The type of the functional cardiovascular response to upright posture is associated with arterial stiffness: a cross-sectional study in 470 volunteers.

BACKGROUND: In a cross-sectional study we examined whether the haemodynamic response to upright posture could be divided into different functional phenotypes, and whether the observed phenotypes were associated with known determinants of cardiovascular risk. METHODS: Volunteers (n = 470) without medication with cardiovascular effects were examined using radial pulse wave analysis, whole-body impedance cardiography, and heart rate variability analysis. Based on the passive head-up tilt induced changes in systemic vascular resistance and cardiac output, the principal determinants of blood pressure, a cluster analysis was performed. RESULTS: The haemodynamic response could be clustered into 3 categories: upright increase in vascular resistance and decrease in cardiac output were greatest in the first (+45 % and -27 %, respectively), smallest in the second (+2 % and -2 %, respectively), and intermediate (+22 % and -13 %, respectively) in the third group. These groups were named as 'constrictor' (n = 109), 'sustainer' (n = 222), and 'intermediate' (n = 139) phenotypes, respectively. The sustainers were characterized by male predominance, higher body mass index, blood pressure, and also by higher pulse wave velocity, an index of large arterial stiffness, than the other groups (p < 0.01 for all). Heart rate variability analysis showed higher supine and upright low frequency/high frequency (LF/HF) ratio in the sustainers than constrictors, indicating increased sympathovagal balance. Upright LF/HF ratio was also higher in the sustainer than intermediate group. In multivariate analysis, independent explanatory factors for higher pulse wave velocity were the sustainer (p < 0.022) and intermediate phenotypes (p < 0.046), age (p < 0.001), body mass index (p < 0.001), and hypertension (p < 0.001). CONCLUSIONS: The response to upright posture could be clustered to 3 functional phenotypes. The sustainer phenotype, with smallest upright decrease in cardiac output and highest sympathovagal balance, was independently associated with increased large arterial stiffness. These results indicate an association of the functional haemodynamic phenotype with an acknowledged marker of cardiovascular risk. TRIAL REGISTRATION: ClinicalTrials.gov NCT01742702.

Daily liquorice consumption for two weeks increases augmentation index and central systolic and diastolic blood pressure.

BACKGROUND: Liquorice ingestion often elevates blood pressure, but the detailed haemodynamic alterations are unknown. We studied haemodynamic changes induced by liquorice consumption in 20 subjects versus 30 controls with average blood pressures of 120/68 and 116/64 mmHg, respectively. METHODS: Haemodynamic variables were measured in supine position before and after two weeks of liquorice consumption (daily glycyrrhizin dose 290-370 mg) with tonometric recording of radial blood pressure, pulse wave analysis, and whole-body impedance cardiography. Thirty age-matched healthy subjects maintaining their normal diet were studied as controls. RESULTS: Two weeks of liquorice ingestion elevated peripheral and central systolic and diastolic blood pressure (by 7/4 and 8/4 mmHg, 95% confidence intervals [CI] 2-11/1-8 and 3-13/1-8, respectively, P<0.05), and increased extracellular volume by 0.5 litres (P<0.05 versus controls). Also augmentation index adjusted to heart rate 75/min (from 7% to 11%, 95% CI for change 0.3-7.5, P<0.05) and aortic pulse pressure (by 4 mmHg, 95% CI 1-7, P<0.05) were elevated indicating increased wave reflection from the periphery. In contrast, peripheral (-3/-0.3 mmHg) and central blood pressure (-2/-0.5 mmHg), aortic pulse pressure (-1 mmHg), and augmentation index adjusted to heart rate 75/min (from 9% to 7%) decreased numerically but not statistically significantly without changes in extracellular volume in the control group. Heart rate, systemic vascular resistance, cardiac output, and pulse wave velocity did not differ between the groups. CONCLUSIONS: Two weeks of daily liquorice consumption increased extracellular volume, amplified pressure wave reflection from the periphery, and elevated central systolic and diastolic blood pressure. TRIAL REGISTRATION: EU Clinical Trials Register EudraCT 2006-002065-39 ClinicalTrials.gov NCT01742702.

Association of resting heart rate with cardiovascular function: a cross-sectional study in 522 Finnish subjects.

BACKGROUND: High resting heart rate (HR) is associated with increased cardiovascular risk in general populations, possibly due to elevated blood pressure (BP) or sympathetic over-activity. We studied the association of resting HR with cardiovascular function, and examined whether the hemodynamics remained similar during passive head-up tilt. METHODS: Hemodynamics were recorded using whole-body impedance cardiography and continuous radial pulse wave analysis in 522 subjects (age 20-72 years, 261 males) without medication influencing HR or BP, or diagnosed diabetes, coronary artery, renal, peripheral arterial, or cerebrovascular disease. Correlations were calculated, and results analysed according to resting HR tertiles. RESULTS: Higher resting HR was associated with elevated systolic and diastolic BP, lower stroke volume but higher cardiac output and work, and lower systemic vascular resistance, both supine and upright (p < 0.05 for all). Subjects with higher HR also showed lower supine and upright aortic pulse pressure and augmentation index, and increased resting pulse wave velocity (p < 0.001). Upright stroke volume decreased less in subjects with highest resting HR (p < 0.05), and cardiac output decreased less in subjects with lowest resting HR (p < 0.009), but clear hemodynamic differences between the tertiles persisted both supine and upright. CONCLUSIONS: Supine and upright hemodynamic profile associated with higher resting HR is characterized by higher cardiac output and lower systemic vascular resistance. Higher resting HR was associated with reduced central wave reflection, in spite of elevated BP and arterial stiffness. The increased cardiac workload, higher BP and arterial stiffness, may explain why higher HR is associated with less favourable prognosis in populations.

