Cardiac baroreceptor sensitivity is impaired after acute stroke

Blood pressure variability at rest and during pressor challenges in patients with acute ischemic stroke

INTRODUCTION

Patients with acute ischemic stroke (AIS) have elevated blood pressure (BP) variability (BPV) and reduced baroreflex sensitivity (BRS) at rest for several days after initial stroke symptoms. We aimed to assess BPV and BRS in AIS patients during pressor challenge maneuvers in the acute and subacute phases of stroke. Pressor challenge maneuvers simulate day-to-day activities and can predict the quality of life.

METHODS

Continuous beat-to-beat BP and ECG in 15 AIS patients (mean age 69 ± 7.5 years) and 15 healthy controls (57 ± 16 years) were recorded at rest and during a 5-min rapid head positioning (RHP) paradigm. Patients were assessed within 24 h (acute phase) and 7 days (subacute phase) of stroke onset. Low frequency (LF) SBP power (measure of BPV), LF-α, and combined α-index (measure of BRS) were calculated from the recordings.

RESULTS

In the acute phase, at rest, LF-SBP power was higher ( P  = 0.024) and α-index was lower ( P  = 0.006) in AIS patients than in healthy controls. There was no change in LF-SBP during RHP in the patients but in healthy controls, it increased significantly ( P  = 0.018). In the subacute phase, at rest, the alpha-index increased ( P  = 0.037) and LF-SBP decreased ( P  = 0.029) significantly in the AIS patients, however, there was still no rise in the LF-SBP power during RHP ( P  = 0.240).

CONCLUSION

AIS patients have a high resting BPV. High resting BPV may be responsible for blunted BPV responses during pressor challenge maneuvers such as RHP, suggesting ongoing autonomic dysfunction and compromised quality of life.

Beat-to-Beat Blood Pressure Variability Within 24 Hours of Ischemic Stroke Onset: A Potential Predictor of Functional Prognosis

BACKGROUND

Beat-to-beat blood pressure variability (BPV) is based on each heartbeat and represents a dynamic equilibrium process modulated by artery and cardiac involvement of pressure-receptive reflexes. To date, there remains a lack of prospective studies illustrating the clinical value of beat-to-beat BPV within 24 hours of acute ischemic stroke onset.

METHODS AND RESULTS

This study prospectively monitored beat-to-beat blood pressure and heart rate in patients with acute ischemic stroke within 24 hours of onset using a noninvasive plethysmograph and calculated beat-to-beat BPV, heart rate variability, and the cross-correlation baroreflex sensitivity. A modified Rankin Scale score of ≥2 at 90 days was defined as an unfavorable prognosis. Multivariate logistic regression was performed, and the nomogram model was developed by adding the beat-to-beat BPV to the traditional model for predicting prognosis. Beat-to-beat BPV increased significantly in the unfavorable outcome group (P<0.05) compared with that in the favorable outcome group, whereas no difference was observed in beat-to-beat heart rate variability and cross-correlation baroreflex sensitivity between both groups (P>0.05). Furthermore, beat-to-beat BPV within 24 hours of acute ischemic stroke onset was independently associated with unfavorable outcome at 90 days (P<0.005). The addition of beat-to-beat BPV to the traditional model for predicting prognosis enhanced the area under the receiver operating characteristic curve from 0.816 to 0.830.

CONCLUSIONS

Increased beat-to-beat BPV within 24 hours of acute ischemic stroke onset was independently associated with a poor prognosis at 90 days and may be a potential predictor for discriminating unfavorable prognosis.

Blood pressure management after endovascular thrombectomy: Insights of recent randomized controlled trials

BACKGROUND

The ideal blood pressure (BP) target in patients who undergo endovascular thrombectomy (EVT) with successful reperfusion is uncertain. Observational studies show that elevated BP during this period is associated with a higher risk of intracranial hemorrhage (ICH) and worse clinical outcomes. Several randomized controlled trials (RCTs) have explored whether intensive BP lowering improves clinical outcomes in these patients.

AIMS

This review aims to summarize the recent RCTs that compare intensive and conventional BP management strategies following EVT and discuss the innovative directions to improve.

RESULT

The recently published RCTs failed to demonstrate the benefit of intensive BP control on the functional outcome and decreasing the risk of ICH. The complex mechanism in cerebral blood flow regulation and the inappropriate BP range chosen in RCTs may be the reasons behind the inconsistent results between observational studies and RCTs. Individualized BP management, reducing BP variability, and multi-stage BP management should be paid more attention in future exploration.

CONCLUSION

Intensive BP target did not improve clinical outcomes after successful EVT as compared with a conventional BP target. Further research is required to identify the optimal BP management strategy after reperfusion.

Emerging Strategies and Effective Prevention Measures for Investigating the Association Between Stroke and Sudden Cardiac Fatality

Stroke-related cardiac death is a significant concern for patients with stroke and their healthcare providers. It is a complex and multifaceted condition that requires careful management of both modifiable and non-modifiable risk factors. This review provides an overview of the pathophysiology, risk factors, and prevention strategies for stroke-related cardiac death. The review highlights the importance of identifying and managing modifiable risk factors such as hypertension, diabetes, and lifestyle factors, as well as non-modifiable risk factors such as age and genetics. Additionally, the review explores emerging strategies for prevention, including the use of wearable devices and genetic testing to identify patients at risk, stem cell therapy and gene therapy for cardiac dysfunction, and precision medicine for personalized treatment plans. Despite some limitations to this review, it provides valuable insights into the current understanding of stroke-related cardiac death and identifies important areas for future research. Ultimately, the implementation of evidence-based prevention strategies and personalized treatment plans has the potential to improve outcomes for patients with stroke and reduce the burden of stroke-related cardiac death in the population.

Antihypertensive Interventions in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis Evaluating Clinical Outcomes Through an Emergency Medicine Paradigm

High blood pressure (HBP) is usually prominent after the onset of acute ischemic stroke (AIS). Although previous studies have found that about half of patients with AIS have a background of hypertension, there is no clear etiology for HBP in AIS. The literature reveals discrepancies in the relationship between HBP and clinical outcomes of AIS, pointing toward the contested effect of blood pressure (BP) reduction clinical outcomes. Thus, the potential benefits and hazards of HBP treatment were explored in the context of clinical outcomes after AIS. An electronic database and a manual search were carried out to identify all the articles related to this topic and published between 2000 and January 2023. The Review Manager software was also used to perform the meta-analysis and quality appraisal. In analyses related to patients not treated with reperfusion therapies, mortality, and dependency outcomes were categorized as short-term (<3 months) or long-term (≥3 months). Our search strategy yielded 2459 articles, of which only 15 met the inclusion criteria. The results of our meta-analysis demonstrate that in patients not treated with reperfusion therapies, BP lowering had no significant impact on either short-term or long-term mortality (risk ratio (RR): 1.18; 95% confidence interval (CI): 0.81-1.73; p = 0.39, and RR: 1.04; 95% CI: 0.77-1.40; p = 0.81, respectively) and dependency (RR: 1.12; 95% CI: 0.97-1.30; p = 0.11, and RR: 0.98; 95% CI: 0.90-1.07; p = 0.61, respectively). Furthermore, BP lowering prior to reperfusion showed no significant effect on mortality (RR: 0.7; 95% CI: 0.23-2.26; p = 0.58), but it did significantly reduce the risk of dependency (RR: 0.89; 95% CI: 0.85-0.94; p < 0.00001). When the dataset was restricted to patients who had successful reperfusion, intensive BP lowering (target systolic BP <120 mmHg) was found to increase the risk of dependency (RR: 1.23; 95% CI: 1.09-1.39; p = 0.0009). In addition, BP reduction had an insignificant effect on the risk of recurrent strokes and combined vascular events (RR: 1.00; 95% CI: 0.54-1.84; p = 1.00, and RR: 0.99; 95% CI: 0.70-1.41; p = 0.95, respectively). Lowering BP in patients not treated with reperfusion therapies is not beneficial in reducing the risk of either short or long-term mortality and dependency. However, BPR before reperfusion reduces the risk of dependency, while aggressive BPR (target systolic blood pressure (SBP) <120 mmHg) after successful reperfusion increases the risk of dependency. Therefore, we recommend BPR as early as possible for patients undergoing reperfusion therapies but suggest against aggressive BPR in patients who have undergone successful reperfusion.

