Association between central systolic blood pressure, white matter lesions in cerebral MRI and carotid atherosclerosis

MRI-based quantification of cardiac-driven brain biomechanics for early detection of neurological disorders

We present a pipeline to quantify biomechanical environment of the brain using solely MRI-derived data in order to elucidate the role of biomechanical factors in neurodegenerative disorders. Neurological disorders, like Alzheimer's and Parkinson's diseases, are associated with physical changes, including the accumulation of amyloid-β and tau proteins, damage to the cerebral vasculature, hypertension, atrophy of the cortical gray matter, and lesions of the periventricular white matter. Alterations in the external mechanical environment of cells can trigger pathological processes, and it is known that AD causes reduced stiffness in the brain tissue during degeneration. However, there appears to be a significant lag time between microscale changes and macroscale obstruction of neurological function in the brain. Here, we present a pipeline to quantify the whole brain biomechanical environment to bridge the gap in understanding how underlying brain changes affect macroscale brain biomechanics. This pipeline enables image-based quantification of subject-specific displacement field of the whole brain to subject-specific strain, strain rate, and stress across 133 labeled functional brain regions. We have focused our development efforts on utilizing solely MRI-derived data to facilitate clinical applicability of our approach and have emphasized automation in all aspects of our methods to reduce operator dependance. Our pipeline has the potential to improve early detection of neurological disorders and facilitate the identification of disease before widespread, irreversible damage has occurred.

Relationship Between Arterial Stiffness Index, Pulse Pressure, and Magnetic Resonance Imaging Markers of White Matter Integrity: A UK Biobank Study

Background

Alzheimer's disease and dementia in general constitute one of the major public health problems of the 21st century. Research in arterial stiffness and pulse pressure (PP) play an important role in the quest to reduce the risk of developing dementia through controlling modifiable risk factors.

Objective

The aim of the study is to investigate the association between peripheral PP, arterial stiffness index (ASI) and brain integrity, and to discover if ASI is a better predictor of white matter integrity than peripheral PP.

Materials and Methods

17,984 participants 63.09 ± 7.31 from the UK Biobank were used for this study. ASI was estimated using infrared light (photoplethysmography) and peripheral PP was calculated by subtracting the diastolic from the systolic brachial blood pressure value. Measure of fractional anisotropy (FA) was obtained from diffusion imaging to estimate white matter microstructural integrity. White matter hyperintensities were segmented from the combined T1 and T2-weighted FLAIR images as a measure of irreversible white matter damage.

Results

An important finding is that peripheral PP better predicts white matter integrity when compared to ASI. This finding is consistent until 75 years old. Interestingly, no significant relationship is found between either peripheral PP or ASI and white matter integrity after 75 years old.

Conclusion

These results suggest that ASI from plethysmography should not be used to estimate cerebrovascular integrity in older adults and further question the relationship between arterial stiffness, blood pressure, and white matter damage after the age of 75 years old.

Risk factors analysis according to regional distribution of white matter hyperintensities in a stroke cohort

OBJECTIVES

The spectrum of distribution of white matter hyperintensities (WMH) may reflect different functional, histopathological, and etiological features. We examined the relationships between cerebrovascular risk factors (CVRF) and different patterns of WMH in MRI using a qualitative visual scale in ischemic stroke (IS) patients.

METHODS

We assembled clinical data and imaging findings from patients of two independent cohorts with recent IS. MRI scans were evaluated using a modified visual scale from Fazekas, Wahlund, and Van Swieten. WMH distributions were analyzed separately in periventricular (PV-WMH) and deep (D-WMH) white matter, basal ganglia (BG-WMH), and brainstem (B-WMH). Presence of confluence of PV-WMH and D-WMH and anterior-versus-posterior WMH predominance were also evaluated. Statistical analysis was performed with SPSS software.

RESULTS

We included 618 patients, with a mean age of 72 years (standard deviation [SD] 11 years). The most frequent WMH pattern was D-WMH (73%). In a multivariable analysis, hypertension was associated with PV-WMH (odds ratio [OR] 1.79, 95% confidence interval [CI] 1.29-2.50, p = 0.001) and BG-WMH (OR 2.13, 95% CI 1.19-3.83, p = 0.012). Diabetes mellitus was significantly related to PV-WMH (OR 1.69, 95% CI 1.24-2.30, p = 0.001), D-WMH (OR 1.46, 95% CI 1.07-1.49, p = 0.017), and confluence patterns of D-WMH and PV-WMH (OR 1.62, 95% CI 1.07-2.47, p = 0.024). Hyperlipidemia was found to be independently related to brainstem distribution (OR 1.70, 95% CI 1.08-2.69, p = 0.022).

CONCLUSIONS

Different CVRF profiles were significantly related to specific WMH spatial distribution patterns in a large IS cohort.

KEY POINTS

• An observational study of WMH in a large IS cohort was assessed by a modified visual evaluation. • Different CVRF profiles were significantly related to specific WMH spatial distribution patterns. • Distinct WMH anatomical patterns could be related to different pathophysiological mechanisms.

Sex differences in risk factors for white matter hyperintensities in non-demented older individuals

White matter hyperintensities (WMH) are generally considered to be associated with cerebral small vessel disease, especially, in older age. Although significant sex differences have been reported in the severity of WMH, it is not yet known if the risk factors for WMH differ in men and women. In this study, magnetic resonance imaging brain scans from 2 Australian cohorts were analyzed to extract WMH volumes. The objective of this study is to examine the moderation effect by sex in the association between known risk factors and WMH. The burden of WMH was significantly higher in women compared to men, especially in the deep WMH (DWMH). In the generalized linear model that included the interaction between sex and body mass index (BMI), there was a differential association of BMI with DWMH in men and women in the exploratory sample, that is, the Sydney Memory and Aging Study, n = 432, aged between 70 and 90. The finding of a higher BMI associated with a higher DWMH in men compared to women was replicated in the Older Australian Twins Study sample, n = 179, aged between 65 and 90. The risk factors of WMH pathology are suggested to have a different impact on the aging brains of men and women.

Usefulness of Carotid Ultrasonography for Risk Stratification of Cerebral and Cardiovascular Disease

Carotid ultrasonography is useful for the assessments of the risk stratification for stroke or coronary artery disease, because it is a simple, repeatable, and noninvasive procedure. The carotid intima-media thickness (IMT), which is assessed using carotid ultrasonography, is a widely used surrogate marker for the severity of atherosclerosis. Several large clinical studies showed that increased carotid IMT is associated with the future stroke or cardiovascular events. In addition, in many clinical trials, it has been adopted for surrogate markers of clinical endpoints of medical intervention. Moreover, carotid ultrasonography allows the measurement of the presence and characteristics of plaques and the severity of carotid artery stenosis. The unstable morphology of plaque, such as hypoechoic, ulcer, and mobility, is associated with future ischemic stroke events. The screening tool of asymptomatic carotid artery stenosis is also important, although whether routine carotid ultrasonography assessment is recommended in the general population remains controversial. The screening of carotid artery stenosis using ultrasonography is essential for not only daily clinical settings but also management of patients with acute ischemic stroke. The patients with atherothrombotic stroke with severe internal carotid artery stenosis should be considered to surgical intervention, and duplex ultrasound approach is important to estimate for the severity of carotid stenosis. Physicians should keep in mind the usefulness of carotid ultrasonography for risk stratification of cerebral and cardiovascular disease based on various aspects. In addition, visual assessment or dynamic changes using carotid ultrasonography could provide the various and valuable insights in clinical settings.

