Changes In Central Blood Pressure Research Articles

Carotid Reservoir Pressure Decrease After Prolonged Head Down Tilt Bed Rest in Young Healthy Subjects Is Associated With Reduction in Left Ventricular Ejection Time and Diastolic Length.

BackgroundThe arterial pressure waveform reflects the interaction between the heart and the arterial system and carries potentially relevant information about circulatory status. According to the commonly accepted ‘wave transmission model’, the net BP waveform results from the super-position of discrete forward and backward pressure waves, with the forward wave in systole determined mainly by the left ventricular (LV) ejection function and the backward by the wave reflection from the periphery, the timing and amplitude of which depend on arterial stiffness, the wave propagation speed and the extent of downstream admittance mismatching. However, this approach obscures the ‘Windkessel function’ of the elastic arteries. Recently, a ‘reservoir-excess pressure’ model has been proposed, which interprets the arterial BP waveform as a composite of a volume-related ‘reservoir’ pressure and a wave-related ‘excess’ pressure.MethodsIn this study we applied the reservoir-excess pressure approach to the analysis of carotid arterial pressure waveforms (applanation tonometry) in 10 young healthy volunteers before and after a 5-week head down tilt bed rest which induced a significant reduction in stroke volume (SV), end-diastolic LV volume and LV longitudinal function without significant changes in central blood pressure, cardiac output, total peripheral resistance and aortic stiffness. Forward and backward pressure components were also determined by wave separation analysis.ResultsCompared to the baseline state, bed rest induced a significant reduction in LV ejection time (LVET), diastolic time (DT), backward pressure amplitude (bP) and pressure reservoir integral (INTPR). INTPR correlated directly with LVET, DT, time to the peak of backward wave (bT) and stroke volume, while excess pressure integral (INTXSP) correlated directly with central pressure. Furthermore, Δ.INTPR correlated directly with Δ.LVET, and Δ.DT, and in multivariate analysis INTPR was independently related to LVET and DT and INTXSP to central systolic BP.ConclusionThis is an hypothesis generating paper which adds support to the idea that the reservoir-wave hypothesis applied to non-invasively obtained carotid pressure waveforms is of potential clinical usefulness.

Ultrafast Ultrasound-Derived Muscle Strain Measure Correlates with Carotid Local Pulse Wave Velocity in Habitual Resistance-Trained Individuals

Purpose: this study investigated the effects of the intensity of machine-based bicep curl resistance exercise on ultrafast ultrasound-derived muscle strain rate and carotid ultrafast pulse wave velocity (ufPWV), and examined the association between muscle strain rate, ufPWV, and established carotid function measures in habitual resistance-trained individuals. Methods: twenty-three young habitual resistance-trained males (age: 24 ± 1 year, body mass index = 24 ± 1 kg/m2) were recruited to participate in two bouts of acute bicep curl exercise. After one-repetition maximum determination (1RM), the participants were randomly assigned to engage in bicep curls at 40 or 80%1RM intensity (10 reps × five sets) by a crossover study design. The muscle strain rate of bicep muscle, carotid ufPWV during systole(ufPWV-sys), and diastole (ufPWV-dia) were obtained pre- and post-exercise. In addition, carotid function measures were calculated by obtained carotid diameter and central blood pressure changes. Results: compared with pre-exercise, the reduction in post-exercise muscle strain rate and its area under the curve of 80%1RM was greater than those of 40%1RM. Both ufPWV-sys and ufPWV-dia increased regardless of exercise intensity. Baseline bicep muscle strain rate correlated not only with ufPWV-sys (r = −0.71, p = 0.001), ufPWV-dia (r = −0.74, p = 0.001), but also carotid compliance (r = 0.49, p = 0.02), distensibility (r = 0.54, p = 0.01) and ß stiffness (r= −0.84, p < 0.0001). The ufPWVs also correlated with ß stiffness (r = 0.64–0.76, p = 0.01). Conclusion: muscle stiffness measured by ultrafast ultrasound elastography increases positively with resistance exercise intensity, and it appears to correlate with carotid ufPWV and established carotid function measures in habitual resistance-trained individuals.

Effects of Simvastatin on Augmentation Index Are Transient: Outcomes From a Randomized Controlled Trial.

