摘要:

ObjectiveThe rostral ventrolateral medulla is an important center for the regulation of sympathetic and cardiovascular activities. Reportedly, neurovascular compression of the rostral ventrolateral medulla may be causally related to essential hypertension. We aimed to determine the mechanism behind elevated blood pressure in hypertensive patients with compression of the rostral ventrolateral medulla and to investigate whether genetic factors contribute to the etiology of hypertension with compression.Design and methodsThe study included 56 patients with essential hypertension and 25 normotensive individuals. With the use of magnetic resonance imaging, the essential hypertension group was subdivided into hypertension with compression and without compression groups. We compared plasma levels of hormones that raise blood pressure and family histories of hypertension between the two hypertension groups and the normotension group.ResultsPlasma norepinephrine levels, but not plasma renin activity, aldosterone, epinephrine, or vasopressin levels, were significantly higher in the hypertension with compression group (389 ± 53 pg/ml) than in the hypertension without compression group (217 ± 38,P< 0.05) or in the normotension group (225 ± 30,P< 0.05). The percentage of individuals who had two hypertensive parents was significantly higher in the hypertension with compression group (39.4%) than in the hypertension without compression group (13.0%,P< 0.05) or in the normotension group (8.0%,P< 0.01).ConclusionsThese results indicate that neurovascular compression of the rostral ventrolateral medulla might be, at least in part, causally related to essential hypertension by increasing sympathetic nerve activity. They also suggest that genetic factors might contribute to the etiology of hypertension with neurovascular compression.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveBesides arterial blood pressure, nonhemodynamic factors are known to induce cardiac hypertrophy. In Cushing's syndrome, severe ventricular hypertrophy has been linked not only to increased aortic pressure, but also to elevated plasma cortisol. The aim of this study was to examine the relationship between the cortisol/cortisone levels and left ventricular mass index (LVMI) in essential arterial hypertension with and without echocardiographic left ventricular hypertrophy (LVH).DesignEighteen untreated Caucasian patients (nine men, nine women, mean age 48 ± 6 years) with essential hypertension (163 ± 26/100 ± 14 mmHg) were enrolled. An age-matched control group of 13 subjects (seven men, six women) with normotension (121 ± 9/79 ± 7 mmHg) were enrolled also. Left ventricular dimensions were echocardiographically assessed and cortisol production evaluated by 24-h urinary free cortisol and cortisone concentrations.ResultsLVMI averaged 115 ± 31 g/m2and 24-h urinary free cortisol and cortisone were 23 ± 14 μg per 24 h and 31 ± 18 μg per 24 h. Prevalence of echocardiographic LVH was 56%. LVMI correlated significantly with 24-h urinary free cortisol (r= 0.61,P= 0.007) and cortisone (r= 0.60,P= 0.009). Patients with echocardiographic LVH were characterized by higher daytime ambulatory blood pressure, LVMI (particularly the posterior wall), and 24-h urinary cortisol, while office blood pressure, septal: posterior wall ratio and 24-h urinary cortisone were comparable in all patients. In control individuals, LVMI averaged 91 ± 18 g/m2and 24-h urinary free cortisol and cortisone, respectively, were 34.7 ± 6.6 μg per 24 h and 64.3 ± 10.8 μg per 24 h (P< 0.05 versus patients). Neither LVMI nor the contributing ventricular dimensions showed significant correlation with 24-h urinary free cortisol or cortisone in the control group.ConclusionsOur data provide evidence for a significant relationship between LVMI and cortisol production independently of arterial blood pressure in untreated mild to moderate hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThe purpose of this investigation was to assess the effects of age, gender, posture and their interactions, and of body mass index and lifestyle factors, on heart rate, its total variance and its variability in the frequency domain in a population-based sample of healthy subjects.MethodsRR interval and respiration were registered in the supine and in the standing position in 302 men and 312 women, aged 25–89 years; 424 subjects were healthy and had recordings suitable for analysis. Power spectral analysis was performed by use of autoregressive modelling and by fast Fourier transform, and the low-frequency (LF) and high-frequency (HF) components were expressed in both absolute (ms2) and normalized units (%).ResultsIn the supine position, heart rate was higher in women than in men (P< 0.001) and was not affected by age. Total variance and absolute LF and HF power markedly declined with age in each gender (P< 0.001). Men had higher absolute LF power than women (P< 0.001), whereas HF power was similar by gender; the age-related decline of HF power tended to be steeper in women (P= 0.06). The normalized LF and HF powers also decreased with age (P< 0.01), except for the LF component in women; young men had higher LF power and lower HF power than young women, but the gender difference disappeared in the sixth decade of life. The LF: HF ratio was not influenced by age in supine men; the ratio was lower in women at young age, but increased to the level of men at greater age. Heart rate increased on standing, whereas its total variance was reduced; HF power declined, irrespective of the units, normalized LF power and the LF: HF ratio increased, whereas absolute LF power decreased (P< 0.001). The postural changes of heart rate and of the frequency components did not differ by gender, but were attenuated with increasing age (P< 0.05). Alcohol consumption did not influence heart rate and its variability, whereas independent effects of habitual physical activity, smoking habits and body mass index explained no more than 4% of the variance of some measures of heart rate variability.ConclusionsAge, gender and/or some lifestyle factors significantly affect heart rate and various components of its variability in the supine position and in response to standing. The results are similar for autoregressive modelling and fast Fourier transform, but may differ according to the units in which the spectral components are expressed.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveMyocardial perfusion abnormalities may occur in hypertensive patients in absence of significant coronary artery disease. However, it is not well established whether hypertensive patients without known coronary artery disease have a higher prevalence or extent of myocardial perfusion abnormalities compared with normotensive patients with similar clinical features.DesignThis study compares the prevalence and extent of rest and stress-induced myocardial perfusion abnormalities in patients with and without hypertension.MethodsDobutamine (up to 40 μg/kg per min) stress technetium-99m myocardial perfusion SPECT imaging was performed for evaluation of myocardial ischaemia in 350 patients (mean age = 60 ± 13 years, 146 men) without known coronary artery disease. One hundred and forty-eight patients were hypertensive. Rest SPECT images were acquired 24 h after the test. Abnormal perfusion was defined as the presence of reversible or fixed perfusion defects.ResultsNo significant difference was detected between patients with and without hypertension regarding gender, prevalence of symptoms, risk factors, pretest probability of coronary artery disease (52 ± 28 versus 53 ± 29%), peak rate pressure product (21040 ± 4755 versus 20774 ± 4865) or number of patients achieving the target heart rate during stress (85 versus 86%). Hypertensive patients were significantly older (62 ± 11 versus 58 ± 13 years,P= 0.005) and were receiving beta-blockers more frequently (34 versus 18%,P= 0.0001). The prevalence of myocardial perfusion abnormalities was similar in patients with and without hypertension (28 versus 31% in patients with low, 38 versus 33% in patients with intermediate and 60 versus 58% in patients with high pretest probability of coronary artery disease, respectively). No significant difference was detected between the two groups regarding stress perfusion defect score (1.45 ± 2.5 versus 1.50 ± 2.6) or rest score (0.72 ± 1.8 versus 0.68 ± 1.6).ConclusionTreated hypertensive patients without known coronary artery disease have a similar prevalence and severity of myocardial perfusion abnormalities at rest and at dobutamine stress compared with normotensive patients with similar clinical characteristics.