ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ObjectiveTo investigate whether baseline systolic blood pressure variability was a risk factor for stroke, cardiovascular mortality or cardiac events during the Syst-Eur trial.DesignThe Syst-Eur study was a randomized, double-blind, placebo-controlled trial, powered to detect differences in stroke rate between participants on active antihypertensive treatment and placebo. Systolic blood pressure variability measurements were made on 744 participants at the start of the trial. Systolic blood pressure variability was calculated over three time frames: 24 h, daytime and night-time. The placebo and active treatment subgroups were analysed separately using an intention-to-treat principle, adjusting for confounding factors using a multiple Cox regression model.ParticipantsAn elderly hypertensive European population.Main outcome measuresStroke, cardiac events (fatal and non-fatal heart failure, fatal and non-fatal myocardial infarction and sudden death) and cardiovascular mortality (death attributed to stroke, heart failure, myocardial infarction, sudden death, pulmonary embolus, peripheral vascular disease and aortic dissection).ResultsThe risk of stroke increased by 80% (95% confidence interval: 17–176%) for every 5 mmHg increase in night-time systolic blood pressure variability in the placebo group. Risk of cardiovascular mortality and cardiac events was not significantly altered. Daytime variability readings did not predict outcome. Antihypertensive treatment did not affect systolic blood pressure variability over the median 4.4-year follow-up.ConclusionIn the placebo group, but not the active treatment group, increased night-time systolic blood pressure variability on admission to the Syst-Eur trial was an independent risk factor for stroke during the trial.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ObjectiveBlood pressure measurements taken by patients at home (HBP) are usually referred to as ‘self’ or ‘home’ measurements. To demonstrate the most appropriate term we compared self-home measurements (S-HBP), with home measurements taken by relatives (R-HBP), clinic measurements taken by physicians (P-CBP) and self-measurements in the clinic (S-CBP).Patients and methodsThirty treated hypertensives were randomized to an initial clinic BP (CBP) monitoring period (week 1, P-CBP followed by S-CBP measurements, or the opposite; 1 visit each), then to a HBP monitoring period (weeks 2–3, S-HBP followed by R-HBP or the opposite; 3 workdays each), and finally to a second CBP monitoring period (week 4, S-CBP followed by P-CBP, or the opposite). Triplicate morning trough measurements were taken per occasion using the same fully automated device.ResultsThere was no difference between S-CBP and P-CBP (mean difference−1.9±6.1 mmHg, 95% confidence interval (CI)−4.2, 0.4/−1.6±4.7, 95% CI−3.3, 0.2, systolic/diastolic), or between S-HBP and R-HBP (−0.9±6.9, 95% CI−3.5, 1.8/−0.4±4.3, 95% CI−2.0, 1.2). S-CBP was higher than S-HBP (mean difference 9.3±9.0/4.9±5.4 mmHg, systolic/diastolic,P<0.001) and R-HBP (8.4±9.1/4.5±5.0,P<0.001). P-CBP was also higher than S-HBP (11.2±11.9/6.5±6.8,P<0.001) and R-HBP (10.3±11.2/6.1±6.5,P<0.001).ConclusionsSelf-measurements provide similar BP levels to measurements taken by relatives or physicians, provided that measurements are taken in the same setting. ‘Self-BP’ is a misnomer because self-measurement has no impact on the difference between home and clinic BP. Given that this difference can be exclusively attributed to the effect of the different setting, the term ‘home BP’ represents a more appropriate term.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ObjectivesPrevious results have indicated that ambulatory monitoring provides a pressor effect on patients using the device for the first time, but not on successive sessions of monitoring. Our objective was to validate and quantify the extent and duration of this pressor effect in hypertensive patients repeatedly evaluated every few months.MethodsWe studied 823 mild-to-moderate hypertensive subjects (347 men), 53.4 ± 14.1 years of age. Blood pressure was measured at 20-min intervals during the day and at 30-min intervals at night for 48 consecutive hours, and physical activity was simultaneously evaluated every minute with a wrist actigraph. Forty per cent of the patients were evaluated twice or more.ResultsIn patients evaluated for the first time, results indicated a highly statistically significant (P<0.001) reduction during the second day of monitoring as compared to the first in the diurnal mean of systolic and diastolic blood pressure, but not in heart rate or physical activity. This pressor effect remained statistically significant for the first 10 h of monitoring, independent of gender, day of the week of monitoring, or number of antihypertensive drugs used by the patients. The nocturnal mean of blood pressure was, however, similar between both days of sampling. This ‘ambulatory monitoring effect’ was diminished, although not eliminated, in extent and duration for successive sessions of ambulatory monitoring.ConclusionsAmbulatory monitoring for 48 h revealed a statistically significant pressor response that could mostly reflect a novelty effect in the use of the monitoring device. This effect has marked implications in both research and clinical daily practice for a proper diagnosis of hypertension and evaluation of treatment efficacy by the use of ambulatory monitoring.