Heart-Rate-to-Blood-Pressure Ratios Correlate with Malignant Brain Edema and One-Month Death in Large Hemispheric Infarction: A Cohort Study

INTRODUCTION

Large hemispheric infarction (LHI) can lead to fatal complications such as malignant brain edema (MBE). We aimed to investigate the correlation between heart-rate-to-blood-pressure ratios and MBE or one-month death after LHI.

METHODS

We prospectively included LHI patients from a registered cohort. Hourly heart-rate-to-blood-pressure ratios were recorded as a variation of the traditional shock index (SI), SIs and SId (systolic and diastolic pressures, respectively), and calculated for mean and variability (standard deviation) in 24 h and two 12 h epochs (1-12 h and 13-24 h) after onset of symptoms. MBE was defined as neurological deterioration symptoms with imaging evidence of brain swelling. We employed a generalized estimating equation to compare the trend in longitudinal collected SIs and SId between patients with and without MBE. We used multivariate logistic regression to investigate the correlation between SIs, SId and outcomes.

RESULTS

Of the included 162 LHI patients, 28.4% (46/162) developed MBE and 25.3% (40/158) died within one month. SIs and SId increased over baseline in all patients, with a similar ascending profile during the first 12 h epoch and a more intensive increase in the MBE group during the second 12 h epoch (p < 0.05). During the overall 24 h, patients with greater SId variability had a significantly increased MBE risk after adjustment (OR 3.72, 95%CI 1.38-10.04). Additionally, during the second 12 h epoch (13-24 h after symptom onset), patients developing MBE had a significantly higher SId level (OR 1.18, 95%CI 1.00-1.39) and greater SId variability (OR 3.16, 95%CI 1.35-7.40). Higher SId and greater SId variability within 24 h independently correlated with one-month death (all p < 0.05). Within the second 12 h epoch, higher SIs, higher SId and greater SId variability independently correlated with one-month death (all p < 0.05). No significant correlation was observed in the first 12 h epoch.

CONCLUSIONS

Higher and more fluctuated heart-rate-to-blood-pressure ratios independently correlated with MBE development and one-month death in LHI patients, especially during the second 12 h (13-24 h) epoch after onset.

Exploring Autonomic Alterations during Seizures in Temporal Lobe Epilepsy: Insights from a Heart-Rate Variability Analysis

Epilepsy's impact on cardiovascular function and autonomic regulation, including heart-rate variability, is complex and may contribute to sudden unexpected death in epilepsy (SUDEP). Lateralization of autonomic control in the brain remains the subject of debate; nevertheless, ultra-short-term heart-rate variability (HRV) analysis is a useful tool for understanding the pathophysiology of autonomic dysfunction in epilepsy patients. A retrospective study reviewed medical records of patients with temporal lobe epilepsy who underwent presurgical evaluations. Data from 75 patients were analyzed and HRV indices were extracted from electrocardiogram recordings of preictal, ictal, and postictal intervals. Various HRV indices were calculated, including time domain, frequency domain, and nonlinear indices, to assess autonomic function during different seizure intervals. The study found significant differences in HRV indices based on hemispheric laterality, language dominancy, hippocampal atrophy, amygdala enlargement, sustained theta activity, and seizure frequency. HRV indices such as the root mean square of successive differences between heartbeats, pNN50, normalized low-frequency, normalized high-frequency, and the low-frequency/high-frequency ratio exhibited significant differences during the ictal period. Language dominancy, hippocampal atrophy, amygdala enlargement, and sustained theta activity were also found to affect HRV. Seizure frequency was correlated with HRV indices, suggesting a potential relationship with the risk of SUDEP.

The role of the autonomic nervous system in cerebral blood flow regulation in stroke: A review

Stroke is a pathophysiological condition which results in alterations in cerebral blood flow (CBF). The mechanism by which the brain maintains adequate CBF in presence of fluctuating cerebral perfusion pressure (CPP) is known as cerebral autoregulation (CA). Disturbances in CA may be influenced by a number of physiological pathways including the autonomic nervous system (ANS). The cerebrovascular system is innervated by adrenergic and cholinergic nerve fibers. The role of the ANS in regulating CBF is widely disputed owing to several factors including the complexity of the ANS and cerebrovascular interactions, limitations to measurements, variation in methods to assess the ANS in relation to CBF as well as experimental approaches that can or cannot provide insight into the sympathetic control of CBF. CA is known to be impaired in stroke however the number of studies investigating the mechanisms by which this occurs are limited. This literature review will focus on highlighting the assessment of the ANS and CBF via indices derived from the analyses of heart rate variability (HRV), and baroreflex sensitivity (BRS), and providing a summary of both clinical and animal model studies investigating the role of the ANS in influencing CA in stroke. Understanding the mechanisms by which the ANS influences CBF in stroke patients may provide the foundation for novel therapeutic approaches to improve functional outcomes in stroke patients.

Peri-Procedural Management of Hemodynamic Instability in Patients Undergoing Carotid Revascularization

Acute perioperative changes in arterial pressure occur frequently, particularly in patients with cardiovascular disease or those receiving vasoactive medications, or in relation to certain cardiovascular surgical procedures. Hemodynamic Instability (HI) are common in patients undergoing carotid revascularization because of unique patho-physiological and surgical factors. The operation, by necessity, disrupts the afferent pathway of the baroreflex, which can lead to postendarterectomy HI. Poor arterial pressure control is associated with increased morbidity and mortality after carotid revascularization, but good control of arterial pressure is often difficult to achieve in practice. The incidence, implications, and etiology of HI associated with carotid surgery are reviewed, and some recommendations made for its management. Close monitoring and titration of therapy are probably the most important considerations rather than specific choice of agents.

Acute-phase heart rate trajectories and functional outcomes in acute ischemic stroke

The heart rate (HR) trajectory is a dynamic metric that shows how HR changes over time. Previous studies have demonstrated that elevated HR is associated with stroke events. However, little research has been done on the influence of shifting HR throughout the acute period on clinical outcomes. This study aims to investigate the effect of HR trajectories on functional outcomes in patients with acute ischemic stroke (AIS). A total of 981 AIS patients were included in the study. A latent mixture model was used to assess HR trends over the first 7 days following disease onset. The patients were divided into four groups based on different HR trajectories: markedly decreasing in 48 h (T1), mildly decreasing in 48 h (T2), sustained moderate in 7 days (T3), and sustained high in 7 days (T4). Poor outcome was defined as a modified Rankin Scale (mRS) score of ≥3 in 3 months. Logistic regression was used to analyze the correlation between different HR trajectories and outcomes. The incidence of poor outcomes was 9.02%, 10.80%, 11.79%, 16.36% in T1 (n = 133), T2 (n = 352), T3 (n = 441), and T4 (n = 55) groups, respectively. Compared with T1 group, T4 group was significantly associated with a higher risk of poor outcome at 3 months (odds ratio = 3.00, 95% confidence interval = 1.06-8.54, p value = .0392). This suggests that in AIS patients, a sustained high HR trajectory is linked to a greater likelihood of poor functional outcome than a markedly decreasing HR trajectory. HR trajectories demonstrate the utility of repeated HR measurements for outcome assessment.

24-hour blood pressure variability and treatment effect of intravenous alteplase in acute ischaemic stroke

Introduction

To assess the association between 24 h blood pressure variability (BPV) on functional outcome and treatment effect of intravenous alteplase in acute ischaemic stroke.

Patients and methods

In all patients with acute ischaemic stroke of unknown onset randomised in the WAKE-UP (Efficacy and Safety of magnetic resonance imaging [MRI]-based Thrombolysis in Wake-Up Stroke) trial, blood pressure (BP) was measured before randomisation and after initiation of treatment at regular intervals up to 24 hours. Individual BPV was measured by coefficient of variation (CV) of all BP values. Primary outcome measure was favourable outcome defined by a modified Rankin Scale (mRS) score 0 or 1 at 90 days after stroke.

