Cerebral blood flow and its pathophysiology in hypertension

L-Arginine and Taurisolo® Effects on Brain Hypoperfusion-Reperfusion Damage in Hypertensive Rats

Acute and chronic hypertension causes cerebral vasculopathy, increasing the risk of ischemia and stroke. Our study aimed to compare the effects of arterial pressure reduction on the pial microvascular responses induced by hypoperfusion and reperfusion in spontaneously hypertensive Wistar rats, desamethasone-induced hypertensive Wistar rats and age-matched normotensive Wistar rats fed for 3 months with a normal diet or normal diet supplemented with L-arginine or Taurisolo® or L-arginine plus Taurisolo®. At the end of treatments, the rats were submitted to bilateral occlusion of common carotid arteries for 30 min and reperfusion. The microvascular parameters investigated in vivo through a cranial window were: arteriolar diameter changes, permeability increase, leukocyte adhesion to venular walls and percentage of capillaries perfused. Hypoperfusion-reperfusion caused in all rats marked microvascular changes. L-arginine treatment was effective in reducing arterial blood pressure causing vasodilation but did not significantly reduce the damage induced by hypoperfusion-reperfusion. Taurisolo® treatment was less effective in reducing blood pressure but prevented microvascular damage from hypoperfusion-reperfusion. L-arginine plus Taurisolo® maintained blood pressure levels within the physiological range and protected the pial microcirculation from hypoperfusion-reperfusion-induced microvascular injuries. Therefore, the blood pressure reduction is not the only fundamental aspect to protect the cerebral circulation from hypoperfusion-reperfusion damage.

Individualized Perioperative Hemodynamic Management Using Hypotension Prediction Index Software and the Dynamics of Troponin and NTproBNP Concentration Changes in Patients Undergoing Oncological Abdominal Surgery

INTRODUCTION

Abdominal oncologic surgeries pose significant risks due to the complexity of the surgery and patients' often weakened health, multiple comorbidities, and increased perioperative hazards. Hypotension is a major risk factor for perioperative cardiovascular complications, necessitating individualized management in modern anesthesiology.

AIM

This study aimed to determine the dynamics of changes in troponin and NTproBNP levels during the first two postoperative days in patients undergoing major cancer abdominal surgery with advanced hemodynamic monitoring including The AcumenTM Hypotension Prediction Index software (HPI) (Edwards Lifesciences, Irvine, CA, USA) and their association with the occurrence of postoperative cardiovascular complications.

METHODS

A prospective study was conducted, including 50 patients scheduled for abdominal cancer surgery who, due to the overall risk of perioperative complications (ASA class 3 or 4), were monitored using the HPI software. Hypotension was qualified as at least one ≥ 1 min episode of a MAP < 65 mm Hg. Preoperatively and 24 and 48 h after the procedure, the levels of NTproBNP and troponin were measured, and an ECG was performed.

RESULTS

We analyzed data from 46 patients and found that 82% experienced at least one episode of low blood pressure (MAP < 65 mmHg). However, the quality indices of hypotension were low, with a median time-weighted average MAP < 65 mmHg of 0.085 (0.03-0.19) mmHg and a median of 2 (2-1.17) minutes spent below MAP < 65 mmHg. Although the incidence of perioperative myocardial injury was 10%, there was no evidence to suggest a relationship with hypotension. Acute kidney injury was seen in 23.9% of patients, and it was significantly associated with a number of episodes of MAP < 50 mmHg. Levels of NTproBNP were significantly higher on the first postoperative day compared to preoperative values (285.8 [IQR: 679.8] vs. 183.9 [IQR: 428.1] pg/mL, p < 0.001). However, they decreased on the second day (276.65 [IQR: 609.4] pg/mL, p = 0.154). The dynamics of NTproBNP were similar for patients with and without heart failure, although those with heart failure had significantly higher preoperative concentrations (435.9 [IQR: 711.15] vs. 87 [IQR: 232.2] pg/mL, p < 0.001). Patients undergoing laparoscopic surgery showed a statistically significant increase in NTproBNP.

CONCLUSIONS

This study suggests that advanced HPI monitoring in abdominal cancer surgery effectively minimizes intraoperative hypotension with no significant NTproBNP or troponin perioperative dynamics, irrespective of preoperative heart failure.

The Effect of Ciprofol on Postoperative Delirium in Elderly Patients Undergoing Thoracoscopic Surgery for Lung Cancer: A Prospective, Randomized, Controlled Trial

Purpose

This study was conducted to assess whether ciprofol vs propofol could affect the incidence of postoperative delirium (POD) in elderly patients with lung cancer after thoracoscopic surgery.

Patients and Methods

In this study, a total of 84 elderly patients undergoing thoracoscopic surgery for lung cancer were recruited and randomized into two groups to receive anesthesia with either ciprofol or propofol. The primary outcome was the incidence of POD within three days after surgery. Secondary outcomes included the Confusion Assessment Method (CAM) score, intraoperative indicators related to mean arterial pressure (MAP), and cerebral tissue oxygen saturation (SctO2). Moreover, MAP- and SctO2-related indicators associated with POD were analyzed.

Results

The incidence of POD was 7.1% and 16.7%, respectively, in the ciprofol group and the propofol group (risk ratio [RR], 0.37; 95% confidence interval [CI], 0.07 to 2.03; risk difference [RD], -9.6%; 95% CI, -23.3% to 4.1%; p = 0.178). Compared with those in the propofol group, patients in the ciprofol group had lower CAM scores three days after surgery (13 (12, 15) vs 15 (14, 17); 12 (11, 13) vs 14 (13, 16); 12 (11, 12) vs 13 (12, 14), p<0.05). Besides, patients in the ciprofol group exhibited higher mean and minimum MAP (88.63 ± 6.7 vs 85 ± 8.3; 69.81 ± 9.59 vs 64.9 ± 9.43, p<0.05) and SctO2 (77.26 ± 3.96 vs 75.3 ± 4.49, 71.69 ± 4.51 vs 68.77 ± 6.46, p<0.05) and percentage of time for blood pressure stabilization (0.6 ± 0.14 vs 0.45 ± 0.14, p<0.05) than those in the propofol group. Furthermore, MAP and SctO2-related indicators were validated to correlate with POD.

Conclusion

Anesthesia with ciprofol did not increase the incidence of POD compared with propofol. The results demonstrated that ciprofol could improve intraoperative MAP and SctO2 levels and diminish postoperative CAM scores.

