ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Correction of structural abnormalities in resistance arteries of patients with essential hypertension is a potential treatment goal, in addition to blood pressure reduction. However, available evidence from human as well as from animal studies indicates that antihypertensive therapy is not always accompanied by normalization of resistance vessel structure, despite normalization of blood pressure. Thus, blood pressure is not the only factor determining resistance vessel structure, and experimental studies show that several factors could play a role, including shear stress and hormonal stimulation. To date, there has been no systematic review of the many published papers which have studied the structural effects of antihypertensive therapy, and it is not known which conditions are best able to normalize resistance vessel structure. We have therefore made a survey of the available literature. The survey shows that change in blood pressure in indeed a poor indicator of change in resistance vessel structure. However, it is a remarkably consistent finding that normalization of resistance vessel structure is obtained with therapeutic regimens which reduce blood pressure by vasodilation rather than by lowering cardiac output. Thus, to the extent that normalization of resistance vessel structure is deemed a goal of antihypertensive treatment, the survey points towards the importance of considering not only the treatment effect on blood pressure, but also the haemodynamic effects within patients with essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectiveThe purpose of the present investigation was to examine the age-dependency of blood pressure heritability by use of the twin method in different age groups.DesignIn 272 (150 monozygous and 122 dizygous) twin pairs, aged 18 to 76 years, both conventional and ambulatory blood pressure were measured. After correction for possible confounders, model fitting was used to estimate heritability and 95% confidence limits in three age groups of similar size, i.e. 18–29, 30–39 and⩾40 years.ResultsHeritability estimates were significant in each age group, ranging from 35 to 67% for the various blood pressure measurements. The estimates tended to decrease with increasing age, except for conventional diastolic blood pressure, but the intergroup differences did not reach statistical significance, despite adequate power.ConclusionsIn conclusion, blood pressure heritability is significant in various age groups, but does not substantially change with advancing age. Twin analysis does not indicate that models for blood pressure regulation in various age groups should take into account the possibility of age-related changes in the expression of relevant genes, in the presence of relevant environmental agents, or in the susceptibility to the latter (gene-environment interaction).