Association Between Central Blood Pressure and Subclinical Cerebrovascular Disease in Older Adults

Elevated blood pressure (BP) level is one of the most consistently identified risk factors for silent brain disease. BP values obtained at the proximal segment of the aorta (central BP) are more directly involved than brachial BP in the pathogenesis of cardiovascular disease. However, the association between central BP and silent cerebrovascular disease has not been clearly established. Participants in the CABL (Cardiovascular Abnormalities and Brain Lesions) study (n=993; mean age, 71.7±9.3 years; 37.9% men) underwent 2-dimensional echocardiography, arterial wave reflection analysis for determination of central BPs, and brain magnetic resonance imaging. Central BPs were calculated from the radial pulse waveform. Subclinical silent cerebrovascular disease was defined as silent brain infarction and white matter hyperintensity volume. Both brachial (P=0.014) and central pulse pressure (P=0.026) were independently associated with silent brain infarctions after adjustment for clinical variables, but not adjusting for each other. None of the brachial BP values was associated with upper quartile of white matter hyperintensity volume in multivariable analysis. Both central systolic BP (P<0.001) and central pulse pressure (P<0.001) were significantly associated with upper quartile of white matter hyperintensity volume in multivariable analysis, even after adjustment for brachial BP. In a predominantly older population-based cohort, both brachial and central pulse pressure were independently associated with silent brain infarction. However, higher central systolic BP and central pulse pressure, but not brachial BP, were significantly associated with white matter hyperintensity volume.

Education moderates the effects of large central artery aging on cognitive performance in middle-aged and older adults

Central artery aging, including elevated aortic stiffness, central blood pressure (BP), and pulse pressure (PP), is a novel risk factor for the development of age-associated cognitive dysfunction. Individuals with higher educational attainment may develop greater brain pathology prior to the onset of cognitive decline. However, whether education moderates relations between central artery aging and cognitive performance is unknown. We hypothesized that years of formal education would moderate the relation between central artery aging and cognitive performance in middle-aged/older (MA/O) adults (n = 113, age 67.3 ± 0.7 years). Significant interactions between education*central systolic BP (β = .21, p = .02) and education*central PP (β = .22, p = .01) demonstrated weaker associations between central BP and PP with processing speed performance in those with higher education. Similarly, education moderated the relation between aortic stiffness (carotid-femoral pulse wave velocity, cfPWV) and executive function performance (β = .21, p = .02). To test if the relation between central arterial aging and cognitive performance was captured by a predetermined education threshold, MA/O adults were secondarily categorized as ≤high school (HS) (i.e., ≤12 years, n = 36) or >HS (≥13 years, n = 77). Higher central systolic BP was associated with slower processing speed (≤HS: r = -.59, p < .001 vs. >HS: r = -.25, p = .03) and weaker executive function (r = -.39, p = .03 vs. r = -.32, p = .006). Higher cfPWV was selectively correlated with weaker executive function performance (r = -.39, p = .03) in ≤HS only and this association significantly differed between education groups. Educational attainment appears to moderate the adverse effects of central artery aging on cognitive performance among MA/O adults.

Arterial stiffness and brain integrity: A review of MRI findings

BACKGROUND

Given the increasing incidence of vascular diseases and dementia, a better understanding of the cerebrovascular changes induced by arterial stiffness is important for early identification of white and gray matter abnormalities that might antedate the appearance of clinical cognitive symptoms. Here, we review the evidence from neuroimaging demonstrating the impact of arterial stiffness on the aging brain.

METHOD

This review presents findings from recent studies examining the association between arterial stiffness, cognitive function, cerebral hypoperfusion, and markers of neuronal fiber integrity using a variety of MRI techniques.

RESULTS

Overall, changes associated with arterial stiffness indicates that the corpus callosum, the internal capsule and the corona radiata may be the most vulnerable regions to microvascular damage. In addition, the microstructural integrity of these regions appears to be associated with cognitive performance. Changes in gray matter structure have also been found to be associated with arterial stiffness and are present as early as the 5th decade. Moreover, low cerebral perfusion has been associated with arterial stiffness as well as lower cognitive performance in age-sensitive tasks such as executive function.

CONCLUSION

Considering the established relationship between arterial stiffness, brain and cognition, this review highlights the need for future studies of brain structure and function in aging to implement measurements of arterial stiffness in parallel with quantitative imaging.

Aging and Hypertension - Independent or Intertwined White Matter Impairing Factors? Insights From the Quantitative Diffusion Tensor Imaging

Aging disrupts white matter integrity, and so does continuous elevated blood pressure that accompanies hypertension (HTN). Yet, our understanding of the interrelationship between these factors is still limited. The study aimed at evaluating patterns of changes in diffusion parameters (as assessed by quantitative diffusion fiber tracking - qDTI) following both aging, and hypertension, as well as the nature of their linkage. 146 participants took part in the study: the control group (N = 61) and the patients with hypertension (N = 85), and were divided into three age subgroups (25-47, 48-56, 57-71 years). qDTI was used to calculate the values of fractional anisotropy, mean, radial and axial diffusivity in 20 main tracts of the brain. The effects of factors (aging and hypertension) on diffusion parameters of tracts were tested with a two-way ANOVA. In the right hemisphere there was no clear effect of the HTN, nor an interaction between the factors, though some age-related effects were observed. Contrary, in the left hemisphere both aging and hypertension contributed to the white matter decline, following a functional pattern. In the projection pathways and the fornix, HTN and aging played part independent of each other, whereas in association fibers and the corpus callosum if the hypertension effect was significant, an interaction was observed. HTN patients manifested faster decline of diffusion parameters but also reached a plateau earlier, with highest between-group differences noted in the middle-aged subgroup. Healthy and hypertensive participants have different brain aging patterns. The HTN is associated with acceleration of white matter integrity decline, observed mainly in association fibers of the left hemisphere.

Exercise Improves Vascular Function, but does this Translate to the Brain?

The number of adults with Alzheimer’s disease (AD) or related dementia is expected to increase exponentially. Interventions aimed to reduce the risk and progression of AD and dementia are critical to the prevention and treatment of this devastating disease. Aging and cardiovascular disease risk factors are associated with reduced vascular function, which can have important clinical implications, including brain health. The age-associated increase in blood pressure and impairment in vascular function may be attenuated or even reversed through lifestyle behaviors. Greater volumes of habitual exercise and higher cardiorespiratory fitness are associated with beneficial effects on vascular health and cognition. Exercise and cardiorespiratory fitness may be most important during midlife, as physical activity and cardiorespiratory fitness during the middle-aged years are associated with future cognitive function. The extent to which exercise, and more specifically aerobic exercise, influences the cerebral circulation is not well established. In this review, we present our working hypothesis showing how cerebrovascular function may be a mediating factor underlying the association between exercise and cognition, as well as discuss recent studies evaluating the effect of exercise interventions on the cerebral circulation.

Carotid Flow Augmentation, Arterial Aging, and Cerebral White Matter Hyperintensities

Objective—

Aortic stiffness and pressure wave reflection are associated with age-related cerebral microvascular disease, but the underlying mechanism remains obscure. We hypothesized that cerebral (carotid) flow alterations potentially mediate these associations.

Approach and Results—

Doppler waveforms were recorded in 286 patients with hypertension to measure the carotid flow augmentation index (FAIx) as the late/early-systolic velocity amplitude ratio. Tonometric waveforms were recorded to estimate the aortic pressure AIx (PAIx), aortic compliance, and carotid-femoral and carotid-radial pulse wave velocities. Additionally, white matter hyperintensities on brain magnetic resonance imaging were evaluated using the Fazekas scale. With increasing age, the carotid late systolic velocity increased, whereas the early systolic velocity decreased, although the aortic augmented pressure increased in parallel with the incident wave height ( P <0.001). Both FAIx and PAIx increased with age, but the age-dependent curves were upwardly concave and convex, respectively. FAIx increased exponentially with increasing PAIx ( r =0.71). Compared with PAIx, FAIx was more closely ( P ≤0.001) correlated with the aortic pulse wave velocity, aortic compliance, and elastic/muscular pulse wave velocity ratio. FAIx was associated with white matter hyperintensities scores independently of confounders including age, sex, diabetes mellitus, hypercholesterolemia, and aortic pulse wave velocity ( P =0.01), and was more predictive of white matter hyperintensities presence than PAIx.

