Cerebral flow velocities during daily activities depend on blood pressure in patients with chronic ischemic infarctions

Factors predicting functional outcome after rtPA for patients with acute ischemic stroke

Background

Accurate outcome prediction for patients with acute ischemic stroke after intravenous recombinant tissue plasminogen activator (rtPA) treatment is essential for optimizing patients’ management. We aimed to identify factors associated with unfavorable outcomes following intravenous rtPA treatment. This study was carried out on 162 patients who presented with acute ischemic stroke within 4.5 h from onset of neurological symptoms and were eligible for intravenous rtPA. After exclusion of 48 patients, 114 patients were finally eligible for follow-up. After complete medical and neurological history, complete medical and neurological examination and brain image (CT and or MRI brain) were collected from the patients. patients eligible were included in the study. NIHS scale was assessed for all patients at time of admission, after 24 h, and follow-up for 3 months.

Results

After a 90-day follow-up period for 114 patients with acute ischemic stroke after rtPA, 35.8% had good outcome (MRS; 0–2), 18.5% had partial outcome (MRS; 3–4) and 12.5% had poor outcome (MRS; 5–6). Atrial fibrillation (AF), PH of stroke, stroke severity, and severity of symptom (NIHSS) score were significantly (P: 0.004, 0.001, 0.007 and 0.001) correlated with poor outcome after rtPA. Similarly, old age, high blood pressure at time of presentation, hypertension, and dyslipidemia were showed to carry poor outcome.

Conclusions

AF, high NIHSS score, PH of stroke, previous stroke, hypertension, dyslipidemia, and high blood pressure on presentation were significantly correlated with poor functional outcome.

Association Between Base Excess and Mortality Among Patients in ICU With Acute Kidney Injury

Objective: This study aimed to explore the association between base excess (BE) and the risk of 30-day mortality among patients with acute kidney injury (AKI) in the intensive care unit (ICU). Methods: This retrospective study included patients with AKI from the Medical Information Mart for Intensive Care (MIMIC)-IV database. We used a multivariate Cox proportional-hazards model to obtain the hazard ratio (HR) for the risk of 30-day mortality among patients with AKI. Furthermore, we utilized a Cox proportional-hazard model with restricted cubic splines (RCS) to explore the potential non-linear associations. Results: Among the 14,238 ICU patients with AKI, BE showed a U-shaped relationship with risk of 30-day mortality for patients with AKI, and higher or lower BE values could increase the risk. Compared with normal base excess (-3~3 mEq/L), patients in different groups (BE ≤ -9 mEq/L, -9 mEq/L < BE ≤ -3 mEq/L, 3 mEq/L < BE ≤ 9 mEq/L, and BE > 9 mEq/L) had different HRs for mortality: 1.57 (1.40, 1.76), 1.26 (1.14, 1.39), 0.97 (0.83, 1.12), 1.53 (1.17, 2.02), respectively. The RCS analyses also showed a U-shaped curve between BE and the 30-day mortality risk. Conclusion: Our results suggest that higher and lower BE in patients with AKI would increase the risk of 30-day mortality. BE measured at administration could be a critical prognostic indicator for ICU patients with AKI and provide guidance for clinicians.

Numerical analysis of hemodynamic effect under different enhanced external counterpulsation (EECP) frequency for cerebrovascular disease: a simulation study

Based on the changes in phase characteristics of blood flow and pressure, enhanced external counterpulsation (EECP) reduces cardiac load and improves cerebral perfusion in patients with cerebrovascular diseases. However, increased cerebral blood flow (CBF) is associated with the rise in blood pressure and its complications. Increased EECP frequency is a valuable solution when combined with the electrical equivalent impedance characteristics of the lumped parameter model (LPM) of the human blood circulation system. Herein, to investigate the effect of different EECP frequencies on CBF perfusion, an LPM was established with cardiopulmonary circulation and eight systemic blood flow units with cerebral autoregulation module of ischemic stroke patients. Then, using differential equations, we analyzed those parameters through hemodynamic simulations in four EECP modes. With related influencing parameters remaining constant, we adjusted the pressure frequency of EECP and found that when compared to the traditional sequential EECP mode, the relative increase rate of CBF was 16.68%, 18.95%, and 21.21% from 1 to 3 Hz, respectively. This study validates the effect of improving blood prefusion with increasing EECP frequency through numerical analysis.

