Association between carotid hemodynamics and asymptomatic white and gray matter lesions in patients with essential hypertension

Blood Pressure Rhythm and Blood Pressure Variability as Risk Factors for White Matter Lesions: A Cross-Sectional Study

Background

White matter lesions are common in the elderly. The aim of this study was to explore the correlation between blood pressure rhythm and blood pressure variability with white matter lesions.

Material/Methods

A total of 144 subjects aged 40 to 80 years underwent MRI scanning to assess the degree of white matter lesions using the Fazekas scale. The regional cerebral blood flow was detected by brain perfusion imaging, and an ambulatory blood pressure monitor was used to measure the circadian blood pressure rhythm. Odds ratio and the 95% confidence interval was computed using logistics regression analysis. The relationship between various factors and blood pressure was calculated by curve simulation.

Results

With the increase of white matter lesions, the regional cerebral blood flow at the lesion decreased gradually. Systolic blood pressure day/night difference ratio (OR=0.815, 95% CI 0.729–0.910), diastolic blood pressure day/night difference ratio (OR=0.895, 95% CI 0.831–0.964), systolic blood pressure coefficient of variation (OR=1.589, 95% CI 1.273–1.983), and diastolic blood pressure coefficient of variation (OR=1.363, 95% CI 1.150–1.616) were significantly associated with Fazekas score (P<0.05 for all).

Conclusions

Greater blood pressure variability and blood pressure rhythm disorders were associated with lower regional cerebral blood flow in patients with white matter lesions.

Cerebral Small Vessel Disease Associated with Subclinical Vascular Damage Indicators in Asymptomatic Hypertensive Patients

Background: Cerebral small vessel disease (CSVD) is frequent in patients with cardiovascular risk factors including arterial hypertension, and it is associated with vascular damage in other organs and the risk of stroke, cognitive impairment, and dementia. Early diagnosis of CSVD could prevent deleterious consequences. Objective: To characterize CSVD associated with indicators of subclinical vascular damage in asymptomatic hypertensive patients. Materials and Methods: Participants were hypertensive (HT) and non-hypertensive (non-HT) individuals; without signs of cerebrovascular disease, dementia, and chronic renal failure. For CSVD, white matter hyperintensities (WMH), enlarged Virchow-Robin perivascular spaces (EVRPS), lacunar infarcts, and microbleeds were investigated. Subclinical vascular damage was evaluated (hypertensive retinopathy, microalbuminuria, and extracranial carotid morphology: intima media thickness (IMT) and atheroma plaque). Results: CSVD MRI findings were more frequent in HT; as well as greater intimal thickening. The IMT + plaque was significantly associated with all MRI variables; but retinopathy was correlated with EVRPS and lacunar infarcts. Only microalbuminuria was related to the greater severity of WMH in HT. Multivariate analysis evidenced that CSVD was independently associated with the combination of indicators of vascular damage and systolic blood pressure. Conclusions: Combining indicators of subclinical vascular damage, such as carotid morphological variables, microalbuminuria, and hypertensive retinopathy for early detection of CSVD in asymptomatic hypertensive patients could prove to be useful to take actions for the prevention of irreversible brain damage, which could lead to cognitive impairment, dementia and stroke.

Correlation of Brain Perfusion with White Matter Hyperintensity, Brain Atrophy, and Cognition in Patients with Posterior Cerebral Artery Stenosis and Subjective Cognitive Decline