[Thrombotic microangiopathy]

In the emergency room, patients with anemia and thrombocytopenia are common. Although these findings can often be explained by the medical situation, thrombotic microangiopathy is an important differential diagnosis. In this case, occlusion of the smallest vessels consequently leads to functional impairment of the affected organs. Patients generally present with symptoms of organ dysfunction, e.g., in the kidney or brain. Characteristically, Coombs-negative fragmentation of erythrocytes with hemolysis occurs in the area of the occluded vessels. Lactate dehydrogenase levels are elevated, and platelets and haptoglobin are reduced. Differential diagnoses beyond thrombotic microangiopathy that should be considered are numerous and diverse in their pathophysiology. Rapid workup is needed, because sometimes a specific treatment must be initiated rapidly. For example, thrombotic thrombocytopenic purpura leads to death in about 90% of patients if left untreated. However, by reconstitution of the underlying deficiency of the so-called ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) by plasma separation, survival can be ensured in most cases. Complement-mediated hemolytic uremic syndrome should also be considered and, if suspected, treated with complement inhibition. In many cases, however, thrombotic microangiopathy reflects a disorder elsewhere and may be a manifestation of severe hypertension or a coagulation disorder, such as disseminated intravascular coagulation or antiphospholipid syndrome. It can also be observed as a consequence of drug therapies or metabolic derangement. Systemic workup is therefore necessary for rapid clarification of differential diagnoses.

Hypertension and childhood stroke

Cerebrovascular disease (stroke) is one of the ten leading causes of death in children and adolescents. Multiple etiologies, from arteriopathies to prothrombic states, can cause stroke in youth. In adult stroke, hypertension has been shown to be the single most important modifiable risk factor. Although hypertension has not been strongly identified as a risk factor in childhood stroke to date, there is preliminary evidence that suggests that hypertension may also be associated with stroke in children. In this review, we summarize the literature that may link hypertension to stroke in the young. We have identified a series of barriers and limitations in the fields of pediatric hypertension and pediatric neurology that might explain why hypertension has been overlooked in childhood stroke. We suggest that hypertension may be a relevant risk factor that, alone or in combination with other multiple factors, contributes to the development of stroke in children. Currently, there are no consensus guidelines for the management of post-stroke hypertension in children. Thus, we recommend that blood pressure be assessed carefully in every child presenting with acute stroke in order to better understand the effects of hypertension in the development and the outcome of childhood stroke. We suggest a treatment algorithm to help practitioners manage hypertension after a stroke.

Secondary Headache: Current Update

PURPOSE

The purpose of this paper is to review some of the causes of secondary headache particularly focusing on the subcategories of secondary headache in the International Classification of Headache Disorders, 3rd edition, the clinical features of these headaches, and their associated features and management.

OVERVIEW

Headache attributed to trauma or injury to the head and/or neck, headache attributed to cranial or cervical vascular disorder, headache attributed to non-vascular intracranial disorder, headache attributed to a substance or its withdrawal, headache attributed to infection, headache attributed to disorder of homeostasis, and headache or facial pain attributed to disorder of the cranium, neck, eye, ears, nose, sinuses, teeth, mouth, or other facial or cervical structure are discussed in this paper.

DISCUSSION

Headache is a common symptom of multiple medical conditions. Although a minority of headache patients have a secondary basis for their headaches, it is important to identify clinical features of secondary headache disorders including both the headache and non-headache features of the condition, diagnose the secondary etiology correctly, and treat them appropriately.

N-Terminal Pro Brain, N-Terminal Pro Atrial Natriuretic Peptides, and Dynamic Cerebral Autoregulation

Background

Elevated natriuretic peptides (NP) are associated with adverse cerebrovascular conditions including stroke, cerebral small vessel disease, and dementia. However, the mechanisms underlying these associations remain unclear. In this study, we examined the relationship of NT‐proBNP (N‐terminal pro brain NP) and NT‐proANP (N‐terminal pro atrial NP) with cerebrovascular function, measured by cerebral autoregulation.

Methods and Results

We included 154 participants (mean age 56±4 years old) from the CARDIA (Coronary Artery Risk Development in Young Adults) cohort. NT‐proBNP and NT‐proANP were measured in blood samples from the year 25 examination using electrochemiluminescence Immunoassay and enzyme‐linked immunoassay, respectively. Dynamic cerebral autoregulation (dCA) was assessed at the year 30 examination by transcranial Doppler ultrasound, using transfer function analysis (phase and gain) of spontaneous blood pressure and flow velocity oscillations, where lower phase and higher gain reflect less efficient cerebral autoregulation. We used multivariable linear regression models adjusted for demographics, vascular risk factors, and history of kidney and cardiac diseases. Higher NT‐proBNP levels at year 25 were associated with lower phase (β [95% CI]=−5.30 lower degrees of phase [−10.05 to −0.54]) and higher gain (β [95% CI]=0.06 higher cm/s per mm Hg of gain [0.004–0.12]) at year 30. Similarly, higher NT‐proANP levels were associated with lower phase (β [95% CI]=−9.08 lower degrees of phase [−16.46 to −1.70]).

Conclusions

Higher circulating levels of NT‐proBNP and NT‐proANP are associated with less efficient dCA 5 years later. These findings link circulating NP to cerebral autoregulation and may be one mechanism tying NP to adverse cerebrovascular outcomes.

Posterior reversible encephalopathy syndrome in scrub typhus fever

The clinical course of a 40-year-old female patient, who presented with acute febrile illness due to scrub typhus fever became complicated by seizures and posterior reversible encephalopathy syndrome (PRES), leading to a fatal outcome. She had normal blood pressure at admission; however, she later developed hypotension and shock. PRES is a syndrome of vasogenic cerebral oedema and accompanying neurological deficits resulting from the breakdown of blood-brain barrier due to high blood pressure or radical blood pressure changes. PRES is a clinico-radiographic diagnosis of heterogeneous aetiologies and is rare in the context of infections. Although there are many neurological manifestations in scrub typhus, to the best of our knowledge, PRES has never been reported.

Clinical Relevance of Orthostatic Hypotension in Patients with Atrial Fibrillation and Suspected Transient Ischemic Attack

INTRODUCTION

Orthostatic hypotension (OH) and atrial fibrillation (AF) are both regarded as independent risk factors for transient ischemic attack (TIA). However, the clinical implication of OH in the presence of AF is unclear. This study investigates, for the first time, the association between blood pressure (BP), OH and mortality in a cohort of patients with AF and TIA symptoms.

AIM

To investigate the incidence of the association between OH, AF and TIA.

