Mean Brachial Blood Pressure Research Articles

Hydrochlorothiazide--Teaching an Old Drug New Tricks.

Hydrochlorothiazide--Teaching an Old Drug New Tricks.

Repeatability of SphygmoCor pulse wave analysis in assessing arterial wave reflection in pregnancy using applanation tonometry

Objective: To estimate clinical agreement in relation to measuring aortic augmentation index (AIX-75) in pregnancy in a routine clinical setting. Methods: A hospital-based clinical agreement study of 20 women in which two trained nurses alternated in measuring arterial function (AIX standardized to a heart rate of 75 beats-per-minute, AIX-75) on a single occasion in triplicate, after participants had rested semi-recumbent for 15 min. Right brachial blood pressure (BP) was measured using the Microlife 3BTO-A oscillometric device. Radial applanation pulse wave analysis (PWA) was undertaken according to current guidelines using the SphygmoCor device with a hand-held Millar tonometer applanated at the right radial artery. Each nurse was blinded to others PWA results. Observer agreement was assessed using the Bland–Altman “limits of agreement” (LOA, mean difference ±2 SD) approach. Results: Median gestation was 37 weeks (range: 12–42), mean age 31 years, 30% nulliparous, mean brachial BP 128/79 mm Hg. Based on all six PWA measurements, mean AIX-75 was 11.7 (range: −18 to +35). The between-observer LOA was 0.1 ± 11.0 and the within-observer LOA’s were 1 ± 10 and −2 ± 8 for the two nurses. Observer differences did not vary systematically with the magnitude of AIX-75. Conclusion: AIX-75 can be measured by nurses using PWA in pregnancy with a high level of observer agreement.

Characteristics of pulse wave velocity in elastic and muscular arteries

Although aortic pulse wave velocity (PWV) has been accepted as gold standard of arterial stiffness, characteristics of PWVs in other arteries have never been reported. We measured carotid-femoral, carotid-pedis, carotid-radial, and femoral-pedis PWVs by a validated tonometry PulsePen, and assessed body fat percentage by bioelectrical impedance analyzer, carotid intima-media thickness (IMT) by ultrasonograph, and other cardiovascular risk factors, in 198 patients from our ambulatory cardiovascular department. Carotid-femoral and carotid-pedis PWVs increased significantly and progressively with age in both men and women (P ≤ 0.03), whereas only in men, a slight increase and decrease in carotid-radial and femoral-pedis PWVs, respectively, were detected with aging (P ≤ 0.006). Carotid-femoral and carotid-pedis PWVs, but not carotid-radial and femoral-pedis PWVs, were significantly associated with age, body height and body fat percentage, brachial mean blood pressure (MBP), and pulse pressure (PP), carotid PP, PP amplification, carotid IMT, plasma glucose and taking antihypertensive agent (P ≤ 0.047). In full adjustment models, carotid-femoral PWV increased by 0.89 ± 0.21, 0.38 ± 0.13, 0.74 ± 0.26, 0.40 ± 0.16, 0.51 ± 0.23 m/s, with an increase of 10 years in age, of 1 mmol/l in plasma glucose, of 10 mmHg in brachial PP, of 100 μm in IMT, and of 10 mmHg in brachial MBP, respectively, whereas carotid-pedis PWV increased by 0.31 ± 0.11 and 0.33 ± 0.12 m/s with an increase of 10 years in age and of 10 mmHg in brachial MBP, respectively. Arterial stiffness in elastic arteries, but not in muscular arteries, increased significantly and progressively with age, and was more closely correlated to BP, plasma glucose and arterial thickness.

