Arterial distensibility and circadian blood pressure variability

OBJECTIVE: To analyse the relationships between arterial distensibility and blood pressure level and its circadian variability assessed by non-invasive ambulatory blood pressure monitoring. DESIGN: One hundred and six patients (69 men, 37 women; aged 20-72 years) without any cardiovascular complication or treatment underwent 24 h ambulatory blood pressure monitoring. Aortic distensibility was evaluated by carotid-femoral artery pulse-wave velocity measurements performed with a validated automatic device (Complior). RESULTS: The pulse-wave velocity correlated significantly with age (P < 0.001), systolic blood pressure (P < 0.01) and heart rate (P < 0.05). Subjects with higher pulse-wave velocities (above the median value) had higher ambulatory blood pressure and heart rate values, mainly during night-time, and present a smaller nocturnal fall both in systolic and in diastolic blood pressure than do those with lower pulse-wave velocities (below the median). The pulse-wave velocity was revealed to be an independent predictor of the nocturnal fall in systolic blood pressure (multiple r = 0.272, P < 0.02) whereas age and, to a lesser extent, mean 24 h diastolic blood pressure were independent predictors of the nocturnal fall in diastolic blood pressure (multiple r = 0.387, P < 0.001). CONCLUSION: Reductions in arterial distensibility are associated with increased blood pressure and heart rate levels whereas perturbations of the circadian blood pressure profile are associated with increased nocturnal values. The increased risk of end-organ damage and vascular events in the presence of higher nocturnal blood pressure values suggests that a study of arterial distensibility in the normal follow-up of hypertensive patients might be of benefit.     

Pulse pressure amplification, pressure waveform calibration and clinical applications

Obtaining pulse pressure non-invasively from applanation tonometry requires the calibration of pressure waveform with brachial systolic and diastolic blood pressure. In the literature, several calibration methodologies are applied, and clinical studies disagree about the predictive value of central hemodynamic parameters. Our aim was to compare 4 calibration methodologies and assess the usefulness of pulse pressure amplification as an index independent of calibration. We investigated 108 subjects with tonometry in carotid, femoral, brachial, radial and dorsalis-pedis arteries; pulse pressure amplification between arterial waveforms was calculated. Four methods to calibrate the waveforms were compared: the 1/3 rule, the 40% rule, the integral of radial and brachial waveforms. Pulse pressure amplification in 5 arterial territories (carotid-femoral, carotid-brachial, carotid-radial and carotid-pedis amplifications; femoral-pedis amplification) was studied. Pulse pressure was successfully measured non-invasively at the 5 arterial sites. Pulse pressure was markedly dependent on calibration, with differences up to 18 mmHg between methods. Calculation of pulse pressure amplification eliminated effects of calibration method. Furthermore, pulse pressure amplifications in the 5 arterial sites presented a distinct pattern of clinical/biological determinants: heart rate and body height were common determinants of carotid to brachial, radial and femoral amplifications; diabetes was related to carotid to brachial amplification and pulse wave velocity to femoral to pedis amplification. In conclusion, the calibration of pulse pressure will influence results of clinical trials, but calculation of pulse pressure amplification can avoid this. We also suggest that the alteration of amplification in each arterial territory might be considered as a signal of clinical/subclinical damage.     

Evaluation of two devices for self-measurement of blood pressure according to the international protocol: the Omron M5-I and the Omron 705IT

BACKGROUND: Two devices for self-measurement of blood pressure at the brachial artery-the Omron M5-I and the Omron 705IT-were evaluated according to the international protocol of the European Society of Hypertension. DESIGN: The international validation protocol is divided into two phases: the first phase is performed on 15 selected subjects and if the device passes this phase, 18 supplementary subjects are included making a total number of 33 subjects on which the final validation is performed. METHODS: For each subject, four blood pressure (BP) measurements were performed simultaneously by two trained observers using mercury sphygmomanometers alternately with three measurements by the tested device. The difference between the BP value given by the device and that obtained by the two observers (mean of the two observers) was calculated for each measure. The 99 differences were classified into categories (相似文献   

Validation of the OMRON M7 (HEM-780-E) blood pressure measuring device in a population requiring large cuff use according to the International Protocol of the European Society of Hypertension