Conclusions—

Carotid FAIx had closer associations with age, aortic stiffness, and cerebral white matter hyperintensities than aortic PAIx. These results indicate that carotid flow augmentation (enhanced by aortic stiffening and pressure wave reflection from the lower body) causes microcerebrovascular injury potentially through increasing cerebral flow pulsations, but this detrimental effect is greater than that estimated from PAIx.

The efficacy of intravenous thrombolysis in acute ischemic stroke patients with white matter hyperintensity

OBJECTIVES

We aimed to investigate effects of deep white matter hyperintensity (DWMH) and periventricular hyperintensity (PVH) on the efficacy of intravenous thrombolysis (IVT) in patients with acute ischemic stroke (AIS).

METHODS

A total of 113 AIS patients with WMH were categorized into the PVH group and the DWMH group according to the lesion location, with the division of two subgroups based on whether or not they received IVT treatment: the thrombolysis group and the control group. Kaplan-Meier analysis was used for proportional hazards of recurrent stroke. Further, multivariate Cox regression analysis was employed.

RESULTS

Of total patients, there were 62 PVH patients and 51 DWMH patients: 27 of PVH patients and 22 of DWMH patients received IVT, and the remaining patients only received routine treatment. DWMH patients had a higher risk of END (36.4% vs. 11.1%; p = 0.034) and HT (22.7% vs. 3.7%; p = 0.038) than PVH patients in the thrombolysis group. Moreover, DWMH patients undergoing IVT also had a higher risk of END (36.4% vs. 10.3%; x²  = 5.050; p = 0.025) and HT (22.7% vs. 3.4%; x²  = 4.664; p = 0.031) than DWMH patients without IVT. Again, PVH patients had a higher rate of recurrent stroke (20.0% vs. 3.4%; p = 0.034) than DWMH patients in the control group after 90-day follow-up. Kaplan-Meier analysis showed a significant difference in cumulative probability of no major endpoint events (p = 0.039). Further, multivariate Cox regression revealed that PVH is an independent risk factor for stroke recurrence in AIS patients after adjusting confounding factors.

CONCLUSIONS

The location of WMH is closely associated with the efficacy of IVT in AIS patients.

The effect of age-related risk factors and comorbidities on white matter injury and repair after ischemic stroke

White matter injury is a crucial component of human stroke, but it has often been neglected in preclinical studies. Most human stroke is associated with one or more comorbidities, including aging, hypertension, diabetes and metabolic syndrome including hyperlipidemia. The purpose of this review is to examine how age and hypertension impact stroke-induced white matter injury as well as white matter repair in both human stroke and preclinical models. It is essential that comorbidities be examined in preclinical trials as they may impact translatability to the clinic. In addition, understanding how comorbidities impact white matter injury and repair may provide new therapeutic opportunities for patients with those conditions.

White matter hyperintensities in migraine: Clinical significance and central pulsatile hemodynamic correlates

Background The role of central pulsatile hemodynamics in the pathogenesis of white matter hyperintensities in migraine patients has not been clarified. Methods Sixty patients with migraine (20-50 years old; women, 68%) without overt vascular risk factors and 30 demographically-matched healthy controls were recruited prospectively. Cerebral white matter hyperintensities volume was determined by T1-weighted magnetic resonance imaging with CUBE-fluid-attenuated-inversion-recovery sequences. Central systolic blood pressure, carotid-femoral pulse wave velocity, and carotid augmentation index were measured by applanation tonometry. Carotid pulsatility index was derived from Doppler ultrasound carotid artery flow analysis. Results Compared to the controls, the migraine patients had higher white matter hyperintensities frequency (odds ratio, 2.75; p = 0.04) and greater mean white matter hyperintensities volume (0.174 vs. 0.049, cm³, p = 0.04). Multivariable regression analysis showed that white matter hyperintensities volume in migraine patients was positively associated with central systolic blood pressure ( p = 0.04) and carotid-femoral pulse wave velocity ( p < 0.001), but negatively associated with carotid pulsatility index ( p = 0.04) after controlling for potential confounding factors. The interaction effects observed indicated that the influence of carotid-femoral pulse wave velocity ( p = 0.004) and central systolic blood pressure ( p = 0.03) on white matter hyperintensities formation was greater for the lower-carotid pulsatility index subgroup of migraine patients. White matter hyperintensities volume in migraine patients increased with decreasing carotid pulsatility index and with increasing central systolic blood pressure or carotid-femoral pulse wave velocity. Conclusions White matter hyperintensities are more common in patients with migraine than in healthy controls. Increased aortic stiffness or central systolic blood pressure in the presence of low intracranial artery resistance may predispose patients with migraine to white matter hyperintensities formation.

Central Hemodynamics for Management of Arteriosclerotic Diseases

Arteriosclerosis, particularly aortosclerosis, is the most critical risk factor associated with cardiovascular, cerebrovascular, and renal diseases. The pulsatile hemodynamics in the central aorta consists of blood pressure, flow, and stiffness and substantially differs from the peripheral hemodynamics in muscular arteries. Arteriosclerotic changes with age appear earlier in the elastic aorta, and age-dependent increases in central pulse pressure are more marked than those apparent from brachial pressure measurement. Central pressure can be affected by lifestyle habits, metabolic disorders, and endocrine and inflammatory diseases in a manner different from brachial pressure. Central pulse pressure widening due to aortic stiffening increases left ventricular afterload in systole and reduces coronary artery flow in diastole, predisposing aortosclerotic patients to myocardial hypertrophy and ischemia. The widened pulse pressure is also transmitted deep into low-impedance organs such as the brain and kidney, causing microvascular damage responsible for lacunar stroke and albuminuria. In addition, aortic stiffening increases aortic blood flow reversal, which can lead to retrograde embolic stroke and renal function deterioration. Central pressure has been shown to predict cardiovascular events in most previous studies and potentially serves as a surrogate marker for intervention. Quantitative and comprehensive evaluation of central hemodynamics is now available through various noninvasive pressure/flow measurement modalities. This review will focus on the clinical usefulness and mechanistic rationale of central hemodynamic measurements for cardiovascular risk management.

Relationship between Carotid Computed Tomography Dual-Energy and Brain Leukoaraiosis

BACKGROUND

The purpose of this study was to assess if there is a correlation between the carotid computed tomography (CT) Hounsfield unit (HU)-based plaque attenuation values measured using dual-energy CT (DECT) scanner and brain leukoaraiosis (LA).

METHODS

Fifty consecutive patients (34 males, 16 females; mean age, 69 years; age range, 46-84 years) who underwent carotid CT and brain magnetic resonance imaging were included in the study. CT examinations were performed with a DECT scanner, and LA lesion volume quantification was performed using a semiautomated segmentation technique.

RESULTS

We found an inverse statistically significant correlation between the HU-based carotid artery plaque attenuation and the LA lesion volume. Because of the presence of calcified plaques, a second model was calculated at low kiloelectron volt levels from 66 to 100 and 100 kV by taking into consideration the fatty and mixed plaques, and this further led to the associations between HU-based attenuation and LA volume in brain and vascular territories.

CONCLUSIONS

The results of our study suggest that the associations between HU attenuation of the carotid artery plaques (with the exclusion of calcified plaques) and the volume of LA are emphasized at low keV energy levels.

Ultrasound and dynamic functional imaging in vascular cognitive impairment and Alzheimer's disease

BACKGROUND

The vascular contributions to neurodegeneration and neuroinflammation may be assessed by magnetic resonance imaging (MRI) and ultrasonography (US). This review summarises the methodology for these widely available, safe and relatively low cost tools and analyses recent work highlighting their potential utility as biomarkers for differentiating subtypes of cognitive impairment and dementia, tracking disease progression and evaluating response to treatment in various neurocognitive disorders.

METHODS

At the 9th International Congress on Vascular Dementia (Ljubljana, Slovenia, October 2015) a writing group of experts was formed to review the evidence on the utility of US and arterial spin labelling (ASL) as neurophysiological markers of normal ageing, vascular cognitive impairment (VCI) and Alzheimer's disease (AD). Original articles, systematic literature reviews, guidelines and expert opinions published until September 2016 were critically analysed to summarise existing evidence, indicate gaps in current knowledge and, when appropriate, suggest standards of use for the most widely used US and ASL applications.