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

BackgroundHypertension guidelines recommend 24 h ambulatory blood pressure (ABP) monitoring in hypertensive subjects with suspected isolated clinic hypertension (ICH). However, the pre-test probability of ICH based on the distribution of its independent predictors has not yet been estimated in hypertensive subjects with mildly elevated blood pressure.ObjectiveTo ascertain the independent predictors of ICH in mildly hypertensive subjects.MethodsIn the setting of the HARVEST-PIUMA collaboration, we studied 1564 subjects with hypertension stage I. At entry, all subjects were untreated and all underwent ABP monitoring and echocardiography. Diabetes, hypertension grade>I, renal failure or previous cardiovascular morbid events were exclusion criteria. Clinic BP was 143/92 mmHg (SD 9/5) and 24 h ABP was 128/81 mmHg (SD 10/8).ResultsPrevalence of ICH (daytime ABP<130 mmHg systolic and 80 mmHg diastolic) was 10.4%. In a multivariate logistic regression analysis, sex (P= 0.002), smoking (P= 0.038) and clinic diastolic BP (P= 0.0002) were the sole independent predictors of ICH according to the following equation:Y= 2.6438 + 0.5128×sex (0 = men; 1 = women) + 0.4543×current smoking (0 = yes; 1 = no)−0.0531×clinic diastolic BP (mmHg) andP(probability of ICH) = exp(Y)/[1 + (exp(Y)]. Left ventricular (LV) mass at echocardiography was a further independent predictor (P= 0.002) of ICH according to the following equation:Y= 3.4343 + 0.4603×sex + 0.5989×current smoking−0.0482×clinic diastolic BP−0.0312×LV mass [g/height (m)2.7]. LV mass was greater (P<0.01) in the group with ambulatory hypertension [42.3 g/height (m)2.7] than in that with ICH [39.2 g/height (m)2.7] and not dissimilar between the ICH group and a control group of 370 healthy normotensive subjects [38.1 g/height (m)2.7].ConclusionsIn untreated subjects with stage I hypertension, ICH is most frequent among women, non-smokers and subjects with low clinic BP and smaller LV mass. These findings allow identification of subjects with indication to ABP monitoring because of suspected ICH.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectiveStudies on the effects of chronic exposure to industrial noise on clinic blood pressure (BP) at rest have yielded inconsistent results. The aim of this study was to evaluate the effect of occupational noise exposure on ambulatory blood pressure (ABP) in normotensive subjects.MethodsWe studied 476 normotensive workers, aged 20–50 years (systolic blood pressure (SBP) < 140, diastolic blood pressure (DBP) < 90), at a metallurgical factory; 238 were exposed to high levels of noise (>85 dB), while 238 were not exposed (<80 dB). Clinical evaluation included measurements of casual BP (by standard mercury sphygmomanometer, Korotkoff sound phase I and V) and heart rate (HR) (by pulse palpation), body height and weight. All subjects underwent a 24 h non-invasive ABP monitoring (by SpaceLabs 90207 recorder; SpaceLabs, Redmond, Washington, USA) twice within 14 days: one during a normal working day and one during a non-working day. Measurements were performed every 15 min. Computed analysis of individual recordings provided average SBP, DBP and HR values for 24 h, daytime working hours (0800–1700 h), daytime non-working hours (1700–2300 h) and night-time (2300–0800 h).ResultsNo significant difference in clinic SBP, DBP and HR was observed between exposed and non-exposed subjects. Results obtained by ABP monitoring showed in the exposed workers: (a) a higher SBP (by a mean of 6 mmHg,P<0.0001 versus controls) and DBP (by a mean of 3 mmHg,P<0.0001) during the time of exposure and the following 2 or 3 h, whereas no difference between the two groups was found during the non-working day; (b) an increase in HR, which was present not only during the time of exposure to noise (+3.7 beats-per-minute (bpm),P<0.0001 versus controls), but also during the non-working hours (+2.8 bpm,P<0.001) and during the day-time hours of the non-working day (+2.8 bpm,P<0.003); (c) a significant increase in BP variability throughout the working day.ConclusionsThese findings suggest that in normotensive subjects below the age of 50 years, chronic exposure to occupational noise is associated with a transient increase in BP, which is not reflected in a sustained BP elevation. The possible role of repeated BP and HR fluctuations due to frequent and prolonged exposure to noise in accounting for the higher prevalence of hypertension reported in noise-exposed workers above age 50 years, requires longitudinal studies to be clarified.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectiveTo audit the performances of the analytes used in the diagnosis of pheochromocytoma and to present a graphical guideline to help the diagnosis.DesignA 5 year retrospective study.SettingsLaboratory and departments of a university hospital.ParticipantsIn-patients, suspected of bearing a pheochromocytoma, were investigated for urinary metanephrines and catecholamines (photometric method) and vanillylmandelic acid, fractionated catecholamines and metanephrines [high pressure liquid chromatography (HPLC) coupled to electrochemical detection (ED)] urinary excretion.Main outcomePatients with a pheochromocytoma (24 out of 2003 patients) were diagnosed by the combination of normetanephrine and metanephrine determination.ResultsAll analytes but dopamine were significantly elevated in patients with a pheochromocytoma. The area under the receiver operating characteristics (ROC) curves were the highest for total metanephrines, normetanephrine and metanephrine determinations. Because of analytical interferences in the metanephrines determination, the normetanephrine and metanephrine performed better. It is noteworthy that all pheochromocytomas had either normetanephrine or metanephrine levels above their respective optimal threshold (sensitivity 100%). The best optimal threshold performance was reached by the mean of three daily samples. Total or fractionated catecholamines or vanillylmandelic acid were less accurate tools.ConclusionAmongst urinary tests, the combined use of HPLC/ED determination of normetanephrine and metanephrine seems the most effective screening strategy for the diagnosis of pheochromocytoma. The older total metanephrine photometric assay is grieved by analytical interferences.