Results

BP measurements were available for 498 of 503 patients randomised (177 women [35.5%], mean age [SD] of 65.2 [11.5] years). Systolic BPV was not associated with the treatment effect of thrombolysis (test for interaction, p = 0.46). The adjusted odds ratio (aOR) for favourable outcome with alteplase, adjusted for age, stroke severity and baseline BP on admission, did not show an association across the quintiles of increasing systolic BPV with an aOR 1.89 (95% confidence interval [CI], 0.76-4.70) in the lowest quintile to aOR 1.05 (95% CI, 0.43-2.56) in the highest quintile. Higher mean systolic BP was associated with a smaller treatment effect of thrombolysis with a significant interaction (p = 0.033). The aOR for favourable outcome with alteplase decreased with quintiles of increasing mean systolic BP from aOR 3.16 (95% CI, 1.26-7.93) in the lowest quintile to aOR 0.84 (95% CI, 0.34-2.10) in in the highest quintile.

Conclusions

There was a significant interaction between mean systolic BP and treatment effect of thrombolysis with higher mean systolic BP being associated with poorer outcome. BPV was not associated with outcome after thrombolysis.ClinicalTrials.gov identifier NCT01525290.

Relation between Blood Pressure Variability within a Single Visit and Stroke

Blood pressure variability (BPV) has been identified as an important risk factor for cardiovascular events. The white coat effect (WCE), which is measured as the first systolic blood pressure (SBP) measurement minus the mean of the second and third measurements, is a BPV indicator within a single visit. In total, 2,972 participants who had three measurements of BP within a single visit were included. The participants were divided into three groups based on their WCE percentiles: Group 1 (WCE_2.5-97.5, 2.5–97.5th percentiles of WCE), Group 2 (WCE_2.5, 0–2.4th percentiles of WCE), and Group 3 (WCE_97.5, 97.6–100th percentiles of WCE). A multiple logistic regression model was used to analyze the relationship between WCE and stroke after adjusting for cardiovascular disease risk factors. Compared with the WCE_2.5-97.5 group, the OR for stroke in the WCE_2.5 group was 2.78 (95% CI: 1.22, 6.36, p=0.015). After adjusting for cardiovascular factors, OR increased to 3.12 (95% CI: 1.22, 7.96, p=0.017). The OR of WCE for stroke was 0.93 (95%CI: 0.87, 0.99, p=0.036). BPV within a single visit is associated with stroke. The value and direction of the change may be important as well.

QSM in canine model of acute cerebral ischemia: A pilot study

PURPOSE

In the present study, we investigated the potential of QSM to assess the physiological state of cortical tissue in the middle cerebral artery occlusion canine model of a cerebral ischemia.

METHODS

Experiments were performed in 8 anesthetized canines. Gradient echo, perfusion, and DWI data of brains at normal and ischemic states were acquired. In the postprocessed susceptibility and quantitative cerebral blood flow maps, changes in values within the middle cerebral artery-fed cortical territories were quantified both on the ischemic and normal contralateral hemisphere side.

RESULTS

QSM values in critically ischemic tissue were significantly different from contralateral values-namely, susceptibility increase was observed in the cases in which cerebral perfusion was maintained above the threshold of neuronal death. Furthermore, the data indicates presence of a significant correlation between the changes in susceptibility values, cerebral perfusion, and the infarct volume and pial collateral scores. Additionally, our data suggests that difference in cortical susceptibility is prospectively indicative of the infarct growth rate.

CONCLUSION

In an experimental permanent middle cerebral artery occlusion model, QSM was shown to correlate with the functional parameters characterizing viability of ischemic tissue, thus warranting further research on its ability to provide complementary information during acute stroke MRI examinations in humans.

Interictal autonomic dysfunction

PURPOSE OF REVIEW

Epilepsy is associated with autonomic dysfunction. Here, we provide an up-to-date review on measures of interictal autonomic function, focusing on heart rate variability (HRV), baroreflex sensitivity (BRS) and electrodermal activity (EDA).

RECENT FINDINGS

Resting HRV, BRS and EDA are altered in patients with epilepsy compared with healthy controls. A larger body of work is available for HRV compared with BRS and EDA, and points to interictal HRV derangements across a wide range of epilepsies, including focal, generalized, and combined generalized and focal epilepsies. HRV alterations are most pronounced in temporal lobe epilepsy, Dravet syndrome and drug-resistant and chronic epilepsies. There are conflicting data on the effect of antiseizure medications on measures of interictal autonomic function. However, carbamazepine has been associated with decreased HRV. Epilepsy surgery and vagus nerve stimulation do not appear to have substantial impact on measures of interictal autonomic function but well designed studies are lacking.

SUMMARY

Patients with epilepsy, particularly those with longstanding uncontrolled seizures, have measurable alterations of resting autonomic function. These alterations may be relevant to the increased risk of premature mortality in epilepsy, including sudden unexpected death in epilepsy, which warrants investigation in future research.

Obstructive and Central Sleep Apnea in First Ever Ischemic Stroke are Associated with Different Time Course and Autonomic Activation

INTRODUCTION

Sleep-related breathing disorders are highly prevalent in patients with ischemic stroke. Among sleep-disordered breathing disorders, obstructive sleep apnea is the most represented one, but central sleep apnea, isolated or in the context of a periodic breathing/Cheyne-Stokes respiration, is frequently reported in these patients. Altered baroreflex responses have been reported in the acute phases of a cerebral event.

METHODS

We conducted, in a group of patients with ischemic stroke (n=60), a prospective 3-month follow-up physiological study to describe the breathing pattern during sleep and baroreflex sensitivity in the acute phase and in the recovery phase.

RESULTS

In the acute phase, within 10 days from the onset of symptoms, 22.4% of patients had a normal breathing pattern, 40.3% had an obstructive pattern, 16.4% had a central pattern, and 29.9% showed a mixed pattern. Smaller variations in the Apnea-Hypopnea Index were found in normal breathing and obstructive groups (ΔAHI 2.1±4.1 and -2.8±11.6, respectively) in comparison with central and mixed patterns (ΔAHI -6.9±15.1 and -12.5±13.1, respectively; ANOVA p=0.01). The obstructive pattern became the most frequent pattern, in 38.3% of patients at baseline and 61.7% of patients at follow-up. Modification of baroreflex sensitivity over time was influenced by the site of the lesion and by the sleep disorder pattern in the acute phase (MANOVA p=0.005).

CONCLUSION

We suggest that a down-regulation of autonomic activity, possibly related to reduced vagal modulation, may help the recovery after stroke, or a transitory disconnection from the cortical node that participates in the regulation of sympathetic outflow.

Blood pressure management after mechanical thrombectomy in stroke patients

Endovascular treatment of acute ischemic stroke (AIS) and mechanical thrombectomy (MT) is proven as a safe and effective novel treatment for emergent large vessel occlusion in the anterior cerebral circulation. However, there are still many unanswered questions on peri and post-procedural management including blood pressure (BP) control. The current guidelines recommend maintaining BP <180/105 mmHg in the first 24 h after MT. However, recent studies suggest that maintaining BP levels at lower levels in the first 24 h after successful revascularization have been associated with favorable functional outcome, reduced mortality rate, and hemorrhagic complications. Not only absolute BP but also its variation in the first 24 h after MT have been associated with neurological outcomes. Evidence on the effect of BP variability (BPV) after MT in AIS even though limited, it does indicate the association of the higher BPV in the first 24 h after MT and poor functional outcomes in AIS. In this review, we will discuss the current literature on BP management in the first 24 h after MT and the impact of BPV in the first 24 h after MT.