RESULTS

Cerebral hypoperfusion has been linked to cognitive decline either as a risk or an aggravating factor. Hypoperfusion as a consequence of microangiopathy, macroangiopathy or cardiac dysfunction can promote or accelerate neurodegeneration, blood-brain barrier disruption and neuroinflammation. US can evaluate the cerebrovascular tree for pathological structure and functional changes contributing to cerebral hypoperfusion. Microvascular pathology and hypoperfusion at the level of capillaries and small arterioles can also be assessed by ASL, an MRI signal. Despite increasing evidence supporting the utility of these methods in detection of microvascular pathology, cerebral hypoperfusion, neurovascular unit dysfunction and, most importantly, disease progression, incomplete standardisation and missing validated cut-off values limit their use in daily routine.

CONCLUSIONS

US and ASL are promising tools with excellent temporal resolution, which will have a significant impact on our understanding of the vascular contributions to VCI and AD and may also be relevant for assessing future prevention and therapeutic strategies for these conditions. Our work provides recommendations regarding the use of non-invasive imaging techniques to investigate the functional consequences of vascular burden in dementia.

Impact of night-time blood pressure on cerebral white matter hyperintensity in elderly hypertensive patients

AIM

Cerebral white matter hyperintensity (WMH) is highly prevalent in the elderly population, and increases the risk of dementia and stroke. We investigated the relationship between ambulatory blood pressure monitoring levels and quantitatively measured WMH volumes among elderly hypertensive patients with well-controlled blood pressure (BP) to re-evaluated effective hypertension management methods to prevent the progression of WMH.

METHODS

Participants comprised 84 hypertensive patients aged between 65 and 75 years without symptomatic heart failure, ischemic heart disease, atrial fibrillation, stroke or cognitive dysfunction.

RESULTS

Linear regression analysis showed that office BP was not associated with WMH volume increases. Raised night-time systolic BP (P = 0.013) were associated with greater WMH volumes during ambulatory blood pressure monitoring. To clarify the effect of asleep systolic BP on WML volume, we then classified patients into two systolic BP groups as follows: <125 mmHg (n = 47) and ≥125 mmHg (n = 37). Baseline characteristics were almost similar in both groups, except the dipper type of circadian BP variation was significantly common in the group with night-time systolic BP <125 mmHg. However, WMH volume was greater in the group with night-time systolic BP ≥125 mmHg than that in the <125 mmHg group (9.0 ± 8.4 mL vs 4.1 ± 4.3 mL, P = 0.015).

CONCLUSION

Higher night-time systolic BP levels were observed to contribute greater WMH volumes in elderly hypertensive patients. To prevent the progression of WMH, controlling BP on the basis of ambulatory blood pressure monitoring is important.

Carotid atherosclerosis, silent ischemic brain damage and brain atrophy: A systematic review and meta-analysis

BACKGROUND

The widespread use of brain imaging has led to increased recognition of subclinical brain abnormalities, including white matter hyperintensities (WMH) and silent brain infarctions (SBI), which have a vascular origin, and have been associated to a high risk of stroke, disability and dementia. Carotid atherosclerosis (CA) may be causative in the development of WMH, SBI and eventually brain atrophy. Aim of the present systematic review and meta-analysis was to assess the existing evidence linking CA to WMH, SBI and brain atrophy.

METHODS

The relation between CA and WMH, SBI and brain atrophy was investigated through the systematic search of online databases up to September 2015 and manual searching of references and related citations. Pooled estimates were calculated by random-effects model, using restricted maximum likelihood method with inverse variance weighting method.

RESULTS

Of the 3536 records identified, fifteen were included in the systematic review and 9 were found to be eligible for the meta-analysis. CA was significantly associated with the presence of WMH (Odds Ratio, OR 1.42, confidence interval, CI 1.22-1.66, p<0.0001) and of SBI (OR 1.89, CI 1.46-2.45, p<0.0001). No meta-analysis could be performed for the relation between CA and brain atrophy due to the lack of suitable studies.

CONCLUSIONS

CA was found to be associated to WMH and SBI. While no causative association can be inferred from the available data, the presence of carotid plaque may be considered a significant risk factor for subclinical cerebral damage.

Pulsatile and steady components of blood pressure and subclinical cerebrovascular disease: the Northern Manhattan Study

OBJECTIVES

To assess whether pulse pressure (PP) is associated, independently of mean arterial pressure (MAP), with perivascular spaces (PVS), lacunar lesions presumably ischemic (LPI), and white matter hyperintensity volume (WMHV) seen on brain MRI.

METHODS

Participants in the Northern Manhattan Study had their blood pressure (BP) taken during their baseline enrollment visit and again during a visit for a brain MRI a mean of 7 years later. We assessed small and large PVS, lacunar LPI, and WMHV on MRI. We examined the association of SBP, DBP, MAP, and PP at baseline with subclinical markers of cerebrovascular disease using generalized linear models and adjusting for vascular risk factors.

RESULTS

Imaging and BP data were available for 1009 participants (mean age 68 ± 8 years, 60% women, 60% Hispanic). DBP was associated with lacunar LPI and WMHV, whereas SBP was associated with small and large PVS. Using MAP and PP together disclosed that the effect size for PP was greater for large PVS, whereas the effect of MAP was greater for lacunar LPI and WMHV. The effects of DBP were flat or negative at any degree of SBP higher than 120 mmHg for small and large PVS, whereas a positive association was noted for lacunar LPI and WMHV with any DBP increase over any degree of SBP.

CONCLUSION

We report here a segregated association between the pulsatile and steady components of the BP with subclinical markers of cerebrovascular disease. These differential associations may reflect the underlying disease of these biomarkers.

Blood pressure and sodium: Association with MRI markers in cerebral small vessel disease

Dietary salt intake and hypertension are associated with increased risk of cardiovascular disease including stroke. We aimed to explore the influence of these factors, together with plasma sodium concentration, in cerebral small vessel disease (SVD). In all, 264 patients with nondisabling cortical or lacunar stroke were recruited. Patients were questioned about their salt intake and plasma sodium concentration was measured; brain tissue volume and white-matter hyperintensity (WMH) load were measured using structural magnetic resonance imaging (MRI) while diffusion tensor MRI and dynamic contrast-enhanced MRI were acquired to assess underlying tissue integrity. An index of added salt intake (P = 0.021), pulse pressure (P = 0.036), and diagnosis of hypertension (P = 0.0093) were positively associated with increased WMH, while plasma sodium concentration was associated with brain volume (P = 0.019) but not with WMH volume. These results are consistent with previous findings that raised blood pressure is associated with WMH burden and raise the possibility of an independent role for dietary salt in the development of cerebral SVD.

Carotid Intima-Media Thickness for Atherosclerosis

The carotid intima-media thickness (IMT) is a widely used surrogate marker for atherosclerosis worldwide. The carotid IMT can be simply, noninvasively, and reproducibly measured through B-mode carotid ultrasound. The carotid IMT is also a strong predictor of future cerebral and cardiovascular events. In addition, regressions of increased carotid IMT by lipid-lowering and antihypertensive drugs have been reported. Despite the strong association between increased carotid IMT and cardiovascular disease, it remains unclear whether routine carotid IMT measurement is useful for the detection of subclinical atherosclerosis in clinical practice. Researches should consider other methodological aspects, such as the definition of carotid plaques, the choice of measurement sites on the common or internal carotid artery, and the assessment of maximum or minimum IMT. The detailed guidelines for measuring carotid IMT vary by county. Thus, the usefulness of the carotid IMT may be assessed in different countries taking racial differences into account. Other important parameters revealed by carotid ultrasound, such as artery stenosis and the characteristics and size of plaques, should also be considered. Physicians should comprehensively interpret the results of carotid ultrasonography. Therefore, carotid ultrasonography is an essential tool for assessing cardiovascular risk in clinical settings.

