Diffusion- and perfusion-weighted magnetic resonance imaging of the brain before and after coronary artery bypass grafting surgery

Protease-Activated Receptors (PARs): Biology and Therapeutic Potential in Perioperative Stroke

Perioperative stroke is a devastating complication that occurs during surgery or within 30 days following the surgical procedure. Its prevalence ranges from 0.08 to 10% although it is most likely an underestimation, as sedatives and narcotics can substantially mask symptomatology and clinical presentation. Understanding the underlying pathophysiology and identifying potential therapeutic targets are of paramount importance. Protease-activated receptors (PARs), a unique family of G-protein-coupled receptors, are widely expressed throughout the human body and play essential roles in various physiological and pathological processes. This review elucidates the biology and significance of PARs, outlining their diverse functions in health and disease, and their intricate involvement in cerebrovascular (patho)physiology and neuroprotection. PARs exhibit a dual role in cerebral ischemia, which underscores their potential as therapeutic targets to mitigate the devastating effects of stroke in surgical patients.

Silent Brain Infarction, Delirium, and Cognition in Three Invasive Cardiovascular Procedures: a Systematic Review

Silent brain infarctions (SBIs) are brain lesions noted on neuroimaging that are not associated with clinical symptoms. SBIs are associated with a number of vascular risk factors and are common following invasive cardiovascular procedures such as atrial fibrillation (AF) ablation, coronary artery bypass graft (CABG), and transcatheter aortic valve replacement (TAVR). Although not eliciting signs of clinical stroke, SBIs are associated with increased frailty, and motor and mood features. Less is known, however, about the relationship between SBI, cognition, and delirium following invasive cardiac procedures and most investigations into these relationships have been reported in large-scale epidemiological studies. In the current paper, we conducted a systematic review to evaluate evidence of a relationship between SBI, delirium, and cognitive decline following CABG, AF ablation, and TAVR. Twenty studies met inclusion criteria. In general, our review identified conflicting results for each cardiac procedure, with some studies suggesting a relationship between SBI, cognitive impairment, and delirium, whereas others showed no relationship between SBI, cognitive impairment, and delirium. Potential reasons for this discrepancy as well as suggestions for future research are discussed.

Overview of FDA Circulatory System Devices Panel virtual meeting on TriGUARD 3 cerebral embolic protection

Despite advances in transcatheter aortic valve replacement (TAVR) technology, periprocedural stroke remains a complication of TAVR procedures. The TriGUARD 3 device is designed to be positioned in the aortic arch to deflect debris away from the brachiocephalic, left common carotid, and left subclavian arteries during TAVR. The United States Food and Drug Administration (FDA) assembled the Circulatory System Devices Panel to review safety and effectiveness data for the TriGUARD 3 device. Because of the coronavirus disease 2019 pandemic, this meeting was held virtually. In this manuscript, we summarize the data presented by both the sponsor and FDA, as well as the panel discussion.

Targeted temperature management in cardiac surgery: a systematic review and meta-analysis on postoperative cognitive outcomes

BACKGROUND

Postoperative cognitive decline occurs commonly after cardiac surgery. The available literature is inconclusive on the role of intraoperative causal or protective factors.

METHODS

We systematically reviewed studies evaluating delayed neurocognitive recovery (DNR), postoperative neurocognitive disorder (NCD), stroke, and the mortality rates among patients undergoing hypothermic or normothermic cardiopulmonary bypass (CPB). We further performed a subgroup analysis for age, surgery type (coronary artery bypass grafting [CABG], valve surgery, or combined), and the mean arterial blood pressure (MAP) during CPB, and conducted a proportion meta-analysis after calculation of single proportions and confidence intervals (CIs).

RESULTS

We included a total of 58 studies with 9609 patients in our analysis. Among these, 1906 of 4010 patients (47.5%) had DNR, and 2071 of 7160 (28.9%) had postoperative NCD. Ninety of 4625 patients (2.0%) had a stroke, and 174 of 7589 (2.3%) died. There was no statistically significant relationship between the considered variables and DNR, NCD, stroke, and mortality. In the subgroup analysis comparing hypothermic with normothermic CPB, we found higher NCD rates after combined surgery; for normothermic CPB cases only, the rates of DNR and NCD were lower after combined surgery compared with CABG surgery. A MAP >70 mm Hg compared with MAP=50-70 mm Hg during CPB was associated with a lower rate of DNR.