Slow-Paced Breathing and Autonomic Function in People Post-stroke

Purpose: To determine if acute slow breathing at 6 breaths/min would improve baroreflex sensitivity (BRS) and heart rate variability (HRV), and lower blood pressure (BP) in adults after stroke. Methods: Twelve individuals completed two randomized study visits where they performed a 15-min bout of breathing exercises at 6 breaths/min (slow) and at 12 breaths/min (control). Continuous BP and heart rate (HR) were measured throughout, and BRS, BRS response to elevations in blood pressure (BRSup), BRS response to depressions in blood pressure (BRSdown), and HRV were calculated and analyzed before (pre), during, and after (post) breathing exercises. Results: BRS increased from pre to post slow breathing by 10% (p = 0.012), whereas BRSup increased from pre to during slow breathing by 30% (p = 0.04). BRSdown increased from pre to post breathing for both breathing conditions (p < 0.05). HR (control: Δ - 4 ± 4; slow: Δ - 3 ± 4 beats/min, time, p < 0.01) and systolic BP (control: Δ - 0.5 ± 5; slow: Δ - 6.3 ± 8 mmHg, time, p < 0.01) decreased after both breathing conditions. Total power, low frequency power, and standard deviation of normal inter-beat intervals (SDNN) increased during the 6-breaths/min condition (condition × time, p < 0.001), whereas high frequency increased during both breathing conditions (time effect, p = 0.009). Conclusions: This study demonstrated that in people post-stroke, slow breathing may increase BRS, particularly BRSup, more than a typical breathing space; however, paced breathing at either a slow or typical breathing rate appears to be beneficial for acutely decreasing systolic BP and HR and increasing HRV.

Cerebral hemodynamics in stroke thrombolysis (CHiST) study

Despite careful patient selection, successful recanalization in intravenous thrombolysis is only achieved in approximately 50% of cases. Understanding changes in cerebral autoregulation during and following successful recanalization in acute ischemic stroke patients who receive intravenous thrombolysis, may inform the management of common physiological perturbations, including blood pressure, in turn reducing the risk of reperfusion injury. Cerebral blood velocity (Transcranial Doppler), blood pressure (Finometer) and end-tidal carbon dioxide (capnography) were continuously recorded in 11 acute ischemic stroke patients who received intravenous thrombolysis (5 female, mean ± SD age 68±12 years) over 4-time points, during and at the following time intervals after intravenous thrombolysis: 23.9±2.6 hrs, 18.1±7.0 days and 89.6±4.2 days. Reductions in blood pressure (p = 0.04) were observed during intravenous thrombolysis. Reductions in heart rate (p<0.005) and critical closing pressure [Affected hemisphere (p = 0.02) and non-affected hemisphere (p<0.005)] were observed post intravenous thrombolysis. End-tidal CO2 increased during the sub-acute and chronic stages (p = 0.028). Reduction in affected hemisphere phase at low frequency was observed during intravenous thrombolysis (p = 0.021) and at subsequent visits (p = 0.048). No changes were observed in cerebral blood velocity, coherence, gain and Autoregulation Index during the follow-up period. Intravenous thrombolysis in acute ischemic stroke patients induced changes in affected hemisphere phase and other key hemodynamic parameters, but not Autoregulation Index. Further investigation of cerebral autoregulation is warranted in a larger acute ischemic stroke cohort to inform its potential role in individualized management plans.

The Effects of Gradual Change in Head Positioning on the Relationship between Systemic and Cerebral Haemodynamic Parameters in Healthy Controls and Acute Ischaemic Stroke Patients

(1) Background: Larger blood pressure variability (BPv) in the first 3 h post-stroke onset increases pathophysiological effects such as infarct size, and leads to greater risk of disability, comorbidities and mortality at 90 days. However, there is limited information on the relationship between systemic and cerebral haemodynamic and variability parameters. (2) Objectives: This study determined the effect of a gradual change in head position (GHP) on cerebral blood flow velocity variability (CBFVv) and mean arterial blood pressure variability (MABPv), in healthy controls and acute ischaemic stroke (AIS) patients. Methods: CBFVv and MABPv were expressed as standard deviation (SD) and coefficient of variation. A total of 16 healthy controls (mean age 57 ± 16 years) were assessed over two visits, 12 ± 8 days apart, and 15 AIS patients (mean age 69 ± 8.5 years) were assessed over three visits (V1: 13.3 ± 6.9 h, V2: 4.9 ± 3.2 days and V3: 93.9 ± 11.5 days post-stroke). (3) Results: In response to GHP, MABPv does not initially increase, but over time MABPv showed a significant increase in response to GHP in AIS (visits 2 and 3) and controls (visit 2). Additionally, in response to GHP in AIS, CBFVv increased in the affected hemisphere. Lastly, in AIS, a significant correlation between CBFVv and MABPv, assessed by SD, was seen in the unaffected hemisphere, whereas this relationship was not demonstrated in the affected hemisphere. (4) Conclusions: To our knowledge, this is the first study to analyse the relationship between CBFVv and MABPv. Shedding light on the effect of head position on the relationship between cerebral blood flow and blood pressure is important to improve our understanding of the underlying effects of cerebral autoregulation impairment. This early mechanistic study provides evidence supporting supine head positioning in healthy controls and stroke patients, through demonstration of a reduction of MABPv and increase in CBFVv.

Blood pressure variability and outcome after acute intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is life threatening neurologic event that results in significant rate of morbidity and mortality. Unfortunately, several randomized clinical trials aiming at limiting the hematoma expansion (HE) in the acute phase of ICH have not shown significant effects in improving the functional outcomes. Blood pressure variability (BPV) is common following ICH. High BPs have been associated with increased risk of bleeding and HE. Conversely, recurrent sudden decrease in BP promote perihematomal ischemia. However, it is still not clear weather BPV causes adverse prognosis following ICH or large ICHs cause fluctuations in BP. In the current review, we will discuss the mechanistic pathophysiology of BPV and the evidence regarding the role of BPV on the ICH outcomes.

Involvement of small nerve fibres and autonomic nervous system in AL amyloidosis: comprehensive characteristics and clinical implications

Peripheral nerve involvement in immunoglobulin light chain (AL) amyloidosis is common, characterised by severe progressive mixed neuropathy with autonomic dysfunction but there is limited data on the implications and the characteristics of small nerve fibres dysfunction (SNFD). The aim of our prospective study was to evaluate SNFD and its clinical implications in newly diagnosed AL patients. Twenty-three consecutive patients (10 male, mean age 61.78 years) and 21 age- and gender-matched healthy controls (8 male, mean age 61.28 years) underwent clinical evaluation and standard nerve conduction studies (NCS), baroreflex sensitivity (BRS) test, quantitative sensory testing (QST) and skin biopsy at the lower leg for measuring the density of the nerve fibres innervating the epidermis (IENFD). Axonal degeneration of the large nerve fibres was revealed in 15 out of 23 patients while SNFD was indicated by QST and skin biopsy in 56% and 61% of the patients respectively. BRS index significantly correlated with the IENFD and the QST results while low IENFD was associated with significantly poorer survival. Our study provides new insights and also an initial evaluation of new tools for assessment of the involvement of autonomic and small nerve fibres in AL amyloidosis. These findings also appear to have prognostic implications.

Blood pressure variability in the management of hypertensive emergency: A narrative review

Hypertensive emergencies (HTNe) primarily focus on decreasing the blood pressure to specific targets. However, there are emerging data surrounding the potential clinical effects of blood pressure variability (BPV) in patients with HTNe. This narrative review highlights the various definitions of BPV, the emerging role of BPV, and the clinical data surrounding BPV in the HTNe setting. Clinical studies were obtained from a PubMed search through October 2018 utilizing PICO methodology. Original research articles, systematic reviews, and meta-analyses were considered for inclusion. Articles were selected for inclusion based on the relevancy of the article investigating BPV in the HTNe setting. There is currently no accepted standard to express BPV in the acute care setting of HTNe, and various parameters have been reported. There are very limited data regarding BPV outside of the neurologic HTNe setting. In the acute treatment phase of neurologic HTNe, BPV is consistently associated with increased risk of unfavorable outcomes. In the HTNe setting, continuous infusion of calcium channel blockers may optimize BPV compared to other agents. Based on current data, BPV should be investigated in a prospective systemic fashion. Efforts should be taken to ensure that BPV is minimized in the acute phase of HTNe, especially for those patients with intracranial hemorrhage. This reduced BPV is associated with improved favorable outcomes, but further study investigating specific pharmacologic agents is needed.

The Effect of Stroke Subtypes on Baroreceptor Sensitivity, a Predict for Acute Stroke Outcome

Background

Reduced baroreflex sensitivity (BRS) has been reported in patients with acute cardiovascular events. We tested the hypothesis that BRS varies in different subtypes of acute ischemic stroke (AIS) and that BRS is a predictor of clinical outcomes.