Fetal ECG Extraction from Maternal ECG using Attention-based CycleGAN

A non-invasive fetal electrocardiogram (FECG) is used to monitor the electrical pulse of the fetal heart. Decomposing the FECG signal from the maternal ECG (MECG) is a blind source separation problem, which is hard due to the low amplitude of the FECG, the overlap of R waves, and the potential exposure to noise from different sources. Traditional decomposition techniques, such as adaptive filters, require tuning, alignment, or pre-configuration, such as modeling the noise or desired signal to map the MECG to the FECG. The high correlation between maternal and fetal ECG fragments decreases the performance of convolution layers. Therefore, the masking region of interest based on the attention mechanism was performed to improve the signal generators' precision. The sine activation function was also used to retain more details when converting two signal domains. Three available datasets from the Physionet, including the A&D FECG, NI-FECG, and NI-FECG challenge, and one synthetic dataset using FECGSYN toolbox, were used to evaluate the performance. The proposed method could map an abdominal MECG to a scalp FECG with an average of 98% R-Square [CI 95%: 97%, 99%] as the goodness of fit on the A&D FECG dataset. Moreover, it achieved 99.7 % F1-score [CI 95%: 97.8-99.9], 99.6% F1-score [CI 95%: 98.2%, 99.9%] and 99.3% F1-score [CI 95%: 95.3%, 99.9%] for fetal QRS detection on the A&D FECG, NI-FECG and NI-FECG challenge datasets, respectively. Also, the distortion was in the very good and good ranges. These results are comparable to the state-of-the-art results; thus, the proposed algorithm has the potential to be used for high-performance signal-to-signal conversion.

Outcome predictors of intravenous thrombolytic therapy in acute ischemic stroke patients: an Egyptian center experiences

Background

Intravenous thrombolytic therapy remains the guideline-recommended treatment to improve outcomes after acute ischemic stroke. However, the functional outcome among patients with acute ischemic stroke after receiving intravenous thrombolytic therapy is influenced by huge variety of factors, and this was the aim of our study to evaluate the outcome predictors of intravenous thrombolytic therapy in a sample of Egyptian patients with acute ischemic stroke.

Methods

We enrolled 183 acute ischemic stroke patients who were treated with intravenous recombinant tissue plasminogen activator (IV rtPA) according to the last updated guidelines of American Heart Association and American Stroke Association (AHA/ASA) from February 2018 to February 2020; however, only 150 patients of them completed our study plan till the end. Data of study variables were collected, analyzed statistically and correlated with the functional outcome 3 months after receiving IV rtPA using the modified Rankin Scale (mRS).

Results

Good functional outcome was seen in 98 (65.3%) patients and poor functional outcome was seen in 52 (34.7%) patients. Multivariate analysis of the study variables was done to detect the significant independent predictors of the functional outcome. Atrial fibrillation (AF) (P value < 0.001*OR 6.28* (95% C.I)), hypertension (P value 0.001*OR 3.65*(95% C.I)), diabetes mellitus (DM) (P value 0.009*OR 2.805*(95% C.I)), increased National Institute of Health Stroke Scale (NIHSS) score 24 h after receiving IV rtPA (P value 0.003* OR 8.039* (95% C.I)), increased pulsatility index (PI) value in cerebral vessels at the same side of stroke lesion (P value 0.038* OR 42.48*(95% C.I)) were the significant independent predictors of poor functional outcome. On the other hand decreased NIHSS score 24 h after receiving IV rtPA (P value 0.003* OR 0.124*(95% C.I)), Normal value of PI in cerebral vessels at the same side of stroke lesion (P value 0.038* OR 42.48*(95% C.I)) were the significant independent predictors of good functional outcome.

Conclusion

Intravenous thrombolytic therapy improves the functional outcome of acute ischemic stroke patients. Also, AF, hypertension, DM, NIHSS 24 h after receiving IV rtPA and PI could be used as independent predictors of the functional outcome.

