老年高血压患者局部脑血流改变对预后的影响

目的探讨无并发症的老年原发性高血压患者的局部脑血流（ｒＣＢＦ）改变及其对预后的影响。方法对经治疗将血压控制正常的３４例住院老年高血压患者（高血压组）和３０例血压正常的老年人（对照组）应用单光子发射计算机断层扫描行ｒＣＢＦ检查,并进行随访。结果高血压组有２９例（８５．３％）ｒＣＢＦ减少,而对照组有１３例（４３．３％,Ｐ＜０．００１）。高血压病程１０～３５年者,平均每例ｒＣＢＦ减少２．７处;病程２～９年者,平均减少１．５处（Ｐ＜０．０５）。高血压组３１例、对照组２９例平均随访（３６±２２）个月,原ｒＣＢＦ减少的高血压组患者中有１２例（４１．４％）发生脑梗死,１例脑出血死亡;对照组只有１例发生脑梗死（７．７％,Ｐ＜０．０５）。结论老年高血压患者尽管经治疗将血压控制正常,但ｒＣＢＦ减少仍十分常见,是发生缺血性脑卒中的主要原因。ｒＣＢＦ减少区域的数量与病程呈正相关。及早治疗高血压和改善脑血液循环,对预防缺血性脑卒中有重要意义     

Antihypertensive drug therapy prevents cerebral microvascular abnormalities in hypertensive rats

Studies were performed on anesthetized 16-18 week old normotensive Wistar-Kyoto rats, spontaneously hypertensive rats, and Goldblatt two-kidney one clip renal hypertensive rats, treated from age 4-5 weeks with an oral antihypertensive regimen consisting of hydralazine, reserpine, and chlorothiazide. Measurements of flow and intravascular pressure in the cerebral microvasculature were made via a constantly suffused open cranial window using video microscopy. A significant upward shift was seen in the pressure range for cerebral blood flow autoregulation in both groups of untreated hypertensive animals. Following treatment, the autoregulatory range in both hypertensive models was restored to a level nearly identical to control. The prevention of this shift in treated animals was due primarily to the prevention of structural microvascular adaptations that occur in untreated hypertensive animals. By preventing elevations in microvascular pressure, treatment may have eliminated the major stimulus for development of hypertrophy in resistance vessels. However, a persistent increment of arteriolar wall mass in treated spontaneously hypertensive rats may represent a hyperplastic response not influenced by treatment. Likewise, a persistent constriction of the smallest arterioles in treated renal hypertensive rats may represent a differential sensitivity of microvessels to circulating vasoactive agents. It appears that treatment initiated in the prehypertensive state, or before significant sustained hypertension has occurred, can markedly reduce the cerebrovascular morbidity associated with two different forms of hypertension.     

Amlodipine lowers blood pressure without affecting cerebral blood flow as measured by single photon emission computed tomography in elderly hypertensive subjects.

AIM: To evaluate the effect of amlodipine on blood pressure and cerebral blood flow in elderly subjects with mild to moderate hypertension. METHODS: A double-blind, parallel group study of 26 patients. After a 4-week placebo run-in period, amlodipine (5-10 mg) or matching placebo was given once daily for 8 weeks. RESULTS: Amlodipine significantly reduced blood pressure compared with baseline. Diastolic blood pressure was significantly reduced by amlodipine compared with placebo (P< 0.02 to P< 0.01). Ambulatory blood pressure monitoring showed that blood pressure control was sustained over the 24-h dosing interval. Relative regional cerebral blood flow, assessed using single photon emission computed tomography, was not significantly affected by amlodipine. Three placebo patients, but no amlodipine patients, withdrew because of adverse events. CONCLUSION: Amlodipine was a well-tolerated and effective antihypertensive agent, and did not reduce regional cerebral blood flow in elderly hypertensive patients.     

Maximal hand blood flow in hypertensive and normal subjects

The present study examined whether patients with systemic hypertension have evidence of structural vascular changes, whether such changes can be detected in early stages of hypertension and whether they are reversible with treatment. Hypertensive and normal subjects were studied under conditions of maximal vasodilation in which flow at a given driving pressure was considered to give an index of structural changes in resistance vessels. Thirty-two subjects were separated into 4 groups: 8 with sustained hypertension, 8 with intermittent hypertension, 8 treated hypertensive subjects maintained at systolic pressures of less than 125 mm Hg with drugs for 5 years, and 8 normal subjects. Flow was measured by venous occlusion plethysmography after 10 minutes of ischemia, using a water-filled plethysmograph at 43 degrees C. Arterial blood pressure was measured by the arm cuff method. Transmural pressure, calculated as mean arterial minus external pressure, was varied by imposing varying external hydrostatic pressures. Flow at a transmural pressure of 85 mm Hg was calculated for each subject from the least-mean-square plot of transmural pressure vs flow. Mean flow for normal subjects was 41 ml/100 ml/min and differed significantly from that for sustained hypertensive patients (30 ml/100 ml/min), treated hypertensive patients (33 ml/100 ml/min), and intermittent hypertensive patients (32 ml/100 ml/min) (p less than 0.05). There was no overlap between sustained hypertensives and normal subjects, but half of the treated hypertensive patients were normal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acute water ingestion increases arterial blood pressure in hypertensive and normotensive subjects