CONCLUSIONS

Temperature, MAP during cardiopulmonary bypass age, and surgery type were not associated with neurocognitive disorders, stroke, and mortality in cardiac surgery. Normothermic cardiopulmonary bypass, particularly when performed with MAP >70 mm Hg, may reduce the risk of postoperative neurocognitive decline after cardiac surgery.

PROSPERO REGISTRATION NUMBER

CRD42019140844.

Incidence and Risk Factors for Silent Brain Infarction After On-Pump Cardiac Surgery: A Meta-analysis and Meta-regression of 29 Prospective Cohort Studies

BACKGROUND

Silent brain infarction (SBI) happens at a considerable rate after on-pump cardiac surgery. Though termed silent, SBI is related to unfavorable clinical outcomes including higher incidence of future stroke and neurocognitive impairment in the general population. The risk factors of SBI have not been fully identified in both individual studies and several meta-analyses addressing the topic. In this meta-analysis, we aimed to conduct meta-regression analysis for the first time to explore risk factors for SBI after on-pump cardiac surgery.

METHODS

This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Medline, Embase, Central, Web of Science, and Wiley databases were searched for relevant studies. Preoperative patient baseline characteristics and intraoperative surgical parameters were extracted from included studies. For meta-regression, a P value of less than 0.1 was considered statistically significant in both univariable and multivariable analyses.

RESULTS

Twenty-nine studies with 1478 patients were included in this meta-analysis. The summarized SBI rate after on-pump cardiac surgery was 37% (95% CI 0.27-0.47, P < 0.0001). Heterogeneity between studies was significant (I2 = 94.9%, P < 0.0001). In multivariable meta-regression, we found that age (coefficient 0.014, 95% CI 0.001-0.029, P = 0.043), diabetes (coefficient 0.006, 95% CI - 0.001 to 0.013, P = 0.075), and proportion of CABG (coefficient - 0.001, 95% CI - 0.003 to 0.0003, P = 0.096) were significantly associated with SBI incidence.

CONCLUSION

From the meta-regression, we concluded that advanced age and diabetes were related to increased SBI incidence after on-pump cardiac surgery, while CABG procedure alone was associated with less SBI onset. Studies with more accurate diagnoses of SBI are required to add more conclusive evidence to the field.

The role of heparin in preventing the early silent ischemia in carotid stenting

INTRODUCTION AND AIMS

Serebral silent ischemia is a complication of carotid stenting. If silent ischemia occurs 24 h later of carotid stenting, it called early serebral silent ischemia. The aim of this study was to evaluate the effect of heparin infusion on the prevention of early silent ischemia in patients who underwent carotid stenting.

MATERIALS AND METHODS

We included 26 patients who underwent carotid stenting. Patients who had carotid stenting, we randomized into two groups. The first group of patients were given continuously heparin infusion a maximum of 20,000 units for 24 h, and screened the aPTT value each 6 h. The aPTT value aimed a range of 2-3 times to up baseline. The second group didn't take heparin infusion. Diffusion weighted magnetic resonance imaging (DWI-MRI) and gradient echo (GRE) sequences performed in all patients at the 24 h of carotid stenting.

RESULTS

Early serebral silent ischemia was detected by DWI-MRI in 13 (50%) of 26 patients who underwent carotid stenting. Seven (53.80%) of 13 patients whit early serebral silent ischemia did not receive heparin treatment, while 6 (46.20%) received heparin treatment. There was no symptomatic or asymptomatic acute hemorrhage in patients who treated with heparin.

CONCLUSION

In our study, the continuation of anticoagulant therapy for 24 h to prevent early silent ischemia was not statistically significant. Also there is no reduction for count of serebral silent ischemia between two groups. However, due to the small number of patients in the study, future studies are required with more patients.

Risk Factors for Delirium and Cognitive Decline Following Coronary Artery Bypass Grafting Surgery: A Systematic Review and Meta-Analysis

Background

Coronary artery bypass grafting (CABG) is known to improve heart function and quality of life, while rates of surgery‐related mortality are low. However, delirium and cognitive decline are common complications. We sought to identify preoperative, intraoperative, and postoperative risk or protective factors associated with delirium and cognitive decline (across time) in patients undergoing CABG.