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ObjectivesWe assessed whether third-generation oral contraceptive (OC) treatment (30 μg ethinylestradiol + 75 μg gestodene daily) could affect the endothelial function of healthy women.MethodsIn 20 young healthy women (HW) and 10 hypercholesterolemic women (CW) we assessed forearm blood flow (strain-gauge plethysmography) changes induced by the intrabrachial infusion of acetylcholine (ACH) (0.15–15 μg/100 ml forearm tissue/min) and sodium nitroprusside (SNP) (1–4 μg/100 ml forearm tissue/min). ACH was repeated during the nitric oxide synthase inhibitor intra-arterialNG-monomethyl-l-arginine (l-NMMA) (100 μg/100 ml forearm tissue/min) or the antioxidant vitamin C (8 mg/100 ml forearm tissue/min). HW repeated the protocol after 6-month OC (n= 10) or placebo (n= 10) treatment.ResultsIn HW the maximal vasodilation to ACH, similar between placebo and OC subgroups, was significantly reduced in CW (P<0.01). Vasodilation to ACH was blunted (P<0.01) by l-NMMA and unaffected by vitamin C, in both OC and placebo groups. In CW the vasodilation to ACH, not modified by l-NMMA, was improved by vitamin C (P<0.01). OC treatment raised (P<0.01) plasma total and low-density lipoprotein cholesterol, and values were similar to those shown by CW. Both OC and placebo intake did not change the response to ACH and the modulation induced by l-NMMA or vitamin C. Vasodilation to SNP was similar in all groups.ConclusionsIn HW 6-month treatment with third-generation OC, although associated with an abnormal lipid profile, does not adversely affect endothelium-dependent vasodilation. This neutral effect could be the balance between a deleterious effect of hypercholesterolemia and a protective effect of OC on endothelial function.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundConsumption of flavonoid-rich beverages, including tea and red wine, has been associated with a reduction in coronary events, but the physiological mechanism remains obscure. Cocoa can contain extraordinary concentrations of flavanols, a flavonoid subclass shown to activate nitric oxide synthasein vitro.ObjectiveTo test the hypothesis that flavanol-rich cocoa induces nitric-oxide-dependent vasodilation in humans.DesignThe study prospectively assessed the effects of Flavanol-rich cocoa, using both time and beverage controls. Participants were blinded to intervention; the endpoint was objective and blinded.MethodsPulse wave amplitude was measured on the finger in 27 healthy people with a volume-sensitive validated calibrated plethysmograph, before and after 5 days of consumption of Flavanol-rich cocoa [821 mg of flavanols/day, quantitated as (−)-epicatechin, (+)-catechin, and related procyanidin oligomers]. The specific nitric oxide synthase inhibitor,NG-nitro-l-arginine methyl ester (l-NAME) was infused intravenously on day 1, before cocoa, and on day 5, after an acute ingestion of cocoa.ResultsFour days of flavanol-rich cocoa induced consistent and striking peripheral vasodilation (P= 0.009). On day 5, pulse wave amplitude exhibited a large additional acute response to cocoa (P= 0.01). l-NAME completely reversed this vasodilation (P= 0.004). In addition, intake of flavanol-rich cocoa augmented the vasodilator response to ischemia. Flavanol-poor cocoa induced much smaller responses (P= 0.005), and none was induced in the time-control study. Flavanol-rich cocoa also amplified the systemic pressor effects of l-NAME (P= 0.005).ConclusionIn healthy humans, flavanol-rich cocoa induced vasodilation via activation of the nitric oxide system, providing a plausible mechanism for the protection that flavanol-rich foods induce against coronary events.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundFibromuscular dysplasia (FD) is a non-atherosclerotic, non-inflammatory arterial disease of unknown cause, and most frequently affects the renal and internal carotid arteries. Our objectives were to determine whether quantitative and qualitative lesions could be detected by high-resolution echotracking techniques at two arterial sites generally considered as free of echographic lesions: the common carotid and the radial arteries, and to compare their frequency with a control population.Methods and resultsWe studied 70 patients with renal FD and 70 control subjects matched for age, sex and systolic blood pressure. Arterial parameters were determined using non-invasive high-resolution echotracking systems. Carotid B-mode scans and radiofrequency signals were analysed and quoted by three observers blinded to diagnosis. FD patients had thicker carotid (+12%,P<0.001) and radial arteries (+10%,P<0.05) than controls. Abnormal echographic patterns of the carotid artery, including supernumerary interfaces and/or interruption of the blood–intima acoustic interfaces, were frequently observed in FD patients and rarely in control subjects. These abnormalities were quantified with a phenotypic score ranging from 2 to 7, and their sensitivity and specificity were 73 and 81%, respectively, as markers of FD. Having a phenotypic score>3 conferred an odds ratio of 12.9 (95% CI 5.7–29.3) of having renal FD.ConclusionWe defined a new carotid phenotype in FD patients using a non-invasive echotracking system, and showed an increased wall thickness and distensibility of the radial artery. These data indicate the presence of subclinical lesions at arterial sites distant from the renal arteries, suggesting that renal FD is not a focal but a systemic arterial disease.