Methods

We examined autonomic parameters in 34 patients with AIS, including the small deep hemisphere infarction, the large hemisphere infarction, and the brainstem infarction groups on Day 1, Day 7, and Day 30 after AIS. Autonomic parameters were also evaluated in 18 age- and sex-matched healthy volunteers as a control group. The clinical outcomes were analyzed using the modified Rankin scale at 30 days after stroke.

Results

The BRS, Valsalva ratio, and heart rate response to deep breathing (HR-DB) were significantly lower in patients after AIS on admission than in controls (p<0.01). The frequency domain of HRV (LF/HF ratio) was significantly increased in patients after AIS compared to controls (p<0.05). BRS was significantly reduced in patients with large hemisphere infarction or brainstem infarction compared to patients with small deep hemisphere infarction on Day 1 after AIS (p<0.01). Stepwise logistic regression showed that the levels of BRS and NIHSS are prognostic factors of 1-month outcomes in patients with AIS.

Conclusion

Beside NIHSS score on admission, BRS is a potential prognostic factor of 1-month outcomes in patients with AIS. Patients with large hemisphere infarction or brainstem infarction have more blunting BRS than do those with lacunar infarction, which provides some insight into which patients may be expected to have a poor outcome.

Randomised controlled trial of a Calcium Channel or Angiotensin Converting Enzyme Inhibitor/Angiotensin Receptor Blocker Regime to Reduce Blood Pressure Variability following Ischaemic Stroke (CAARBS): a protocol for a feasibility study

INTRODUCTION

Raised blood pressure (BP) is common after stroke and is associated with a poor prognosis, yet trials of BP lowering in the immediate poststroke period have not demonstrated a benefit. One possible explanation for this may be that BP variability (BPV) rather than absolute levels predicts outcome, as BPV is increased after stroke and is associated with poor outcomes. Furthermore, there is evidence of distinct antihypertensive class effects on BPV despite similar BP-lowering effects. However, whether BPV in the immediate poststroke period is a therapeutic target has not been prospectively investigated.The objectives of this trial are to assess the feasibility and safety of recruiting patients following an acute ischaemic stroke or transient ischaemic attack (TIA) to an interventional randomised controlled trial comparing the effects of two different antihypertensive drug classes on BPV. Secondary exploratory objectives are to assess if different therapeutic strategies have diverse effects on levels of BPV and if this has an impact on outcomes.

METHODS

150 adult patients with first-ever ischaemic stroke or TIA who require antihypertensive therapy for secondary prevention will be recruited within 7 days of the event from stroke services across three sites. After baseline assessments they will be randomly assigned to treatment with a calcium channel blocker or ACE inhibitor/angiotensin receptor blocker-based regimen and followed up for a period of three months.

ETHICS AND DISSEMINATION

Ethical and regulatory approvals have been granted. Dissemination is planned via publication in peer-reviewed medical journals and presentation at relevant conferences.

TRIAL REGISTRATION NUMBER

ISRCTN10853487.

Blood Pressure Variability in Acute Ischemic Stroke: Influence of Infarct Location in the Insular Cortex

Background: The aim of this study was to elucidate the influence of insular infarction on blood pressure (BP) variability and outcomes according to the region of the insular cortex affected. Methods: A total of 90 patients diagnosed with acute unilateral ischemic stroke were registered. The BP variability was calculated over 24 h after admission (hyperacute) and for 2–3 days after admission (acute). Patients were classified into groups of right and left, and then right anterior, right posterior, left anterior, and left posterior insular infarction. Results: Patients with insular infarction showed a significantly larger infarct volume, higher modified Rankin scale scores, and lower SD and coefficient of variation (CV) of ­systolic BP in the hyperacute phase than shown by patients without insular infarction (p < 0.01, p < 0.01, p = 0.02, and p = 0.03, respectively). The SD and CV of systolic BP in the hyperacute phase showed significant differences among the 3 groups with right insular infarction, with left insular infarction, and without insular infarction (p < 0.05 and p < 0.05, respectively). There was a tendency for the systolic BP variability to be lower in patients with right anterior insular infarction than in patients with infarcts in other areas. Conclusion: The right insular cortex, especially the anterior part, might be a hub for autonomic nervous regulation.

Intra-operative Video Characterization of Carotid Artery Pulsation Patterns in Case Series with Post-endarterectomy Hypertension and Hyperperfusion Syndrome

Cerebral hyperperfusion syndrome (CHS) is a complication that can occur after carotid endarterectomy (CEA), the treatment of choice to decrease the subsequent risk of fatal or disabling stroke for patients with symptomatic severe stenosis of the carotid artery. Because of its rarity and complexity, the mechanism of the condition is still unclear, making its prevention via prediction and monitoring challenging. This is especially true during surgery, when multiple factors can induce physiological changes, including blood pressure and baroreceptor functions, which are crucial factors for post-CEA hypertension and CHS. Thus, with intra-operative videos taken by surgical microscopes, we employed a new video processing technique to magnify ordinarily invisible carotid artery pulsation patterns as rhythmic color fluctuations. We applied the technique for three CEA cases, two of which developed CHS with post-CEA hypertension. For those with CHS, abnormal pulsation patterns were detected at the site of the baroreceptors. The results suggested that intra-operative baroreceptor dysfunction can potentially be linked with post-operative hypertension, as well as the occurrence of CHS. Guided by the preliminary discovery, further investigation may help establish the introduced technique as a simple and contactless technique to help predict post-CEA hypertension and CHS in order to facilitate the management and understanding of the condition and improve the care of CEA.

Comparison of Autonomic Function before and after Surgical Intervention in Patients with Temporal Lobe Epilepsy

Background and Purpose

Refractory temporal lobe epilepsy (TLE) is commonly associated with imbalances in cardiovascular (CV) parasympathetic and sympathetic functions, which are treated using TLE surgery. We investigated the effect of hemispheric lateralization of seizure foci on autonomic CV functions before and after TLE surgery.

Methods

The study was conducted on patients with left TLE (LTLE, n = 23) and right TLE (RTLE, n = 30) undergoing unilateral TLE surgery. To assess the autonomic CV functions, changes in the heart rate (ΔHR) and blood pressure (BP) were measured using a standardized battery of autonomic reactivity tests before surgery and at 3 and 6 months after surgery.

Results

Before surgery, ΔHR and the expiration to inspiration ratio (E:I) during the deep breathing test were higher in the LTLE group than in the RTLE group (both p < 0.001), but both outcomes were comparable between the groups at 3 and 6 months. ΔHR decreased at 3 and 6 months (p < 0.001 and 0.01, respectively) compared with preoperative values. The E:I at 3 months in the LTLE group was lower (p = 0.04) than the preoperative values. Decrease in systolic BP during the head-up tilt test was greater in the LTLE group than in the RTLE group (p = 0.002) before surgery. The maximum increase in diastolic BP during the cold pressor test was lower in the RTLE group at 6 months than that before surgery (p = 0.001) and in the LTLE group (p = 0.002).

Conclusions

We found that hemispheric lateralization of seizure foci in the temporal lobe had a differential effect on autonomic CV functions before surgery. Before surgery, parasympathetic reactivity was higher in the LTLE group, and sympathetic reactivity was higher in the RTLE group. After surgery, autonomic CV functions were comparable between the groups, suggesting that TLE surgery stabilizes autonomic CV functions.

Prognostic Significance of Blood Pressure Variability on Beat-to-Beat Monitoring After Transient Ischemic Attack and Stroke

Supplemental Digital Content is available in the text.

Background and Purpose—

Visit-to-visit and day-to-day blood pressure (BP) variability (BPV) predict an increased risk of cardiovascular events but only reflect 1 form of BPV. Beat-to-beat BPV can be rapidly assessed and might also be predictive.

Methods—

In consecutive patients within 6 weeks of transient ischemic attack or nondisabling stroke (Oxford Vascular Study), BPV (coefficient of variation) was measured beat-to-beat for 5 minutes (Finometer), day-to-day for 1 week on home monitoring (3 readings, 3× daily), and on awake ambulatory BP monitoring. BPV after 1-month standard treatment was related (Cox proportional hazards) to recurrent stroke and cardiovascular events for 2 to 5 years, adjusted for mean systolic BP.