The Probability of Ischaemic Stroke Prediction with a Multi-Neural-Network Model

As is known, cerebral stroke has become one of the main diseases endangering people’s health; ischaemic strokes accounts for approximately 85% of cerebral strokes. According to research, early prediction and prevention can effectively reduce the incidence rate of the disease. However, it is difficult to predict the ischaemic stroke because the data related to the disease are multi-modal. To achieve high accuracy of prediction and combine the stroke risk predictors obtained by previous researchers, a method for predicting the probability of stroke occurrence based on a multi-model fusion convolutional neural network structure is proposed. In such a way, the accuracy of ischaemic stroke prediction is improved by processing multi-modal data through multiple end-to-end neural networks. In this method, the feature extraction of structured data (age, gender, history of hypertension, etc.) and streaming data (heart rate, blood pressure, etc.) based on a convolutional neural network is first realized. A neural network model for feature fusion is then constructed to realize the feature fusion of structured data and streaming data. Finally, a predictive model for predicting the probability of stroke is obtained by training. As shown in the experimental results, the accuracy of ischaemic stroke prediction reached 98.53%. Such a high prediction accuracy will be helpful for preventing the occurrence of stroke.

Cerebral haemodynamics with head position changes post-ischaemic stroke: A systematic review and meta-analysis

The effects of upright postures on the cerebral circulation early post-ischaemic stroke are not fully understood. We conducted a systematic review and meta-analysis to investigate the effects of head positioning on cerebral haemodynamics assessed by imaging methods post-ischaemic stroke. Of the 21 studies included (n = 529), 15 used transcranial Doppler. Others used near-infrared, diffuse correlation spectroscopy and nuclear medicine modalities. Most tested head positions between 0° and 45°. Seventeen studies reported changes in CBF parameters (increase at lying-flat or decrease at more upright) in the ischaemic hemisphere with position change. However, great variability was found and risk of bias was high in many studies. Pooled data of two studies ≤24 h (n = 28) showed a mean increase in cerebral blood flow (CBF) velocity of 8.5 cm/s in the ischaemic middle cerebral artery (95%CI,-2.2-19.3) from 30° to 0°. The increase found ≤48 h (n = 50) was of 2.3 cm/s (95%CI,-4.6-9.2), while ≤7 days (n = 38) was of 8.4 cm/s (95%CI, 1.8-15). Few very early studies (≤2 days) tested head positions greater than 30° and were unable to provide information about the response of acute stroke patients to upright postures (sitting, standing). These postures are part of current clinical practice and knowledge on their effects on cerebral haemodynamics is required.

Transient Laterality of Cerebral Oxygenation Changes in Response to Head-of-Bed Manipulation in Acute Ischemic Stroke

Background: Cerebral oxygenation monitoring provides important information for optimizing individualized management in patients with acute ischemic stroke (AIS). Although changes in cerebral oxygenation are known to occur in response to head-of-bed (HOB) elevation within 72 h after onset, changes in cerebral oxygenation during stroke recovery are unclear. We compared changes in total- (tHb), oxygenated- (HbO2), and deoxygenated-hemoglobin (deoxyHb) concentrations in response to HOB manipulation between the timeframes within 72 h and 7–10 days after AIS onset. Methods: We measured forehead ΔtHb, ΔHbO2, and ΔdeoxyHb in response to HOB elevation (30°) within 72 h (first measurement) and 7–10 days (second measurement) after AIS onset using time-resolved near-infrared spectroscopy. Results: We enrolled 30 participants (mean age 72.8 ± 11.3 years; 13 women) with a first AIS. There were no significant differences in ΔtHb, ΔHbO2, or ΔdeoxyHb measurements on the infarct or contra-infarct side. At the first measurement, ΔtHb, ΔHbO2, and ΔdeoxyHb measured on the contra-infarct side did not correlate with those measured on the infarct side: ΔtHb (r = 0.114, p = 0.539); ΔHbO2 (r = 0.143, p = 0.440); ΔdeoxyHb (r = 0.227, p = 0.221). Notably, at the second measurement, correlation coefficients of ΔtHb and ΔHbO2 between the contra-infarct and infarct sides were statistically significant: ΔtHb (r = 0.491, p = 0.008); ΔHbO2 (r = 0.479, p = 0.010); ΔdeoxyHb (r = 0.358, p = 0.054). Conclusion: Although changes in cerebral oxygenation in response to HOB elevation had a laterality difference between hemispheres within 72 h of AIS onset, the difference had decreased, at least partially, 7–10 days after AIS onset.

