White matter lesions characterise brain involvement in moderate to severe chronic obstructive pulmonary disease, but cerebral atrophy does not

Correlation between frailty and reduction in cortical thickness in patients with chronic obstructive pulmonary disease

Physical inactivity and cognitive impairment in patients with chronic obstructive pulmonary disease (COPD) can lead to frailty and poor prognoses. However, little is known regarding the association between frailty and the human brain. We hypothesized that the brain structure could change according to frailty in patients with COPD and focused on cortical thickness. Cortical thickness measured by magnetic resonance imaging and frailty scores using the Kihon Checklist (KCL) were assessed in 40 patients with stable COPD and 20 healthy controls. Among the 34 regions assessed, multiple regions were thinner in patients with COPD than in healthy individuals (p < 0.05). We found significant negative correlations between the eight regions and the KCL scores only in patients with COPD. After adjusting for age and cognitive impairment, the association between the left and six right regions remained statistically significant. The correlation coefficient was the strongest in the bilateral superior frontal gyrus (left: ρ = - 0.5319, p = 0.0006) (right: ρ = - 0.5361, p = 0.0005). Interestingly, among the KCL scores, the daily activity domain showed the strongest correlation (sensitivity, 90%; specificity, 73%) with the bottom quartile of the reduction in the superior frontal gyrus. Frailty in patients with COPD is associated with a thickness reduction in the cortical regions, reflecting social vulnerability.

The PASTIS trial: Testing tadalafil for possible use in vascular cognitive impairment

INTRODUCTION

There are few randomized clinical trials in vascular cognitive impairment (VCI). This trial tested the hypothesis that the PDE5 inhibitor tadalafil, a widely used vasodilator, increases cerebral blood flow (CBF) in older people with symptomatic small vessel disease, the main cause of VCI.

METHODS

In a double-blind, placebo-controlled, cross-over trial, participants received tadalafil (20 mg) and placebo on two visits ≥7 days apart (randomized to order of treatment). The primary endpoint, change in subcortical CBF, was measured by arterial spin labelling.

RESULTS

Tadalafil increased CBF non-significantly in all subcortical areas (N = 55, age: 66.8 (8.6) years) with greatest treatment effect within white matter hyperintensities (+9.8%, P = .0960). There were incidental treatment effects on systolic and diastolic blood pressure (-7.8, -4.9 mmHg; P < .001). No serious adverse events were observed.

DISCUSSION

This trial did not identify a significant treatment effect of single-administration tadalafil on subcortical CBF. To detect treatment effects may require different dosing regimens.

Test-retest reliability of arterial spin labelling for cerebral blood flow in older adults with small vessel disease

Cerebral small vessel disease (SVD) is common in older people and is associated with lacunar stroke, white matter hyperintensities (WMH) and vascular cognitive impairment. Cerebral blood flow (CBF) is reduced in SVD, particularly within white matter.Here we quantified test-retest reliability in CBF measurements using pseudo-continuous arterial spin labelling (pCASL) in older adults with clinical and radiological evidence of SVD (N=54, mean (SD): 66.9 (8.7) years, 15 females/39 males). We generated whole-brain CBF maps on two visits at least 7 days apart (mean (SD): 20 (19), range 7-117 days).Test-retest reliability for CBF was high in all tissue types, with intra-class correlation coefficient [95%CI]: 0.758 [0.616, 0.852] for whole brain, 0.842 [0.743, 0.905] for total grey matter, 0.771 [0.636, 0.861] for deep grey matter (caudate-putamen and thalamus), 0.872 [0.790, 0.923] for normal-appearing white matter (NAWM) and 0.780 [0.650, 0.866] for WMH (all p<0.001). ANCOVA models indicated significant decline in CBF in total grey matter, deep grey matter and NAWM with increasing age and diastolic blood pressure (all p<0.001). CBF was lower in males relative to females (p=0.013 for total grey matter, p=0.004 for NAWM).We conclude that pCASL has high test-retest reliability as a quantitative measure of CBF in older adults with SVD. These findings support the use of pCASL in routine clinical imaging and as a clinical trial endpoint.All data come from the PASTIS trial, prospectively registered at: https://eudract.ema.europa.eu (2015-001235-20, registered 13/05/2015), http://www.clinicaltrials.gov (NCT02450253, registered 21/05/2015).