In patients with severe autonomic dysfunction, water ingestion elicits an acute pressor response. Hypertension may be associated with changes in cardiovascular autonomic modulation, but there is no information on the acute effects of water ingestion in patients with hypertension. In this study, we compared the effect of acute water ingestion on haemodynamic and autonomic responses of hypertensive and normotensive individuals. Eight patients with mild hypertension were compared to 10 normotensive individuals. After 30 min resting in the supine position all subjects ingested 500 ml of water. At baseline and after water ingestion, venous blood samples for plasma volume determination were collected, and electrocardiographic tracings, finger blood pressure, forearm blood flow and muscle sympathetic nerve activity (MSNA) were obtained. Water ingestion resulted in similar and minor reduction in plasma volume. Systolic and diastolic blood pressure increased in both hypertensive (mean+/-s.d.: 19/14+/-6/3 mm Hg) and normotensive subjects (17/14+/-6/3 mm Hg). There was an increase in forearm vascular resistance and in MSNA. Heart rate was reduced (hypertensive: 5+/-1 beats/min, normotensive: 5+/-6 beats/min) and the high-frequency component of heart rate and systolic blood pressure variability was increased. In hypertensive and normotensive individuals, acute water ingestion elicits a pressor response, an effect that is most likely determined by an increased vasoconstrictor sympathetic activity, and is counterbalanced by an increase in blood pressure and heart rate vagal modulation.     

Antihypertensive therapy in the elderly

Recent studies have documented that arterial hypertension increases cardiovascular morbidity and mortality even in the geriatric population. Some elderly hypertensive patients, like younger patients, can benefit from antihypertensive therapy. Antihypertensive therapy should be carefully adjusted to suit the cardiovascular pathophysiology of elderly patients.     

老年高血压患者降压治疗对脑血液循环影响初探

目的探索老年高血压患者长期降压治疗对脑血液循环的影响。方法采用颈部血管超声测定全脑血流量（CBF）技术,前瞻性随访142例老年高血压患者降压治疗前、治疗后1／2年及1年时血压与血流动力学参数。结果老年高血压患者降压治疗后CBF增高（治疗前616．41±107．96mL／min,疗程1／2年时629．73±103．63mL／min,疗程1年时635．69±106．31mL／min,P〈0．05）,SBP降幅大者治疗后CBF高（疗程1／2年时β0．147,95％,CI0．022～0．272,P=0．021,疗程1年时B0．161,95％CI0．018～0．313,P=0．037）,基础DBP高者治疗后CBF下降风险大（疗程1／2年时0R1．117,95％CI1．001～1．247,P=0．048,疗程1年时0R1．213,95％CI1．028～1．473,P=0．024）。结论老年高血压患者积极降压治疗安全且益丁脑血液循环,但对基础DBP高者需加强监测。     

Context sensitivity of activity-dependent increases in cerebral blood flow

Functional neuroimaging in humans is used widely to study brain function in relation to human disease and cognition. The neural basis of neuroimaging signals is probably synaptic activity, but the effect of context, defined as the interaction between synaptic inhibition, excitation, and the electroresponsive properties of the targeted neurons, is not well understood. We examined here the effect of interaction of synaptic excitation and net inhibition on the relationship between electrical activity and vascular signals in the cerebellar cortex. We show that stimulation of the net inhibitory parallel fibers simultaneously with stimulation of the excitatory climbing fibers leads to a further rise in total local field potentials (LFP) and cerebral blood flow (CBF) amplitudes, not a decrease, as predicted from theoretical studies. However, the combined stimulation of the parallel and climbing fiber systems produced changes in CBF and LFP that were smaller than their algebraic sum evoked by separate stimulation of either system. This finding was independent of the starting condition, i.e., whether inhibition was superimposed on a state of excitation or vice versa. The attenuation of the increases in LFP and CBF amplitudes was similar, suggesting that synaptic activity and CBF were coupled under these conditions. The result might be explained by a relative neuronal refractoriness that relates to the intrinsic membrane properties of Purkinje cells, which determine the recovery time of these cells. Our work implies that neuronal and vascular signals are context-sensitive and that their amplitudes are modulated by the electroresponsive properties of the targeted neurons.     