Relationship between Ischemic Stroke and Pulse Rate Variability as a Surrogate of Heart Rate Variability

Autonomic reflex ascertains cardiovascular homeostasis during standing. Impaired autonomic reflex could lead to dizziness and falls while standing; this is prevalent in stroke survivors. Pulse rate variability (PRV) has been utilized in the literature in lieu of heart rate variability (HRV) for ambulatory and portable monitoring of autonomic reflex predominantly in young, healthy individuals. Here, we compared the PRV with gold standard HRV for monitoring autonomic reflex in ischemic stroke survivors. Continuous blood pressure and electrocardiography were acquired from ischemic stroke survivors (64 ± 1 years) and age-matched controls (65 ± 2 years) during a 10-minute sit-to-stand test. Beat-by-beat heart period (represented by RR and peak-to-peak (PP) intervals), systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse arrival time (PAT), an indicator of arterial stiffness, were derived. Time and frequency domain HRV (from RR intervals) and PRV (from PP intervals) metrics were extracted. PAT was lower (248 ± 7 ms vs. 270 ± 8 ms, p < 0.05) suggesting higher arterial stiffness in stroke survivors compared to controls during standing. Further, compared to controls, the agreement between HRV and PRV was impaired in stroke survivors while standing. The study outcomes suggest that caution should be exercised when considering PRV as a surrogate of HRV for monitoring autonomic cardiovascular control while standing in stroke survivors.

Predictors of thrombolysis in the telestroke and non telestroke settings for hypertensive acute ischemic stroke patients

BACKGROUND

In acute ischemic stroke patients, telestroke technology provides sustainable approaches to improve the use of thrombolysis therapy. How this is achieved as it relates to inclusion or exclusion of clinical risk factors for thrombolysis is not fully understood. We investigated this in a population of hypertensive stroke patients.

METHODS

Structured data from a regional stroke registry that contained telestroke and non telestroke patients with a primary diagnosis of acute ischemic stroke with history of hypertension were collected between January 2014 and June 2016. Clinical risk factors associated with inclusion or exclusion for recombinant tissue plasminogen activator (rtPA) in the telestroke and non telestroke were identified using multiple regression analysis. Associations between variables and rtPA in the regression models were determined using variance inflation factors while the fitness of each model was determined using the ROC curve to predict the power of each logistic regression model.

RESULTS

The non telestroke admitted more patients (62% vs 38%), when compared with the telestroke. Although the telestroke admitted fewer patients, it excluded 11% and administered thrombolysis therapy to 89% of stroke patients with hypertension. In the non telestroke group, adjusted odd ratios showed significant associations of NIH stroke scale score (OR = 1.059, 95% CI, 1.025-1.093, P < 0.001) and coronary artery disease (OR = 2.003, 95% CI, 1.16-3.457, P = 0.013) with inclusion, while increasing age (OR = 0.979, 95% CI, 0.961-0.996, P = 0.017), higher INR (OR = 0.146, 95% CI, 0.032-0.665, P = 0.013), history of previous stroke (OR = 0.39, 95% CI, 0.223-0.68, P = 0.001), and renal insufficiency (OR = 0.153, 95% CI, 0.046-0.508, P = 0.002) were associated with rtPA exclusion. In the telestroke, only direct admission to the telestroke was associated with rtPA administration, (OR = 4.083, 95% CI, 1.322-12.611, P = 0.014).

CONCLUSION

The direct admission of hypertensive stroke patients to the telestroke network was the only factor associated with inclusion for thrombolysis therapy even after adjustment for baseline variables. The telestroke technology provides less restrictive criteria for clinical risk factors associated with the inclusion of hypertensive stroke patients for thrombolysis.