BACKGROUND This study aimed to investigate the correlation of brain perfusion with white matter hyperintensity (WMH), brain atrophy, and cognition in patients with moderate to severe posterior cerebral artery stenosis (PCAS). MATERIAL AND METHODS 65 patients with memory decline as the main complaint and no history of brain infarction were recruited from the Department of Neurology of Tongji Hospital. Patients with moderate to severe PCAS were included in case group, and subjects with normal intracranial blood vessels served as controls. The demographics and vascular risk factors were recorded. Montreal Cognitive Assessment (MoCA) was used to evaluate the cognition. CT perfusion imaging was performed, and WASID was employed for the assessment of intracranial artery stenosis. The region of interest (ROI) was analyzed based on the whole brain perfusion. Cranial MRI was performed, and Scheltens scoring system was used for the assessment of WMH on FLAIR. T1 weighed images were obtained, and global cortical atrophy (GCA) scale was employed for the assessment of brain atrophy. The detections of brain perfusion, WMH and brain atrophy were done at centrum ovale, parietal lateral ventricle and basal ganglia layers. RESULTS In PCAS patients we found low perfusion in the antecornu and postcornu blood supply areas at the lateral ventricle, the blood supply area of the anterior cerebral artery, the blood supply area of the posterior cerebral artery, and the blood supply area at the hippocampus as compared with control subjects (p<0.05). As compared with control subjects, the incidence of WMH in the blood supply areas at the deep brain and lateral ventricle was significantly higher in PCAS patients (p<0.05). When compared with controls, the incidence of brain atrophy increased significantly in PCAS patients (p<0.01). Correlation analysis showed the brain perfusion at the blood supply area of the posterior cerebral artery was positively correlated to the total MoCA score and negatively correlated to the severity of WMH at the blood supply area of the posterior cerebral artery (p<0.05). Further analysis showed the brain perfusion at the blood supply area of the posterior cerebral artery was negatively associated with cortex supplied by the posterior cerebral artery, posterior cingulate, and hippocampus (p<0.01). CONCLUSIONS PCAS patients have a higher incidence of brain atrophy, and the perfusion at the area supplied by the posterior cerebral artery is correlated to the severity of brain atrophy and of WMH, as well as to cognition decline.

Carotid Intima-Media Thickness Is Associated With White Matter Hyperintensities: The Northern Manhattan Study

BACKGROUND AND PURPOSE

Brain white matter hyperintensities (WMH) have been associated with increased risk of stroke, cognitive decline, and dementia. WMH can be a manifestation of small vessel disease, although the total microvascular contribution to multifactorial WMH pathophysiology remains unknown. We hypothesized a possible relationship between carotid intima-media thickness (cIMT), an ultrasound imaging marker of subclinical vascular disease, and brain WMH in a multiethnic, elderly stroke-free community-based cohort.

METHODS

We evaluated the relationship between cIMT and WMH in the population-based Northern Manhattan Study, among individuals free of stroke. We used linear regression to examine the association of continuous measures of cIMT with quantitatively derived WMH volume, as a proportion of cranial volume, measured from fluid-attenuaded inversion recovery magnetic resonance imaging while adjusting for sociodemographics, lifestyle, and vascular risk factors.

RESULTS

In a cohort of 1229 participants (mean age, 71±9 years; 60% women, 15% White; 18% Black; 65% Hispanics), the mean cIMT was 0.71±0.08 mm and the median log-transformed WMH volume was 0.36 (interquartile range, 0.21-0.76). In a multivariable model, larger cIMT was significantly associated with greater WMH volume (β=0.046 per SD cIMT; P=0.04). Age and race/ethnicity were significant modifiers (P for age, 0.02; and P for race/ethnicity, 0.04). cIMT was associated with WMH volume in participants 70 years or older (β=0.088 per SD cIMT; P=0.01) and among Hispanics (β=0.084 per SD cIMT; P=0.003).

CONCLUSIONS

Larger cIMT was associated with greater burden of cerebral WM lesions independently of demographics and traditional vascular risk factors, particularly among elderly and Hispanic participants, who are at high risk for stroke and cognitive decline.

Carotid hemodynamics is associated with monocyte count determined by serum homocysteine level in patients with essential hypertension

To examine the association between pulsatility index (PI) in the common carotid artery (CCA) as a marker of vascular resistance and cardiovascular risk factors, including serum homocysteine and inflammation, 67 hypertensive patients were enrolled. PI correlated with homocysteine and interleukin-6, monocyte count, gender, age and BMI, with monocyte count and age being independent determinants for PI. In turn, monocyte count correlated with homocysteine, tumor necrosis factor-alpha, and HDL-cholesterol, BMI, and gender, with HDL-cholesterol and homocysteine being independent determinants for monocyte count. These results indicated monocyte count determined by homocysteine is associated with arterial stiffness in hypertensive patients.

