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 bỹ 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.
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.
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 À4 (À5 to À3) 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 supineto-upright change in aortic SBP, two tertiles presented with a decrease [À15 (À14 to À16) and À4 (À3 to À4) mmHg, respectively] whereas one tertile presented with an increase [R7 (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.
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, r = 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, r = 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.
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