Systemic blood pressure and cerebral blood flow velocity during carotid surgery

BACKGROUND: To evaluate the effect of mean arterial blood pressure (MAP) on cerebral perfusion during carotid surgery, we investigated blood flow velocity in the middle cerebral (Vs,mca) using transcranial Doppler ultrasonography (TCD). METHODS: During carotid crossclamping, treatment included either phenylephrine-induced hypertension without shunting (Group XC; n = 11) or insertion of a shunt (Group S; n = 12). RESULTS: Increasing MAP in Group XC before crossclamping (81 + /-13 mmHg to 107 +/- 12 mmHg) caused an increase of Vs,mca (59 +/- 17 cm/s to 75 +/- 20 cm/s; p < 0.001). During crossclamping without a shunt, Vs,mca was not dependent on MAP, and was reduced (mean 47 +/- 24 cm/s) in relation to preclamp values. In Group S, Vs,mca was always dependent on MAP and the preclamp velocity was maintained (before shunt: 75 +/- 26 cm/sec; during shunt: 79 +/- 30 cm/sec). CONCLUSIONS: Although we found an impaired cerebral autoregulation, Vs,mca was independent of MAP during carotid crossclamping. Thus, TCD measurements have to be interpreted with caution during crossclamping, and the effect of induced hypertension has to be confirmed with more invasive measures of cerebral blood flow.     

老年高血压患者大动脉弹性研究

目的：比较老年高血压患者和非老年高血压患者大动脉扩张性的改变程度，为临床选择敏感反映老年高血压患者大动脉损害和预后危险的指标。方法：选择原发性高血压患者和老年高血压患者，应用自动脉搏波速度（PWV）测定仪测定颈动脉-股动脉PWV作为反映大动脉节段扩张性的参数；应用B型超声对颈动脉进行扫查。比较两组间动脉一股动脉PWV值、颈总动脉腔径、横断面顺应性、容积扩张性的变化。多因素分析用于筛选敏感反映PWV改变的因素。结果：脉压水平、PWV、颈总动脉收缩期内径在老年高血压组明显增高（P=0.0053，P=0.0001，P=0.0300）；颈总动脉横断面顺应性、容积扩张性在两组间无显著性差异（P=0.8138，P=0.8550）；多因素分析结果表明年龄、收缩压是与PWV关系最为密切的因素。结论：高血压导致大动脉损害；PWV能敏感反映大动脉扩张性的变化；年龄和收缩压是影响PWV的两个主要因素；PWV测定为临床提供了一种重要的无创、简便、可动态评估老年高血压患者大动脉损害和预后危险程度的方法。     

老年高血压脑出血患者的立体定向治疗

目的研究老年高血压脑出血患者的治疗方法 ,为老年高血压脑出血患者寻找合适、安全的治疗途径。方法利用立体定向穿刺引流治疗年龄>75岁的高血压脑出血患者21例,其中血肿量20～30 ml 5例,30～60 ml 16例。结果所有患者血肿均得到了有效清除,术后第1、3天格拉斯哥昏迷评分(GCS)明显升高。术后除1例少量再出血,2例肺炎、1例一过性肾功能障碍外,无其他严重并发症出现。所有患者平均住院时间为13.2 d。术后随访6个月,恢复良好者7例,中度残疾12例,重度残疾2例,无死亡。结论立体定向血肿穿刺抽吸引流微创、安全、有效,能有效减少并发症,并缩短住院时间。     

老年高血压患者动态血压与颈动脉粥样硬化的相关性研究

高血压是动脉粥样硬化的主要危险因素之一,在动脉粥样硬化的发展过程中,颈动脉内膜是最早累及的部位。本研究旨在探讨老年高血压病动态血压与颈动脉粥样硬化的相关性。     

Antihypertensive efficacy and acceptability of perindopril in elderly hypertensive patients

The antihypertensive efficacy and acceptability of perindopril, an angiotensin-converting enzyme (ACE) inhibitor, was evaluated in 2,927 elderly (≥70 years) hypertensive patients in general practice, as part of an open 6-month trial conducted on a total of 23,460 patients with mild-to-moderate hypertension. Patients were ambulatory and selected if diastolic blood pressure (DBF) was between 94 and 115 mm Hg and no serious illness or ACE inhibitor intolerance was known. Perindopril was started at 2 or 4 mg once daily and, if supine DBP remained >90 mm Hg, the daily dose could be doubled after 1 or 3 months (or a diuretic added if perindopril titration reached 8 mg). At entry, the 2,927 patients (65% females) were on average 74 years old, body weight was 68.2 kg, duration of hypertension was 9.4 years, and prior antihypertensive treatment was present in 78%. Percentage of normal DBP (≤90 mm Hg) was 69% at 1 month, 86% at 3 months (in patients on perindopril alone), and 94% at 6 months. At 6 months the reduction of systolic blood pressure and DBP was 28 and 16.6 mm Hg, respectively. Of the 2,927 patients at entry, 8.6% dropped out during the trial, including 6.1% due to side effects. Cough was the most common symptom (8.9%) leading to withdrawal in 3.4% of cases. In one patient, serum creatinine increased (3-fold at 1 month), but overall no significant variation of renal function occurred, as shown by stable plasma creatinine and potassium levels.     