Blood pressures immediately following ischemic strokes are associated with cerebral perfusion and neurologic function

The optimal range of blood pressure levels in the early phase of ischemic stroke with hypertension is still controversial. Based on our stroke registry database, we explored the relationship between blood pressure levels and cerebral perfusion in the early phase of ischemic stroke with hypertension and neurofunctional recovery at 3 months after stroke. Total 732 stroke patients with hypertension were finally analyzed. Patients were divided into quintiles according to systolic blood pressure (SBP) and diastolic blood pressure (DBP) to perform multivariable logistic regression to analyze their relation with neurofunctional recovery, respectively. The cerebral perfusion levels displayed a reverse "U" shape curve with the change of blood pressure levels. Sufficient estimated cerebral blood flow (ECBF) in the early phase of ischemic stroke was associated with good neurofunctional recovery at 3 months after stroke. The best neurofunctional recovery was observed in the middle quintiles with SBP at 161 to 177 mm Hg and DBP at 103 to 114 mm Hg, respectively. So maintaining appropriate blood pressure levels in the early phase of ischemic stroke might be beneficial to cerebral perfusion and neurofunctional recovery.

Comparing Different Recording Lengths of Dynamic Cerebral Autoregulation: 5 versus 10 Minutes

We compared the dynamic cerebral autoregulation (dCA) indices between 5- and 10-minute data lengths by analyzing 37 patients with ischemic stroke and 51 controls in this study. Correlation coefficient (Mx) and transfer function analysis were applied for dCA analysis. Mx and phase shift in all frequency bands were not significantly different between 5- and 10-minute recordings [mean difference: Mx = 0.02; phase shift of very low frequency (0.02–0.07 Hz) = 0.3°, low frequency (0.07–0.20 Hz) = 0.6°, and high frequency (0.20–0.50 Hz) = 0.1°]. However, the gains in all frequency bands of a 5-minute recording were slightly but significantly higher than those of a 10-minute recording (mean difference of gain: very low frequency = 0.05 cm/s/mmHg, low frequency = 0.11 cm/s/mmHg, and high frequency = 0.14 cm/s/mmHg). The intraclass correlation coefficients between all dCA indices of 5- and 10-minute recordings were favorable, especially in Mx (0.93), phase shift in very low frequency (0.87), and gain in very low frequency (0.94). The areas under the receiver operating characteristic curve for stroke diagnosis between 5- and 10-minute recordings were not different. We concluded that dCA assessed by using a 5-minute recording is not significantly different from that using a 10-minute recording in the clinical application.

[Orthostatic hypotension; that great unknown]

Orthostatic hypotension is an anomaly of growing interest in scientific research. Although certain neurogenic diseases are associated with this phenomenon, it can also be associated with non-neurological causes. Although orthostatic hypotension is defined by consensus as a decrease in the systolic blood pressure of at least 20mmHg, or a decrease in diastolic blood pressure of at least 10mmHg, within 3min of standing, the studies differ on how to diagnose it. Orthostatic hypotension is associated with certain cardiovascular risk factors and with drug treatment, but the results are contradictory. The purpose of this review is to update the knowledge about orthostatic hypotension and its treatment, as well as to propose a method to standardise its diagnosis.

Errata Corrige. Orthostatic Reactivity in Patients with Ischemic Stroke in the Chronic Period. http://dx.doi.org/10.3889/oamjms.2015.090

AIM:

This study aims to trace the influence of specialized kinesitherapeutic methodology (SKTM) on orthostatic reactivity in patients with ischemic stroke in the chronic period (ISChP).

MATERIAL AND METHODS:

An active orthostatic test is used for the evaluation of the orthostatic reactions. The arterial blood pressure and heart rate were defined in the 10 minutes of supine position, before and after 1, 5 and 10 minutes of active upright position. The orthostatic autoregulation is evaluated four times - at the beginning of the study, on the 10th day, on the 1st month and three months after the start of the KT. The classification by Thulesius was used to separate the patients into two groups depending on the type of their orthostatic reactivity.

RESULTS:

At the beginning of the study of infringements symptomatic type orthostatic reactivity (SOR) was observed in 24 patients and hypertensive type orthostatic reactivity (HOR) was observed in the remaining 32 patients. Once applied SKTM establish improvement of orthostatic autoregulation for the groups SOR and HOR at the 10th day and the 1st month with a level of significance p <0.05.