Association of serum-free fatty acid level with reduced reflection pressure wave magnitude and central blood pressure: the Nagahama study

Central blood pressure (BP) has been suggested to be a better predictor of cardiovascular disease risk than brachial BP. Given that central BP and arterial waveform are both influenced by insulin resistance, major initiators of insulin resistance, such as serum-free fatty acid (FFA), are suspected of potentially being involved in central hemodynamics. To confirm that insulin signaling is an important modulator of central hemodynamics, we investigated this hypothesis in a large-scale general population. Brachial BP and radial arterial waveform were measured simultaneously in 9393 middle-aged to elderly individuals. The augmentation index was calculated from the radial waveform as the ratio of the height of the late systolic peak to that of the first peak. Central systolic BP was defined as the absolute pressure of the late systolic peak of the waveform. Differences in central and brachial pulse pressure (PP) were considered to represent PP amplification. PP amplification differed significantly among serum FFA level quartiles (Q1, 7.8±5.3; Q2, 8.6±5.0; Q3, 9.3±5.7; Q4, 10.3±6.1 mm Hg; P<0.001), and the maximum difference in combination with diabetes mellitus status was 4.9 mm Hg. Multivariate analysis adjusted for major covariates indicated that higher serum FFA was an independent determinant for higher PP amplification (β=0.145, P<0.001) and lower augmentation index (β=-0.122, P<0.001) and central systolic BP (β=-0.044, P<0.001), whereas the association between FFA and PP amplification significantly decreased (β=0.022, P<0.001) after further adjustment for augmentation index. Serum FFA is an overlooked factor favorably influencing central hemodynamics. A low-magnitude reflection pressure wave might be involved in this paradoxical relationship.

The association between leukoaraiosis and carotid atherosclerosis: a systematic review and meta-analysis

The association between large-artery atherosclerosis and leukoaraiosis (LA) has been increasingly reported with inconsistent conclusion. This systematic review examines the relationship between LA and carotid atherosclerosis, manifested as atherosclerotic stenosis, plaques and increased intima-media thickness (IMT). PubMed, Embase, and Web of Science were searched for articles published up to February 2014. Thirty-two studies that examined the relationship between LA and carotid atherosclerosis were included. All statistical analysis was conducted with Review Manager 5.2.4. Finally, 32 studies including 17,721 patients were identified. There were 7 (30%) out of 23 studies reporting significant association between LA and carotid stenosis; 11 (79%) out of 14 studies reporting significant association between LA and carotid plaque; all 9 studies reporting significant association between LA and carotid IMT; one study showing an association between LA and CAWT (similar to the role of the IMT). The quantitative meta-analysis of 10 studies showed that carotid atherosclerosis was not associated with LA (OR: 1.10; 95% CI: 0.61-1.98). A significant association was found between LA and carotid plaque (OR = 3.53; 95% CI = 1.83-6.79), and the result of IMT group showed that IMT increased risk of LA (MD = 0.11; 95% CI = 0.01-0.22). This systematic review suggested that LA has a tendency of association with carotid plaques but no association with simple carotid stenosis.

Blood pressure, internal carotid artery flow parameters, and age-related white matter hyperintensities

White matter hyperintensities (WMH) are associated with hypertension. We examined interactions among blood pressure (BP), internal carotid artery (ICA) flow velocity parameters, and WMH. We obtained BP measurements from 694 community-dwelling subjects at mean ages 69.6 (±0.8) years and again at 72.6 (±0.7) years, plus brain MRI and ICA ultrasound at age 73±1 years. Diastolic and mean BP decreased and pulse pressure increased, but systolic BP did not change between 70 and 73 years. Multiple linear regression, corrected for vascular disease and risk factors, showed that WMH at the age of 73 years were associated with history of hypertension (β=0.13; P<0.001) and with BP at the age of 70 years (systolic β=0.08, mean β=0.09, diastolic β=0.08; all P<0.05); similar but attenuated associations were seen for BP at the age of 73 years. Lower diastolic BP and higher pulse pressure were associated with higher ICA pulsatility index at the age 73 years (diastolic BP age 70 years: standardized β=-0.24, P<0.001; pulse pressure age 70 years: β=0.19, P<0.001). WMH were associated with higher ICA pulsatility index (β=0.13; P=0.002) after adjusting for BP and correction for multiple testing. Therefore, falling diastolic BP and increased pulse pressure are associated with increased ICA pulsatility index, which in turn is associated with WMH. This suggests that hypertension and WMH may either associate indirectly because hypertension increases arterial stiffness that leads to WMH over time, or coassociate through advancing age and stiffer vessels, or both. Reducing vascular stiffness may reduce WMH progression and should be tested in randomized trials, in addition to testing antihypertensive therapy.

Migraine and structural changes in the brain: a systematic review and meta-analysis

OBJECTIVE

To evaluate the association between migraine without aura (MO) and migraine with aura (MA) and 3 types of structural brain abnormalities detected by MRI: white matter abnormalities (WMAs), infarct-like lesions (ILLs), and volumetric changes in gray and white matter (GM, WM) regions.

METHODS

PubMed as well as the reference lists of identified studies and reviews were used to identify potentially eligible studies through January 2013. Candidate studies were reviewed and eligible studies were abstracted. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated for WMAs and ILLs.

RESULTS

Six population-based and 13 clinic-based studies were identified. The studies suggested that structural brain changes, including WMAs, silent ILLs, and volumetric changes in GM and WM regions, were more common in migraineurs than in control groups. The results were strongest for MA. The meta-analysis of WMAs showed an association for MA (OR 1.68; 95% CI 1.07-2.65; p = 0.03) but not for MO (OR 1.34; 95% CI 0.96-1.87; p = 0.08). The association of ILLs was greater for MA (OR 1.44; 95% CI 1.02-2.03; p = 0.04) than for MO, but no association was found for MA (p = 0.52) and MO (p = 0.08) compared to controls.

CONCLUSION

These data suggest that migraine may be a risk factor for structural changes in the brain. Additional longitudinal studies are needed to determine the differential influence of migraine without and with aura, to better characterize the effects of attack frequency, and to assess longitudinal changes in brain structure and function.

Association of longer QT interval with arterial waveform and lower pulse pressure amplification: the Nagahama Study

BACKGROUND

Central systolic blood pressure (cSBP) has been postulated to correlate closely with cardiovascular risk. Identifying factors associated with cSBP is therefore important. Prolonged QT interval is known to be associated with cardiovascular outcomes and might also be associated with the arterial waveform and cSBP. We investigated the possible associations between electrocardiogram wave interval and cSBP in general population samples.

METHODS

Brachial blood pressure and radial arterial waveform were measured simultaneously. Augmentation index (AIx) was calculated from the radial waveform as the ratio of the height of the late systolic peak to that of the first peak. cSBP was defined as the absolute pressure of the late systolic peak.

RESULTS

In the first panel (n = 8,085), QT interval was strongly association with AIx (r = 0.330; P < 0.001). This association remained significant even in the heart rate-adjusted analysis (r = 0.184; P < 0.001). Although subjects with a longer QT interval were older and had higher blood pressure, heart rate, and pulse wave velocity, multivariable analysis with adjustment for these covariables nevertheless identified longer corrected QT interval as an independent determinant of increased AIx and smaller pulse pressure amplification (PPa; brachial SBP minus cSBP) (β = -0.066; P < 0.001). This association was replicated in the independent second panel (n = 1,412) (β = -0.105; P < 0.001). In contrast, QRS interval was positively associated with PPa (β = 0.056; P < 0.001).

CONCLUSIONS

Longer QT interval and short QRS duration were significantly associated with arterial waveform and PPa. Our results provide a clue to the elucidation of unidentified mechanisms of the increased cardiovascular outcome and mortality risks in subjects with longer QT interval.