METHODS

This retrospective observational study utilised the Leicester one-stop transient TIA clinic patient database to consider the initial systolic and diastolic BP of 688 patients with a diagnosis of AF. The primary outcome was time until death. Covariant measures included status of AF diagnosis (known or new AF), cardiovascular risk factors, and primary clinic diagnosis [cerebrovascular (CV) versus non-cerebrovascular (non-CV)]. Statistical models adjusted for sex, age, previous AF diagnosis.

RESULTS

Mortality rate was higher in the over 85 age group [191.5 deaths per 1000 person years (py) (95% CI 154.0-238.1)] and lower in the aged 75 and younger age group [40.0 deaths per 1000 py (95% CI 27.0-59.2)] compared to intermediate groups. A 10 mmHg increase in supine diastolic BP was associated with a significant reduction in the hazard of mortality for patients suspected of TIA with AF [adjusted HR 0.79 (95% CI 0.68-0.92), p < 0.001]. The mortality rate for patients with OH was 119.0 deaths per 1000 py compared with a rate of 98.0 for patients without OH (rate ratio 1.2, p = 0.275).

CONCLUSION

Higher diastolic BP may be a marker for reduced mortality risk in patients with a previous AF diagnosis and non-CV diagnosis. Lower diastolic BP and the presence of AF pertain to a higher mortality risk. This study raises the importance of opportunistic screening for both OH and AF in patients presenting to TIA clinic.

Österreichischer Blutdruckkonsens 2019

Erhöhter Blutdruck bleibt eine Hauptursache von kardiovaskulären Erkrankungen, Behinderung und frühzeitiger Sterblichkeit in Österreich, wobei die Raten an Diagnose, Behandlung und Kontrolle auch in rezenten Studien suboptimal sind. Das Management von Bluthochdruck ist eine häufige Herausforderung für Ärztinnen und Ärzte vieler Fachrichtungen. In einem Versuch, diagnostische und therapeutische Strategien zu standardisieren und letztendlich die Rate an gut kontrollierten Hypertoniker/innen zu erhöhen und dadurch kardiovaskuläre Erkrankungen zu verhindern, haben 13 österreichische medizinische Fachgesellschaften die vorhandene Evidenz zur Prävention, Diagnose, Abklärung, Therapie und Konsequenzen erhöhten Blutdrucks gesichtet. Das hier vorgestellte Ergebnis ist der erste Österreichische Blutdruckkonsens. Die Autoren und die beteiligten Fachgesellschaften sind davon überzeugt, daß es einer gemeinsamen nationalen Anstrengung bedarf, die Blutdruck-assoziierte Morbidität und Mortalität in unserem Land zu verringern.

Association Between Elevated Mean Arterial Blood Pressure and Neurologic Outcome After Resuscitation From Cardiac Arrest: Results From a Multicenter Prospective Cohort Study

OBJECTIVES

Laboratory studies suggest elevated blood pressure after resuscitation from cardiac arrest may be protective; however, clinical data are limited. We sought to test the hypothesis that elevated postresuscitation mean arterial blood pressure is associated with neurologic outcome.

DESIGN

Preplanned analysis of a prospective cohort study.

SETTING

Six academic hospitals in the United States.

PATIENTS

Adult, nontraumatic cardiac arrest patients treated with targeted temperature management after return of spontaneous circulation.

INTERVENTIONS

Mean arterial blood pressure was measured noninvasively after return of spontaneous circulation and every hour during the initial 6 hours after return of spontaneous circulation.

MEASURES AND MAIN RESULTS

We calculated the mean arterial blood pressure and a priori dichotomized subjects into two groups: mean arterial blood pressure 70-90 and greater than 90 mm Hg. The primary outcome was good neurologic function, defined as a modified Rankin Scale less than or equal to 3. The modified Rankin Scale was prospectively determined at hospital discharge. Of the 269 patients included, 159 (59%) had a mean arterial blood pressure greater than 90 mm Hg. Good neurologic function at hospital discharge occurred in 30% of patients in the entire cohort and was significantly higher in patients with a mean arterial blood pressure greater than 90 mm Hg (42%) as compared with mean arterial blood pressure 70-90 mm Hg (15%) (absolute risk difference, 27%; 95% CI, 17-37%). In a multivariable Poisson regression model adjusting for potential confounders, mean arterial blood pressure greater than 90 mm Hg was associated with good neurologic function (adjusted relative risk, 2.46; 95% CI; 2.09-2.88). Over ascending ranges of mean arterial blood pressure, there was a dose-response increase in probability of good neurologic outcome, with mean arterial blood pressure greater than 110 mm Hg having the strongest association (adjusted relative risk, 2.97; 95% CI, 1.86-4.76).

CONCLUSIONS

Elevated blood pressure during the initial 6 hours after resuscitation from cardiac arrest was independently associated with good neurologic function at hospital discharge. Further investigation is warranted to determine if targeting an elevated mean arterial blood pressure would improve neurologic outcome after cardiac arrest.

Small separation diffuse correlation spectroscopy for measurement of cerebral blood flow in rodents

Diffuse correlation spectroscopy (DCS) has shown promise as a means to non-invasively measure cerebral blood flow in small animal models. Here, we characterize the validity of DCS at small source-detector reflectance separations needed for small animal measurements. Through Monte Carlo simulations and liquid phantom experiments, we show that DCS error increases as separation decreases, although error remains below 12% for separations > 0.2 cm. In mice, DCS measures of cerebral blood flow have excellent intra-user repeatability and strongly correlate with MRI measures of blood flow (R = 0.74, p<0.01). These results are generalizable to other DCS applications wherein short-separation reflectance geometries are desired.

A Case of Recurrent Thrombotic Microangiopathy Caused by Hypertensive Urgency

A 26-year-old man presented to the emergency room with abdominal pain, nausea, and vomiting for four days. His medical history was significant for hypertension and end-stage renal disease managed with hemodialysis. He had been noncompliant with the antihypertensive regimen which included nifedipine, hydralazine, and spironolactone. At presentation, his blood pressure was 231/123 mmHg. Laboratory workup showed white blood count 17.3 × 109/L (normal range: 4.5 to 11.0 × 109/L), hemoglobin 7.8 gm/dL (normal range: 13.5 to 17.5 g/dL), platelet count 46 × 109/L (normal range: 150 to 400 × 109/L), reticulocyte count 7.8%, total bilirubin 1 mg/dL (normal range: 0.1 to 1.2 mg/dL), lactate dehydrogenase 1,235 U/L (normal range: 140 to 280 U/L), haptoglobin < 10 mg/dL, and a direct Coomb's test was negative. Numerous schistocytes were identified on the peripheral blood smear. The patient was diagnosed with thrombotic microangiopathy secondary to severe hypertension and was started on intravenous nicardipine. With appropriate blood pressure control, hematological parameters improved with normalization of the platelet count within 10 days. Notably, the patient had one similar episode of hypertension-induced thrombotic microangiopathy within a period of the last three months and ADAMTS-13 (a disintegrin and metalloprotease with thrombospondin type 1 motif 13) activity was normal on his previous admission.