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveIn a model of hypertriglyceridemia and hypertension in rats (HTG), induced by adding refined sugar to the animals' drinking water, we investigated the response to an acute stress, such as ischemia and reperfusion. In addition, we examined the contribution of calcium overload and free radical release to the injury caused by the post-ischemic reperfusion in a pathological state compared with the normal state.MethodsIschemia was induced in the whole anaesthetized animal, by occlusion of the left coronary artery for 4 min, followed by reperfusion for 6 min. To prevent either calcium overload or lipid oxidative processes during reperfusion, either Ketorolac (KET), a calcium ionophore-like drug, or α-Phenyl-N-ter-butyl nitrone (PBN), a spin-trapping agent, was administered beforehand.ResultsKetorolac failed to protect the HTG animals from heart damage, as seen by the incidence of reperfusion dysrhythmias, release of lactate dehydrogenase and creatine kinase to the plasma, and non-recovery of the sinus rhythm. On the other hand, PBN was able to prevent these harmful events in the HTG heart by diminishing lipoperoxidation.ConclusionsThe results suggest that, in HTG animals, the oxidative processes make a major contribution to the reperfusion injury and that the sole protection from calcium overload provided by KET is not sufficient to avoid damage compared with control rats.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo investigate whether one kidney one clip (1K-1C) hypertensive rats associated with high levels of angiotensin II (Ang II) exhibit enhanced expression and functions of G proteins in the heart and whether the enhanced expression can be attributed to Ang II.MethodsThe levels of G protein and G protein mRNA in hearts from 1K-1C hypertensive rats were determined by immunoblotting and Northern blotting techniques using specific antibodies and cDNA probes, respectively, for different isoforms of G proteins. Adenylyl cyclase activity, stimulated or inhibited by agonists, was determined to examine the function of G proteins.ResultsThe levels of Giα-2 and Giα-3 proteins and mRNA were significantly increased in hearts from 1K-1C hypertensive rats compared with control rats, whereas the levels of Gsα were unchanged. Guanosine 5′-[3′-thio] triphosphate (GTPγS), isoproterenol, glucagon, sodium fluoride (NaF) and forskolin (FSK) stimulated adenylyl cyclase activity in hearts from control and hypertensive rats to varying degrees; however, the stimulations were significantly less in hypertensive rats compared with control rats. On the other hand, the inhibitory effect of low concentrations of GTPγS on FSK-stimulated adenylyl cyclase activity (an index of Gi function) was significantly enhanced in hearts from 1K-1C hypertensive rats, whereas the inhibitory effect of C-ANF4-23on adenylyl cyclase was increased and that of Ang II was decreased in hearts from 1K-1C hypertensive rats. Captopril, an angiotensinconverting enzyme inhibitor, restored the augmented levels of Gi proteins and also the altered stimulation and inhibition of adenylyl cyclase by GTPγS, stimulatory and inhibitory hormones, respectively, in hearts from hypertensive rats.ConclusionThese data suggest that 1K-1C hypertensive rats exhibit enhanced expression of Giα proteins and associated functions that may be attributable to the enhanced levels of Ang II in this model of hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo compare enalapril 20 mg once daily with 10 mg twice daily in terms of blood pressure reduction and patient compliance.DesignCross-over study of patients randomly assigned to a sequence of enalapril 20 mg once daily or 10 mg twice daily in three 4-week periods following a 4-week placebo run-in.SettingGeneral practices in the greater Belfast and Lisburn area in Northern Ireland.PatientsTwenty-five hypertensive patients who had a mean diastolic blood pressure of between 90 and 110 mmHg after receiving placebo for 4 weeks.Main outcome measuresReduction in blood pressure and estimation of patient compliance.ResultsPatient compliance was superior on the once daily regimen. However, the twice daily regimen was associated with a greater blood pressure reduction which almost reached statistical significance at the 5% level.ConclusionsEnalapril 20 mg should be prescribed as 10 mg twice daily and measures taken to improve patient compliance.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveTo define: (1) the prevalence of and (2) factors associated with undertreatment of hypertension in older persons; and (3) the prevalence of specific drug regimens and reasons for their selection.ParticipantsCross-sectional survey of persons aged ≥ 65 years living in Dicomano, Italy.Main outcome measuresPrevalence of untreated and uncontrolled hypertension, both defined on the basis of two blood pressure (BP) cut-off points (≥ 140/90 and ≥ 160/90 mmHg) and of the presence of pharmacological treatment. Predictors of undertreatment were analysed for the higher BP cut-off only.ResultsFive hundred of 692 (72.3%) and 380/692 (54.9%) participants met the 140/90 and the 160/90 mmHg BP criterion, respectively. Of the latter, 162 (42.6%) were untreated, 119 (31.3%) had uncontrolled and 99 (26.1%) controlled hypertension. Women [odds ratio (OR), 0.4; 95% confidence