CONCLUSION:

The applied specialized kinesitherapeutic methodology continued later as an adapted exercise program at home, has significantly improved the orthostatic reactivity in patients with orthostatic dysregulation due to the ISChP.

Orthostatic Reactivity in Patients with Ischemic Stroke in the Chronic Period

AIM:

This study aims to trace the influence of specialized kinesitherapeutic methodology (SKTM) on orthostatic reactivity in patients with ischemic stroke in the chronic period (ISChP).

MATERIAL AND METHODS:

An active orthostatic test is used for the evaluation of the orthostatic reactions. The arterial blood pressure and heart rate were defined in the 10 minutes of supine position, before and after 1, 5 and 10 minutes of active upright position. The orthostatic autoregulation is evaluated four times - at the beginning of the study, on the 10th day, on the 1st month and three months after the start of the KT. The classification by Thulesius was used to separate the patients into two groups depending on the type of their orthostatic reactivity.

RESULTS:

At the beginning of the study of infringements symptomatic type orthostatic reactivity (SOR) was observed in 24 patients and hypertensive type orthostatic reactivity (HOR) was observed in the remaining 32 patients. Once applied SKTM establish improvement of orthostatic autoregulation for the groups SOR and HOR at the 10th day and the 1st month with a level of significance p <0.05.

CONCLUSION:

The applied specialized kinesitherapeutic methodology continued later as an adapted exercise program at home, has significantly improved the orthostatic reactivity in patients with orthostatic dysregulation due to the ISChP.

Propranolol use in PHACE syndrome with cervical and intracranial arterial anomalies: collective experience in 32 infants

The objective of this retrospective study of patients evaluated between July 2008 and October 2011 in seven pediatric dermatology centers was to combine collective clinical experience using oral propranolol therapy in 32 infants with PHACE syndrome (Posterior fossa [brain malformations present at birth], Hemangioma [usually covering a large area of the skin of the head or neck >5 cm]; Arterial lesions [abnormalities of the blood vessels in the neck or head]; Cardiac abnormalities or aortic coarctation [abnormalities of the heart or blood vessels that are attached to the heart]; Eye abnormalities) with cervical or intracranial arterial anomalies. Patients were given an average daily dose of oral propranolol of 1.8 mg/kg divided two or three times per day for an average duration of 12.3 months. The main outcome measure was adverse neurologic events. Seven (22%) patients were categorized as being at higher risk for stroke, defined on magnetic resonance imaging as severe, long-segment narrowing or nonvisualization of major cerebral or cervical vessels without anatomic evidence of collateral circulation, often in the presence of concomitant cardiovascular comorbidities. Only one patient developed a change in neurologic status during propranolol treatment: mild right hemiparesis that remained static and improved while propranolol was continued. An additional three patients had worsening hemangioma ulceration or tissue necrosis during therapy. This is the largest report thus far of patients with PHACE syndrome treated with propranolol. Although no catastrophic neurologic events occurred, serious complications, particularly severe ulcerations, were seen in a minority of patients, and given the sample size, we cannot exclude the possibility that propranolol could augment the risk of stroke in this population. We propose radiologic criteria that may prove useful in defining PHACE patients as being at high or standard risk for stroke. We continue to advise caution in using systemic beta-blockers, particularly for children with vascular anomalies at higher risk for stroke. Use of the lowest possible dosage, slow dosage titration, three times per day dosing to minimize abrupt changes in blood pressure, and close follow-up, including neurologic consultation as needed, are recommended.

Impaired cerebral autoregulation is associated with brain atrophy and worse functional status in chronic ischemic stroke

Dynamic cerebral autoregulation (dCA) is impaired following stroke. However, the relationship between dCA, brain atrophy, and functional outcomes following stroke remains unclear. In this study, we aimed to determine whether impairment of dCA is associated with atrophy in specific regions or globally, thereby affecting daily functions in stroke patients.

We performed a retrospective analysis of 33 subjects with chronic infarctions in the middle cerebral artery territory, and 109 age-matched non-stroke subjects. dCA was assessed via the phase relationship between arterial blood pressure and cerebral blood flow velocity. Brain tissue volumes were quantified from MRI. Functional status was assessed by gait speed, instrumental activities of daily living (IADL), modified Rankin Scale, and NIH Stroke Score.