Results—

Among 520 patients, 26 had inadequate beat-to-beat recordings, and 22 patients were in atrial fibrillation. Four hundred five patients had all forms of monitoring. Beat-to-beat BPV predicted recurrent stroke and cardiovascular events independently of mean systolic BP (hazard ratio per group SD, stroke: 1.47 [1.12–1.91]; P=0.005; cardiovascular events: 1.41 [1.08–1.83]; P=0.01), including after adjustment for age and sex (stroke: 1.47 [1.12–1.92]; P=0.005) and all risk factors (1.40 [1.00–1.94]; P=0.047). Day-to-day BPV was less strongly associated with stroke (adjusted hazard ratio, 1.29 [0.97–1.71]; P=0.08) but similarly with cardiovascular events (1.41 [1.09–1.83]; P=0.009). BPV on awake ambulatory BP monitoring was nonpredictive (stroke: 0.89 [0.59–1.35]; P=0.59; cardiovascular events: 1.08 [0.77–1.52]; P=0.65). Despite a weak correlation (r=0.119; P=0.02), beat-to-beat BPV was associated with risk of recurrent stroke independently of day-to-day BPV (1.41 [1.05–1.90]; P=0.02).

Conclusions—

Beat-to-beat BPV predicted recurrent stroke and cardiovascular events, independently of mean systolic BP and risk factors but short-term BPV on ambulatory BP monitoring did not. Beat-to-beat BPV may be a useful additional marker of cardiovascular risk.

Long-term caregiving is associated with impaired cardiovagal baroreflex

OBJECTIVE

Caregiving stress is associated with increased risk of cardiovascular disease (CVD). Inability to adequately regulate blood pressure is a possible underlying mechanism explaining this risk. We examined the relationship between length of caregiving and cardiovagal baroreflex sensitivity (cBRS) to better understand the link between caregiving and CVD risk.

METHODS

A total of 146 elderly individuals (≥55years) participated in this study, of whom 96 were providing in-home care to a spouse with dementia and 50 were healthy controls married to a non-demented spouse (i.e., non-caregivers). Among the caregivers, 56 were short-term caregivers (caring<4years) and 40 were long-term caregivers (caring≥4years). A multiple linear regression model, with contrast codes comparing short and long-term caregivers with non-caregivers was used to understand relationships between chronic caregiving and cBRS.

RESULTS

After controlling for relevant demographic and health characteristics, mean±SE log transformed cBRS for non-caregivers was 0.971±0.029. Relative to non-caregivers, the long-term caregivers had significantly impaired cBRS (0.860±0.033; p=0.013). However, mean cBRS for short-term caregivers did not significant differ from non-caregivers (0.911±0.028; p=0.144).

CONCLUSION

These results suggest that long-term caregiving stress is associated with an impaired cBRS. Accumulation of stress from years of caregiving could result in worse cBRS function, which could be a mechanistic explanation for the correlation between caregiving stress and the increased risk of CVD.

Role of infarct location and pre-existing depression on cardiac baroreceptor sensitivity in subacute ischemic stroke

Reduced cardiac baroreceptor sensitivity (BRS) after acute stroke is associated with worse outcome. The underlying mechanisms of reduced BRS are unclear. We evaluated cross correlation BRS (xBRS) in 184 patients with suspected acute ischemic stroke within 72 h of symptom onset. Among these patients, 22 had a transient ischemic attack (TIA) and 27 had a stroke mimic. Sixty-four age- and sex-matched ambulant control subjects without stroke were included. Compared with controls, xBRS was significantly lower in patients with ischemic stroke, TIA, and stroke mimics (4.6, 4.7, and 4.4, respectively, vs 6.6, p < 0.01). There was no difference in xBRS between right and left hemispheric infarctions (4.3 vs 4.9, p = 0.144), right and left insular infarctions (4.5 vs 5.3, p = 0.286), and insular infarction vs non-insular infarctions (4.7 vs 4.5, p = 0.996). Stroke patients with pre-existing depression/use of antidepressant medication had lower xBRS values than stroke patients with normal mental health (2.9 vs 4.8, p < 0.05). Control patients with depression also had lower xBRS compared to controls without depression (3.4 vs 5.9, p < 0.01). Our results suggest that decreased xBRS in the subacute phase after stroke is not associated with infarct localization. We found preliminary evidence for an association between pre-existing depression and use of antidepressant medication, and decreased BRS.

Early Asymmetric Cardio-Cerebral Causality and Outcome after Severe Traumatic Brain Injury

The brain and heart are two vital systems in health and disease, increasingly recognized as a complex, interdependent network with constant information flow in both directions. After severe traumatic brain injury (TBI), the causal, directed interactions between the brain, heart, and autonomic nervous system have not been well established. Novel methods are needed to probe unmeasured, potentially prognostic information in complex biological networks that are not revealed by traditional means. In this study, we examined potential bidirectional causality between intracranial pressure (ICP), mean arterial pressure (MAP), and heart rate (HR) and its relationship to mortality in a 24-h period early post-TBI. We applied Granger causality (GC) analysis to cardio-cerebral monitoring data from 171 severe TBI patients admitted to a single neurocritical care center over a 10-year period. There was significant bidirectional causality between ICP and MAP, MAP and HR, and ICP and HR in the majority of patients (p < 0.01). MAP influenced both ICP and HR to a greater extent (higher GC, p < 0. 00001), but there was no dominant unidirectional causality between ICP and HR (p = 0.85). Those who died had significantly lower GC for ICP causing MAP and HR causing ICP (p = 0.006 and p = 0.004, respectively) and were predictors of mortality independent of age, sex, and traditional intracranial variables (ICP, cerebral perfusion pressure, GCS, and pressure reactivity index). Examining the brain and heart with GC-based features for the first time in severe TBI patients has confirmed strong interdependence and reveals a significant relationship between select causality pairs and mortality. These results support the notion that impaired causal information flow between the cerebrovascular, autonomic, and cardiovascular systems are of central importance in severe TBI.

Effects of stroke on changes in heart rate variability during hemodialysis

Background

Stroke and low heart rate variability (HRV) are both associated with an unfavorable prognosis in hemodialysis patients. The relationship between stroke and changes in HRV during hemodialysis remains unclear.

Methods

This study measured differences between predialysis and postdialysis HRV (△HRV) in 182 maintenance hemodialysis patients, including 30 patients with stroke, to assess changes in HRV during hemodialysis, and also to compare results to 114 healthy controls.

Results

All predialysis HRV measurements had no differences between stroke patients and those without stroke, but were lower than healthy controls. Postdialysis very low frequency (VLF) (P < 0.001), low frequency (LF) (P = 0.001), total power (TP) (P < 0.001) and the LF/high frequency (HF) ratio (P < 0.001) increased significantly relative to predialysis values in patients without stroke, whereas postdialysis HRV did not increase in stroke patients. After multivariate adjustment, dialysis vintage was negatively associated with △VLF (β = -0.698, P = 0.046), △LF (β = -0.931, P = 0.009), and △TP (β = -0.887, P = 0.012) in patients without stroke. Serum intact parathyroid hormone (β = -0.707, P = 0.019) was negatively associated with △LF. Total cholesterol (β = -0.008, P = 0.001) and high sensitivity C-reactive protein (β = -0.474, P = 0.012) were inversely correlated with the △LF/HF ratio in patients without stroke.

Conclusion

HRV in hemodialysis patients is lower than in the general population. Increase in △HRV was observed in hemodialysis patients without stroke but not in stroke patients. This result suggests suppressed autonomic nervous reactions against volume unloading during hemodialysis, which might contribute to unfavorable outcomes in hemodialysis patients but even more so in those with prior stroke. Nephrologists should notice the importance of △HRV especially in high-risk patients.