Sedentary Time and Cognitive Impairment in Patients Using Long-Term Oxygen Therapy: A Cross-Sectional Study

Physical inactivity is a predictor of death in patients with chronic respiratory disease. Cognitive impairment is common among patients with chronic respiratory disease. However, the association between sedentary time and cognitive impairment in patients with chronic respiratory disease using long-term oxygen therapy is unclear. This study aimed to determine the relationship between sedentary time and cognitive impairment in patients on long-term oxygen therapy. This cross-sectional study included 96 patients with chronic respiratory disease on long-term oxygen therapy (mean age 77.3 years; female, 22%). The primary outcomes measured were sedentary time (Japanese version of the International Physical Activity Questionnaire Short Form), cognitive function (Montreal Cognitive Assessment), and dyspnea (modified Medical Research Council scale). The factors associated with sedentary time were confirmed by multiple regression analysis. The median sedentary time was 600.0 min. The median Montreal Cognitive Assessment score was 24.0 points, and 67 (70%) patients had mild cognitive impairment. In multiple regression analysis, sedentary time was associated with dyspnea (β = 0.397, p < 0.001) and cognitive function (β = −0.239, p = 0.020). This study indicates that sedentary time in patients on long-term oxygen therapy was associated with dyspnea and cognitive impairment.

Associations of Pulmonary Function with MRI Brain Volumes: A Coordinated Multi-Study Analysis

BACKGROUND

Previous studies suggest poor pulmonary function is associated with increased burden of cerebral white matter hyperintensities and brain atrophy among elderly individuals, but the results are inconsistent.

OBJECTIVE

To study the cross-sectional associations of pulmonary function with structural brain variables.

METHODS

Data from six large community-based samples (N = 11,091) were analyzed. Spirometric measurements were standardized with respect to age, sex, height, and ethnicity using reference equations of the Global Lung Function Initiative. Associations of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and their ratio FEV1/FVC with brain volume, gray matter volume, hippocampal volume, and volume of white matter hyperintensities were investigated using multivariable linear regressions for each study separately and then combined using random-effect meta-analyses.

RESULTS

FEV1 and FVC were positively associated with brain volume, gray matter volume, and hippocampal volume, and negatively associated with white matter hyperintensities volume after multiple testing correction, with little heterogeneity present between the studies. For instance, an increase of FVC by one unit was associated with 3.5 ml higher brain volume (95% CI: [2.2, 4.9]). In contrast, results for FEV1/FVC were more heterogeneous across studies, with significant positive associations with brain volume, gray matter volume, and hippocampal volume, but not white matter hyperintensities volume. Associations of brain variables with both FEV1 and FVC were consistently stronger than with FEV1/FVC, specifically with brain volume and white matter hyperintensities volume.

CONCLUSION

In cross-sectional analyses, worse pulmonary function is associated with smaller brain volumes and higher white matter hyperintensities burden.

Novel pharmacological strategies to treat cognitive dysfunction in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major incurable global health burden and currently the 3rd largest cause of death in the world, with approximately 3.23 million deaths per year. Globally, the financial burden of COPD is approximately €82 billion per year and causes substantial morbidity and mortality. Importantly, much of the disease burden and health care utilisation in COPD is associated with the management of its comorbidities and viral and bacterial-induced acute exacerbations (AECOPD). Recent clinical studies have shown that cognitive dysfunction is present in up to 60% of people with COPD, with impairments in executive function, memory, and attention, impacting on important outcomes such as quality of life, hospitalisation and survival. The high prevalence of cognitive dysfunction in COPD may also help explain the insufficient adherence to therapeutic plans and strategies, thus worsening disease progression in people with COPD. However, the mechanisms underlying the impaired neuropathology and cognition in COPD remain largely unknown. In this review, we propose that the observed pulmonary oxidative burden and inflammatory response of people with COPD 'spills over' into the systemic circulation, resulting in damage to the brain and leading to cognitive dysfunction. As such, drugs targeting the lungs and comorbidities concurrently represent an exciting and unique therapeutic opportunity to treat COPD and cognitive impairments, which may lead to the production of novel targets to prevent and reverse the debilitating and life-threatening effects of cognitive dysfunction in COPD.