BackgroundStatins improve endothelial function, but their effects on arterial stiffness and aortic blood pressure in middle‐aged adults are uncertain.Methods and ResultsThis was a prospective, randomized, double‐blind, placebo‐controlled trial of middle‐aged (40‐72 years old) adults who were randomly assigned to receive simvastatin 40 mg (n=44) or placebo (n=44) daily for 18 months to evaluate impact on dementia‐related biomarkers (primary end points) and measures of vascular health (secondary end points). This analysis focuses on the predetermined secondary end points of changes in central aortic blood pressure, aortic augmentation index, and brachial artery flow‐mediated dilation. Measurements were performed at baseline and after 6, 12, and 18 months. Multivariable models were used to identify predictors of these prespecified vascular end points. Study groups were similar at baseline; low‐density lipoprotein cholesterol declined in the statin group but not in the placebo group (P<0.01). There were no significant differences in changes in central blood pressure parameters or flow‐mediated dilation (all P>0.2). After 12 months, augmentation index decreased from baseline in the statin group compared with the placebo group (−2.3% [5.5%] versus 1.2% [5.7%], P=0.007), but by 18 months the response in both groups trend toward baseline (−1.1% [5.8%] versus 0.2% [4.8%], P=0.3). Low‐density lipoprotein cholesterol was not associated with changes in augmentation index at any time point.ConclusionsStatin therapy led to a short‐term reduction in augmentation index after 12 months, but this effect did not persist after 18 months despite continued reduction in low‐density lipoprotein cholesterol levels. These findings suggest that statins may have a transient effect on aortic stiffness.Clinical Trial RegistrationURL: https://www.clinicaltrials.gov/. Unique identifier: NCT00939822.

PATTERN OF CHANGES OF CENTRAL BLOOD PRESSURE AND VOLUME DEPENDENT ECHOCARDIOGRAPHIC PARAMETERS IN MONITORING OF NORMOTENSIVE PREGNANCY

Objective: We investigated changes of brachial and central blood pressure (BP) as well as volume dependent echocardiographic parameters in different time points of pregnancy.Design and method: Data from 60 healthy pregnant women (mean age 31.4 ± 4.3 years) were analysed. Hypertensive women were excluded from the study. In all women complete echocardiographic study, brachial and central BP measurements were performed at 11–13, 20–22 and 30–32 weeks of pregnancy. Central and brachial BP was measured by Pulsecor (CardioScope) device. In echocardiography: left ventricle end diastolic volume (LVEDV), early diastolic peak flow velocity (E velocity), late diastolic peak flow velocity (A velocity), left atrium area (LAA) and left atrium volume index (LAVI) were assessed. Also E/A index was calculated. Results: Brachial systolic BP (SBP) was higher and brachial diastolic BP (DBP) was lower as compared to respectively central SBP and central DBP at all three time points (p < 0.0001- for each). Brachial and central SBP and DBP levels were higher at 11–13 as compared to 20–22 weeks, but no difference was found between 20–22 and 30–32 weeks (Table). There was a significant increase of LAVI between all three-time points. LVEDV and LAA increased between 11–13 and 20–22 weeks but not between 20–22 and 30–32 weeks. Significant decrease in E velocity between 20–22 and 30–32 weeks was observed. There were no differences in E/A between subsequent measurements (Table). There were no significant differences in heart rate between time points. Conclusions: Our results indicate that LAVI is the best echocardiographic parameter reflecting physiological changes in blood volume overload in normal uncomplicated pregnancy. We also observed that changes in brachial BP were consistent with changes in central BP. Brachial BP and LAVI are sufficient parameters in monitoring physiological pregnancy.