Methods and Results

We conducted a systematic search of Medline, PsycINFO, EMBASE, and Cochrane (March 26, 2019) for peer‐reviewed, English publications reporting post‐CABG delirium or cognitive decline data, for at least one risk factor. Random‐effects meta‐analyses estimated pooled odds ratio for categorical data and mean difference or standardized mean difference for continuous data. Ninety‐seven studies, comprising data from 60 479 patients who underwent CABG, were included. Moderate to large and statistically significant risk factors for delirium were as follows: (1) preoperative cognitive impairment, depression, stroke history, and higher European System for Cardiac Operative Risk Evaluation (EuroSCORE) score, (2) intraoperative increase in intubation time, and (3) postoperative presence of arrythmia and increased days in the intensive care unit; higher preoperative cognitive performance was protective for delirium. Moderate to large and statistically significant risk factors for acute cognitive decline were as follows: (1) preoperative depression and older age, (2) intraoperative increase in intubation time, and (3) postoperative presence of delirium and increased days in the intensive care unit. Presence of depression preoperatively was a moderate risk factor for midterm (1–6 months) post‐CABG cognitive decline.

Conclusions

This meta‐analysis identified several key risk factors for delirium and cognitive decline following CABG, most of which are nonmodifiable. Future research should target preoperative risk factors, such as depression or cognitive impairment, which are potentially modifiable.

Registration

URL: https://www.crd.york.ac.uk/prosp​ero/; Unique identifier: CRD42020149276.

Silent Brain Infarcts Following Cardiac Procedures: A Systematic Review and Meta-Analysis

Background

Silent brain infarcts (SBI) are increasingly being recognized as an important complication of cardiac procedures as well as a potential surrogate marker for studies on brain injury. The extent of subclinical brain injury is poorly defined.

Methods and Results

We conducted a systematic review and meta‐analysis utilizing studies of SBIs and focal neurologic deficits following cardiac procedures. Our final analysis included 42 studies with 49 separate intervention groups for a total of 2632 patients. The prevalence of SBIs following transcatheter aortic valve implantation was 0.71 (95% CI 0.64‐0.77); following aortic valve replacement 0.44 (95% CI 0.31‐0.57); in a mixed cardiothoracic surgery group 0.39 (95% CI 0.28‐0.49); coronary artery bypass graft 0.25 (95% CI 0.15‐0.35); percutaneous coronary intervention 0.14 (95% CI 0.10‐0.19); and off‐pump coronary artery bypass 0.14 (0.00‐0.58). The risk ratio of focal neurologic deficits to SBI in aortic valve replacement was 0.22 (95% CI 0.15‐0.32); in off‐pump coronary artery bypass 0.21 (95% CI 0.02‐2.04); with mixed cardiothoracic surgery 0.15 (95% CI 0.07‐0.33); coronary artery bypass graft 0.10 (95% CI 0.05‐0.18); transcatheter aortic valve implantation 0.10 (95% CI 0.07‐0.14); and percutaneous coronary intervention 0.06 (95% CI 0.03‐0.14). The mean number of SBIs per patient was significantly higher in the transcatheter aortic valve implantation group (4.58 ± 2.09) compared with both the aortic valve replacement group (2.16 ± 1.62, P=0.03) and the percutaneous coronary intervention group (1.88 ± 1.02, P=0.03).

Conclusions

SBIs are a very common complication following cardiac procedures, particularly those involving the aortic valve. The high frequency of SBIs compared with strokes highlights the importance of recording this surrogate measure in cardiac interventional studies. We suggest that further work is required to standardize reporting in order to facilitate the use of SBIs as a routine outcome measure.

Silent brain infarcts on diffusion-weighted imaging after carotid revascularisation: A surrogate outcome measure for procedural stroke? A systematic review and meta-analysis

Aim

To investigate whether lesions on diffusion-weighted imaging (DWI+) after carotid artery stenting (CAS) or endarterectomy (CEA) might provide a surrogate outcome measure for procedural stroke.