Controlling Hypertension After Severe Cerebrovascular Event (CHASE): study protocol for a randomized controlled trial

Background

No ideal blood pressure (BP) range has been scientifically determined for acute stroke, and no studies on BP management have been carried out for patients with severe stroke. This trial aims to investigate whether individualized lowering of elevated BP would improve the outcome in patients with severe stroke.

Methods/design

The CHASE trial is a multicenter, randomized, controlled study. A total of 500 adult patients with acute severe stroke will be enrolled in 18 study sites in China and randomized to individualized BP lowering (10–15% reduction from admission level) or guideline-recommended BP lowering. The primary outcome measurement is the proportion of participants with a poor outcome (modified Rankin Scale ≥ 3) at day 90 of enrollment. Secondary outcomes include disability at hospital discharge and the ability of activities of daily living at day 90 of enrollment. The relationship between intervention and the primary outcome will be analyzed using multivariate logistic regression adjusted for study site, demographics, and baseline characteristics.

Discussion

The CHASE trial will be the first study to explore the optimum BP management for acute severe stroke. This trial potentially offers a strong argument for individualized target for lowering elevated BP in patients with severe stroke.

Trial registration

ClinicalTrials.gov, NCT02982655. Registered on 30 November 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2530-x) contains supplementary material, which is available to authorized users.

The Association Between Mild Intraoperative Hypotension and Stroke in General Surgery Patients

BACKGROUND

Intraoperative hypotension may contribute to perioperative strokes. We therefore tested the hypothesis that intraoperative hypotension is associated with perioperative stroke.

METHODS

After institutional review board approval for this case-control study, we identified patients who had nonneurological, noncardiac, and noncarotid surgery under general anesthesia at the Cleveland Clinic between 2005 and 2011 and experienced a postoperative stroke. Control patients not experiencing postoperative stroke were matched in a 4-to-1 ratio using propensity scores and restriction to the same procedure type as stroke patients. The association between intraoperative hypotension, measured as time-integrated area under a mean arterial pressure (MAP) of 70 mm Hg, and postoperative stroke was assessed using zero-inflated negative binomial regression.

RESULTS

Among 106 337 patients meeting inclusion criteria, we identified 120 who had confirmed postoperative stroke events based on manual chart review. Four-to-one propensity matching yielded a final matched sample of 104 stroke cases and 398 controls. There was no association between stroke and intraoperative hypotension. Stroke patients were not more likely than controls to have been hypotensive (odds ratio, 0.49 [0.18-1.38]), and among patients with intraoperative hypotension, stroke patients did not experience a greater degree of hypotension than controls (ratio of geometric means, 1.07 [0.76-1.53]).

CONCLUSIONS

In our propensity score-matched case-control study, we did not find an association between intraoperative hypotension, defined as MAP < 70 mm Hg, and postoperative stroke.

Functional vascular contributions to cognitive impairment and dementia: mechanisms and consequences of cerebral autoregulatory dysfunction, endothelial impairment, and neurovascular uncoupling in aging

Increasing evidence from epidemiological, clinical and experimental studies indicate that age-related cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. Understanding and targeting the age-related pathophysiological mechanisms that underlie vascular contributions to cognitive impairment and dementia (VCID) are expected to have a major role in preserving brain health in older individuals. Maintenance of cerebral perfusion, protecting the microcirculation from high pressure-induced damage and moment-to-moment adjustment of regional oxygen and nutrient supply to changes in demand are prerequisites for the prevention of cerebral ischemia and neuronal dysfunction. This overview discusses age-related alterations in three main regulatory paradigms involved in the regulation of cerebral blood flow (CBF): cerebral autoregulation/myogenic constriction, endothelium-dependent vasomotor function, and neurovascular coupling responses responsible for functional hyperemia. The pathophysiological consequences of cerebral microvascular dysregulation in aging are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages, microvascular rarefaction, and ischemic neuronal dysfunction and damage. Due to the widespread attention that VCID has captured in recent years, the evidence for the causal role of cerebral microvascular dysregulation in cognitive decline is critically examined.

Cerebral blood flow regulation, exercise and pregnancy: why should we care?

Cerebral blood flow (CBF) regulation is an indicator of cerebrovascular health increasingly recognized as being influenced by physical activity. Although regular exercise is recommended during healthy pregnancy, the effects of exercise on CBF regulation during this critical period of important blood flow increase and redistribution remain incompletely understood. Moreover, only a few studies have evaluated the effects of human pregnancy on CBF regulation. The present work summarizes current knowledge on CBF regulation in humans at rest and during aerobic exercise in relation to healthy pregnancy. Important gaps in the literature are highlighted, emphasizing the need to conduct well-designed studies assessing cerebrovascular function before, during and after this crucial life period to evaluate the potential cerebrovascular risks and benefits of exercise during pregnancy.

Differentiating malignant hypertension-induced thrombotic microangiopathy from thrombotic thrombocytopenic purpura

OBJECTIVES

Malignant hypertension can cause thrombotic microangiopathy (TMA) and the overall presentation may mimic thrombotic thrombocytopenic purpura (TTP). This presents a dilemma of whether or not to initiate plasma exchange. The objective of the study was to determine the clinical and laboratory manifestations of malignant hypertension-induced TMA, and its outcomes.

METHODS

Using several search terms, we reviewed English language articles on malignant hypertension-induced TMA, indexed in MEDLINE by 31 December 2013. We also report a new case. All these cases were analyzed using descriptive statistics.

RESULTS

A total of 19 patients, with 10 males, had a median age of 38 years at diagnosis; 58% had a history of hypertension. Mean arterial pressure at presentation was 159 mmHg (range 123-190 mmHg). All had prominent renal dysfunction (mean creatinine of 5.2 mg/dl, range 1.7-13 mg/dl) but relatively modest thrombocytopenia (mean platelet count of 60 × 103/µl, range 12-131 × 10(3)/µl). Reported cases (n = 9) mostly had preserved ADAMTS-13 activity (mean 64%, range 18-96%). Following blood pressure control, the majority had improvement in presenting symptoms (100%) and platelet counts (84%); however, only 58% had significant improvement in creatinine. More than half (53%) needed hemodialysis. One patient died of cardiac arrest during pacemaker insertion.