Diurnal changes in central blood pressure and pulse pressure amplification in patients with obstructive sleep apnoea

Study objectivesRecent evidence suggests that compared to peripheral blood pressure (BP), central BP may be more strongly associated with target organ damage and cardiovascular morbidity and mortality. Technological advances now allow the ambulatory measurement of peripheral and central BP over 24 ​h. For the first time, we set out to characterise the diurnal profile of central BP and pulse pressure amplification (PPA) in patients with obstructive sleep apnoea (OSA). MethodsIn this observational study, patients with moderate to severe OSA underwent 24 ​h central and peripheral BP testing before and after at least 4 weeks of CPAP therapy. Concurrent actigraphy was performed to confirm sleep and wake times. Results36 patients were screened, 31 had successful testing (mean (SD) age 45 ​± ​10 years, AHI 58 ​± ​27 events/hr, Office BP 136/89 ​± ​10.7/9.5 ​mmHg, 32% on anti-hypertensives, 77% dippers), 21 completed testing post CPAP. Central systolic and diastolic BP followed the same nocturnal dipping profile as peripheral BP, however the peripheral pulse pressure (PP) narrowed in sleep (−3.2 ​mmHg, p ​< ​0.001), whereas the central PP remained unchanged (0.124 ​mmHg, NS), causing a significant reduction in PPA overnight (−10.7%, p ​< ​0.001). The magnitude of dip in central systolic pressure was less than peripheral systolic pressure (by 2.3 ​mmHg, p ​< ​0.001). After treatment with CPAP, the PPA reduction overnight was attenuated (by −3.3%, p ​= ​0.004). ConclusionsIn moderate to severe OSA, central BP and PPA reduce overnight during sleep. Further randomised controlled studies are needed to quantify the differential effects of CPAP and anti-hypertensives on central versus peripheral BP.

(336) Gender Differences in Cardiovascular Reactivity to Experimental Pain Assessment in Pain-Free Adults

There is a broad literature indicating gender differences in cardiovascular heart diseases. However, gender differences in cardiovascular reactivity to experimental pain have revealed conflicting results. Therefore, we aimed to establish gender differences to experimental pain assessment in cardiovascular reactivity. Cardiovascular reactivity was measured by the change in Central Blood Pressure (CBP), Peripheral Arterial Stiffness (PAS), and Heart Rate Variability (HRV) before and after experimental pain assessment in 28 healthy subjects (12 males, age = 43.7046±6 years; 16 females, age= 49.31±7). CBP and PAS were determined non-invasively by pulse wave analysis (XCEL, SyphgmoCor). High-frequency (HF) and low-frequency (LF) bands were explored as a HRV parameter during each of the phases as an index of vagal cardiac control and sympathetic cardiac activation (MP-150, Biopac). Thermal stimuli were applied to the forearm by a contact thermode to assess thermal pain Tolerance. Repeated measures ANOVA showed a significant interaction term between gender and central diastolic blood pressure [F(1,25)=4.66, p=0.04], where males experienced a significantly steeper increase than females (males ΔCBP 11.35 mm Hg vs. females ΔCBP 2.21 mm Hg) . The Central Augmented pressure and the AIX@HR75 (PAS indicators) increased significantly between baseline and pain tolerance with a significant main effect of gender, where females had a higher central augmented pressure and AIX@HR75 than males. No interaction term was observed between HRV variables and gender. These preliminary results imply that in general males have a higher cardiovascular reactivity due to pain induction than females. However, females showed larger PAS, which could produce a ceiling effect on their cardiovascular reactivity. Further studies in a larger sample and in patients with chronic pain could provide stronger evidence about the relationship between chronic pain and cardiovascular risk.

Augmenting central arterial stiffness following eradication of HCV by direct acting antivirals in advanced fibrosis patients

Chronic hepatitis C (CHC) is strongly associated with risks of cardiovascular diseases. The impact of direct acting antiviral (DAA) therapy on central blood pressure remains unclear. This investigation evaluates changes in central blood pressure following DAA therapy. One hundred and two DAA-treated patients were prospectively enrolled. Lipid profiles and pulse wave analysis of brachial artery by cuff sphygmomanometry including augmentation index (AIx), a parameter of central artery stiffness, were evaluated. All of the 102 patients achieved sustained virological response (SVR12). Cholesterol and LDL significantly increased following SVR12. Along with lipid changes, significantly higher central diastolic pressure (78.2 ± 14.2 mm Hg at baseline vs. 83.3 ± 13.9 mm Hg at SVR12, p = 0.011) and AIx (33.0 ± 12.7% at baseline vs. 36.9 ± 12.9% at SVR12, p = 0.012) were only observed in the advanced fibrosis patients. Co-morbid diseases, including hypertension (33.4 ± 13.0% vs. 39.7 ± 12.6%, p = 0.003), abnormal waist circumference (33.8 ± 12.2% vs. 38.0 ± 13.2%, p = 0.027), and metabolic syndrome (34.5 ± 12.1% vs. 39.0 ± 11.2%, p = 0.043) were associated with augmented AIx upon SVR12. The augmented central artery stiffness following viral eradication by DAA therapy may raise the concern of short-term cardiovascular risk in CHC patients.