Materials and Methods

Systematic MedLine® database search with selection of all studies published up to the end of 2016 in which DWI scans were obtained before and within seven days after CAS or CEA. The correlation between the underlying log odds of stroke and of DWI+ across all treatment groups (i.e. CAS or CEA groups) from included studies was estimated using a bivariate random effects logistic regression model. Relative risks of DWI+ and stroke in studies comparing CAS vs. CEA were estimated using fixed-effect Mantel-Haenszel models.

Results

We included data of 4871 CAS and 2099 CEA procedures (85 studies). Across all treatment groups (CAS and CEA), the log odds for DWI+ was significantly associated with the log odds for clinically manifest stroke (correlation coefficient 0.61 (95% CI 0.27 to 0.87), p = 0.0012). Across all carotid artery stenting groups, the correlation coefficient was 0.19 (p = 0.074). There were too few CEA groups to reliably estimate a correlation coefficient in this subset alone. In 19 studies comparing CAS vs. CEA, the relative risks (95% confidence intervals) of DWI+ and stroke were 3.83 (3.17-4.63, p < 0.00001) and 2.38 (1.44-3.94, p = 0.0007), respectively.

Discussion

This systematic meta-analysis demonstrates a correlation between the occurrence of silent brain infarcts on diffusion-weighted imaging and the risk of clinically manifest stroke in carotid revascularisation procedures.

Conclusion

Our findings strengthen the evidence base for the use of DWI as a surrogate outcome measure for procedural stroke in carotid revascularisation procedures. Further randomised studies comparing treatment effects on DWI lesions and clinical stroke are needed to fully establish surrogacy.

Neural network imaging to characterize brain injury in cardiac procedures: the emerging utility of connectomics

Cognitive dysfunction is a poorly understood but potentially devastating complication of cardiac surgery. Clinically meaningful assessment of cognitive changes after surgery is problematic because of the absence of a means to obtain reproducible, objective, and quantitative measures of the neural disturbances that cause altered brain function. By using both structural and functional connectivity magnetic resonance imaging data to construct a map of the inter-regional connections within the brain, connectomics has the potential to increase the specificity and sensitivity of perioperative neurological assessment, permitting rational individualized assessment and improvement of surgical techniques.

The influence of carbon dioxide field flooding in mitral valve operations with cardiopulmonary bypass on S100ß level in blood plasma in the aging brain

Introduction

The risk of air microembolism during cardiopulmonary bypass (CPB) is high and influences the postoperative outcome, especially in elderly patients. The use of carbon dioxide (CO₂) atmosphere during cardiac surgery may reduce the risk of cerebral air microembolism. The aim of our study was to assess the influence of CO₂ field flooding on microembolism-induced brain damage assessed by the level of S100ß protein, regarded as a marker of brain damage.

Materials and methods

A group of 100 patients undergoing planned mitral valve operation through median sternotomy using standard CPB was recruited for the study. Echocardiography was performed prior to and after the CPB. CO₂ insufflation at 6 L/minute was conducted in the study group. Blood samples for S100ß protein analysis were collected after induction of anesthesia, 2 hours after aorta de-clamping, and 24 hours after operation.

Results

The S100ß level in blood plasma did not differ significantly between the study and the control group (0.13±0.08 µg/L, 1.12±0.59 µg/L, and 0.26±0.23 µg/L and 0.18±0.19 µg/L, 1.31±0.62 µg/L, and 0.23±0.12 µg/L, P=0.7, 0.14, and 0.78). The mean increase of the S100ß concentration was 13% lower in the group with CO₂ protection than in the control group (0.988 µg/L vs 1.125 µg/L), although statistically insignificant. Tricuspid valve annuloplasties (TVAs) had significant impact on the increase in S100ß concentration in the treatment group after 24 hours (TVA [−] 0.21±0.09 vs TVA [+] 0.42±0.42, P=0.05). In patients <60 years, there were significant differences in the S100ß level 2 and 24 hours after the procedure (1.59±0.682 µg/L vs 1.223±0.571 µg/L, P=0.048, and 0.363±0.318 µg/L vs 0.229±0.105 µg/L, P=0.036) as compared with younger patients.

Conclusion

The increase in S100ß concentration was lower in the group with CO₂ protection than in the control group. Age and an addition of TVA significantly influenced the level of S100ß concentration in the tests performed 2 hours after aortic clamp release.