Carotid plaque score and intima media thickness as predictors of stroke and mortality in hypertensive patients

The mean intima media thickness (IMT) and plaque score from carotid ultrasonography are both widely used to evaluate macrovascular atherosclerotic change. The present study sought to examine which parameter more effectively predicts patient prognosis. This hospital-based cohort study included 356 patients with essential hypertension (mean age: 62.4 ± 0.6). We investigated how the mean IMT and plaque score correlated with various parameters, including pulse wave velocity (PWV), and we assessed the ability of the mean IMT and plaque score to predict cardiovascular events and total mortality. The mean IMT and plaque score significantly correlated with systemic atherosclerotic change, target organ damage, age and PWV. Subjects with a higher mean IMT and subjects with higher plaque scores showed higher frequencies of stroke and total mortality. In addition, subjects with marginal thickening of the intima media (mean ≥ 0.7) showed a significantly higher frequency of stroke than subjects with a mean IMT of <0.7. After adjustment for traditional risk factors, plaque score was significantly and independently predictive of stroke, and the predictive ability of the plaque score for the onset of stroke was equivalent to that of PWV. The mean IMT and plaque score showed a nonsignificant trend of higher risk of mortality after adjustment for traditional risk factors. The mean IMT and plaque score were significantly correlated with systemic atherosclerotic change. We revealed that plaque score predicted the onset of stroke more accurately than the mean IMT, and the accuracy of this prediction was equivalent to that from PWV in hypertensive patients. We also showed that marginal thickening of the intima media (as measured by mean IMT) may be a predictor of stroke.

Aortic stiffness determines diastolic blood flow reversal in the descending thoracic aorta: potential implication for retrograde embolic stroke in hypertension

Aortic stiffening often precedes cardiovascular diseases, including stroke, but the underlying pathophysiological mechanisms remain obscure. We hypothesized that such abnormalities could be attributable to altered central blood flow dynamics. In 296 patients with uncomplicated hypertension, Doppler velocity pulse waveforms were recorded at the proximal descending aorta and carotid artery to calculate the reverse/forward flow ratio and diastolic/systolic flow index, respectively. Tonometric waveforms were recorded on the radial artery to estimate aortic pressure and characteristic impedance (Z0) and to determine carotid-femoral (aortic) and carotid-radial (peripheral) pulse wave velocities. In all subjects, the aortic flow waveform was bidirectional, comprising systolic forward and diastolic reverse flows. The aortic reverse/forward flow ratio (35 ± 10%) was positively associated with parameters of aortic stiffness (including pulse wave velocity, Z0, and aortic/peripheral pulse wave velocity ratio), independent of age, body mass index, aortic diameter, and aortic pressure. The carotid flow waveform was unidirectional and bimodal with systolic and diastolic maximal peaks. There was a positive relationship between the carotid diastolic/systolic flow index (28 ± 9%) and aortic reverse/forward flow ratio, which remained significant after adjustment for aortic stiffness and other related parameters. The Bland-Altman plots showed a close time correspondence between aortic reverse and carotid diastolic flow peaks. In conclusion, aortic stiffness determines the extent of flow reversal from the descending aorta to the aortic arch, which contributes to the diastolic antegrade flow into the carotid artery. This hemodynamic relationship constitutes a potential mechanism linking increased aortic stiffness, altered flow dynamics, and increased stroke risk in hypertension.

High Blood Pressure and Cerebral White Matter Lesion Progression in the General Population

High blood pressure is considered an important risk factor for cerebral white matter lesions (WMLs) in the aging population. In a longitudinal population-based study of 665 nondemented persons, we investigated the longitudinal relationship of systolic blood pressure, diastolic blood pressure, and pulse pressure with annual progression of WMLs. Means of blood pressure were calculated over a 5-year period before longitudinal MRI scanning. WML progression was subsequently measured on 2 scans 3.5 years apart. We performed analyses with linear regression models and evaluated adjustments for age, sex, cardiovascular risk factors, and baseline WML volume. In addition, we evaluated whether treatment of hypertension is related to less WML progression. Both systolic and diastolic blood pressures were significantly associated with annual WML progression (regression coefficient [95% confidence interval], 0.08 [0.03; 0.14] mL/y and 0.09 [0.03; 0.15] mL/y per SD increase in systolic and diastolic blood pressure, respectively). Pulse pressure was also significantly associated with WML progression, but not independent from hypertension. After adjustment for baseline WML volume, only systolic blood pressure remained significantly associated: 0.05 (0.00; 0.09) mL/y per SD increase. People with uncontrolled untreated hypertension had significantly more WML progression than people with uncontrolled treated hypertension (difference [95% confidence interval], 0.12 [0.00; 0.23] mL/y). The present study further establishes high blood pressure to precede WMLs and implies that hypertension treatment could reduce WML progression in the general population.

Central versus peripheral blood pressure in malignant hypertension; effects of antihypertensive treatment

BACKGROUND

Sodium nitroprusside (SNP) and labetalol are recommended for the immediate treatment of malignant hypertension. Both are intravenous agents but have different effects on systemic hemodynamics, and may have differential effects on pulse-wave reflection and pulse-pressure amplification, with consequences for peripheral versus central blood pressures (BPs).

METHODS

We conducted a nonrandomized, open-label study of 8 patients treated with sodium nitroprusside (mean age (±SD), 44±14 years; 6 males; diastolic/systolic BP, 225±22/135±8mm Hg) and 6 patients treated with intravenous labetalol (mean age, 39±15 years; 4 males; systolic/diastolic BP, 232±22/138±17mm Hg) before and after treatment for malignant hypertension, aiming at a 25% reduction in mean arterial pressure. We measured peripheral pressures with an intra-arterial catheter in the radial artery and derived central pressures with a generalized transfer filter.

RESULTS

Mean arterial pressure was similarly reduced with sodium nitroprusside and labetalol (by 27% and 30%, respectively; P = 0.76). There was a nonsignificantly greater reduction in peripheral systolic blood pressure (SBP) with labetalol than with sodium nitroprusside (29±11% vs. 18±7%, P = 0.08). The decline in peripheral diastolic blood pressure (DBP) with the two agents was comparable, whereas the reduction in peripheral pulse pressure was 8±16% with SNP and 33±17% with labetalol (P = 0.01). The decline in reflection magnitude was greater with SNP than with labetalol. There were no significant differences in the reduction of central BP with SNP and labetalol. The amplification of PP increased with SNP but did not change with labetalol.

CONCLUSIONS

We found no difference in central SBP or PP in subjects treated with SNP and labetalol, but labetalol produced a greater reduction in peripheral SBP and PP in the immediate treatment of malignant hypertension.

Significance of increased CIMT with coexisting carotid plaques in cerebral white matter lesions in elders

It is very common that increased carotid intima media thickness (CIMT) and carotid plaque coexist in a single subject in elderly patients with white matter lesions (WMLs). In this study we investigated whether the coexistence of increased CIMT and carotid plaque is more strongly associated with the presence and extent of WMLs than either alone. All patients were classified into 1 of the following 4 groups: without either increased CIMT (I) or carotid plaque (P): I(-)P(-); with only increased CIMT: I(+)P(-); with only carotid plaque: I(-)P(+); and with both increased CIMT and carotid plaque: I(+)P(+). The presence and severity of periventricular WMLs (PWMLs) and deep WMLs (DWMLs) were assessed and the prevalence of MRI findings by the Cochran-Armitage trend test was calculated. The characteristics of subjects showed that the percentages of patients with increased CIMT and carotid plaque in the DWMLs group and the PWMLs group were significantly higher than those without WMLs group. Both DWMLs and PWMLs were strongly associated with age, carotid plaque and CIMT. Furthermore, the Cochran-Armitage trend test indicated that the prevalence of MRI findings of PWMLs and DWMLs increased in the order of I(-)P(-)< I(+)P(-)< I(-)P(+)< I(+)P(+) (P<0.0001). For the patients with DWMLs, the grades of both I(+)P(-) and I(+)P(+) were increased significantly compared to I(-)P(-) (P<0.0025, P<0.05, respectively) without such a difference found in patients with PWMLs. Our results suggested that the coexistence of increased CIMT and carotid plaque is most closely associated with WMLs, and that increased CIMT is associated with the severity of DWMLs, whereas carotid plaque is related to the presence of WMLs.