Diurnal changes in central blood pressure and pulse pressure amplification in obstructive sleep apnoea

Diurnal changes in central blood pressure and pulse pressure amplification in obstructive sleep apnoea

Comparison of the Assessment of Orthostatic Hypotension Using Peripheral and Central Blood Pressure Measurements.

BackgroundOrthostatic hypotension (OH) is associated with falls and cardiovascular events. There is growing evidence that central blood pressure (CBP) is better than peripheral blood pressure (PBP) in predicting adverse outcomes. The objectives of this study were to assess 1) the prevalence of OH identified using PBP and CBP and the levels of agreement, 2) the respective associations between OH and falls and cardiovascular comorbidities, by PBP and CBP, and 3) the association of OH with arterial wall stiffness markers (augmentation pressure (AP) and augmentation index (AI)).MethodsAn observational case-control study of subjects aged 50 years and above was conducted at the University of Alberta Hospital inpatient wards and outpatient clinics. This study used a non-invasive technology called SphygmoCor to assess changes in CBP between lying, 1, 3 and 6 min of standing. AP and AI, which are markers of arterial wall stiffness, were also measured in this study. Dementia, significant psychological problems, and isolation precautions were exclusion criteria. Both PBP and CBP were measured with arm cuffs in lying and standing positions. OH was diagnosed using consensus criteria.ResultsOf the 71 participants recruited, mean age was 72.3 ±10.3 years, 52% were males, 32% had a history of falls and 72% had hypertension. OH occurred within 1, 3 or 6 min of standing (transient OH) in 31% by PBP and 27% by CBP (kappa = 0.56). OH persisted for all 6 min (persistent OH) in 16% by both PBP and CBP (kappa = 0.68). A significant relationship was observed between transient OH by CBP and baseline hypertension (P = 0.05) and dyslipidemia (P = 0.02). There was a significant difference in the mean AP between subjects with and without central persistent OH (P = 0.02), but not between subjects with and without peripheral persistent OH. The mean AI was not significantly different between subjects with or without central or peripheral persistent OH and between subjects with and without peripheral or central transient OH.ConclusionPrevalence of OH was similar between PBP and CBP. However, there was only moderate agreement with OH identified by PBP and CBP indicating some inconsistencies across the sample in identifying OH.

The effect of intermittent fasting on blood pressure variability in patients with newly diagnosed hypertension or prehypertension

Intermittent fasting is a phenomenon which can be observed in most humans. The effect of intermittent fasting on blood pressure variability (BPV) has not previously been investigated. The purpose of this study was to assess the effect of fasting on blood pressure (BP) (with office, home, central, and ambulatory blood pressure monitoring [ABPM]) and on BPV. Sixty individuals were included in the study. Office, home, ABPM, and central BP measurements were performed before and during intermittent fasting. Standard deviation and coefficient variation were used for office and home BPV measurement, while the smoothness index was used to calculate ABPM variability. Patients’ BP and BPV values before and during intermittent fasting were then compared. Intermittent fasting resulted in a significant decrease in office BP values and ABPM measurements but caused no significant change in home and central BP measurements. Twenty-four hour urinary sodium excretion decreased. Smoothness values obtained from ABPM measurements were low; in other words, BPV was greater. BPV was higher in patients who woke up to eat before sunrise, but BPV was low in patients with high body mass index. Intermittent fasting produced a significant decrease in BP values in terms of office and ABPM measurements in this study but caused no significant change in central BP and home measurements. We also identified an increase in BPV during intermittent fasting, particularly in patients who rose before sunrise.

Evaluation of the reduction in central and peripheral arterial blood pressure following an oral glucose load.