Association between airflow limitation and leukoaraiosis of the brain

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) have several comorbidities. Leukoaraiosis (LA) is an abnormal appearance of brain white matter on neuroimaging, and it has been linked to microangiopathy of the brain. In this study, we explored the association between airflow limitation (AL) and LA volume and localization.

METHODS

This observational cross-sectional study included 3,945 subjects who underwent medical check-ups between January 2015 and December 2017. LA was automatically assessed and quantified on brain MRI images using a morphometric program. Spirometry without bronchodilator was performed, and AL was defined as the ratio of forced expiratory volume in 1 s/forced vital capacity <0.70.

RESULTS

In the multivariate analysis, AL was an independent predictor of LA volume (t = 3.06, P < 0.01), in addition to age, hypertension, and dyslipidemia. Compared with the propensity-matched subjects without AL, the subjects with AL (n = 157) had significantly higher LA volumes (4.65 cm³ vs. 3.26 cm³, P < 0.05) and frequency of LA in the frontal lobe, but not in the parietal, temporal, and occipital lobes.

CONCLUSIONS

Our findings suggest that AL is associated with increased LA volume and with more frequent localization of LA in the frontal lobe.

Cognitive performance in relation to metabolic disturbances in patients with COPD

BACKGROUND & AIMS

Cognitive impairment (CI) and metabolic abnormalities, including the metabolic syndrome (MetS) and sarcopenia, are more prevalent in COPD patients compared to controls without diagnosed lung disease. Because earlier studies have shown these metabolic abnormalities may affect cognitive performance, this study investigated whether cognitive performance is more impaired in subgroups of COPD patients with MetS or sarcopenia.

METHODS

Cognitive performance patterns of 170 COPD patients referred for pulmonary rehabilitation (53.5% male, 63.4 ± 9.4 years, FEV₁ 54.5 ± 22.7% predicted) were compared between COPD subgroups stratified by presence of MetS and sarcopenia. Cognitive performance was assessed using a detailed neuropsychological test battery, which measured psychomotor speed (Stroop Color-Word Test, Concept Shifting Test, Letter-Digit Substitution Test), planning (Behavioral Assessment of the Dysexecutive Syndrome), working memory (Visual-Verbal Learning Test, Digit Span), verbal memory (Visual-Verbal Learning Test) and cognitive flexibility (Stroop Color-Word Test, Concept Shifting Test). MetS was determined according to the NCEP ATP-III criteria. Sarcopenia was determined based on decreased appendicular lean mass by dual-energy x-ray absorptiometry and impaired physical performance by 6-min walking distance.

RESULTS

MetS was observed in 54.7% and sarcopenia in 30.0% of COPD patients. The prevalence of general CI was not different between patients with and without MetS (30.4% and 39.0%, respectively) or those with and without sarcopenia (34.0% and 34.5%, respectively, both p > 0.05). Domain-specific cognitive performance was not different between metabolic subgroups, but those with sarcopenia displayed a lower prevalence of CI on verbal memory than those without (21.7% and 29.7%, respectively, p = 0.011). Only the digit span (working memory) subtest was significantly different between metabolic subgroups, in favor of those without MetS (p = 0.017).

CONCLUSION

Cognitive performance was not affected more in COPD patients with sarcopenia or MetS.

Influencing Factors and Exercise Intervention of Cognitive Impairment in Elderly Patients with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common respiratory condition characterized by airflow limitation in the elderly. Airflow limitation is partially reversible and progressive. COPD not only causes a gradual decline in lung function but also affects the function of other systems throughout the body; it also has adverse effects on the central nervous system that can lead to cognitive impairment, especially in elderly patients. Therefore, understanding the influencing factors of cognitive impairment in elderly patients with COPD and applying early intervention are crucial in improving the quality of life of patients and reducing the burden on their families and society. This article mainly discusses the related factors of cognitive impairment in elderly patients with COPD and expands the possible mechanism of exercise in improving cognitive impairment in patients with COPD to provide a reference for the clinical prevention and treatment of cognitive impairment in elderly patients with COPD.

Reduced forced vital capacity is associated with cerebral small vessel disease burden in cognitively normal individuals

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Decreased FVC (% pred) was associated with increased cerebral small vessel disease burden even in cognitively normal subjects.