Associations between T1 white matter lesion volume and regional white matter microstructure in aging

White matter lesions, typically manifesting as regions of signal intensity abnormality (WMSA) on MRI, increase in frequency with age. However, the role of this damage in cognitive decline and disease is still not clear, as lesion volume has only loosely been associated with clinical status. Diffusion tensor imaging (DTI) has been used to examine the quantitative microstructural integrity of white matter, and has applications in the examination of subtle changes to tissue that appear visually normal on conventional imaging. The primary goal of this study was to determine whether major macrostructural white matter damage, (total WMSA volume), is associated with microstructural integrity of normal appearing white matter, and if these macrostructural changes fully account for microstructural changes. Imaging was performed in 126 nondemented individuals, ages 43-85 years, with no history of cerebrovascular disease. Controlling for age, greater WMSA volume was associated with decreased fractional anisotropy (FA) in widespread brain regions. Patterns were similar for FA and radial diffusivity but in contrast, WMSA was associated with axial diffusivity in fewer areas. Age was associated with FA in several regions, and many of these effects remained even when controlling for WMSA volume, suggesting the etiology of WMSAs does not fully account for all age-associated white matter deterioration. These results provide evidence that WMSA volume is associated with the integrity of normal-appearing white matter. In addition, our results suggest that overt lesions may not account for the association of increasing age with decreased white matter tissue integrity.

Large-vessel correlates of cerebral small-vessel disease

OBJECTIVE

Our aim was to investigate the relationship of carotid structure and function with MRI markers of cerebral ischemic small-vessel disease.

METHODS

The study comprised 1,800 participants (aged 72.5 ± 4.1 years, 59.4% women) from the 3C-Dijon Study, a population-based, prospective cohort study, who had undergone quantitative brain MRI and carotid ultrasound. We used multivariable logistic and linear regression adjusted for age, sex, and vascular risk factors.

RESULTS

Presence of carotid plaque and increasing carotid lumen diameter (but not common carotid artery intima-media thickness) were associated with higher prevalence of lacunar infarcts: odds ratio (OR) = 1.60 (95% confidence interval [CI]: 1.09-2.35), p = 0.02 and OR = 1.24 (95% CI: 1.02-1.50), p = 0.03 (by SD increase). Carotid plaque was also associated with large white matter hyperintensity volume (WMHV) (age-specific top quartile of WMHV distribution): OR = 1.32 (95% CI: 1.04-1.67), p = 0.02, independently of vascular risk factors. Increasing Young elastic modulus and higher circumferential wall stress, reflecting augmented carotid stiffness, were associated with increasing WMHV (effect estimate [β] ± standard error: 0.0003 ± 0.0001, p = 0.024; β ± standard error: 0.005 ± 0.002, p = 0.008). Large WMHV was also associated with increasing Young elastic modulus (OR = 1.22 [95% CI: 1.04-1.42], p = 0.01) and with decreasing distensibility coefficient (OR = 0.83 [95% CI: 0.69-0.99], p = 0.04), independently of vascular risk factors. Associations of carotid lumen diameter with lacunar infarcts and of carotid stiffness markers with WMHV were independent of carotid plaque.

CONCLUSIONS

In addition to and independently of carotid plaque, increasing carotid lumen diameter and markers of carotid stiffness were associated with increasing prevalence of lacunar infarcts and increasing WMHV, respectively.

Relation of pulse pressure to long-distance gait speed in community-dwelling older adults: findings from the LIFE-P study

Background

Reduced gait speed is associated with falls, late-life disability, hospitalization/institutionalization and cardiovascular morbidity and mortality. Aging is also accompanied by a widening of pulse pressure (PP) that contributes to ventricular-vascular uncoupling. The purpose of this study was to test the hypothesis that PP is associated with long-distance gait speed in community-dwelling older adults in the Lifestyle Interventions and Independence for Elders Pilot (LIFE-P) study.

Methods

Brachial blood pressure and 400-meter gait speed (average speed maintained over a 400-meter walk at “usual” pace) were assessed in 424 older adults between the ages of 70–89 yrs at risk for mobility disability (mean age = 77 yrs; 31% male). PP was calculated as systolic blood pressure (BP) – diastolic BP.

Results

Patients with a history of heart failure and stroke (n = 42) were excluded leaving 382 participants for final analysis. When categorized into tertiles of PP, participants within the highest PP tertile had significantly slower gait speed than those within the lowest PP tertile (p<0.05). Following stepwise multiple regression, PP was significantly and inversely associated with 400-meter gait speed (p<0.05). Other significant predictors of gait speed included: handgrip strength, body weight, age and history of diabetes mellitus (p<0.05). Mean arterial pressure, systolic BP and diastolic BP were not predictors of gait speed.

Conclusions

Pulse pressure is associated long-distance gait speed in community-dwelling older adults. Vascular senescence and altered ventricular-vascular coupling may be associated with the deterioration of mobility and physical function in older adults.

Aortic pulse wave velocity predicts focal white matter hyperintensities in a biracial cohort of older adults

Although the cross-sectional relationship of arterial stiffness with cerebral small vessel disease is consistently shown in middle-aged and young-old adults, it is less clear whether these associations remain significant over time in very old adults. We hypothesize that arterial stiffness is longitudinally associated with white matter characteristics, and associations are stronger within watershed areas. Neuroimaging was obtained in 2006-2008 from 303 elderly (mean age 82.9 years, 59% women, 41% black) with pulse wave velocity (PWV) measures in 1997-1998. Multivariable regression models estimated the coefficients for PWV (cm/sec) in relationship to presence, severity, and spatial distribution of white matter hyperintensities (WMH), gray matter volume, and fractional anisotropy from diffusion tensor, adjusting for demographic, cardiovascular risk factors, and diseases from 1997-1998 to 2006-2008. Higher PWV in 1997-1998 was associated with greater WMH volume in 2006-2008 within the left superior longitudinal fasciculus (age and total brain WMH adjusted, P=0.023), but not with WMH in other tracts or with fractional anisotropy or gray matter volume from total brain (P>0.2). Associations were stronger in blacks than in whites, remaining significant in fully adjusted models. Elderly with WMH in tracts related to processing speed and memory are more likely to have had higher PWV values 10 years prior, before neuroimaging data being available. Future studies should address whether arterial stiffness can serve as an early biomarker of covert brain structural abnormalities and whether early arterial stiffness control can promote successful brain aging, especially in black elderly.

Differences between daytime and nighttime blood pressure variability regarding systemic atherosclerotic change and renal function

Recently, new parameters related to hypertension, such as variability in blood pressure and ambulatory arterial stiffness index (AASI), were demonstrated to correlate with arteriosclerotic change. In this study, we investigated the correlation between circadian variability in blood pressure/AASI and renal function. We also investigated differences in the clinical impact of 24 h, daytime and nighttime blood pressure variability on renal and systemic atherosclerotic changes. We analyzed data from 120 patients who underwent renal Doppler ultrasonography (RDU) and ambulatory blood pressure monitoring (ABPM) at our hospital ward, and investigated the correlation between circadian variability in blood pressure/AASI and renal function, including resistive index (RI) evaluated with RDU, which is thought to be a good indicator of renal vascular resistance. Subjects with higher circadian variability in systolic blood pressure (SBP) had significantly higher RI. Daytime variability in SBP correlated more strongly with RI than nighttime variability. Meanwhile, only nighttime variability, but not daytime variability, in SBP was related to carotid atherosclerosis. Similarly, AASI was significantly correlated with RI. Circadian variability in SBP and AASI were both significantly correlated with renal function. Daytime SBP s.d. was especially more strongly correlated with renal vascular resistance, and nighttime SBP s.d. was significantly correlated with intima-media thickness (IMT) and plaque score. These results indicate that evaluating both daytime and nighttime blood pressure variability enables an assessment of pathological conditions in hypertensive patients to prevent cardiovascular diseases.