Compared to the non-stroke group, stroke subjects showed degraded dCA bilaterally, and showed gray matter atrophy in the frontal, parietal and temporal lobes ipsilateral to infarct. In stroke subjects, better dCA was associated with less temporal lobe gray matter atrophy on the infracted side ( = 0.029), faster gait speed ( = 0.018) and lower IADL score (0.002). Our results indicate that better dynamic cerebral perfusion regulation is associated with less atrophy and better long-term functional status in older adults with chronic ischemic infarctions.

Cognition and Hemodynamics

The relationship between cerebral hemodynamics and cognitive performance has increasingly become recognized as a major challenge in clinical practice for older adults. Both diabetes and hypertension worsen brain perfusion and are major risk factors for cerebrovascular disease, stroke and dementia. Cerebrovascular reserve has emerged as a potential biomarker for monitoring pressure-perfusion-cognition relationships. Endothelial dysfunction and inflammation, microvascular disease, and mascrovascular disease affect cerebral hemodynamics and play an important role in pathohysiology and severity of multiple medical conditions, presenting as cognitive decline in the old age. Therefore, the identification of cerebrovascular vascular reactivity as a new therapeutic target is needed for prevention of cognitive decline late in life.

Application of the Sit-Up Test for orthostatic hypotension in individuals with stroke

Orthostatic hypotension (OH) is an important consideration for individuals with stroke, given the shared occurrence of mobility limitations, fall risk and association with adverse cardiovascular outcomes. This study aimed to 1) establish the application of a simple bedside test of orthostatic challenge to identify OH after stroke, 2) examine differences in characteristics between those with and without OH and 3) determine cardiovascular correlates with hemodynamic responses. Forty-nine participants (n=29 men, mean ± SD age 66 ± 7 years, time post-stroke 4.5 ± 3.1 years) performed an orthostatic challenge (Sit-Up Test). Eleven (22%) of the 49 participants presented with OH (n=7, of which 5 were asymptomatic) or symptoms of cerebral hypoperfusion with position change (n=4). Compared to participants without OH, those with OH had higher total:high-density lipoprotein cholesterol ratios (4.2 ± 0.9 vs. 3.3 ± 0.8, P=0.009) and triglyceride levels (2.2 ± 0.8 vs. 1.4 ± 0.5 mmol/L, P=0.001). Multivariate linear regression revealed that high-density lipoprotein cholesterol and triglyceride levels explained 20% of the variance of the change in systolic blood pressure from the Sit-Up Test (F(2,45)=5.68, P=0.006). In conclusion, we used a simple bedside test of orthostatic tolerance to identify that over 20% of individuals with stroke presented with OH or symptoms of hypoperfusion. They also had more impaired cardiovascular risk profiles relative to those without OH. These individuals may be at even higher risk for mobility limitations and falls beyond that associated with stroke-related deficits alone.

Nocturnal hypotension in patients after ischemic stroke: does it really matter?

BACKGROUND

We aimed to evaluate the presence of nocturnal hypotension (NHP) in ischemic stroke (IS) survivors using ambulatory blood pressure (BP) monitoring (ABPM).

METHODS

We included fifty consecutive patients presenting at our outpatient clinic for review and who had been discharged for IS in the previous six months. 24-h ABPM was performed with Spacelab 90207 monitor. NHP episodes were considered those values on which the mean arterial pressure (MAP)<70mm Hg. Patients were divided into two groups according to the presence or absence of NHP.

RESULTS

We studied 31 men and 19 women, mean age 68±11years. Episodes of NHP were observed in 21 patients (42%). There were no significant differences with regard to clinical characteristics between groups. With regard to BP, patients with NHP had significantly lower mean 24-hour BPs, mean daytime BPs and mean nighttime BPs. Dipper pattern occurred more often in patients with NHP, although differences were only statistically significant in the diastolic BP values. Mean office readings were 142±26/77±13mm Hg (149±26 versus 133±20; P=0.06; 82±12 versus 71±12; P=0.008). None of the patients showed office SBP <90mmHg and only four had office DBP <60mmHg.

CONCLUSIONS

Episodes of NHP in patients with recent IS are common and difficult to detect with clinical cuff measurements. It is necessary to redefine the target BP levels in secondary stroke prevention, possibly because we are subjecting our patients to increased risk of NHP and cerebral hypoperfusion.