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This reduced lung function was related to low Mini-Mental Status Examination (MMSE) scores in cognitively normal subjects.

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Path analyses showed that white matter hyperintensities partially mediated the positive relationship between FVC (% pred) and MMSE score.

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There was no significant association between low FVC (% pred) and cortical thickness in cognitively normal subjects.

Background

Pulmonary dysfunction is associated with elevated risk of cognitive decline. However, the mechanism underlying this relationship has not been fully investigated. In this study, we investigate the relationships between pulmonary function, cerebral small vessel disease (CSVD) markers, cortical thickness, and the Mini-Mental Status Examination (MMSE) scores in cognitively normal individuals.

Methods

We used a cross-sectional study design. We identified 1924 patients who underwent pulmonary function testing, three-dimensional brain magnetic resonance imaging (MRI), and the MMSE. Pulmonary function was analyzed according to the quintiles of percentage predicted values (% pred) for forced vital capacity (FVC) or forced expiratory volume in 1 s (FEV₁). Regarding CSVD markers, we visually rated white matter hyperintensities (WMH) and manually counted lacunes and microbleeds. Cortical thickness was measured by surface-based methods.

Results

Compared with the highest quintile of FVC, the lowest quintile of FVC (% pred) showed a higher risk of WMH (OR 1.98, 95% CI: 1.21–3.24) and lacunes (OR 1.86, 95% CI: 1.12–3.08). There were no associations between FVC or FEV₁ and cortical thickness. Low FVC, but not FEV₁, was associated with low MMSE scores. Path analyses showed that WMH partially mediated the positive relationship between FVC (% pred) and MMSE score.

Conclusions

Our findings suggested that decreased pulmonary function was associated with increased CSVD burdens, which in turn wass associated with decreased cognition, even in cognitively normal subjects.

Diffusion tensor imaging of white matter integrity in relation to smoking index and exacerbations in severe chronic obstructive pulmonary disease

Background

Diffusion tensor imaging (DTI) is a non-invasive MR modality that provides an evaluation of brain tissue microstructure and architecture in vivo. We aimed to assess the diagnostic value of DTI parameters in evaluating cerebral white matter integrity in patients of severe chronic obstructive pulmonary disease (COPD) and correlate these parameters with smoking index (SI) and the number of exacerbations in the last year.

This prospective study included 30 COPD male past smoker patients and 15 age- and sex-matched nonsmoker controls. Staging of COPD, SI and number of exacerbations in the last year were obtained. Routine brain MRI and DTI were done in all subjects. The selected white matter tracts’ fractional anisotropy (FA), and mean diffusivity (MD) were calculated in the region of interest in axial slices.

Results

The mean FA and MD values of all selected white matter tracts showed a high significant difference (p < 0.001) between patients and control group. The correlation between FA, SI and exacerbation frequency was not significant in the majority of white matter tracts (p > 0.05). The correlation between MD, SI and exacerbation frequency was significant for the majority of tracts (p < 0.05).

Conclusion

DTI metrics are valuable non-invasive tools in evaluating the white matter abnormalities in COPD patients. Smoking index and frequency of exacerbations have possible relation to extra-pulmonary cerebral manifestations of COPD.

Disruption of white matter connectivity in chronic obstructive pulmonary disease

Background

Mild cognitive impairment is a common systemic manifestation of chronic obstructive pulmonary disease (COPD). However, its pathophysiological origins are not understood. Since, cognitive function relies on efficient communication between distributed cortical and subcortical regions, we investigated whether people with COPD have disruption in white matter connectivity.

Methods

Structural networks were constructed for 30 COPD patients (aged 54–84 years, 57% male, FEV₁ 52.5% pred.) and 23 controls (aged 51–81 years, 48% Male). Networks comprised 90 grey matter regions (nodes) interconnected by white mater fibre tracts traced using deterministic tractography (edges). Edges were weighted by the number of streamlines adjusted for a) streamline length and b) end-node volume. White matter connectivity was quantified using global and nodal graph metrics which characterised the networks connection density, connection strength, segregation, integration, nodal influence and small-worldness. Between-group differences in white matter connectivity and within-group associations with cognitive function and disease severity were tested.