The clinical significance of measuring central arterial blood pressure has been recently discussed. Although the postprandial reduction in blood pressure is well known, postprandial changes in central blood pressure have not been intensively studied. The present study investigated differences in the reduction of central and peripheral arterial blood pressure after administration of an oral glucose load.An oral glucose tolerance test (75 g) was performed in 360 participants in our physical checkup program. Brachial and central systolic blood pressures were assessed before and after the glucose load. Central arterial blood pressure was measured noninvasively using an automated device.The mean age was 53.6 ± 8.2 years. Both brachial (127.9 ± 17.7 to 125.0 ± 16.3 mm Hg) and central arterial blood pressures were significantly decreased after an oral glucose load (118.9 ± 17.9 to 112.8 ± 16.8 mm Hg). The reduction in blood pressure was greater in central (7.3 ± 11.5 mm Hg) than in brachial blood pressure measurements (3.4 ± 11.3 mm Hg, P < .001). Extreme blood pressure reduction (>20 mm Hg) was recorded more frequently in central (n = 43, 12.3%) than brachial blood pressure measurements (n = 20, 5.6%).An oral glucose load decreases both central and brachial systolic blood pressure, with more pronounced effects on central blood pressure. Postprandial reductions in blood perfusion of the important organs such as the brain may be underestimated when postprandial BP reduction is assessed using brachial BP measurements.

Regulation of blood flow and volume exchange across the microcirculation.

Oxygen delivery to cells is the basic prerequisite of life. Within the human body, an ingenious oxygen delivery system, comprising steps of convection and diffusion from the upper airways via the lungs and the cardiovascular system to the microvascular area, bridges the gap between oxygen in the outside airspace and the interstitial space around the cells. However, the complexity of this evolutionary development makes us prone to pathophysiological problems. While those problems related to respiration and macrohemodynamics have already been successfully addressed by modern medicine, the pathophysiology of the microcirculation is still often a closed book in daily practice. Nevertheless, here as well, profound physiological understanding is the only key to rational therapeutic decisions. The prime guarantor of tissue oxygenation is tissue blood flow. Therefore, on the premise of intact macrohemodynamics, the microcirculation has three major responsibilities: 1) providing access for oxygenated blood to the tissues and appropriate return of volume; 2) maintaining global tissue flood flow, even in the face of changes in central blood pressure; and 3) linking local blood flow to local metabolic needs. It is an intriguing concept of nature to do this mainly by local regulatory mechanisms, impacting primarily on flow resistance, be this via endothelial or direct smooth muscle actions. The final goal of microvascular blood flow per unit of time is to ensure the needed exchange of substances between tissue and blood compartments. The two principle means of accomplishing this are diffusion and filtration. While simple diffusion is the quantitatively most important form of capillary exchange activity for the respiratory gases, water flux across the blood-brain barrier is facilitated via preformed specialized channels, the aquaporines. Beyond that, the vascular barrier is practically nowhere completely tight for water, with paracellular filtration giving rise to generally low but permanent fluid flux outwards into the interstitial space at the microvascular high pressure segment. At the more leaky venular aspect, both filtration and diffusion allow for bidirectional passage of water, nutrients, and waste products. We are just beginning to appreciate that a major factor for maintaining tissue fluid homeostasis appears to be the integrity of the endothelial glycocalyx.

Change in home blood pressure associates more strongly with change in ECG-LVH than change in office blood pressure does: the Finn-home Study