Hyperhomocysteinemia is one of the risk factors associated with cerebrovascular stiffness in hypertensive patients, especially elderly males

Hyperhomocystemia has been reported to be associated with cardiovascular disease, especially stroke. The resistive index (RI) estimated by carotid ultrasound is an established variable for estimating the risk of cerebral infarction. The aim of this study was to evaluate the relationship between homocysteine concentration and carotid RI, a marker of cerebral vascular resistance in essential hypertensive patients. We measured serum total homocysteine and carotid RI in 261 patients. Multiple linear regression analysis was used to determine the association of homocysteine with carotid RI and intima media thickness (IMT). Age, sex, BMI, systolic blood pressure (SBP), homocysteine, total cholesterol, high density lipoprotein-cholesterol (HDL-C), uric acid, CRP, HbA1c, estimated glomerular filtration rate, and use of antihypertensive agents were included as independent variables. Age, sex, use of antihypertensive agents, HDL-C and homocysteine levels were shown to be significant predictors of carotid RI, but not IMT. Multiple regression analysis in men older than 65 years showed homocysteine and SBP were associated significantly with carotid RI. In elderly male patients, homocysteine was the strongest predictor of carotid RI (B = 0.0068, CI = 0.0017-0.0120, P = 0.011) in the multivariate model. In conclusion, hyperhomocysteinemia is associated with carotid RI, a surrogate marker of cerebral vascular resistance, especially in elderly men.

Association of ultrasonographic parameters with subclinical white-matter hyperintensities in hypertensive patients

Background and Purpose. Cerebral white matter hyperintensities (WMHs) are regarded as typical MRI expressions of small-vessel disease (SVD) and are common in hypertensive patients. Hypertension induces pathologic changes in macrocirculation and in microcirculation. Changes in microcirculation may lead to SVD of brain and consequently to hypertensive end-organ damage. This damage is regarded the result of interactions between the macrovascular and microvascular levels. We sought to investigate the association of cerebral WMHs with ultrasonographic parameters of cerebral macrocirculation evaluated by carotid duplex ultrasound (CDU) and transcranial doppler (TCD). Subjects and Methods. The study was prospective, cross-sectional and consecutive and included hypertensive patients with brain MRI with WMHs. Patients underwent CDU and TCD. The clinical variables recorded were demographic characteristics (age, gender, race) and vascular risk factors (hypertension, diabetic mellitus, hypercholesterolemia, current smoking, and body mass index). Excluded from the study were patients with history of clinical stroke (including lacunar stroke and hemorrhagic) or transient ischemic attack (either hemispheric or ocular), hemodynamically significant (>50%) extra- or intracranial stenosis, potential sources of cardioembolism, and absent transtemporal windows. WMHs were quantified with the use of a semiquantitative visual rating method. Ultrasound parameters investigated were (1) common carotid artery (CCA) diameter and intima-media thickness, (2) blood flow velocity in the CCA and internal carotid artery (ICA), and (3) blood flow velocity and pulsatility index of middle cerebral artery (MCA). Results. A total of 52 patients fulfilled the study inclusion criteria (mean age 71.4 ± 4.5 years, 54% men, median WMH-score: 20). The only two ultrasound parameters that were independently associated with WMH score in multivariate linear regression models adjusting for demographic characteristics and vascular risk factors were increased mean common carotid artery (CCA) diameter (beta = 0.784, SE = 0.272, P = 0.006, R² = 23.9%) and increased middle cerebral artery pulsatility index (MCA-PI; beta = 0.262, SE = 0.110, P = 0.025, R² = 9.0%). Among all ultrasound parameters the highest AUC (areas under the receiver operating characteristic curve) were documented for MCA-PI (AUC = 0.82, 95% CI = 0.68−0.95, P < 0.001) and mean CCA diameter (AUC = 0.80, 95% CI = 0.67−0.92, P < 0.001). Conclusions. Our study showed that in hypertensive individuals with brain SVD the extent of structural changes in cerebral microcirculation as reflected by WMHs burden is associated with the following ultrasound parameters of cerebral macrocirculation: CCA diameter and MCA-PI.