78 CHARACTERISTICS OF PULSE WAVE VELOCITIES IN ELASTIC AND MUSCULAR ARTERIES

Background: Although aortic pulse wave velocity (PWV) has been accepted as the gold standard of arterial stiffness, and applied as a cardiovascular risk factor in various populations, the characteristics of PWVs in other arteries has never been reported. Methods: We measured carotid-femoral, carotid-pedis, carotid-radial, and femoral-pedis PWVs by a validated tonometry PulsePen (DiaTecne s.r.l., Milan, Italy), and assessed body fat percentage and carotid intema-media thickness (IMT) by bioelectrical impedance analyzer and ultrasonograph in 198 consecutive patients from our ambulatory cardiovascular department. Results: Carotid-femoral and carotid-pedis PWVs increased significantly and progressively with age in both men and women (P≤0.03), while only in men, a slight increase and decrease in carotid-radial and femoral-pedis PWVs were observed with age (P≤0.006). Carotid-femoral and carotid-pedis PWVs, but not carotid-radial and femoral-pedis PWVs, were significantly associated with age, body height and body fat percentage, brachial mean blood pressure (MBP) and pulse pressure (PP), carotid PP, PP amplification, and IMT (r: -0.24 to 0.51, P≤0.047). In full adjustment models, carotid-femoral PWV increased by 0.93 ± 0.21, 0.82 ± 0.27, 0.40 ± 0.16, 0.55 ± 0.23 m/s, with an increase of 10 years in age, of 10 mmHg in brachial PP, of 100 μm in IMT, and of 10 mmHg in brachial MBP, respectively, whereas carotid-pedis PWV increased by 0.34 ± 0.12 and 0.30 ± 0.11 m/s with an increase of 10 mmHg in brachial MBP and 10 years in age, respectively. Conclusion: Arterial stiffness in elastic arteries, but not in muscular arteries, increased significantly and progressively with age, and was more closely associated with BP and arterial wall thickness.Carotid-femoral (filled circles with solid line), carotid-pedis (filled circles with spotted line), carotid-radial (unfilled circles with solid line), and pedis-femoral (unfilled circles with spotted line) pulse wave velocities were presented in different age groups, in men and women, respectively.

Contrasting Hemodynamic Mechanisms of Losartan- vs. Atenolol-Based Antihypertensive Treatment: A LIFE Study

Pharmaceutical differences in central hemodynamics might influence cardiac response to antihypertensive treatment despite similar lowering of brachial blood pressure (BP). Data from all patients with at least two echocardiographic examinations in the Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) echocardiographic substudy (n = 801); high-risk patients on losartan- vs. atenolol-based antihypertensive therapy. Echocardiography was performed annually for 4 years to measure stroke index (SI), heart rate, cardiac index (CI), conduit artery stiffness assessed as pulse pressure/stroke index (PP/SI) and total peripheral resistance index (TPRI). Atenolol- and losartan-based therapy reduced BP similarly (cumulative difference in mean brachial blood pressure 0.3 mm Hg, P = 0.65). After 4 years the cumulative means of SI and heart rate were 1.8 ml/m(2) higher and 5.7 beats/min lower on atenolol-based treatment, respectively (both P < 0.001). This kept CI below baseline in atenolol-treated patients, whereas in the losartan group CI was unchanged from baseline throughout the study. TPRI was decreased more and remained lower in the losartan group (cumulative difference in mean TPRI 287 dynes/sec(-5)/cm/m(2), P < 0.001). These findings partly explained univariate differences in systolic- and diastolic function indices between the two treatments; fully adjusted losartan was only associated with a smaller left atrial diameter (cumulative mean difference 0.07 cm; 95% confidence intervals, -0.13 to -0.01, P = 0.03). Contrasting hemodynamics impacted cardiac response to similar reductions in brachial BP on losartan- vs. atenolol-based therapy. The similar reduction of PP/SI suggests that the antihypertensive regimens used in the LIFE study had comparable effects on arterial stiffness (LIFE study; NCT00338260)

Mineralocorticoid receptor blockade does not affect arterial compliance in middle‐aged and older adults with and without metabolic syndrome

Aging and metabolic syndrome (MS) are associated with decreased arterial compliance but the underlying mechanisms are not completely understood. Aldosterone and activation of the mineralocorticoid receptors (MR) are thought to be elevated in MS and may contribute to reduced arterial compliance. We hypothesized that chronically elevated activation of MR is partly responsible for reduced arterial compliance in aging/MS and that MR blockade would lead to greater improvements in carotid artery compliance (CAC: high resolution ultrasonography and applanation tonometry) in middle‐aged (MA) and older (O) adults with vs. without MS. To test this hypothesis, we administered 100 mg of Eplerenone (MR blocker) or placebo per day for 4 weeks in a randomized, double blind, crossover design, in 6 MA/O adults with and 14 without MS. At baseline, brachial blood pressure (BP) was higher (mean BP: 98±2 vs. 90±3 mmHg, P=0.03) and CAC was lower (0.12±0.02 vs. 0.19±0.03 mm2/mmHg, P=0.03) in the MS group. MR blockade reduced brachial BP similarly in both groups (delta mean BP: −6±2 vs. −3±1 mmHg, P=0.1, with vs. without MS) but it did not affect CAC in either group (delta CAC: −0.01±0.01 vs. −0.02±0.03 mm2/mmHg, P=0.4, with vs. without MS). In conclusion, arterial compliance in MA/O adults with or without MS is not affected by short‐term MR blockade.Supported by AHA Grant 0865117F and NIH Grant AG032067.