Blood pressure management in acute stroke

Blood pressure (BP) is elevated in 75% or more of patients with acute stroke and is associated with poor outcomes. Whether to modulate BP in acute stroke has long been debated. With the loss of normal cerebral autoregulation, theoretical concerns are twofold: high BP can lead to cerebral oedema, haematoma expansion or haemorrhagic transformation; and low BP can lead to increased cerebral infarction or perihaematomal ischaemia. Published evidence from multiple large, high-quality, randomised trials is increasing our understanding of this challenging area, such that BP lowering is recommended in acute intracerebral haemorrhage and is safe in ischaemic stroke. Here we review the evidence for BP modulation in acute stroke, discuss the issues raised and look to on-going and future research to identify patient subgroups who are most likely to benefit.

Cardiac Arrhythmias and Abnormal Electrocardiograms After Acute Stroke

Cardiac arrhythmias and electrocardiogram (ECG) abnormalities occur frequently but are often underrecognized after strokes. Acute ischemic and hemorrhagic strokes in some particular area of brain can disrupt central autonomic control of the heart, precipitating cardiac arrhythmias, ECG abnormalities, myocardial injury and sometimes sudden death. Identification of high-risk patients after acute stroke is important to arrange appropriate cardiac monitoring and effective management of arrhythmias, and to prevent cardiac morbidity and mortality. More studies are needed to better clarify pathogenesis, localization of areas associated with arrhythmias and practical management of arrhythmias and abnormal ECGs after acute stroke.

Heart rate variability and baroreceptor sensitivity in acute stroke: a systematic review

BACKGROUND

Autonomic nervous system dysfunction is common after acute stroke and is associated with elevated risk of cardiac arrhythmia and mortality. Heart rate variability and baroreceptor sensitivity have been investigated as parameters of autonomic nervous system dysfunction for the prediction of stroke outcome.

SUMMARY

We performed a systematic literature review on heart rate variability and baroreceptor sensitivity as parameters for autonomic nervous function in acute stroke. Twenty-two studies were included. Associations between heart rate variability or baroreceptor sensitivity and stroke severity, early and late complications, dependency and mortality were reported. However, interpretability of most studies and extrapolation to general stroke population are limited due to many confounding factors such as varying methodology, small sample sizes, survival selection, and exclusion of patients with frequently occurring comorbidities in stroke. Key issues, such as the effect of thrombolytic therapy on autonomic function, autonomic nervous system dysfunction in the hyperacute phase of stroke, and correlation with the risk of recurrent stroke have not been investigated. Also, nonlinear techniques have remained largely unexplored in this domain, in spite of their advantage to provide more solid evaluation in the occurrence of arrhythmia.

KEY MESSAGES

Cardiac autonomic dysfunction, represented by reduced heart rate variability or impaired baroreceptor sensitivity, is associated with stroke severity, early and late complications, dependency, and mortality. Large-scale prospective studies applying internationally accepted standards of measures for analysis of heart rate variability and baroreceptor sensitivity are needed in patients with acute stroke.

Dominant hemisphere lateralization of cortical parasympathetic control as revealed by frontotemporal dementia

The brain continuously influences and perceives the physiological condition of the body. Related cortical representations have been proposed to shape emotional experience and guide behavior. Although previous studies have identified brain regions recruited during autonomic processing, neurological lesion studies have yet to delineate the regions critical for maintaining autonomic outflow. Even greater controversy surrounds hemispheric lateralization along the parasympathetic-sympathetic axis. The behavioral variant of frontotemporal dementia (bvFTD), featuring progressive and often asymmetric degeneration that includes the frontoinsular and cingulate cortices, provides a unique lesion model for elucidating brain structures that control autonomic tone. Here, we show that bvFTD is associated with reduced baseline cardiac vagal tone and that this reduction correlates with left-lateralized functional and structural frontoinsular and cingulate cortex deficits and with reduced agreeableness. Our results suggest that networked brain regions in the dominant hemisphere are critical for maintaining an adaptive level of baseline parasympathetic outflow.

Early Sitting in Ischemic Stroke Patients (SEVEL): A Randomized Controlled Trial

BACKGROUND

Extended immobility has been associated with medical complications during hospitalization. However no clear recommendations are available for mobilization of ischemic stroke patients.

OBJECTIVE

As early mobilization has been shown to be feasible and safe, we tested the hypothesis that early sitting could be beneficial to stroke patient outcome.

METHODS

This prospective multicenter study tested two sitting procedures at the acute phase of ischemic stroke, in a randomized controlled fashion (clinicaltrials.org registration number NCT01573299). Patients were eligible if they were above 18 years of age and showed no sign of massive infarction or any contra-indication for sitting. In the early-sitting group, patients were seated out of bed at the earliest possible time but no later than one calendar day after stroke onset, whereas the progressively-sitting group was first seated out of bed on the third calendar day after stroke onset. Primary outcome measure was the proportion of patients with a modified Rankin score [0-2] at 3 months post stroke. Secondary outcome measures were a.) prevalence of medical complications, b.) length of hospital stay, and c.) tolerance to the procedure.

RESULTS

One hundred sixty seven patients were included in the study, of which 29 were excluded after randomization. Data from 138 patients, 63 in the early-sitting group and 75 in the progressively-sitting group were analyzed. There was no difference regarding outcome of people with stroke, with a proportion of Rankin [0-2] score at 3 months of 76.2% and 77.3% of patients in the early- and progressive-sitting groups, respectively (p = 0.52). There was also no difference between groups for secondary outcome measures, and the procedure was well tolerated in both arms.

CONCLUSION

Due to a slow enrollment, fewer patients than anticipated were available for analysis. As a result, we can only detect beneficial/detrimental effects of +/- 15% of the early sitting procedure on stroke outcome with a realized 37% power. However, enrollment was sufficient to rule out effect sizes greater than 25% with 80% power, indicating that early sitting is unlikely to have an extreme effect in either direction on stroke outcome. Additionally, we were not able to provide a blinded assessment of the primary outcome. Taking these limitations into account, our results may help guide the development of more effective acute stroke rehabilitation strategies, and the design of future acute stroke trials involving out of bed activities and other mobilization regimens.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01573299.

Cerebral Hemispheric Lateralization Associated with Hippocampal Sclerosis May Affect Interictal Cardiovascular Autonomic Functions in Temporal Lobe Epilepsy

It is well established that the temporal lobe epilepsy (TLE) is linked to the autonomic nervous system dysfunctions. Seizures alter the function of different systems such as the respiratory, cardiovascular, gastrointestinal, and urogenital systems. The aim of this work was to evaluate the possible factors which may be involved in interictal cardiovascular autonomic function in temporal lobe epilepsy with complex partial seizures, and with particular attention to hippocampal sclerosis. The study was conducted in 30 patients with intractable temporal lobe epilepsy (19 with left hippocampal sclerosis, 11 with right hippocampal sclerosis). All subjects underwent four tests of cardiac autonomic function: heart rate changes in response to deep breathing, heart rate, and blood pressure variations throughout resting activity and during hand grip, mental stress, and orthostatic tests. Our results show that the right cerebral hemisphere predominantly modulates sympathetic activity, while the left cerebral hemisphere mainly modulates parasympathetic activity, which mediated tachycardia and excessive bradycardia counterregulation, both of which might be involved as a mechanism of sudden unexpected death in epilepsy patients (SUDEP).

The QT dispersion and QTc dispersion in patients presenting with acute neurological events and its impact on early prognosis

Aims:

To find out and investigate whether the QT dispersion and QTc dispersion is related to type and prognosis of the acute stroke in patients presenting within 24 h of the onset of stroke.

Settings and Design:

This was a observational study conducted at Mahatma Gandhi Hospital, Dr. SN. Medical College, Jodhpur, during January 2014 to January 2015.

Subjects and Methods:

The patients presented within 24 h of onset of acute stroke (hemorrhagic, infarction, or transient ischemic event) were included in the study. The stroke was confirmed by computed tomography scan and magnetic resonance imaging. Patients with (i) altered sensorium because of metabolic, infective, seizures, trauma, or tumor; (ii) prior history of cardiovascular disease, electrocardiographic abnormalities’ because of dyselectrolytemia; and (iii) and patients who were on drugs (antiarrhythmic drugs, antipsychotic drugs, erythromycin, theophylline, etc.,) which known to cause electrocardiogram changes, were excluded from the study. National Institute of Health Stroke Score (NIHSS) was calculated at the time of admission and Modified Rankin Scale (MRS) at the time of discharge. Fifty age- and sex-matched healthy controls included.