Increased brachial-ankle pulse wave velocity is independently associated with white matter hyperintensities

BACKGROUND

White matter hyperintensities (WMHs) are a risk factor for stroke. Their etiology is considered to be cerebral microvascular abnormality. However, the association between WMHs and arteriosclerosis is not yet clear. The aim of this hospital-based cohort study was to identify the arteriosclerotic characteristics associated with WMHs.

METHODS

We cross-sectionally included 240 consecutive patients with no history of stroke. We measured the brachial-ankle pulse wave velocity (baPWV), ankle brachial pressure index, and intima-media thickness of the common carotid artery, and we performed magnetic resonance brain imaging. WMHs were defined as periventricular hyperintensity (Fazekas grade ≥3) and/or separate deep white matter hyperintense signals (Fazekas grade ≥2). We determined the prevalence of WMHs, silent brain infarction (SBI), hypertension, hypercholesterolemia, diabetes mellitus, ischemic heart disease, and smoking. We compared 2 groups of patients, defined by the presence or absence of WMHs, using multiple logistic regression analyses.

RESULTS

In multivariable analysis, SBI (OR 3.38; 95% CI 1.52-7.72), hypertension (OR 2.23; 95% CI 1.03-5.15), female sex (OR 1.95; 95% CI 1.03-3.76), baPWV (OR 1.12; 95% CI 1.02-1.23), and age (OR 1.09; 95% CI 1.04-1.14) were independently associated with WMHs.

CONCLUSIONS

An increased baPWV is associated with WMHs. Management of increased baPWV may help to prevent the progression of WMHs and stroke.

Variation in blood pressure is associated with white matter microstructure but not cognition in African Americans

Although hypertension is a major risk factor for cerebrovascular disease (CVD) and is highly prevalent in African Americans, little is known about how blood pressure (BP) affects brain-behavior relationships in this population. In predominantly Caucasian populations, high BP is associated with alterations in frontal-subcortical white matter and in executive functioning aspects of cognition. We investigated associations among BP, brain structure, and neuropsychological functioning in 52 middle-older-age African Americans without diagnosed history of CVD. All participants underwent diffusion tensor imaging for examination of white matter integrity, indexed by fractional anisotropy (FA). Three regions of interest were derived in the anterior (genu) and posterior (splenium) corpus callosum and across the whole brain. A brief neuropsychological battery was administered from which composite scores of executive function and memory were derived. Blood pressure was characterized by mean arterial blood pressure (MABP). When controlling for age, higher MABP was associated with lower FA in the genu, and there was a trend for this same relationship with regard to whole-brain FA. When the sample was broken into groups on the basis of treatment for BP regulation (medicated vs. nonmedicated), MABP was related to genu and whole-brain FA only in the nonmedicated group. Neither MABP nor FA was significantly related to either neuropsychological composite score regardless of medication use. These data provide important evidence that variation in BP may contribute to significant alterations in specific neural regions of white matter in nonmedicated individuals without symptoms of overt CVD.

Functional consequences of subcortical white matter lesions and MRI-defined brain infarct in an elderly general population

The impact of single and combined effects of subcortical white matter lesions (WMLs) and magnetic resonance imaging (MRI)-defined brain infarct on activities of daily living (ADL), depression, and health status perception was analyzed in community-dwelling elderly individuals. The study included 268 participants from the Memory and Morbidity in Augsburg Elderly (MEMO) project, a population-based study on individuals aged 65 to 83 years, conducted in Augsburg, Germany. Cerebral MRI was performed, and 2 geriatric performance tests, scales to assess ADL, depressive symptoms, and self-perceived health status were assessed. The prevalence of large (>10 mm) subcortical WML was 37.7% and of MRI-defined infarct-like lesions was 15.3%. Both vascular lesion types combined were found in 9% of the participants. Large WMLs were associated with significantly more impairments in basic ADL, inferior results in the performance tests, and a worse self-perceived health status compared to those without large WML. Magnetic resonance imaging-defined brain infarct was associated with impairments in performance tests. Participants with both lesion types were limited in all domains and were 2 to 3 times more likely to have impairments in all examined functions. Their risk of impairment in a specific function was considerably higher than the sum of the single risks associated with each lesion type alone. This study suggests that the single and especially the combined occurrence of common vascular brain lesions are associated with functional impairment. Identifying individuals with severe WML combined with MRI-defined brain infarct can help better understand the development of marked impairments in old age.