CONCLUSION

Prior history of hypertension, high mean arterial pressure, significant renal impairment but relatively modest thrombocytopenia and lack of severe ADAMTS-13 deficiency (activity <10%) at diagnosis are clues to diagnose malignant hypertension-induced TMA. Patients with malignant hypertension respond well to antihypertensive agents and have favorable nonrenal outcomes.

Anesthetic management of labor and delivery in patients with elevated intracranial pressure

The anesthetic management of labor and delivery in patients with elevated intracranial pressure is complex. This review discusses the etiologies of diffuse and focal pathologies which lead to elevated intracranial pressure in pregnancy. The role of neuraxial and general anesthesia in the management of labor and delivery is also examined. Finally, a comprehensive review of strategies to minimize increases in intracranial pressure during general anesthesia for cesarean delivery is presented.

TIA, stroke and orthostatic hypotension: a disease spectrum related to ageing vasculature?

AIMS

We sought to identify the determinants of orthostatic hypotension (OH) among patients referred to the transient ischaemic attack (TIA) clinic.

METHODS

We conducted a retrospective analysis of prospectively collected data on patients who attended the TIA clinic in a UK hospital between January 2006 and September 2009. Each patient had their supine and standing or sitting blood pressure measured. Logistic regression was used to estimate the univariate and multivariate odds of OH for the subgroups of patients based on their diagnosis. A 10% significance level for the univariate analysis was used to identify variables in the multivariate model.

RESULTS

A total of 3222 patients were studied of whom 1131 had a TIA, 665 a stroke and 1426 had other diagnoses. The prevalence of either systolic or diastolic OH in the TIA, stroke and patients with other diagnoses was similar being 22% (n = 251), 24% (n = 162) and 20% (n = 292), respectively. Multivariate analyses showed age, prior history of TIA, and diabetes were independently significantly associated with systolic OH alone or diastolic OH alone or either systolic or diastolic OH [ORs 1.03 (1.02-1.05); 1.56 (1.05-2.31); 1.65 (1.10-2.47), respectively]. Among the patients with the diagnosis of stroke, peripheral vascular disease (PVD) was significantly associated with increased odds of OH (3.56, 1.53-8.31), whereas male gender had a significantly lower odds of OH (0.61, 0.42-0.88). In patients with other diagnoses, age (1.04, 1.02-1.05) and diabetes (1.47, 1.04-2.09) were associated with OH, whereas male gender was (0.76, 0.58-1.00) not associated with OH.

CONCLUSION

Orthostatic hypotension is prevalent among patients presenting to TIA clinic. Previous history of vascular disease (prior TIA/stroke/PVD) appears to be a significant associate of OH in this patient population.

Cerebral desaturation events during shoulder arthroscopy in the beach chair position: patient risk factors and neurocognitive effects

BACKGROUND

Patients undergoing shoulder surgery in the beach chair position may be at increased risk for serious neurocognitive complications due to cerebral ischemia. We sought to define the incidence, patient risk factors, and clinical sequelae of intraoperative cerebral desaturation events.

METHODS

Regional cerebral tissue oxygen saturation (rSO2) was monitored intra-operatively using near-infrared spectroscopy (NIRS) on 50 consecutive patients. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was administered to each patient pre- and postoperatively. Intra-operative decreases in rSO2 of 20% or greater were defined as cerebral desaturation events (CDE). The association between intraoperative CDE and postoperative cognitive decline was assessed.

RESULTS

The incidence of intraoperative CDE in our series was 18% (9/50). Increased body mass index (BMI) was found to have a statistically significant association with intraoperative CDE (mean BMI 37.32 vs 28.59, P < .0001). There was no statistical significance in pre- vs postoperative RBANS either in composite scores or any of the sub-indices in either group.

CONCLUSION

The degree and duration of cerebral ischemia required to produce neurocognitive dysfunction in this patient population remains undefined; however, cerebral oximetry with NIRS allows prompt identification and treatment of decreased cerebral perfusion decreasing the risk of this event. Increased BMI was found to be a statistically significant patient risk factor for the development of intra-operative CDE. The transient intra-operative CDEs were not associated with postoperative cognitive dysfunction in our patient series. We believe protocols aimed at detecting and reversing CDE minimize the risk of neurocognitive dysfunction and improve patient safety.

Hypertensive crisis in young woman with Takayasu arteritis

A young woman who was experiencing repeated convulsions was admitted. The patient's brain magnetic resonance image revealed reversible posterior leukoencephalopathy. Blood pressure fluctuated at times to more than 200 mmHg, and the measurement of the right and left upper arms differed by approximately 70 mmHg. Enhanced computed tomography revealed stenotic lesions of some arteries including the left renal artery. Such findings led to an initial diagnosis of Takayasu arteritis and hypertensive encephalopathy caused by renovascular hypertension. A percutaneous transluminal renal angioplasty was successfully performed. The patient's blood pressure returned to normal value without the use of antihypertensive drugs.

Clevidipine butyrate: a promising new drug for the management of acute hypertension

Clevidipine butyrate is an ultrashort-acting intravenous dihydropyridine calcium-channel blocker that has been approved by the FDA for the reduction of blood pressure when oral therapy is not feasible. Hypertension is a global disease that affects more than 1 billion people worldwide and 75 million people in the USA. There are multiple agents available for the management of hypertension. The acute setting is where the challenge arises for developing new agents that not only decrease, but more importantly, optimally control blood pressure. Many drugs lower blood pressure; however, only a few have the capacity to precisely control hypertension in the acute phase. Clevidipine has unique pharmacodynamic and pharmacokinetic properties that enable the fast, safe and adequate reduction of blood pressure in hypertensive emergencies, with unique precision necessary to maintain the target blood pressure range. Its use in different clinical settings has been evaluated in several Phase I, II and III clinical studies. It is easily administered and titrated with minimal side effects, achieves fast control with low doses, is highly successful as monotherapy and allows excellent transition to oral medication. Thus, clevidipine is a promising new agent for the management of acute hypertension in a variety of clinical settings.

Management of perioperative hypertensive urgencies with parenteral medications

BACKGROUND

Hypertension is the major risk factor for cardiovascular (CV) disease such as myocardial infarction (MI) and stroke. This risk is well known to extend into the perioperative period. Although most perioperative hypertension can be managed with the patient's outpatient regimen, there are situations in which oral medications cannot be administered and parenteral medications become necessary. They include postoperative nil per os status, severe pancreatitis, and mechanical ventilation. This article reviews the management of perioperative hypertensive urgency with parenteral medications.