interval (CI), 0.2–0.7], participants with coronary artery disease (CAD) (OR, 0.2; 95% CI, 0.1–0.6), stroke (OR, 0.3; 95% CI, 0.1–0.7), and preserved cognitive status (Mini Mental State Examination score >21: 0.3; 95% CI, 0.2–0.7) were more frequently treated. Uncontrolled hypertension was less likely in women (OR, 0.5; 95% CI, 0.3–1.0) and CAD patients (OR, 0.3; 95% CI, 0.1–0.7). Angiotensin converting enzyme (ACE)-inhibitors (55%), calcium (Ca)-antagonists (31%) and diuretics (20%) were the drugs most commonly prescribed. ACE-inhibitors were preferred, and diuretics rarely used, in diabetic subjects. Ca-antagonists were used mostly in CAD participants.ConclusionsHypertension is undertreated in the majority of noninstitutionalized older adults, especially in men with impaired cognition and no vascular disease. Drug regimens are mostly based on ACE-inhibitors and Ca-antagonists, as a result of associated clinical conditions, requiring individualized treatment.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundThere is broad agreement that statin treatment should be targeted at absolute coronary heart disease (CHD) risk but no consensus on the level of risk to target. We have examined the implications of adopting three different treatment policies for the management of hypertensive patients in the UK using data from treated hypertensives aged 35–69 years included in the Health Survey for England (1993).MethodsWe calculated the proportion of hypertensive patients with existing atherosclerotic cardiovascular disease requiring statin treatment for secondary prevention of CHD. For those without atherosclerotic cardiovascular disease (primary prevention), we estimated CHD risk from the Framingham equation and examined the proportion with CHD risk exceeding thresholds of 4.5, 3 and 1.5% per year.ResultsTwenty-one percent of treated hypertensives would require statin treatment for secondary prevention of CHD. When the CHD event threshold for statin treatment was set at ≥ 4.5% per year [equivalent to a number needed to treat (NNT) in 5 years of 13] a further 0.6% of hypertensive patients were identified for treatment; at a threshold of 3.0% per year (NNT = 20) 5.5% of patients were identified for primary prevention; and at a threshold of 1.5% per year (NNT = 40) 28.5% of patients were identified for primary prevention.ConclusionsThose needing secondary prevention are first priority for statins and 21% of hypertensive patients will require treatment. Formulation of guidelines for primary prevention should take into account the NNT; the proportion of patients targeted for treatment; the cost-effectiveness and the total cost of treatment. Current British guidance will entail treating an additional 5.5% of hypertensive patients for primary prevention and therefore 27% of hypertensive patients.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

ObjectiveThe primary aim of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS) is to determine the effects of a long-term angiotensin converting enzyme (ACE)-inhibitor-based blood-pressure-lowering regimen on the risk of stroke among patients with a history of stroke or transient ischaemic attack (TIA). Secondary aims include investigation of the effects of treatment on total cardiovascular events, dementia and disability.Design and methodsPROGRESS is a double-blind, placebo-controlled randomized trial. Patients were randomly assigned to treatment with the ACE inhibitor perindopril (and the diuretic indapamide for those with no definite indication or contraindication to treatment with a diuretic) versus matching placebo(s). Both hypertensive and non-hypertensive patients were eligible for inclusion. Follow-up is scheduled for completion in 2001. The study is being conducted in 172 centres in 10 countries (Australia, Belgium, China, France, Italy, Ireland, Japan, New Zealand, Sweden and the United Kingdom).ResultsRecruitment was completed in November 1997, with 6105 patients randomized. Mean age of participants at study entry was 64 years, 30% of whom were female, 84% had an entry diagnosis of stroke, and the remainder had an entry diagnosis of TIA alone. Mean baseline blood pressure was 147/86 mmHg, with about half the patients reporting current drug treatment for hypertension. At randomization, 58% of patients were assigned to combination treatment with both study drugs versus placebos, and 42% were assigned to perindopril alone versus placebo.ConclusionsThe successful completion of recruitment, together with current indicators of statistical power, suggest that PROGRESS should achieve its primary aim on schedule.

ISSN:0263-6352    

出版商:OVID    

年代:1999

数据来源: OVID