Silent cerebral microbleeds associated with arterial stiffness in an apparently healthy subject

Silent cerebral microbleeds (MBs) are a common finding in stroke patients, especially those with intracerebral hemorrhage, and are thought to be a marker of future cerebral hemorrhage. Clinically, two distinct forms of MBs have been documented, those observed with either or both stroke or small vessel disease (SVD) and those associated with cerebral amyloid angiopathy. We investigated a possible association between MBs and arterial stiffness in a general population. Subjects were 443 apparently healthy individuals with a mean age of 67.1+/-8.1 years. The presence of MBs, lacunar infarcts and periventricular hyperintensity (PVH) was determined by 3-tesla magnetic resonance imaging. Carotid intima-media thickness (IMT) was measured by ultrasonography. Arterial stiffness was evaluated by brachial-to-ankle pulse wave velocity (baPWV), and the Framingham stroke risk score (FSRS) was obtained as an integrated cerebrovascular risk factor. The prevalence of MBs was 5.0%. Both baPWV and FSRS were significantly higher in subjects with MBs (1820+/-308 vs. 1645+/-325 cm/s, P=0.014 and 12.1+/-8.6 vs. 8.9+/-7.5%, P=0.047, respectively). Odds ratio of a high baPWV, defined as >or=1500 cm/s, for the presence of MBs was 6.05 even after correction for confounding parameters, including age and hypertension. This association with high baPWV remained irrespective of MBs location, whether strictly located in the lobes or in the basal ganglia and infratentorial regions. These findings indicate an association between arterial stiffness and the presence of MBs. Assessment of arterial stiffness may be useful in identifying subjects at high risk for the presence of MBs.

Long-term effects of angiotensin II receptor blockade with valsartan on carotid arterial stiffness and hemodynamic alterations in patients with essential hypertension

Increased arterial stiffness and intima media thickness (IMT) in the common carotid artery (CCA) are related to cardiovascular risk in essential hypertension. Angiotensin II plays an important role in structural and functional changes in the vasculature. In this study, we evaluated the long-term effect of the angiotensin II receptor blocker, valsartan, on IMT, arterial stiffness, and hemodynamics in the CCA in patients with essential hypertension. A prospective 24 month study of treatment with valsartan (80-160 mg/day) was performed in 24 hypertensive patients. An ultrasound of the CCA was carried out to determine IMT, the cross-sectional distensibility coefficient (CSDC), the carotid arterial stiffness index beta, and diastolic flow velocity to systolic flow velocity ratio (Vd/Vs). Treatment with valsartan for 24 months reduced systolic and diastolic blood pressure significantly. Compared to baseline, the decrease in pulse pressure was greater after 24 months treatment than after 12 months treatment. Valsartan did not influence IMT; however, after 24 months, it caused a significant increase in CSDC and a decrease in stiffness index beta compared to baseline. These changes were not observed after 12 months of treatment. In addition, Vd/Vs, a sensitive marker of relative diastolic blood flow, increased after 24 months' treatment with valsartan. These results suggest that long-term treatment with valsartan improves vascular wall function and hemodynamics in patients with essential hypertension.

Hyperresistinemia is associated with coexistence of hypertension and type 2 diabetes