METHODS

A PubMed search was conducted by cross-referencing the terms "perioperative hypertension," "hypertensive urgency," "hypertensive emergency," "parenteral anti-hypertensive," and "medication." The search was limited to English-language articles published between 1970 and 2008. Subsequent PubMed searches were performed to clarify data from the initial search.

RESULTS

As patients with hypertensive urgency are not at great risk for target-organ damage (TOD), continuous infusions that require intensive care unit (ICU) monitoring and intraarterial catheters seem to be unnecessary and a possible misuse of resources.

CONCLUSIONS

When oral therapy cannot be administered, patients with hypertensive urgency can have their blood pressure (BP) reduced with hydralazine, enalaprilat, metoprolol, or labetalol. Due to the scarcity of comparative trials looking at clinically significant outcomes, the medication should be chosen based on comorbidity, efficacy, toxicity, and cost.

Thrombotic thrombocytopenic purpura: the masquerader

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder with a mortality rate of up to 90% if left untreated, and is characterized by microvascular thrombi, mainly in small arteries and capillaries, thrombocytopenia, hemolysis, and neurological abnormalities. Malignant hypertension (HTN) is a clinical syndrome characterized by severe hypertension associated with end-organ damage; including encephalopathy, renal dysfunction, and retinal hemorrhage due to platelet aggregation in the microcirculation leading to thrombotic microangiopathy (TMA). These are similar to TTP. Malignant hypertension can cause endothelial injury and fibrinoid necrosis in the vessel wall which results in its clinical manifestations. Therefore, it is difficult to differentiate malignant hypertension from TTP. However, it is critical to differentiate these two entities, as early initiation of plasmapheresis in TTP can be life saving. TTP is considered a masquerader as it can present with few clinical features and, if the index of suspicion is not very high, lead to mortality.

Controlling hypertension and hypotension immediately post-stroke (CHHIPS): a randomised, placebo-controlled, double-blind pilot trial

BACKGROUND

Raised blood pressure is common after acute stroke and is associated with an adverse prognosis. We sought to assess the feasibility, safety, and effects of two regimens for lowering blood pressure in patients who have had a stroke.

METHODS

Patients who had cerebral infarction or cerebral haemorrhage and were hypertensive (systolic blood pressure [SBP] >160 mm Hg) were randomly assigned by secure internet central randomisation to receive oral labetalol, lisinopril, or placebo if they were non-dysphagic, or intravenous labetalol, sublingual lisinopril, or placebo if they had dysphagia, within 36 h of symptom onset in this double-blind pilot trial. The doses were titrated up if target blood pressure was not reached. Analysis was by intention to treat. This trial is registered with the National Research Register, number N0484128008.

FINDINGS

179 patients (mean age 74 [SD 11] years; SBP 181 [SD 16] mm Hg; diastolic blood pressure [DBP] 95 [SD 13] mm Hg; median National Institutes of Health stroke scale [NIHSS] score 9 [IQR 5-16] points) were randomly assigned to receive labetolol (n=58), lisinopril (n=58), or placebo (n=63) between January, 2005, and December, 2007. The primary outcome--death or dependency at 2 weeks--occurred in 61% (69) of the active and 59% (35) of the placebo group (relative risk [RR] 1.03, 95% CI 0.80-1.33; p=0.82). There was no evidence of early neurological deterioration with active treatment (RR 1.22, 0.33-4.54; p=0.76) despite the significantly greater fall in SBP within the first 24 h in this group compared with placebo (21 [17-25] mm Hg vs 11 [5-17] mm Hg; p=0.004). No increase in serious adverse events was reported with active treatment (RR 0.91, 0.69-1.12; p=0.50) but 3-month mortality was halved (9.7%vs 20.3%, hazard ratio [HR] 0.40, 95% CI 0.2-1.0; p=0.05).

INTERPRETATION

Labetalol and lisinopril are effective antihypertensive drugs in acute stroke that do not increase serious adverse events. Early lowering of blood pressure with lisinopril and labetalol after acute stroke seems to be a promising approach to reduce mortality and potential disability. However, in view of the small sample size, care must be taken when these results are interpreted and further evaluation in larger trials is needed.

Relation of left ventricular hypertrophy to regional cerebral blood flow: single photon emission computed tomography abnormalities in essential hypertension

Several reports have shown that left ventricular hypertrophy (LVH) is an independent predictor of acute cerebrovascular events. The aim of the present study was to investigate the relationship between LVH and cerebral blood flow in middle-aged patients with essential hypertension. Forty never-treated hypertensive patients (24 men, 16 women, aged 50-60 years) without clinical evidence of target organ damage were studied. Regional cerebral blood flow was measured by means of single photon emission computed tomography of the brain. Twenty-nine patients showed echocardiographic criteria of LVH; 11 patients did not show this feature. No differences were found in regional cerebral blood flow ratio of all brain areas studied between hypertensives with or without LVH except for the striatum area. The regional cerebral blood flow ratio was significantly reduced in the striatum region of hypertensive patients with LVH, compared with patients without LVH (91.5+/-7.4 vs 98.1+/-8.3; P=.023). This relationship remained significant after adjusting for blood pressure. The authors conclude that the presence of LVH in middle-aged patients with essential hypertension is associated with a reduction of regional cerebral blood flow in the striatum area.

Hypertension in the intensive care unit

PURPOSE OF REVIEW

The severity of hypertensive crises is determined by the presence of target organ damage rather than the level of blood pressure. Hypertensive urgencies with no signs of organ dysfunction can therefore be distinguished from hypertensive emergencies in which the presence of severe end-organ damage requires prompt therapy. Hypertensive emergencies include acute aortic dissection, hypertensive encephalopathy, acute myocardial ischaemia, severe pulmonary oedema, eclampsia, and acute renal failure.

RECENT DEVELOPMENTS

Malignant hypertension is a severe form of hypertensive emergency demanding special consideration because of the risks of permanent blindness and renal failure. Catecholamine excess and postoperative hypertension may also sometimes require urgent treatment. The management of patients with hypertensive emergencies must be ensured in an intensive care unit, and must include the parenteral administration of antihypertensive drugs and accurate blood pressure monitoring.