BACKGROUND: A high percentage of hypertensive patients present an arm circumference of over 32 cm; the use of a large cuff is therefore recommended. Validation studies are usually performed in the general population using a standard-size cuff. The aim of this study was to assess the accuracy of the Omron M7 device in a population with an arm circumference ranging from 32 to 42 cm. DESIGN: A validation study was performed according to the International Protocol of the European Society of Hypertension. This protocol is divided into two phases: the first phase is performed on 15 selected participants (45 pairs of blood-pressure measurements); if the device passes this phase, 18 supplementary participants are included (54 pairs of blood-pressure measurements), making a total number of 33 participants (99 pairs of blood-pressure measurements), on whom the analysis is performed. METHODS: For each participant, four blood-pressure measurements were performed simultaneously by two trained observers, using mercury sphygmomanometers fitted with a Y tube; the measurements alternated with three by the test device. The difference between the blood-pressure value given by the device and that obtained by the two observers (mean of the two observations) was calculated for each measure. The 99 pairs of blood-pressure differences were classified into three categories (相似文献   

Repeated measurements of non-invasive ambulatory blood pressure: distinction between reproducibility and the proper effect of placebo

OBJECTIVE: To determine whether non-invasive ambulatory blood pressure is more reproducible and less affected by the placebo treatment than are clinic blood pressure measurements. METHOD: Thirty-four essential hypertensive outpatients were randomly allocated after a 4-week preselection period in two groups in a cross-over study design. One group received placebo for 4 weeks while the other formed the control group (reproducibility), then the treatments were exchanged for another 4 weeks. Clinic and ambulatory blood pressures were measured at three different times for each patient, namely bnefore the random allocation to groups and at the end of each period, using a mercury sphygmomanometer and 24 h non-invasive ambulatory blood pressure monitoring. RESULTS: Administration of placebo was accompanied by a significant reduction in systolic and diastolic clinic blood pressures (by 3.4+/-13 and 3.6+/-8 mmHg, respectively), but not in 24 h, daytime and night-time blood pressures. Circadian hourly blood pressure and heart rate curves were virtually superimposable. In the 13 placebo responder patients selected on the basis of clinic blood pressure, placebo decreased the clinic blood pressure and also reduced systolic and diastolic ambulatory blood pressures, mainly during the day period (by 5.2+/-6.2 and 4.89+/-7.8 mmHg, respectively). This effect is specific and related to the placebo administration because repetition of the measurements without any treatment showed no significant difference. To characterize at baseline the placebo responder patients, comparison with the non-placebo responders showed lower baseline values of ambulatory systolic blood pressure recorded during 24 h daytime and night-time in the placebo responder group. CONCLUSION: The 24 h ambulatory blood pressure average is not affected by placebo in the present group of patients but that a placebo effect occurs mainly during the daytime in patients who decreased their clinic blood pressure under placebo (placebo responders); the placebo-induced reduction in blood pressure is related to a specific effect of placebo and is independent from any alerting reaction or reproducibility hypothesis. This study clearly indicates the necessity of including placebo and ambulatory blood pressure monitoring in the therapeutic and pharmacological trials of antihypertensive drugs.     

Assessment of outcomes other than systolic and diastolic blood pressure: pulse pressure,arterial stiffness and heart rate

In recent years, studies have shown that parameters derived from the arterial pressure wave other than systolic and diastolic blood pressure provide important information on cardiovascular status. Among these parameters, pulse pressure, arterial stiffness and heart rate have emerged as independent markers of cardiovascular risk in different populations. Although a number of studies have used casual measurements of these parameters in a clinic setting, others have focused on their assessment under ambulatory conditions.The pulse pressure represents the amplitude of the pressure wave signal (systolic minus diastolic blood pressure), higher pulse pressure values having been reported in patients possessing cardiovascular risk factors. Close associations between a high pulse pressure and several surrogate end-points have been described. Furthermore, epidemiological studies have shown that a high pulse pressure is an independent predictor of hard end-points in several populations. Arterial stiffness represents one of the major haemodynamic factors determining pulse pressure.Pulse wave velocity, measured from the initial upstroke of the pressure wave, constitutes an established index of arterial stiffness. Studies have reported stiffer arteries in patients with cardiovascular pathology even at an early stage of disease. Close correlations between arterial stiffness and several surrogate markers have been reported, and arterial stiffness and its changes have recently been shown to be an independent predictor of hard end-points in patients with a high cardiovascular risk. Methods to evaluate arterial stiffness under ambulatory conditions are emerging.Heart rate represents the frequency of the cyclical strain of the arterial wall, clinical studies having shown that ambulatory heart rate is correlated to several surrogate markers. A few epidemiological studies have analysed the value of ambulatory heart rate as an independent predictor of hard end-points, but their positive findings need to be confirmed.The analysis of the pressure wave thus allows the determination of several haemodynamic indices other than systolic and diastolic blood pressure. Pulse pressure, arterial stiffness and heart rate constitute other outcomes that may be useful as additional factors in risk assessment for future therapeutic decision-making.