Numerous studies have demonstrated that high blood pressure substantially increases the risk of microvascular and macrovascular complications in patients with type 2 diabetes mellitus (T2DM). Currently, we found that serum resistin, an adipocyte- and monocyte-derived cytokine, was positively correlated with several components of the metabolic syndrome, including hypertension in T2DM. To investigate the association of resistin with an etiologic difference among subjects with hypertension with T2DM, hypertension without T2DM, and normotensive T2DM, we analyzed 210 subjects, including 91 with hypertension with T2DM, 55 with hypertension without T2DM, and 64 with normotensive T2DM. Serum resistin level was higher in subjects with hypertension with T2DM, followed by subjects with normotensive T2DM and hypertension without T2DM, irrespective of antihypertensive treatment status (20.9+/-17.6 and 14.0+/-8.9 versus 11.2+/-7.6 ng/mL, respectively; P<0.01). Simple regression analysis revealed that resistin positively correlated with blood pressure (systolic blood pressure: r=0.29, P<0.01; diastolic blood pressure: r=0.21, P<0.05) and intima-media thickness (r=0.27; P<0.05) in patients with T2DM but not in subjects with hypertension without T2DM. Multiple regression analysis, adjusted for age, gender, body mass index, fasting glucose, high-density lipoprotein cholesterol, white blood cell counts, and glomerular filtration rate, further revealed that resistin was an independent factor for high blood pressure in patients with T2DM (P<0.05). In vitro gene expression analysis in human coronary endothelial cells revealed that resistin induced fatty acid binding protein, a key molecule of insulin resistance, diabetes, and atherosclerosis. These results suggest that hyperresistinemia would contribute to the pathogenesis of hypertension in patients with T2DM, significantly linked to vascular complications and cardiovascular events.

Relationship between cardio-ankle vascular index (CAVI) and carotid atherosclerosis in patients with essential hypertension

Aortic stiffness measured by aorta-iliac or carotid-femoral pulse wave velocity (PWV) predicts all-cause and cardiovascular mortality. Brachial-ankle PWV (baPWV) has been developed as a more convenient assessment of arterial stiffness. However, the problem with clinical use of baPWV is that the index itself is closely dependent on blood pressure. Recently, a new method, termed the cardio-ankle vascular index (CAVI), has been proposed in Japan to overcome the disadvantages associated with measuring PWV. However, its clinical usefulness has not yet been fully clarified. In the present study, we compared the usefulness of CAVI with that of ultrasound for evaluating atherosclerosis in patients with essential hypertension. CAVI was measured in 70 hypertensive patients. The intima-media thickness (IMT), cross-sectional distensibility coefficient (CSDC), stiffness parameter beta, and mean diastolic (V(d)) and systolic (V(s)) flow velocities were evaluated by carotid ultrasound. The V(d)/V(s) ratio, an index of peripheral arterial resistance, was also calculated. CAVI was positively correlated with IMT (r=0.360, p=0.0022) and stiffness beta (r=0.270, p=0.0239) and negatively correlated with V(d)/V(s) (r=-0.471, p<0.0001) and CSDC (r=-0.315, p=0.0079). Stepwise regression analysis revealed that age (r=0.475, p<0.0001) and pulse pressure (r=0.492, r<0.0001) were independent determinants of CAVI. These results suggest that CAVI is a useful clinical marker for evaluating atherosclerosis and arteriolosclerosis in patients with essential hypertension.

Osteopontin and carotid atherosclerosis in patients with essential hypertension

OPN (osteopontin), a pro-inflammatory cytokine, has recently emerged as a key factor in both vascular remodelling and the development of atherosclerosis. However, the relationship between OPN and atherosclerosis in patients without symptomatic cardiovascular disease is not clear. Therefore we measured plasma OPN levels and evaluated the correlation between plasma OPN levels and atherosclerosis as target organ damage in patients with EHT (essential hypertension). Plasma OPN levels were measured in 76 patients with EHT using a solid-phase sandwich ELISA. IMT (intima-media thickness), and Vd and Vs (mean diastolic and systolic flow velocities respectively) were evaluated by carotid ultrasound. The Vd/Vs ratio, an index of peripheral arterial resistance, was also calculated. The patients were divided on the basis of median OPN levels into a high-OPN group and a low-OPN group. The mean IMT and aldosterone levels were higher (P=0.024 and 0.031 respectively) and Vd/Vs was lower (P=0.007) in the high-OPN group than in the low-OPN group. Plasma OPN levels were positively correlated with mean IMT (r=0.308, P=0.0068) and negatively with Vd/Vs (r=−0.293, P=0.010). Stepwise regression analysis revealed that OPN was an independent determinant of mean IMT (P=0.007) and Vd/Vs (P=0.009), and aldosterone was an independent determinant of OPN. These results suggest that OPN plays a role in the development of atherosclerosis and may be a potential clinical marker for the prediction of atherosclerosis in patients with EHT.