Determinants of pressure wave reflection: characterization by the transit time-independent reflected wave amplitude

The effects of pressure wave reflection have been incompletely described by the central augmentation index (cAI) and augmented pressure (Pa). We therefore investigated the determinants of amplitude of the reflected wave (Pb), which is independent of the reflected wave transit time (RWTT) and has been shown to predict cardiovascular mortality in the general population. A total of 180 (117 men, mean age 68 years old) patients were recruited. Carotid pressure waveforms derived by tonometry at baseline and 3 min after administration of sublingual nitroglycerin (NTG) were calibrated and then decomposed into the forward and backward waves to yield Pb. The ratio of pre-ejection period/ejection time (PEP/ET) was measured. By stepwise multivariate analysis, independent determinants of Pb included brachial mean blood pressure (β=0.56, P<0.001), heart rate (β=-0.29, P<0.001), age (β=0.20, P<0.001), PEP/ET (β=-0.16, P=0.004) and height (β=-0.13, P=0.018). RWTT, body mass index and sex were significant independent determinants of Pa and cAI but did not contribute to Pb. Change of Pb but not Pa or cAI significantly predicted the changes of carotid systolic (r=0.550, P<0.001) and pulse pressure (r=0.618, P<0.001) after NTG. In conclusion, determinants of Pb differ from those of cAI and Pa. Pb is independent of sex and RWTT.

Abstract 5151: Waveform Reflections and Arterial Stiffness in the Prediction of 15.1-Year All-Cause and Cardiovascular Mortalities: A Community-Based Study

Background- The role of arterial wave reflection, usually assessed by the transit-time dependent augmentation index (AI) and augmented pressure (Pa), in the prediction of cardiovascular events may have been underestimated. We investigated whether the transit-time independent measurements of reflected wave magnitude predict cardiovascular outcomes independently of arterial stiffness indexed by carotid-femoral pulse wave velocity (PWV). Method- A total of 1272 participants (47.0% women) from a community-based survey were studied. Carotid pressure waveforms derived by tonometry were decomposed to generate forward wave amplitude (Pf), backward wave amplitude (Pb), and reflection index (RI, = [Pb/(Pf+Pb)]), in addition to AI, Pa, and reflected wave transit time (RWTT). Results During a median follow-up of 15.1 years, 225 deaths occurred, including 64 cardiovascular origins. In univariate Cox proportional hazards regression analysis, PWV, Pa and Pb predicted all-cause and cardiovascular mortalities in both men and women whereas AI, RWTT and RI were predictive only in men. In multi-variate Cox analysis accounting for age, height, and heart rate, Pb predicted all-cause mortality in women and cardiovascular mortality in both men and women, whereas Pa only predicted cardiovascular mortality in men but not in women. When PWV and Pb were jointly entered into the multivariate model accounting for age, sex, height, heart rate, and brachial mean blood pressure, Pb (hazard ratio 1.066, 95% confidence interval 1.023–1.110) but not PWV (1.086, 0.993–1.189), independently predicted cardiovascular mortality. Conclusion- Pb, a transit-time independent measurement of reflected wave magnitude, predicted long term cardiovascular mortality in men and women independently of PWV.

Central aortic pressure and clinical outcomes

Central aortic pressure and clinical outcomes

Arterial stiffness and central hemodynamics in treated hypertensive subjects according to brachial blood pressure classification

International recommendations have classified brachial blood pressure (BP) in subgroups enabling better cardiovascular risk stratification. Central BP is an independent predictor of cardiovascular risk, differing from brachial BP through the predominant influence of arterial stiffness and wave reflections. Central BP has never been studied in relation to international guidelines for brachial BP classification. In 580 chronically treated hypertensive subjects we measured: carotid-femoral pulse wave velocity (PWV), carotid artery augmentation index (AI) and carotid blood pressures, using applanation tonometry and pulse wave analysis, and using brachial BP for carotid pressure wave calibration. For each given brachial value, carotid systolic blood pressure (SBP) and PP were significantly lower than the corresponding brachial SBP and PP. This pressure amplification was significantly lower in the 'optimal' and 'normal' BP ranges (6.8-7.4 mmHg) than in the higher BP ranges (10.1-11.3 mmHg), mainly depending on heart rate (HR) and PWV levels. PWV gradually increased as a function of brachial BP classification and was a significant predictor of this classification independently of age, drug treatment, atherosclerotic lesions and even mean BP. Finally, PWV was a highly sensitive marker of the effective BP control throughout all decades of age. Under chronic antihypertensive therapy, central BP does not strictly parallel the corresponding brachial BP classification, depending on differences in aortic stiffness and HR. Whether aortic PWV might predict the brachial BP classification and/or the presence of effective BP control, as suggested in this study, needs further confirmation.