Background: Increased arterial and aortic stiffness is common in patients with end stage renal disease (ESRD) and is significantly associated with all-cause and cardiovascular mortality. Kidney transplantation improves survival in patients with ESRD. However it is unclear whether aortic stiffness as measured by central aortic blood pressure, aortic pulse wave velocity (aPWV) and augmentation index (AIx) improves after transplant or not and if it does, what factors predict this improvement. Methods: The kidney transplant recipients transplanted from January 2014 onwards at our center with at least one year follow up were enrolled in this ongoing prospective study (N1⁄440). The central aortic blood pressure, aPWV and AIx were measured with Cardiograde Mobil-O-Graph pulse wave analysis (PWA) system immediate pre-transplant and at 1, 3, 6, and 12months post-transplant. We collected the baseline demographic and clinical information, and routine laboratory data including immunosuppression drug levels, serum creatinine, e-GFR, PTH, serum Ca2+ and PO4+, serum albumin, and lipid levels at each follow up. Results: From pre-transplant to 12 months post-transplant, we observed a trend in reduction of aPWV (7.9 0.6 m/sec vs. 7.1 0.2 m/s, p1⁄4 0.07), AIx (23.7 2.1% vs. 16.5 2.6%, p1⁄40.08) and an improvement in e-GFR (51.4 3.8 vs. 60 3.1 ml/min/m2, p 1⁄4 0.06). The change in central BP was not significant. The reduction in aPWV and AIx correlated with e-GFR improvement (r1⁄4 -0.72). In addition, the group with reduction in aPWV and/or AIx 10% (n1⁄4 22) as compared with the group with reduction in aPWV and/or AIx < 10% (n1⁄4 18) was significantly younger (39 3.4 vs. 48 4.6 years, p < 0.05), and had lower serum PTH (134 16.7 vs. 504 38.8 pg/ml p < 0.05) and higher e-GFR (65.4 2.8 vs. 48.3 3.2 p < 0.05) at 12 months post-transplant. Other laboratory parameters were not significant between the two groups. Conclusions: These results demonstrate that aortic stiffness tends to improve after kidney transplantation and it correlates with improvement in GFR and reduction in serum PTH. Currently, more patients are being enrolled to validate the above results and to assess the impact of changes in central blood pressure and aortic stiffness on post-transplant cardiovascular and kidney allograft outcomes.

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Objective: To evaluate the behavior of central blood pressure (BP) variables in male athletes before and during a very long distance walking - 310Km route in five days. Design and method: Longitudinal study with 25 participants. This walking nominated as ’Ecological Walk’ happens in Brazil every july since 1991. Its main goals are environmental preservation awareness, health lifestyle incitement as well as exercise practice incitement. The participants traveled the 310 Km during five days alternating walking and light running, a 72 Km/day average. First data collection occurred one month before the walking (V0) and the others, during the second (V2), third (V3) and fourth walking day (V4); just after the athletes finished the daily route. Mobil O Graph was the device used to get central BP variables: pulse wave velocity (PWV), augmentation index (AIx), peripheral vascular resistance (PVR), central pulse pressure (PPc) and amplified pulse pressure (PPA). Results: Sample composition was 25 males, regular physical activity practitioners, mean age 45,3 ± 9,1 years old. Brachial systolic (SBP) and diastolic blood pressure (DBP) had the same response during the route, reduction from V0 to V2, and a slight increase from V2 to V3 and V4. PPc decreased from V0 (33,5mmHg) to V2 (28,7mmHg); p = 0,05 and increased from V2 (28,7mmHg) to V4 (32,9mmHg); p = 0,01. Brachial PP decreased from V0 (49,2mmHg) compared with all the others evaluated days (38,2mmHg; 42,7mmHg; 41,2mmHg), respectively. PPA increased from V0 to V2, and decreased from V0 to V3 and from V0 to V4. PVR increased from V3 (1,07s*mmHg/ml) to V4 (1,13 s*mmHg/ml); p = 0,046. PWV decreased from V0 (7,0m/sec) to V2 (6,6m/sec) and from V0 (7,0m/sec) to V3 (6,5m/sec). Pulse wave velocity showed strong correlation with age during all the measurements. Conclusions: These datas indicate that central blood pressure changes are sharpest in the first days, after this it seems that an exercise physiological accommodation occurred. There was a strong correlation between age and pulse wave velocity in this sample.

Treatment of Sleep Apnea With CPAP Lowers Central and Peripheral Blood Pressure Independent of the Time-of-Day: A Randomized Controlled Study.