Postural changes in blood pressure and incidence of ischemic stroke subtypes: the ARIC study

The relation of orthostatic blood pressure decrease, or increase, with occurrence of ischemic stroke subtypes has not been examined. We investigated the association of orthostatic blood pressure change (within 2 minutes after supine to standing) obtained at baseline (1987 to 1989) in the Atherosclerosis Risk in Communities Study with incidence of ischemic stroke subtypes through 2007. Among 12 817 black and white individuals without a history of stroke at baseline, 680 ischemic strokes (153 lacunar, 383 nonlacunar thrombotic, and 144 cardioembolic strokes) occurred during a median follow-up of 18.7 years. There was a U-shaped association between orthostatic systolic blood pressure change and lacunar stroke incidence (quadratic P=0.004). In contrast, orthostatic systolic blood pressure decrease of 20 mm Hg or more was associated with increased occurrence of nonlacunar thrombotic and cardioembolic strokes independent of sitting systolic blood pressure, antihypertensive medication use, diabetes, and other lifestyle, physiological, biochemical, and medical conditions at baseline (for nonlacunar thrombotic: hazard ratio, 2.02; 95% CI, 1.43 to 2.84; for cardioembolic: hazard ratio, 1.85, 95% CI, 1.01 to 3.39). Orthostatic diastolic blood pressure decrease was associated with increased risk of nonlacunar thrombotic and cardioembolic strokes; the hazard ratios (95% CI) associated with 10 mm Hg lower orthostatic diastolic blood pressure (continuous) were 1.26 (1.06 to 1.50) and 1.41 (1.06 to 1.88), respectively, in fully adjusted models. In conclusion, the present study found that nonlacunar ischemic stroke incidence was positively associated with an orthostatic decrease of systolic and diastolic blood pressure, whereas greater lacunar stroke incidence was associated with both orthostatic increases and decreases in systolic blood pressure.

Spontaneous fluctuations in cerebral blood flow regulation: contribution of PaCO2

To investigate the temporal variability of dynamic cerebral autoregulation (CA), the transient response of cerebral blood flow to rapid changes in arterial blood pressure, a new approach was introduced to improve the temporal resolution of dynamic CA assessment. Continuous bilateral recordings of cerebral blood flow velocity (transcranial Doppler, middle cerebral artery), end-tidal Pco2 (PetCO2, infrared capnograph), and blood pressure (Finapres) were obtained at rest and during breath hold in 30 young subjects (25 ± 6 yr old) and 30 older subjects (64 ± 4 yr old). Time-varying estimates of the autoregulation index [ARI( t)] were obtained with an autoregressive-moving average model with coefficients expanded by orthogonal decomposition. The temporal pattern of ARI( t) varied inversely with PetCO2, decreasing with hypercapnia. At rest, ARI( t) showed spontaneous fluctuations that were significantly different from noise and significantly correlated with spontaneous fluctuations in PetCO2 in the majority of recordings (young: 72% and old: 65%). No significant differences were found in ARI( t) due to aging. This new approach to improve the temporal resolution of dynamic CA parameters allows the identification of physiologically meaningful fluctuations in dynamic CA efficiency at rest and in response to changes in arterial CO2.

The relationship between blood pressure and cognitive function

The relationship between blood pressure (BP) and cognitive outcomes in elderly adults has implications for global health care. Both hypertension and hypotension affect brain perfusion and worsen cognitive outcomes. The presence of hypertension and other vascular risk factors has been associated with decreased performance in executive function and attention tests. Cerebrovascular reserve has emerged as a potential biomarker for monitoring pressure-perfusion-cognition relationships. A decline in vascular reserve capacity can lead to impaired neurovascular coupling and decreased cognitive ability. Endothelial dysfunction, microvascular disease, and mascrovascular disease in midlife could also have an important role in the manifestations and severity of multiple medical conditions underlying cognitive decline late in life. However, questions remain about the role of antihypertensive therapies for long-term prevention of cognitive decline. In this Review, we address the underlying pathophysiology and the existing evidence supporting the role of vascular factors in late-life cognitive decline.