SUMMARY

Except for acute aortic dissection, the recommended goals of treatment are a reduction of mean arterial pressure by no more than 20% during the first few hours, because an abrupt fall in blood pressure in patients with preexisting hypertension may induce severe ischaemic injury in major organs as a result of the chronic adaptation of autoregulation mechanisms. Hypertension in the context of acute stroke should be treated only rarely and cautiously because of the presence of impaired autoregulation.

Changes in the intracranial rheoencephalogram at lower limit of cerebral blood flow autoregulation

Cerebral blood flow (CBF) reactivity monitoring is an appropriate primary parameter to evaluate cerebral resuscitation due to a systemic or regional cerebral injury leading to possible irreversible brain injury. Use of the electrical impedance method to estimate CBF is rare, as the method's anatomical background is not well understood. Use of intracranial rheoencephalography (iREG) during hemorrhage and comparison of iREG to other CBF measurements have not been previously reported. Our hypothesis was that iREG would reflect early cerebrovascular alteration (CBF autoregulation). Studies comparing iREG, laser Doppler flowmetry and ultrasound were undertaken on anesthetized rats to define CBF changes during hemorrhage. Blood was removed at a rate required to achieve a mean arterial blood pressure (MABP) of 40 mm Hg over 15 min. Estimation of CBF was taken with intracranial, bipolar REG (REG I; n=14), laser Doppler flowmetry (LDF; n=3) and carotid flow by ultrasound (n=11). Data were processed off-line. During the initial phase of hemorrhage, when MABP was close to 40 mm Hg, intracranial REG amplitude transiently increased (80.94%); LDF (77.92%) and carotid flow (52.04%) decreased and changed with systemic arterial pressure. Intracranial REG amplitude change suggests classical CBF autoregulation, demonstrating its close relationship to arteriolar changes. The studies indicate that iREG might reflect cerebrovascular responses more accurately than changes in local CBF measured by LDF and carotid flow. REG may indicate promise as a continuous, non-invasive life-sign monitoring tool with potential advantages over ultrasound, the CBF measurement technique normally applied in clinical practice. REG has particular advantages in non-hospital settings such as military and emergency medicine.

[Hypertensive emergencies]

Critical cases of high blood pressure are common clinical occurrences that may account for as many as 25% of all medical emergencies. About 75% of these increases in blood pressure can be judged as hypertensive urgencies, 25% are even hypertensive emergency situations. Nevertheless, only less than 1% of the hypertensive population experiences hypertensive urgency or emergency situations. Hypertensive emergencies are defined as acute cardiac, vascular or cerebral target organ damages. In these cases an acute lowering of blood pressure is inevitable. The rate and intensity of blood pressure depression is dependent on the localization of organ damages. For cardiac and vascular damages it is absolutely necessary to lower the blood pressure rapidly to near normal values. On the contrary, cerebral organ damages are better treated by a moderate lowering of blood pressure peaks to slightly increased blood pressure levels. In hypertensive urgencies no target organ damages occur. For these patients a slow lowering of blood pressure values to normal levels is adequate.

Orthostatic posture affects brain hemodynamics and metabolism in cerebrovascular disease patients with and without coronary artery disease: a positron emission tomography study

To investigate whether a physiological change in the orthostatic condition is associated with a deterioration of cerebrovascular and metabolic homeostasis in patients with neurocardiovascular compromises, we examined 10 patients with unilateral carotid artery occlusive disease (CVD), 6 CVD patients with coronary artery disease (CVDC), and 10 healthy subjects scanned twice under supine and sitting conditions by positron emission tomography (PET). Repeated measures analysis of variance showed significant reductions in regional cerebral blood flow (rCBF) and cerebral oxygen metabolism (rCMRO2) and tendency of increase in oxygen extraction fraction (OEF) in the affected-side parietal cortex during assuming of upright posture in the CVDC group, and there was a significant OEF increase to maintain rCMRO2 constant during sitting in the CVD counterpart. In this ischemic region, there were negative correlations between changes in OEF and rCBF in the CVD (P < 0.05) and CVDC groups (P < 0.01). Postural reductions in rCBF and CMRO2 in the parietal region were significantly greater in the CVDC group than those in the CVD group. While rCBF remained constant with mean arterial blood pressure (MABP) in healthy subjects, an rCBF reduction was found in the affected parietal cortex in proportion to the upright posture-induced MABP decrease in the CVDC group. These results indicate that patients suffering from both cerebral and coronary artery diseases may be at greater risk of deterioration of local perfusion pressure and metabolic regulation in the hemodynamically susceptible brain region during upright posture.

Hypertensive renal damage: insights from animal models and clinical relevance

Investigations using chronic blood pressure (BP) radiotelemetry in conscious animals have provided substantial insights into the pathophysiology of hypertensive renal damage. Normal renal autoregulation protects the renal microvasculature from significant injury in most patients with primary hypertension, unless BP exceeds a certain threshold, when malignant nephrosclerosis develops. However, if autoregulation is impaired, as in chronic renal disease and/or diabetes models, the threshold for renal damage is lowered and glomerulosclerosis (GS) increases linearly with increasing BP. Modest BP reductions are predicted to prevent malignant nephrosclerosis, but prevention of GS in patients with diabetes and chronic renal disease requires that BP be lowered well into the normotensive range, as recognized in the currently recommended BP goals. When BP load is accurately assessed in these experimental models, renal protection is proportional to the achieved BP reductions, and there is little evidence of BP-independent protection, even with agents that block the renin-angiotensin system (RAS). Recent clinical data also suggest that achieving lower BP targets might be vastly more important than the choice of therapeutic regimens. Nevertheless, because aggressive diuretic use is usually necessary to achieve such BP goals, RAS blockade should be included as initial therapy both for antihypertensive synergy and to minimize the potassium and magnesium depletion associated with diuretics.

Cerebral pathophysiology and critical care neurology: basic hemodynamic principles, cerebral perfusion, and intracranial pressure

Pediatric neurologic intensive care differs from standard pediatric intensive care in two important respects. First, the diagnosis, monitoring, and management of problems related to disorders of cerebral perfusion and intracranial pressure (ICP) are central to nearly all of pediatric neurologic and neurosurgical intensive care. Second, various clinical problems normally encountered in the intensive care unit (ICU) have additional implications when associated with neurologic disease. Regardless of the cause, treatment should be undertaken as expeditiously as possible and should be based on the principles of resuscitation, reducing the volume of the intracranial contents, and reassessment. This chapter aims to outline some basic principles underlying the diagnosis and management of elevated ICP in children.