Obstructive sleep apnea (OSA) is a risk factor for hypertension and randomized controlled trials have shown that OSA treatment with continuous positive airway pressure (CPAP) reduces peripheral blood pressure and arterial stiffness. Arterial stiffness is known to augment central aortic blood pressure independent of peripheral brachial blood pressure. Currently, it is unclear whether the reduction in blood pressure with CPAP is similar between central and peripheral sites. It is also unknown whether there are any time-of-day influences on central blood pressure changes after CPAP. Thirty-eight patients received therapeutic and sham CPAP in random order for 8 weeks each with an intervening 1-month washout. Peripheral and central blood pressure and arterial stiffness (augmentation index and time to reflection) were measured by pulse wave analysis at end-of-treatment visits. Measurements were taken in the afternoon (~2 pm) and the next morning (~9 am). Compared to sham, CPAP significantly reduced central systolic (mean difference: -4.1 mm Hg; P = 0.003), central diastolic (-3.9 mm Hg; P = 0.0009), peripheral systolic (-4.1mm Hg; P = 0.004), and peripheral diastolic (-3.8 mm Hg; P = 0.001) blood pressure. These effects were not influenced by time-of-day. Time to reflection was improved with CPAP compared to sham (3.7 ms; P = 0.01). There was no overall difference in augmentation index however when examined by time-of-day, a modest reduction with CPAP was observed in the morning (-2.5%; P = 0.03) but not in the evening (0.12%; P = 0.91). CPAP reduces both central and peripheral blood pressure independent of the time-of-day. In contrast, modest improvements in conduit arterial stiffness after CPAP may only occur in the morning.

Correlation of Central Blood Pressure to Hypertensive Target Organ Damages During Antihypertensive Treatment: The J-TOP Study.

Some previous studies have shown that central blood pressure (BP) is more closely related to cardiovascular risks than brachial BP. This study compared the correlations between asymptomatic organ damages and each of central BP, brachial clinic BP, and home BP during antihypertensive treatment. In the Japan Morning Surge-Target Organ Protection (J-TOP) study, which compared bedtime or awakening dosing of candesartan (+diuretics as needed) among subjects with home systolic BP (SBP) higher than 135 mm Hg, we evaluated 180 hypertensive patients who successfully underwent pulse wave analysis by HEM-9000AI and measured their urinary albumin/creatinine ratio (UACR) and left ventricular mass index (LVMI) (n = 144) at baseline and after 6 months of treatment. During antihypertensive treatment, significant reductions were found in central SBP, UACR, and LVMI (all P < 0.001). Multiple regression analyses showed that the decrease in central SBP was associated with those of log-transformed UACR (β = 0.24, P < 0.01) and LVMI (β = 0.23, P = 0.04), independently of the decrease in both clinic and home SBP. The goodness-of-fit of the association between the reduction in SBP and the UACR (P < 0.01) or LVMI (P = 0.04) was improved by adding central SBP to the SBP measurement. These findings suggest that the change in central BP could be an important therapeutic target during antihypertensive treatment, in addition to peripheral clinic and home BP.

Effect of weight loss on central systolic blood pressure in elderly community-dwelling persons.

Central blood pressure (BP) has been shown to strongly associate with cardiovascular disease and outcome. Recent studies have demonstrated a relationship between changes in body size by exercise training and peripheral BP; however, the effect on changes in central BP is unknown. The aim of this study was to assess whether changes in body size are independently related to changes in central BP in the elderly. The subjects were 11 men (mean age, 68±6 years) and 84 women (68±7 years) from a rural village. Before and at the end of the 12-week training program, metabolic variables, and first peak radial systolic BP (SBP1) and second peak radial SBP (SBP2) as estimates of central SBP, were obtained. Radial augmentation index (AI) was calculated as follows: ((SBP2-diastolic BP (DBP))/(SBP1-DBP)) × 100 (%) and we used AI corrected at heart rate 75 per min (AI@75). After the 12-week training program, weight loss correlated strongly with reduction in brachial mean arterial pressure (MAP), radial SBP1, SBP2 and AI@75. After adjusting for confounding factors, weight loss was significantly and independently associated with each reduction in brachial MAP (β=0.34, P=0.001), radial SBP1 (β=0.31, P=0.002), SBP2 (β=0.37, P<0.001) and AI@75 (β=0.36, P=0.001). These findings suggest that weight loss by a 12-week training program may be an effective strategy to improve central BP parameters among Japanese elderly persons.

