelial function. We examined the contribution of salbutamol-induced increase in heart rate to the observed decrease in augmentation index. Haemodynamics were recorded using whole-body impedance cardiography and continuous pulse wave analysis from tonometric radial blood pressure. All subjects (n = 335, mean age 46, body mass index 26, 48% men) were without medications with cardiovascular influences. The effects of salbutamol inhalation (0.4 mg) versus the endothelium-independent agent nitroglycerin resoriblet (0.25 mg) were examined during passive head-up tilt, as the haemodynamic influences of these compounds depend on body position. Salbutamol decreased augmentation index by ~3-4% units in supine and upright positions. Although salbutamol moderately increased cardiac index (+4.5%) and decreased systemic vascular resistance (-8.5%), the significant haemodynamic explanatory factors for decreased augmentation index in multivariate analysis were increased supine heart rate, and increased upright heart rate and decreased ejection duration (p < 0.001 for all, r2  = 0.36-0.37). Sublingual nitroglycerin decreased supine and upright augmentation index by ~15% units and ~23% units, respectively. The haemodynamic explanatory factors for these changes in multivariate analysis were increased heart rate, reduced ejection duration and reduced systemic vascular resistance (p ≤ 0.021 for all, r2  = 0.22-0.34). In conclusion, the lowering influence of salbutamol on augmentation index may be largely explained by increased heart rate, suggesting that this effect may not predominantly reflect endothelial function.

Haemodynamic Influences of Bisoprolol in Hypertensive Middle-Aged Men: A Double-Blind, Randomized, Placebo-Controlled Cross-Over Study.

Treatment with beta-blockers appears to show inferior reduction in central versus peripheral blood pressure. We aimed to examine simultaneous changes in central and peripheral blood pressure, vascular resistance, cardiac function and arterial stiffness during beta-blockade. Haemodynamics were investigated after 3 weeks of bisoprolol treatment (5 mg/day) in a double-blind, randomized, placebo-controlled cross-over trial in never-treated 16 Caucasian males with grade I-II primary hypertension using continuous tonometric pulse wave analysis and whole-body impedance cardiography. Bisoprolol decreased radial (134/80 versus 144/89 mmHg) and aortic blood pressure (122/80 versus 130/90 mmHg) and heart rate (57 versus 68 beats/min) when compared with placebo (p < 0.05 for all). Ejection duration (336 versus 316 ms) and stroke volume (109 versus 98 ml) were increased (p < 0.01 for all), while cardiac output was not significantly changed (6.2 versus 6.6 l/min). Bisoprolol decreased pulse wave velocity (7.8 versus 8.9 m/s, p < 0.001), but after adjustment for blood pressure, the decrease was not significant (8.16 versus 8.52 m/s, p = 0.464). The treatment reduced pulse pressure amplification from central to peripheral circulation (30 versus 38%, p = 0.002). No differences were observed in systemic vascular resistance, augmentation index, aortic characteristic impedance or total arterial stiffness after bisoprolol versus placebo. Bisoprolol decreased central and peripheral blood pressure and pulse wave velocity in male individuals with grade I to grade II hypertension. The decrease in pulse wave velocity was related to the antihypertensive effect. Reduced pulse pressure amplification indicates that peripheral blood pressure was reduced more efficiently than central blood pressure.