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ObjectiveTo determine the effects of capillary rarefaction on cardiovascular reactivity and microcirculatory functioning in essential hypertension.DesignHypertension is associated with abnormal cardiovascular reactivity and increased vasoconstriction. Capillary rarefaction amplifies these abnormalities, which modify microcirculatory hemodynamics. Hence this study of the hemorheological pattern and the veno-arteriolar reflex in hypertensive patients and normotensive control subjects.MethodsSixty-one men with never-treated essential hypertension and capillary rarefaction (<80 capillaries per field) and 20 age-matched and sex-matched controls underwent a strenuous cycle ergometer test to monitor, during exercise and recovery, the blood pressure profile and the hemorheological pattern: blood viscosity at low shear, hematocrit and leukocyte counts, soluble P-selectin levels, and red and white blood cell filterability rates. The veno-arteriolar reflex was determined by laser-Doppler flowmetry before exercise and at recovery.ResultsHypertensive men with ⩽ 72 capillaries per field had an abnormal hemorheological profile before exercise. The physiological response to exercise was observed only in the controls and in hypertensives with ⩾ 73 capillaries per field. Abnormal responses to exercise worsened as capillaries were more rarefied. At recovery, hemorheological parameters in hypertensives with 65–72 capillaries per field returned to baseline, remaining significantly (P<0.05) different to control values. Variations in the hemorheological pattern in hypertensives with<64 capillary per field persisted at recovery. The veno-arteriolar reflex followed the same pattern.ConclusionA reduced microvascular network may contribute to abnormal cardiovascular reactivity and to exercise-induced rheological abnormalities in hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundDietary potassium supplementation decreases blood pressure and prevents strokes in humans, and prevents strokes and renal damage in Dahl salt-sensitive (DSS) rats.ObjectiveTo study the effects of various concentrations of dietary potassium chloride (KCl) on the hemodynamics of Dahl salt-resistant (DSR) and DSS rats receiving a 1% sodium chloride (NaCl) diet for 8 months, to determine whether there is an optimal dietary concentration of KCl that minimizes increases in blood pressure and causes least impairment of blood flow in the brain and kidneys.Methods and resultsWe found a biphasic effect on hemodynamic parameters as a function of dietary KCl in DSS rats of the Rapp strain fed 1% NaCl with increasing dietary KCl (0.7, 2.6, 4 and 8%). After 8 months receiving a diet containing 1% NaCl and 0.7% KCl, DSS rats had mean arterial pressures (MAP), plasma volumes, cardiac outputs and renal and cerebral vascular resistances that were significantly increased compared with those of DSR rats receiving the same diet. With a 2.6% KCl diet, all these parameters were significantly reduced compared with those in DSS rats fed the 0.7% KCl diet and were similar to those in DSR rats fed 2.6% KCl. Total peripheral resistance in DSR and DSS rats was similar on all diets. When KCl was increased to 4 and 8%, MAP, plasma volume, cardiac output and renal vascular resistance progressively increased in DSR and DSS rats, without changing total peripheral resistance. These changes paralleled increases in plasma aldosterone, which resulted from adrenocortical stimulation by the increasing dietary KCl; however, cerebral vascular resistance of DSR and DSS rats decreased significantly with a 4% KCl diet, despite increased aldosterone and sodium retention. Only DSS rats fed a 2.6% KCl diet had hemodynamics similar to those of DSR control rats fed the same diet, and hyperaldosteronism, sodium retention and increased plasma volume did not occur.Conclusion`Optimal’ dietary KCl (2.6%) prevents hypertension and preserves cerebral and renal hemodynamics in DSS rats fed a diet containing 1% NaCl for 8 months, which causes hypertension when dietary KCl is limited or excessive.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundWe have previously reported the isolation from human placentas of an inhibitor of the sodium pump (Na/K ATP-ase) of molecular weight 370 Da, which is considered to have a dihydropyrone-substituted steroid (bufenolide) structure.ObjectiveTo examine if this inhibitor is present outside of the pregnant state.MethodsWe examined the plasma ultrafiltrate of patients who were clinically volume-expanded. During the period of this study five such patients were identified. One was receiving haemofiltration for acute renal failure and four were being treated by plasma exchange. High performance liquid chromatograph (HPLC) purified fractions obtained from each of these five patients inhibited the human leucocyte sodium pumpin vitro.ResultsEach of the purified fractions that inhibited the leucocyte ATP-asein vitrocontained a compound of mass 370 Da, the same mass as that found previously in placental extracts. This inhibitory factor was absent from HPLC purified fractions of plasma ultrafiltrate obtained from fifty-five patients who were clinically normovolaemic. Negative ion mass spectrometry (MS)/MS of the inhibitory material produced the fragmentation pattern characteristic of the placenta-derived pump inhibitor in only one of the five samples. The other four samples, although having the same mass, exhibited a different fragmentation pattern.ConclusionThe results suggest that an inhibitor of the sodium pump, identical in mass to that obtained from human placentas, circulates in the plasma of volume-expanded patients. The fragmentation pattern observed in negative ion mass spectrometry in the majority of the volume expanded patients may represent the presence of an isomer of the sodium pump inhibitor previously described in placental material.

ISSN:0263-6352    

出版商:OVID    

年代:2003

数据来源: OVID