Results

COPD patients’ brain networks had significantly lower global connection strength (p = 0.03) and connection density (p = 0.04). There was a trend towards COPD patients having a reduction in nodal connection density and connection strength across the majority of network nodes but this only reached significance for connection density in the right superior temporal gyrus (p = 0.02) and did not survive correction for end-node volume. There were no other significant global or nodal network differences or within-group associations with disease severity or cognitive function.

Conclusion

COPD brain networks show evidence of damage compared to controls with a reduced number and strength of connections. This loss of connectivity was not sufficient to disrupt the overall efficiency of network organisation, suggesting that it has redundant capacity that makes it resilient to damage, which may explain why cognitive dysfunction is not severe. This might also explain why no direct relationships could be found with cognitive measures. Smoking and hypertension are known to have deleterious effects on the brain. These confounding effects could not be excluded.

Contributions of cardiovascular risk and smoking to chronic obstructive pulmonary disease (COPD)-related changes in brain structure and function

Background

Brain damage and cardiovascular disease are extra-pulmonary manifestations of chronic obstructive pulmonary disease (COPD). Cardiovascular risk factors and smoking are contributors to neurodegeneration. This study investigates whether there is a specific, COPD-related deterioration in brain structure and function independent of cardiovascular risk factors and smoking.

Materials and methods

Neuroimaging and clinical markers of brain structure (micro- and macro-) and function (cognitive function and mood) were compared between 27 stable COPD patients (age: 63.0±9.1 years, 59.3% male, forced expiratory volume in 1 second [FEV1]: 58.1±18.0% pred.) and 23 non-COPD controls with >10 pack years smoking (age: 66.6±7.5 years, 52.2% male, FEV1: 100.6±19.1% pred.). Clinical relationships and group interactions with brain structure were also tested. All statistical analyses included correction for cardiovascular risk factors, smoking, and aortic stiffness.

Results

COPD patients had significantly worse cognitive function (p=0.011), lower mood (p=0.046), and greater gray matter atrophy (p=0.020). In COPD patients, lower mood was associated with markers of white matter (WM) microstructural damage (p<0.001), and lower lung function (FEV1/forced vital capacity and FEV1) with markers of both WM macro (p=0.047) and microstructural damage (p=0.028).

Conclusion

COPD is associated with both structural (gray matter atrophy) and functional (worse cognitive function and mood) brain changes that cannot be explained by measures of cardiovascular risk, aortic stiffness, or smoking history alone. These results have important implications to guide the development of new interventions to prevent or delay progression of neuropsychiatric comorbidities in COPD. Relationships found between mood and microstructural abnormalities suggest that in COPD, anxiety, and depression may occur secondary to WM damage. This could be used to better understand disabling symptoms such as breathlessness, improve health status, and reduce hospital admissions.

Quantifying deep grey matter atrophy using automated segmentation approaches: A systematic review of structural MRI studies

The deep grey matter (DGM) nuclei of the brain play a crucial role in learning, behaviour, cognition, movement and memory. Although automated segmentation strategies can provide insight into the impact of multiple neurological conditions affecting these structures, such as Multiple Sclerosis (MS), Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD) and Cerebral Palsy (CP), there are a number of technical challenges limiting an accurate automated segmentation of the DGM. Namely, the insufficient contrast of T1 sequences to completely identify the boundaries of these structures, as well as the presence of iso-intense white matter lesions or extensive tissue loss caused by brain injury. Therefore in this systematic review, 269 eligible studies were analysed and compared to determine the optimal approaches for addressing these technical challenges. The automated approaches used among the reviewed studies fall into three broad categories, atlas-based approaches focusing on the accurate alignment of atlas priors, algorithmic approaches which utilise intensity information to a greater extent, and learning-based approaches that require an annotated training set. Studies that utilise freely available software packages such as FIRST, FreeSurfer and LesionTOADS were also eligible, and their performance compared. Overall, deep learning approaches achieved the best overall performance, however these strategies are currently hampered by the lack of large-scale annotated data. Improving model generalisability to new datasets could be achieved in future studies with data augmentation and transfer learning. Multi-atlas approaches provided the second-best performance overall, and may be utilised to construct a "silver standard" annotated training set for deep learning. To address the technical challenges, providing robustness to injury can be improved by using multiple channels, highly elastic diffeomorphic transformations such as LDDMM, and by following atlas-based approaches with an intensity driven refinement of the segmentation, which has been done with the Expectation Maximisation (EM) and level sets methods. Accounting for potential lesions should be achieved with a separate lesion segmentation approach, as in LesionTOADS. Finally, to address the issue of limited contrast, R2*, T2* and QSM sequences could be used to better highlight the DGM due to its higher iron content. Future studies could look to additionally acquire these sequences by retaining the phase information from standard structural scans, or alternatively acquiring these sequences for only a training set, allowing models to learn the "improved" segmentation from T1-sequences alone.