Metabolic syndrome may be associated with increased arterial stiffness even in the absence of hypertension: a study in 84 cases and 82 controls.

OBJECTIVE: To evaluate the hemodynamic characteristics of metabolic syndrome (MetS) in the absence and presence of hypertension. MATERIALS/METHODS: Altogether 166 subjects without previously diagnosed cardiovascular disease, diabetes, or antihypertensive medication, were allocated to four groups: control, hypertension only, MetS without hypertension, and MetS with hypertension (mean age 44-46 years). Cut-point for hypertension was blood pressure ≥140/90 mmHg. Other criteria of MetS were as defined by Alberti et al. 2009. Hemodynamic variables were measured using whole-body impedance cardiography and pulse wave analysis. RESULTS: Pulse wave velocity was higher in hypertensive and normotensive subjects with MetS than controls (p<0.05), and in the hypertensive MetS group than subjects with hypertension only (p<0.05). Aortic pulse pressure was higher in the two hypertensive groups than the two normotensive groups (p<0.05). Systemic vascular resistance index was higher in the hypertensive than normotensive MetS group (p<0.05), and in the group with hypertension alone than in controls (p<0.05). Heart rate was higher in the hypertensive Mets group than in controls and subjects with hypertension only (p<0.05). Cardiac index did not differ, while stroke index was lower in both groups with MetS than groups without MetS. Augmentation pressure was higher in the hypertensive MetS group than in controls and normotensive MetS group (p<0.05). CONCLUSIONS: Pulse wave velocity, an acknowledged marker of arterial stiffness, was associated with MetS even in the absence of hypertension. This emphasizes the importance of the prevention and treatment of MetS.

Hemodynamic alterations in hypertensive patients at rest and during passive head-up tilt.

OBJECTIVE: Hypertension is characterized by increased vascular resistance and arterial stiffness, but information about upright hemodynamics is scarce. We compared hemodynamics in hypertensive versus normotensive patients at rest and during passive head-up tilt. METHODS: Volunteers (n = 387, 19-72 years) without antihypertensive medication were recorded using continuous tonometric pulse wave analysis and whole-body impedance cardiography. Seated office blood pressure was 4/10  mmHg (systolic/diastolic) higher than average supine values during hemodynamic measurements. As there is no accepted cut-off for hypertension during tilt-table tests, supine level at least 135/85  mmHg defined hypertension (n = 155) versus normotension (n = 232). Age, BMI, and proportion of men were higher among hypertensives (49 vs. 42 years, 28 vs. 25, 55 vs. 38%, respectively), and analyses were adjusted for these differences. RESULTS: Both at rest and during head-up tilt radial and aortic blood pressure and pulse pressure, cardiac index (CI) and work, systemic vascular resistance (SVR), and augmentation pressure were higher in hypertensive patients (P < 0.05 for all). Adjusted linear regression analyses showed that during passive head-up tilt aortic SBP and pulse pressure, stroke index, and left cardiac work index decreased less; heart rate increased less; and aortic DBP and SVR increased more in hypertensive patients (P < 0.05 for all); whereas reduction in CI and augmentation index did not differ between the groups. CONCLUSION: Not only supine hemodynamics, but also responses to head-up tilt differed between normotensive and hypertensive patients, indicating functional alterations beyond increased vascular resistance and higher arterial stiffness in hypertension.

Supine and upright haemodynamic effects of sublingual nitroglycerin and inhaled salbutamol: a double-blind, placebo-controlled, randomized study.

OBJECTIVES: Pulse wave analysis is widely applied to measure the haemodynamic effects of nitroglycerin and salbutamol as an endothelium-independent and endothelium-dependent vasodilator, respectively. The recordings are usually performed in supine position from 10 to 20 successive heartbeats without simultaneous measurement of vascular resistance and cardiac function. Our objective was to examine the effects of nitroglycerin and salbutamol on central haemodynamics, arterial stiffness, cardiac function, and vascular resistance in supine and upright positions. METHODS: A placebo-controlled, randomized and double-blinded passive head-up tilt protocol was performed after sublingual nitroglycerin (0.25 mg) or inhaled salbutamol (400 µg) in 35 healthy volunteers. Continuous tonometric pulse wave analysis, whole-body impedance cardiography, and plethysmographic finger blood pressure recordings were applied. RESULTS: Nitroglycerin decreased aortic and finger blood pressure, radial DBP, vascular resistance, augmentation index and pulse wave velocity, and increased heart rate, cardiac index, stroke index and aortic reflection time (P < 0.030 for all). Salbutamol moderately decreased radial and aortic blood pressure and finger DBP, augmentation index and vascular resistance, but increased heart rate and cardiac index (P < 0.030 for all). Almost all of the strong haemodynamic effects of nitroglycerin were emphasized during the head-up tilt, whereas the effects of salbutamol on heart rate and cardiac index were more pronounced in the supine position. CONCLUSION: The haemodynamic changes induced by nitroglycerin and salbutamol were dependent on body position: the effects of nitroglycerin were accentuated during the head-up tilt, whereas those of salbutamol were more evident in the supine position.