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesPulse pressure is not constant throughout the arterial tree. Use of pulse pressure at one arterial site as surrogate for pulse pressure at another arterial site may be erroneous. The present study compares three non-invasive techniques to measure local pulse pressure: (i) internally calibrated readings from applanation tonometry, (ii) alternative calibration of pressure waves obtained with applanation tonometry and (iii) alternative calibration of arterial distension waves obtained with echo-tracking. Alternative calibration assumes mean and diastolic blood pressure constant throughout the large artery tree.Design and methodsStudy 1 used invasive measurements in the ascending aorta as a reference method and internally calibrated tonometer readings and alternatively calibrated pressure waves at the common carotid artery as test methods. Study 2 used alternatively calibrated pressure waves as a reference method and alternatively calibrated distension waves and internally calibrated applanation tonometer readings as test methods.ResultsIn study 1, pulse pressure from internally calibrated tonometer readings was 10.2±14.3 mmHg lower and pulse pressure from alternatively calibrated pressure waves was 1.8±5.2 mmHg higher than invasive pulse pressure. Pulse pressure from calibrated distension waves was 3.4±6.9 mmHg lower than pulse pressure from alternatively calibrated pressure waves. According to British Hypertension Society criteria, pulse pressure from the internally calibrated tonometer achieved grade D and pulse pressure from alternatively calibrated pressure waves achieved grade A. Pulse pressure from calibrated distension waves achieved grade B when alternatively calibrated pressure waves were used as a reference method.ConclusionsPulse pressure obtained from alternatively calibrated tonometer-derived pressure waves and echo-tracking-derived distension waves demonstrates good accuracy. Accuracy of pulse pressure from internally calibrated applanation tonometer readings at the carotid artery is poor.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectiveTo determine the effects of exercise training on the blood pressure (BP) values of older adults, using home blood pressure measurement.DesignRandomized controlled trial.ParticipantsA total of thirty-nine free-living older adults (including 19 men) aged from 60–81 years with home systolic blood pressure>120 mmHg and without significant cardiopulmonary-musculoskeletal disease, were randomly allocated to either 25 weeks of exercise training (exercise group) or to a control program (control group).Main outcome measurementsChange in the 2-week averages of home systolic and diastolic blood pressure values measured with a validated automatic device before, during and after the intervention period.ResultsCompared with the control group, the exercise group showed a significant decrease in values for home systolic blood pressure (maximum between-group difference = 7.7 mmHg,P= 0.003) and home diastolic blood pressure (4.2 mmHg,P= 0.001). These changes were observed for both genders.ConclusionsExercise training was effective for older adults in lowering home blood pressure values. This is the first trial to demonstrate the usefulness of home blood pressure measurement in examining the effect of exercise training on blood pressure values.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesTo evaluate salt sensitivity in elderly subjects with different forms of hypertension and controls and to investigate any modulation by genotypeDesignRandomized, double-blinded, placebo-controlled latin-squareSettingTertiary referral hospitalParticipantsCommunity subjects (n= 46) aged⩾60 years classified as isolated systolic hypertension [ISH; systolic blood pressure (SBP)⩾160, diastolic blood pressure (DBP)<90 mmHg,n= 19], diastolic±systolic hypertension (SDH; DBP⩾90 mmHg,n= 10) and normotension (SBP<160, DBP<90 mmHg,n= 17).InterventionFour 14 day treatments, 50, 100, 200 and 300 mmol/day of sodium chloride supplementation interspersed with 14 day washout periods on a salt-restricted diet.Main outcome measuresThe 24 h blood pressure, heart rate, weight, urinary sodium and creatinine clearance measured during baseline, treatment and washout periods and angiotensinogen (AGT) and angiotensin converting enzyme (ACE) genotypes.ResultsFor the entire cohort, the mean±standard error (SE) of change from baseline in SBP for 50, 100, 200 and 300 mmol/day salt was 7.7±2.4, 12.1±2.4, 16.6±3.0, 18.5±2.6 mmHg, respectively. For DBP, the respective changes were:−0.1±1.5, 2.4±1.6, 3.0±1.5, 5.8±1.7 mmHg. The increase in SBP among ISH subjects was significantly higher than among subjects in the SDH and normotensive groups (P<0.05). AGT genotype influenced the effect of salt dose on the change in DBP (P= 0.006) but not SBP (P= 0.7).ConclusionsIn healthy, older subjects, a linear increase in BP occurred with increasing salt dose, it appeared most pronounced in ISH subjects and could be modulated by AGT genotype.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

ObjectivesTotal genome scans of genetically segregating populations derived from the spontaneously hypertensive rat (SHR) and other rat models of hypertension have suggested the presence of quantitative trait loci (QTL) regulating blood pressure and cardiac mass on multiple chromosomes, including chromosome 2. The objective of the current study was to directly test for the presence of a blood pressure QTL on rat chromosome 2.DesignA new congenic strain was derived by replacing a segment of chromosome 2 in the SHR between D2Rat171 and D2Arb24 with the corresponding chromosome segment from the normotensive Brown Norway rat. Arterial pressures were directly monitored in conscious rats by radiotelemetry.ResultsWe found that the SHR congenic strain (SHR-2) carrying a segment of chromosome 2 from the Brown Norway rat had significantly lower systolic and diastolic blood pressures than the SHR progenitor strain. The attenuation of hypertension in the SHR-2 congenic strain versus the SHR progenitor strain was accompanied by significant amelioration of cardiac hypertrophy.ConclusionsThese findings demonstrate that gene(s) with major effects on blood pressure exist in the differential segment of chromosome 2 trapped within the new SHR.BN congenic strain.

ISSN:0263-6352    

出版商:OVID    

年代:2001

数据来源: OVID