Altered amplitude of low-frequency fluctuation in basal ganglia correlates to pulmonary ventilation function in COPD patients: A resting-state fMRI study

INTRODUCTION

Patients under chronic obstructive pulmonary disease (COPD) has been reported to be associated with a higher prevalence of cognitive impairment (CI). However, it is still largely unknown whether the aberrant resting-state spontaneous neuronal activity pattern reflected by the amplitude of low-frequency fluctuation (ALFF) analysis will be associated with the CI in COPD patients.

MATERIALS

A total of 28 COPD patients and 26 healthy controls were enrolled in this study. Of all the subjects, structural and functional MRI data, spirometry tests performance and neuropsychological assessments of different cognitive domains were collected. Voxel-based two-sample t tests were used to detect brain regions showing differences in the ALFF value between COPD patients and healthy controls. An additional fMRI runs with supplementary oxygen delivery were employed to explore the impact of elevated partial pressure of oxygen (PaO₂ ) or moderate hyperoxia on ALFF in COPD patients and healthy controls respectively.

RESULTS

More extensive white matter lesion was detected in COPD patients. COPD patients exhibit decreased ALFF value in bilateral basal ganglia areas and right thalamus, and aberrant ALFF value is correlated with PaO₂ and pulmonary ventilation function (FEV1%pred). COPD patients performed worse in the Digit Span Test (reverse), Digit Symbol Substitution Test, Trail-making test (A and B) than controls. After supplementary oxygen inhalation, the ALFF value of basal ganglia and right thalamus significantly increased in the controls, but not in the COPD patients.

CONCLUSIONS

COPD patients mainly exhibit impaired executive function but not long-term memory in cognitive function assessment. Aberrant ALFF alteration in the deep brain may be directly related to lower PaO₂ in COPD patients.

Psychological co-morbidities in COPD: Targeting systemic inflammation, a benefit for both?

COPD is a chronic lung disease characterized by persistent respiratory symptoms and airflow limitation due to airway and/or alveolar abnormalities. Furthermore, COPD is often characterized by extrapulmonary manifestations and comorbidities worsening COPD progression and quality of life. A neglected comorbidity in COPD management is mental health impairment defined by anxiety, depression and cognitive problems. This paper summarizes the evidence for impaired mental health in COPD and focuses on current pharmacological intervention strategies. In addition, possible mechanisms in impaired mental health in COPD are discussed with a central role for inflammation. Many comorbidities are associated with multi-organ-associated systemic inflammation in COPD. Considering the accumulative evidence for a major role of systemic inflammation in the development of neurological disorders, it can be hypothesized that COPD-associated systemic inflammation also affects the function of the brain and is an interesting therapeutic target for nutra- and pharmaceuticals.

[Chronic cerebral ischemia in obstructive pulmonary diseases]

Chronic obstructive pulmonary disease (COPD) is one of the main causes of disease and death incidences worldwide. Different organs and systems are involved in COPD activating tissue hypoxia. It affects especially tissue functioning with the high level of intensity of metabolic processes, and the nervous system suffers first. Neuroimaging studies show white and grey matter damage and cerebral atrophy, which may clinically manifest themselves in different neurological symptoms depended on vascular system lesions, and cognitive and affective impairments. Despite of its potential importance, encephalopathy in COPD remains a little-studied concomitant pathology. Application of cytoprotective drugs is pathogenetically justified in this case and must be included in COPD complex therapy. In particular, the inclusion of mexicor in the treatment of patients with chronic pulmonary heart increases the efficacy of treatment of the main and associated diseases (chronic cerebral ischemia, cardiac insufficiency and arrhythmia).