Factors influencing acute blood pressure values in stroke subtypes

The aim of this prospective observational study was to determine the association of acute blood pressure values with independent factors (demographic, clinical characteristics, early complications) in stroke subgroups of different aetiology. We evaluated data of 346 first-ever acute (<24 h) stroke patients treated in our stroke unit. Casual and 24-h blood pressure (BP) values were measured. Stroke risk factors and stroke severity on admission were documented. Strokes were divided into subgroups of different aetiopathogenic mechanism. Patients were imaged with CT-scan on admission and 5 days later to determine the presence of brain oedema and haemorrhagic transformation. The relationship of different factors to 24-h BP values (24-h BP) was evaluated separately in each stroke subgroup. In large artery atherosclerotic stroke (n=59), history of hypertension and stroke severity correlated with higher 24-h BP respectively. In cardioembolic stroke (n=87), history of hypertension, stroke severity, haemorrhagic transformation and brain oedema were associated with higher 24-h BP, while heart failure with lower 24-h BP. History of hypertension and coronary artery disease was related to higher and lower 24-h BP, respectively, in lacunar stroke (n=75). In patients with infarct of undetermined (n=57) cause 24-h BP were mainly influenced by stroke severity and history of hypertension. An independent association between higher 24-h BP and history of hypertension and cerebral oedema was documented in intracerebral haemorrhage (n=68). In conclusion, different factors influence acute BP values in stroke subtypes of different aetiology. If the clinical significance of these observations is verified, a differentiated approach in acute BP management based on stroke aetiology may be considered.

Assessing dynamic cerebral autoregulation after stroke using a novel technique of combining transcranial Doppler ultrasonography and rhythmic handgrip

OBJECTIVES

Dynamic cerebral autoregulation (CA) is impaired after stroke. Methods employed to assess this phenomenon usually involve deliberate alterations in blood pressure (BP) by physical means. We performed a pilot study to assess dynamic CA in acute stroke patients using a novel technique of combining transcranial Doppler (TCD) ultrasonography with rhythmic handgrip.

METHODS

Ten patients with ischaemic stroke in the middle cerebral artery (MCA) territory were studied. We performed continuous recordings of bilateral MCA velocities and used rhythmic handgrip to induce BP oscillations. Changes in autoregulation were indicated by changes in phase shift and gain of MCA velocity in relation to BP. Patients were examined at <7 days, 6 weeks, and 3 months after stroke.

RESULTS

There were no significant differences in phase shift or gain between the affected and unaffected cerebral hemispheres. Combining the results from both hemispheres, there was a trend of increasing phase shift (P=0.04) and decreasing gain (P=0.24) over the first three months after stroke, indicating improving CA. Rhythmic handgrip produced an average percentage change in BP (peak-to-trough) of 10% around the mean, and the frequency of the induced BP oscillations was very similar to that of the rhythmic handgrip.

CONCLUSIONS

Combining TCD with rhythmic handgrip appeared to be a useful technique for assessing dynamic CA and it deserves further studies. In this pilot study, there was some evidence that CA might improve up to 3 months after ischaemic stroke.

Cerebral artery responses to pressure and flow in uremic hypertensive and spontaneously hypertensive rats

Impaired cerebral blood flow autoregulation is seen in uremic hypertension, whereas in nonuremic hypertension autoregulation is shifted toward higher perfusion pressure. The cerebral artery constricts in response to a rise in either lumen pressure or flow; we examined these responses in isolated middle cerebral artery segments from uremic Wistar-Kyoto rats (WKYU), normotensive control rats (WKYC), and spontaneously hypertensive rats (SHR). Pressure-induced (myogenic) constriction developed at 100 mmHg; lumen flow was then increased in steps from 0 to 98 microl/min. Some vessels were studied after endothelium ablation. Myogenic constriction was significantly lower in WKYU (28 +/- 2.9%) compared with both WKYC (39 +/- 2.5%, P = 0.035) and SHR (40 +/- 3.1%, P = 0.018). Flow caused constriction of arteries from all groups in an endothelium-independent manner. The response to flow was similar in WKYU and WKYC, whereas SHR displayed increased constriction compared with WKYU (P < 0.001) and WKYC (P < 0.001). We conclude that cerebral myogenic constriction is decreased in WKYU, whereas flow-induced constriction is enhanced in SHR.

Renoprotection by ACE inhibition or aldosterone blockade is blood pressure-dependent

Renin-angiotensin-aldosterone system blockade has been shown to protect against renal damage in salt-supplemented, stroke-prone spontaneously hypertensive rats (SHRsp). Based on intermittent tail-cuff blood pressure (BP) measurements, it has been claimed that such protection is BP-independent and mediated by a blockade of the direct tissue-damaging effects of angiotensin and/or aldosterone. BP radiotelemetry was performed for 8 weeks in approximately 10-week-old male SHRsp who received a standard diet and either tap water (n=10) or 1% NaCl to drink. Saline-drinking SHRsp were either left untreated (n=12), received enalapril (50 mg/L) in drinking fluid (n=9), or had subcutaneous implantation of time-release 200-mg pellets of aldactone (n=10). The average systolic BP (mean+/-SEM) during the final 3 weeks was significantly higher (P<0.05) in untreated saline-drinking (215+/-6 mm Hg) SHRsp but not aldactone-treated (198+/-4 mm Hg) or enalapril-treated treated SHRsp (173+/-1 mm Hg), as compared with tap water-drinking SHRsp (197+/-3 mm Hg). Histological renal damage scores at 8 weeks paralleled the BP in all groups, with an excellent correlation (r=0.8, P<0.001, n=41). Moreover, a renal damage score of >5 was only observed in SHRsp whose average systolic BP during the final 3 weeks exceeded 200 mm Hg, indicating a threshold relation with BP. These data show that protection by renin-angiotensin-aldosterone system blockade in this model is BP-dependent and mediated by preventing the severe increases in BP seen in untreated salt-supplemented SHRsp and further underscore the limitations of interpretations based on conventional tail-cuff BP measurements.

Effect of calcium antagonist on cerebral blood flow and oxygen metabolism in patients with hypertension and chronic major cerebral artery occlusion: a positron emission tomography study

To evaluate the effect of a calcium antagonist, nilvadipine, on cerebral blood flow and oxygen metabolism, we prospectively examined five ischaemic stroke patients, with both hypertension and chronic major cerebral artery occlusion, using positron emission tomography. The blood pressure showed a significant decrease after 3 months of nilvadipine treatment, the cerebral blood flow in the affected regions showed a significant increase and the oxygen extraction fraction showed a significant decrease. We conclude that nilvadipine is a safe and effective anti-hypertensive agent for patients with both hypertension and chronic major cerebral artery occlusion.