Efficacy of losartan and carvedilol on central hemodynamics in hypertensives: a prospective, randomized, open, blinded end point, multicenter study

Renin-angiotensin system (RAS) blockers have shown clinical outcomes superior to those of the beta (β)-blocker atenolol, despite similar reductions in the peripheral blood pressure (BP), perhaps because of different impacts on central hemodynamics. However, few comparative studies of RAS blockers and newer vasodilating β-blockers have been performed. We compared the central hemodynamic effects of losartan and carvedilol in a prospective, randomized, open, blinded end point study. Of the 201 hypertensive patients enrolled, 182 (49.6±9.9 years, losartan group=88 and carvedilol group=94) were analyzed. Carotid-femoral pulse wave velocity (cfPWV), aortic augmentation index (AIx), AIx corrected for a heart rate (HR) of 75 beats per minute (AIx@HR75) and central BP were measured noninvasively at baseline and after a 24-week treatment regimen with losartan or carvedilol. After 24 weeks, there were no between-group differences in the brachial BP, cfPWV, AIx@HR75 or central BP changes, except for a more favorable AIx effect with losartan. The changes in all measured metabolic and inflammatory parameters were also not significantly different between the two groups, except for uric acid. Losartan and carvedilol showed generally comparable effects on central hemodynamic indices, metabolic profile, inflammatory parameters and peripheral arterial pressure with a 24-week treatment.

Persistent elevation of central pulse pressure during postural stress in patients with type 2 diabetes mellitus

An abnormal increase or decrease in blood pressure (BP) in response to postural stress is associated with increased risk of developing hypertension and stroke. However, the haemodynamic responses contributing to changes in central BP with postural stress are not well characterised. We aimed to determine this in controls compared to patients with type 2 diabetes mellitus (T2DM), whom we hypothesised would have an abnormal postural response. 41 participants (20 control, 21 T2DM) underwent measurement of brachial and central BP (by radial tonometry), with simultaneous bioimpedance cardiography (to determine stroke volume (SV) and cardiac output (CO)) and heart rate variability in seated and standing postures. Systemic vascular resistance (SVR; mean arterial pressure/CO), and arterial elastance (EA; end systolic pressure/SV) were calculated. Postural changes were defined as seated minus standing values. Central pulse pressure (PP) was higher in patients with T2DM and did not change from seated-to-standing positions, whereas there was a significant decrease upon standing in controls (P<0.05). The change in central systolic BP (SBP) correlated with change in SVR and EA in controls (r=0.67 and 0.68, P<0.05, respectively), but not in patients with T2DM (r=-0.05 and r=0.03, P>0.05, respectively). SV was the only significant correlate of change in central SBP in T2DM patients (r=0.62, P<0.05) and this was not observed in controls (r=-0.08 P>0.05). We conclude that central haemodynamic responses to postural stress are altered in patients with T2DM and result in persistent elevation of central PP while standing. This may contribute to increased cardiovascular risk associated with T2DM.

Resistance exercise training reduces arterial reservoir pressure in older adults with prehypertension and hypertension

We examined changes in central blood pressure (BP) following resistance exercise training (RET) in men and women with prehypertension and never-treated hypertension. Both Windkessel theory and wave theory were used to provide a comprehensive examination of hemodynamic modulation with RET. Twenty-one participants (age 61±1 years, n=6 male; average systolic blood pressure (SBP)/diastolic blood pressure (DBP)=138/84 mm Hg) were randomized to either 12 weeks of RET (n=11) or an inactive control group. Central BP and augmentation index (AIx) were derived from radial pressure waveforms using tonometry and a generalized transfer function. A novel reservoir-wave separation technique was used to derive excess wave pressure (related to forward and backward traveling waves) and reservoir pressure (related to the capacitance/Windkessel properties of the arterial tree). Wave separation using traditional impedance analysis and aortic flow triangulation was also applied to derive forward wave pressure (Pf) and backward wave pressure (Pb). There was a group-by-time interaction (P<0.05) for central BP as there was a significant ~6 mm Hg reduction in SBP and ~7 mm Hg reduction in DBP following RET with no change in the control condition. There were also group-by-time interactions (P<0.05) for Pf, excess wave pressure and reservoir pressure attributable to reductions in these parameters in the RET group concomitant with slight increases in the control group. There was no change in AIx or Pb (P>0.05). RET may reduce central BP in older adults with hypertension and prehypertension by lowering Pf and reservoir pressure without affecting pressure from wave reflections.