Antihypertensive efficacy and acceptability of rilmenidine in elderly hypertensive patients

Elderly hypertensive patients (older than 70 years, with a diastolic blood pressure [BP] between 95 and 114 mm Hg) were entered into a study after a 2-week wash-out period and randomized to 2 parallel groups: rilmenidine (n = 28) and methyldopa (n = 30). The initial dose (rilmenidine, 1 mg once daily A.M. or methyldopa, 250 mg twice daily) was doubled (1 mg twice daily or 500 mg twice daily, respectively) on day 21 if supine diastolic BP remained greater than 90 mm Hg. After a 6-week treatment period (days 0 to 42, with weekly examinations), the effects of treatment withdrawal (day 42) were evaluated twice daily (days 43 to 45), with a final examination on day 49. Most of the 58 patients (70%) (aged 81.5 +/- 0.8 years) with a mean diastolic BP of 100.2 +/- 0.7 mm Hg remained treated with the initial dose in both groups. Efficacy in both groups was identical on day 42: decrease in systolic and diastolic BP of approximately 18 mm Hg, with 85% of patients having BP levels normalized (supine diastolic BP less than or equal to 90 mm Hg). Compared with the reference period, no increase in adverse effects was noted apart from a moderate dryness of mouth in 15% of patients in both groups; no orthostatic hypotension was observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

The value of cerebral blood flow measurement in carotid surgery

The considerable risks and high costs associated with carotid surgery have raised the discussion of its expediency. Carotid surgery is only indicated if a source of embolism in the region of the carotid bifurcation has been demonstrated or an endangerment of the blood supply to the brain is certain. Methods to detect a source of embolism with some reliability were not available until the advent of high-resolution Doppler ultrasound and transcranial techniques. The demonstration of an endangerment of the blood supply to the brain requires measurement of the regional cerebral blood flow assessment of the collateral circulations, and determination of the reserve capacity of the cerebral blood system. Diagnostic procedures available for this and their clinical relevance are discussed. Reliable assessment, however, requires functional criteria which still have to be developed.     

Aerobic exercise training increases cerebral blood flow in postmenopausal women

BackgroundAge-related decrease in cerebral blood flow is a risk factor for cognitive decline. Aerobic exercise training improves vascular and cognitive functions. However, the effect of exercise training on age-related reduction in cerebral blood flow is unclear. The present study investigated whether aerobic exercise training can increase cerebral blood flow in postmenopausal women.MethodsTwenty healthy postmenopausal women were assigned to either the exercise training group (n = 10) or the control group (n = 10). The exercise group completed 8 weeks of moderate aerobic exercise intervention. The control group did not change their physical activity level. Before and after each intervention, middle cerebral blood flow velocity and cerebrovascular resistance were measured using transcranial Doppler ultrasonography.ResultsThe baseline middle cerebral blood flow velocity, cerebrovascular resistance, and most other key dependent variables did not significantly differ between the groups. Aerobic exercise training significantly increased middle cerebral blood flow velocity and significantly decreased cerebrovascular resistance, whereas no such changes were observed in the control group.ConclusionsWe showed that aerobic exercise training increased middle cerebral blood flow velocity and decreased cerebrovascular resistance in postmenopausal women. The results of the current study suggest that regular aerobic exercise may attenuate aging-induced decrease in cerebral blood flow.     

老年隐性高血压患者家庭自测血压变异性与颈动脉粥样硬化的相关性

目的探讨老年隐性高血压患者家庭自测血压变异性与颈动脉粥样硬化及尿微量白蛋白(MAU)的关系。方法选择老年体检者197例,根据受试者诊室血压及7d家庭自测血压测定结果,将受试者分为血压正常组62例、隐性高血压组62例及高血压组73例。所有受试者均进行颈动脉内膜中层厚度(IMT)、硬化系数β值及MAU检测。结果隐性高血压组和高血压组诊室收缩压、自测收缩压、自测舒张压、收缩压变异性、舒张压变异性、IMT、硬化系数β值、MAU明显高于血压正常组(P<0.05,P<0.01);隐性高血压组诊室收缩压、诊室舒张压、自测收缩压、硬化系数β值明显低于高血压组(P<0.05,P<0.01)。隐性高血压患者自测血压变异性与IMT、硬化系数β值及MAU呈正相关。收缩压变异性是IMT、硬化系数β值及MAU的独立影响因素。结论老年隐性高血压患者家庭自测血压变异性升高,并与颈动脉粥样硬化及MAU相关。