Correction of carotid augmentation index for heart rate in elderly essential hypertensives

Carotid augmentation index (AI) is used as a surrogate measure of arterial stiffness. Although arterial stiffness has been shown to either remain unchanged or increase with an increase in heart rate, AI decreases as heart rate increases. This study aimed to quantify this confounding effect of heart rate on AI. We investigated 873 hypertensives, mean age 72 ± 5 years, 44% men, mean brachial blood pressure 161 ± 21/82 ± 11 mm Hg. Carotid artery tonometry with simultaneous continuous wave Doppler measurement of ascending aortic blood flow was performed. AI was calculated from the carotid pressure waveform. Waveforms were decomposed into their forward and backward components and the time to reflection between the maxima of the forward and backward pressure waves was measured. AI showed a stronger ( P < .001) association with ejection time (r = 0.48, P < .001) than with heart rate (r = −0.28, P < .001). Although AI is strongly related to the time to reflection (r = −0.51, P < .001), only a weak association was seen between time to reflection and heart rate (r = 0.16, P < .001) or ejection time (r = −0.12, P < .001). Our analysis in an elderly cohort of patients with essential hypertension demonstrates that AI is related to the time to reflection. It also reiterates that AI is confounded by heart rate without any underlying heart rate-dependent change in wave reflection. In population-based studies the confounding effect of heart rate can potentially be corrected. AI remains strongly (r = −0.52) related to time to reflection after correction for the effects of ejection time on AI.

Relationship between ultrasound assessment of arterial wall properties and blood pressure.

Physical properties of an artery can be described in terms of stiffness, distensibility, and compliance. Changes in these properties can predict atherosclerosis disease, but it is necessary to identify an index that is independent of changes in blood pressure. We measured common carotid artery diameter and pulsatile change with an ultrasonic phase-locked, echo-tracking system in 7 subjects whose mean brachial blood pressure had varied 15 mm Hg or more within a month. Patients taking antihypertensive agents were excluded from the study. We measured changes in arterial diameter (n = 41) at least four times during the study period and calculated the pressure-strain elastic modulus (Ep), distensibility coefficient (DC), cross-sectional compliance (CC) and stiffness parameter (beta) from inner diameter, its pulsatile change, and blood pressure. The correlation coefficients of mean blood pressure with each index are as follows: Ep, 0.53; DC, 0.58; CC, 0.63; beta, 0.21. When mean blood pressure increased 1 mm Hg, the change in each index at 100 mm Hg was as follows: Ep, 1.48 +/- 1.30%; DC, -1.05 +/- 0.97%; CC, -0.69 +/- 0.90%; beta, 0.45 +/- 1.11%. Among the four indices that measure the properties of the arterial walls, stiffness parameter beta was the least dependent on blood pressure. Thus, it appears to have usefulness as an index of arterial wall sclerosis.

透析回路の圧力に基づく上腕平均血圧の連続計測法

透析中の急激な血圧降下を直ちに検知し, より安全な透析治療を実現するために, 血圧の連続計測法を考案した. 動静脈のシャント部の血圧が, 上腕血圧と相関が高いことを利用して, 患者に特別な負担をかけずに計測しようとするものである. このため新たに, 透析回路の血液ポンプの上流にも, エアートラップを設け, ダイアライザ下流側と併せて2箇所の圧力を測定した. これらの圧力と上腕血圧, 体外循環血流量の関係式を, 等価電気回路による解析により求めた. コンピュータにより, 回路圧の読み込みと上腕血圧の計算を行い, オンライン表示を行った. 従来のマンシェットによる血圧測定法と比較を行い, 本方法の有効性を確認した.

On the pathogenesis of bedsores. Skin blood flow cessation by external pressure on the back.

This paper is devoted to elucidation of the question: Which external pressure is required to stop skin blood flow at the skin - support interface in humans lying on the back in the supine position? Cessation of blood flow was recorded as cessation of washout of an intracutaneous depot of 131I-antipyrine mixed with histamine. The external pressure was measured by a small airfilled plastic cushion connected to a mercury manometer. In 11 normal subjects, eight patients with hypertension and seven patients with tetra- or paraplegia the "flow cessation external pressure" (FCEP) was strongly correlated to the auscultatory brachial mean blood pressure (p less than or equal to 0.001). The difference mean blood pressure - FCEP was on average 4 mmHg (range (-11) - (+20) mmHg) and there was no significant difference between the three groups studied. Thus external pressure exceeding the actual mean blood pressure will stop skin circulation.