Silent brain infarct is independently associated with arterial stiffness indicated by cardio-ankle vascular index (CAVI)

It is still unclear whether silent brain infarct (SBI) and white-matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) scans are associated with cardio-ankle vascular index (CAVI), a novel parameter of arterial stiffness. We studied 220 consecutive patients (mean age, 69 years) without a history of stroke or transient ischemic attack. Patients were assessed for the presence of SBI, WMHs and risk factors. Arterial stiffness was evaluated using CAVI. Patients were categorized into one of two groups according to the presence or absence of SBI and WMHs, and clinical characteristics were compared between the two groups. CAVI was significantly higher in patients with SBI or in patients with WMHs than in those without those respective findings. The CAVI cutoff values for detection of SBI and WMHs were 9.2 and 8.9, respectively. On multivariable analyses, CAVI, a one point increase in CAVI: odds ratio (OR), 1.25; 95% confidence interval (CI), 1.01-1.56; CAVI ≥9.2: OR, 2.34; 95% CI, 1.16-5.02, was independently associated with SBI, however, CAVI was not independently associated with WMHs. Patients with CAVI ≥9.2 had higher OR for the presence of both SBI and WMHs (OR, 2.57; 95% CI, 1.15-5.98) when compared with patients with CAVI <9.2 after adjustment for age and sex. SBI is independently associated with arterial stiffness indicated by CAVI.

Intracranial deep white matter lesions (DWLs) are associated with chronic kidney disease (CKD) and cognitive impairment: a 5-year follow-up magnetic resonance imaging (MRI) study

Stroke incidence and cognitive decline are related to progression of arteriosclerosis in intracranial DWLs. However, the relationships between DWLs and factors associated with their progression, including CKD, have not been fully elucidated using longitudinal MRI. Of 291 individuals (184 males, 107 females; age 66.9 ± 6.1 years) who had voluntarily participated in a hospital-based health check-up and underwent repeated brain MRI scans in 2003 and 2008, 273 were evaluated in this study. The DWL group included those having DWL without progression, and the DWL progression (DWLP) group included those having an increase in grade number according to the Fazekas classification. Unimpaired age-matched subjects with no brain MRI abnormalities constituted Group C. The Mini-Mental State Examination (MMSE) and verbal fluency tasks were used for objective cognitive evaluations according to the MR evaluation schedule in 2008. Associations between DWLs and vascular risk factors were examined. DWLP occurred in 9.2% of subjects. Compared to Group C subjects, DWL and DWLP group subjects had high odds ratios (ORs) for hypertension (HT) (2.23 and 2.92, respectively) and CKD (1.40 and 2.41, respectively). After adjustment for potential confounders, the ORs of CKD for DWLs remained significant (1.13 and 1.43, p<0.05). DWLs and DWLP were associated with low cognitive scale scores and increased CKD. In conclusion, CKD was associated with DWLs and DWLP as an independent risk factor and a lower level of cognitive function 5 years after CKD was identified. Successful CKD therapy may be expected to prevent DWLP.

Connecting cerebral white matter lesions and hypertensive target organ damage

Chronic hypertension leads to concomitant remodeling of the cardiac and vascular systems and various organs, especially the brain, kidney, and retina. The brain is an early target of organ damage due to high blood pressure, which is the major modifiable risk factor for stroke and small vessel disease. Stroke is the second leading cause of death and the number one cause of disability worldwide and over 80% of strokes occur in the elderly. Preclinical hypertensive lesions in most target organs are clearly identified: left ventricular hypertrophy for the heart, microalbuminuria for the kidney, fundus abnormalities for the eye, and intima-media thickness and pulse wave velocity for the vessels. However, early hypertensive brain damage is not fully studied due to difficulties in access and the expense of techniques. After age, hypertension is the most-important risk factor for cerebral white matter lesions, which are an important prognostic factor for stroke, cognitive impairment, dementia, and death. Studies have shown an association between white matter lesions and a number of extracranial systems affected by high BP and also suggest that correct antihypertensive treatment could slow white matter lesions progression. There is strong evidence that cerebral white matter lesions in hypertensive patients should be considered a silent early marker of brain damage.

The clinical manifestations and pathophysiology of cerebral small vessel disease

Small vessel disease (SVD) is responsible for brain chronic circular disorder, and accounts for 20%-30% cases of ischemic stroke as well as cerebral hemorrhage, and to a great extent, encephalopathy. Binswanger's disease and multiple small strokes, which are common in older people, are also closely associated with SVD. These disorders often cause decline in cognition, vascular dementia, impairment in gait and balance, mood depression, and urinary incontinence, and often brings great social and economic burdens. SVD-related encephalopathy increases the incidences of fall, disability and death in elderly people. With the aging of the society, more attention should be paid to the importance of early diagnosis and prophylactic treatment of SVD. Here the clinical manifestations and pathophysiology of SVD are reviewed.

Efficacy of combination therapy with telmisartan plus amlodipine in patients with poorly controlled hypertension

There is accumulating evidence that blood pressure (BP) control significantly reduces the risk of future cardiovascular events in patients with essential hypertension. However, strict BP control is often difficult to maintain, and half of hypertensive patients fail to attain BP goals on single-drug therapy. Therefore, current guidelines recommend combinations of drugs that have complimentary mode of actions for treatment of patients with moderate hypertension. In this study, we examined in hypertensive patients uncontrolled by the combination treatment with 5 mg amlodipine plus 80 mg valsartan or 8 mg candesartan whether additional BP lowering could be achieved by switching to 5 mg amlodipine plus 40 mg telmisartan. Forty-seven patients with essential hypertension who failed to achieve a target BP level by the treatment of 5 mg amlodipine plus 80 mg valsartan or 8 mg candesartan for at least 2 months were enrolled. Replacement of valsartan or candesartan by telmisartan showed a significant reduction in both mean clinic systolic and diastolic BP at 4, 8 and 12 weeks; BP level decreased from 143.7/82.3 mmHg at baseline to 135.4/77.5 mmHg at 12 weeks. Furthermore, in 8 patients of valsartan group, switching to telmisartan significantly reduced central BP by 11.8 mmHg. Our present study suggests that combination therapy with telmisartan plus amlodipine may be more beneficial than valsartan or candesartan plus amlodipine treatment for controlling brachial and central BP, which could lead to more favorable cardiovascular outcomes with this drug combinations.

Association of central systolic blood pressure with intracerebral small vessel disease in Japanese

BACKGROUND

Recent studies have reported the association between advanced arterial stiffness and brain small vessel diseases (SVDs). Two possible hemodynamic mechanisms, increases in central blood pressure (BP) and pulsatile flow load to the brain, have been speculated to link arterial stiffness and SVD. The carotid flow augmentation index (AI) has been proposed as an index of pulsatile flow to the brain. We compared its association with brain SVD with that of central BP in a general population.

METHODS

Subjects were 500 individuals free from symptomatic cardiovascular diseases with a mean age of 66.9 +/- 8.4 years. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of arterial stiffness. Carotid flow AI was obtained by Doppler ultrasonography. The presence of silent cerebral lacunar infarcts (SCI) was determined as a manifestation of SVD by 3-tesla magnetic resonance imaging (MRI). Second peak radial systolic BP (SBP2) and pulse pressure (PP2) were used as estimates of central BP.

RESULTS

baPWV was significantly associated with radial BP2 (r = 0.55, P < 0.0001) but not with carotid flow AI (r = 0.03, P = 0.51). Radial BPs and baPWV, but not flow AI, were significantly higher in subjects with SCI. Radial SBP2 had higher odds ratio for the presence of SCI than brachial SBP, PP, and radial PP2. Logistic regression analysis showed that radial SBP2, but not flow AI, was independently related to the presence of SCI.

CONCLUSION

These findings indicate that the SBP2, an estimate of central SBP, is significantly associated with the presence of SVD in an apparently healthy general population.