Statistical Analysis Used:

Student's t-test, ANOVA, and area under curve for sensitivity and specificity for the test.

Results:

We included 52 patients (male/female: 27/25) and 50 controls (26/24). The mean age of patients was 63.17 ± 08.90 years. Of total patients, infarct was found in 32 (61.53%), hemorrhage in 18 (34.61%), transient ischemic attack (TIA) in 1 (1.9%), and subarachnoid hemorrhage in 1 (1.9%) patient. The QT dispersion and QTc dispersion were significantly higher in cases as compare to controls. (87.30 ± 24.42 vs. 49.60 ± 08.79 ms; P < 0.001) and (97.53 ± 27.36 vs. 56.28 ± 09.86 ms; P < 0.001). Among various types of stroke, the mean QT dispersion and QTc dispersion were maximum and significantly higher in hemorrhagic stroke as compared to infarct and TIA (P < 0.001). The mean QT dispersion and QTc dispersion was found significantly high in nonsurvivors (n = 16) as compared to survivors group (n = 36) (P < 0.05). The mean QT dispersion was directly correlated with the NIHSS and functional outcome score MRS. Patients with greater QT and QTc dispersion having high NIHSS had poor prognosis.

Conclusion:

We concluded that patients presenting with acute neurological events having increased QT dispersion and QTc dispersion is related to high mortality and poor functional outcomes on hospital discharge and if the values of dispersion score are very high we can predict for hemorrhagic stroke.

Renin-angiotensin-aldosterone-system inhibition is safe in the preoperative period surrounding carotid endarterectomy

OBJECTIVE

Discontinuation of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) medications before surgery has been suggested because of the potentially deleterious effects of hypotension. We investigated the effect of preoperative ACEI and/or ARB use on early outcomes after carotid endarterectomy (CEA).

METHODS

We examined 3752 consecutive CEA patients within the Vascular Study Group of New England from September 2012 to September 2014 and compared outcomes for patients treated (n = 1772) or not treated (n = 1980) with ACEI and/or ARB preoperatively. Outcomes included perioperative need for intravenous vasoactive medication (IVBPmed) for hypotension or hypertension (HTN), major adverse cardiac events (MACEs), and the combined outcome of stroke or death. Adjusted analysis was performed using multivariable logistic regression of the crude cohort and by constructing a propensity score matched cohort (n = 1441).

RESULTS

ACEI and/or ARB users were more likely to be male (64% vs 59%; P = .001), with a higher prevalence of diabetes (41% vs 28%; P < .0001), HTN (97% vs 82%; P < .0001), coronary artery disease (31% vs 25%; P = .0001), congestive heart failure (10% vs 8%; P = .02), and asymptomatic carotid disease (59% vs 54%; P = .004). Patients who received ACEI and/or ARB preoperatively were more likely to be treated with aspirin (92% vs 88%; P = .0002) and statins (89% vs 85%; P = .001) preoperatively. In the unadjusted analysis, no significant differences were identified in hypotension that required IVBPmed (12% vs 11%; odds ratio [OR], 1.1; 95% confidence interval [CI], 0.9-1.4; P = .22), MACE (3% vs 2%; OR, 1.3; 95% CI, 0.8-1.9; P = .32), or stroke or death (3% vs 3%; OR, 1.0; 95% CI, 0.7-1.6; P = .89) for preoperative ACEI and/or ARB treated and nontreated patients, respectively. Preoperative ACEI and/or ARB usage was, however, associated with HTN that required IVBPmed (13% vs 10%; OR, 1.3; 95% CI, 1.1-1.6; P = .01). Analysis of the propensity score matched cohort revealed no significant differences in hypotension that required IVBPmed (12% vs 12%; OR, 1.0; 95% CI, 0.8-1.3; P = .86), MACE (3% vs 2%; OR, 1.1; 95% CI, 0.7-1.8; P = .62; ), or stroke or death (3% vs 3%; OR, 1.0; 95% CI, 0.7-1.6; P = .91) for patients treated or not treated with preoperative ACEI and/or ARB, respectively. ACEI and/or ARB remained associated with HTN that required IVBPmed (13% vs 10%; OR, 1.3; 95% CI, 1.0-1.7; P = .02). Results were similar after adjustment using logistic regression. The incidence of hospital length of stay >1 day was similar between ACEI and/or ARB treated and not treated patients (29% vs 32%; OR, 0.9; 95% CI, 0.8-1.1; P = .21).

CONCLUSIONS

Preoperative ACEI and/or ARB use was associated with marginally increased use of IVBPmed for HTN but not for hypotension and was not associated with increased MACE, stroke, or death. On the basis of these metrics, the use of preoperative ACEI and/or ARB appears safe before CEA.

Timing of blood pressure lowering in acute ischemic stroke

Whether there are any benefits without harm from early lowering of blood pressure (BP) in the setting of acute ischemic stroke (AIS) has been a longstanding controversy in medicine. Whilst most studies have consistently shown associations between elevated BP, particularly systolic BP, and poor outcome, some also report that very low BP (systolic <130 mmHg) and large reductions in systolic BP are associated with poor outcomes in AIS. However, despite these associations, the observed U- or J-shaped relationship between BP and outcome in these patients may not be causally related. Patients with more severe strokes may have a more prominent autonomic response and later lower BP as their condition worsens, often pre-terminally. Fortunately, substantial progress has been made in recent years with new evidence arising from well-conducted randomized trials. This review outlines new evidence and recommendations for clinical practice over BP management in AIS.

Metabolische Störungen

Im folgenden Kapitel werden die verschiedenen metabolischen Störungen betrachtet. Zunächst wird auf die allgemeinen und spezifischen neurologischen Komplikationen bei Organtransplantation eingegangen. Dann geht es um die metabolischen Enzephalopathien: Störungen der Gehirntätigkeit bei angeborenen und erworbenen Stoffwechselerkrankungen im engeren Sinn, Elektrolytstörungen, Hypovitaminosen, zerebrale Folgen einzelner Organdysfunktionen, zerebrale Hypoxien, Endotheliopathien und Mitochondropathien. Anschließend werden das Alkoholdelir und die Wernicke-Enzephalopathie erörtert. Bei zahlreichen akuten Erkrankungen von Gehirn, Rückenmark und peripherem Nervensystem treten typische Störungen vegetativer Systeme auf, deren Erkennung und Therapie insbesondere bei Intensivpatienten eine vitale Bedeutung haben kann: die autonomen Störungen. Bei der zentralen pontinen Myelinolyse kommt es zu einer akuten, vorwiegend fokal-symmetrischen Demyelinisierung im Hirnparenchym. Auch Basalganglienerkrankungen können intensivmedizinisch relevant werden. Und schließlich wird die akute Stressreaktion betrachtet, die aufgrund der vielfältigen metabolischen und endokrinen Veränderungen bei kritischen Erkrankungen entsteht. Gerade das RCVS als neuere Krankheitsentität und wichtige Differenzialdiagnose zur Vaskulitis des ZNS verdient einen eigenen Platz, in diesem Unterkapitel werden ebenfalls verwandte Syndrome wie die hypertensive Enzephalopathie und das PRES abgehandelt.

Autonomic dysfunction in acute ischemic stroke: an underexplored therapeutic area?

Impaired autonomic function, characterized by a predominance of sympathetic activity, is common in patients with acute ischemic stroke. This review describes methods to measure autonomic dysfunction in stroke patients. It summarizes a potential relationship between ischemic stroke-associated autonomic dysfunction and factors that have been associated with worse outcome, including cardiac complications, blood pressure variability changes, hyperglycemia, immune depression, sleep disordered breathing, thrombotic effects, and malignant edema. Involvement of the insular cortex has been suspected to play an important role in causing sympathovagal imbalance, but its exact role and that of other brain regions remain unclear. Although sympathetic overactivity in patients with ischemic stroke appears to be a negative prognostic factor, it remains to be seen whether therapeutic strategies that reduce sympathetic activity or increase parasympathetic activity might improve outcome.