Risks of on-pump coronary artery bypass grafting surgery in patients with chronic obstructive pulmonary disease due to sulfur mustard

Sulfur mustard (SM) is a toxic chemical agent that belongs to a class of vesicant compounds. In the 1980s it was used by the Iraqi army against Iranian forces. Sulfur mustard severely irritates the skin, eyes and lungs. The highest side effects seen in patients affected by this gas are pulmonary complications including different types of lung diseases such as bronchiolitis. It has also led to a certain type of chronic obstructive pulmonary disease called mustard lung. Similar extra-pulmonary, molecular and hormonal effects can be observed in these patients and patients with chronic obstructive pulmonary disease. Here cardiovascular complications may be one of the most dangerous visible effects. And atherosclerosis is probable following the direct effects or consequential long-term effects of SM. The development of atherosclerosis in these patients is associated with an increased risk of cardiovascular and coronary artery disease. Coronary artery bypass grafting surgery is the treatment of coronary artery disease. Doing this surgery by bypass pump has its own morbidity and due to local and systemic inflammation changes in patients with SM pulmonary disorders it may have more side effects. Therefore, detailed knowledge of inflammatory diseases as well as the serum level or even the local lung fluid of the inflammatory factors in these patients before surgery are needed so that it would be possible to reduce the rate of morbidity and mortality by normalizing the inflammatory conditions of the patients before cardiac surgery.

Perioperative Management of Neurological Conditions

Perioperative care of the patients with neurological diseases can be challenging. Most important consideration is the management and understanding of pathophysiology of these disorders and evaluation of new neurological changes that occur perioperatively. Perioperative generally refers to 3 phases of surgery: preoperative, intraoperative, and postoperative. We have tried to address few commonly encountered neurological conditions in clinical practice, such as delirium, stroke, epilepsy, myasthenia gravis, and Parkinson disease. In this article, we emphasize on early diagnosis and management strategies of neurological disorders in the perioperative period to minimize morbidity and mortality of patients.

Aortic Arch Atheroma: Stroke Reduction in Cardiac Surgical Patients

Cardiac surgery is increasingly performed on elderly patients with extensive coronary artery abnormalities who have impaired left ventricular function, decreased physiologic reserve, and multiple comorbid conditions. Considerable numbers of these patients develop perioperative neurologic complications ranging from subtle cognitive dysfunction to more evident postoperative confusion, delirium, and, less commonly, clinically apparent stroke. Magnetic resonance imaging studies have elucidated that a considerable number of patients have new ischemic brain infarcts, particularly after conventional coronary artery bypass graft surgery. Mechanisms of cerebral injury during and after cardiac surgery are discussed. Intraoperative transesophageal echocardiography and epiaortic scanning for detection of atheromatous disease of the proximal thoracic aorta is paramount in identifying patients at high risk from neurologic injury. It is important to recognize that our efforts to minimize neurologic injury should not be limited to the intraoperative period. Particular efforts should be directed to temperature management, glycemia control, and pharmacologic neuroprotection extending into the postoperative period. Preoperative magnetic resonance angiography may be of value for screening patients with significant atheroma of the proximal thoracic aorta. It is likely that for patients with no significant atheromatous disease, conventional coronary artery revascularization is the most effective long-term strategy, whereas patients with atheromatous thoracic aorta may be better managed with beating heart surgery, hybrid techniques, or medical therapy alone. Patient stratification based on the aortic atheromatic burden should be addressed in future trials designed to tailor treatment strategies to improve long-term outcomes of coronary heart disease and reduce the risks of perioperative neurologic injury.

Diffusion-Weighted Imaging-Detected Ischemic Lesions following Endovascular Treatment of Cerebral Aneurysms: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Endovascular treatment of intracranial aneurysms is associated with the risk of thromboembolic ischemic complications. Many of these events are asymptomatic and identified only on diffusion-weighted imaging. We performed a systematic review and meta-analysis to study the incidence of DWI positive for thromboembolic events following endovascular treatment of intracranial aneurysms.

MATERIALS AND METHODS

A comprehensive literature search identified studies published between 2000 and April 2016 that reported postprocedural DWI findings in patients undergoing endovascular treatment of intracranial aneurysms. The primary outcome was the incidence of DWI positive for thromboembolic events. We examined outcomes by treatment type, sex, and aneurysm characteristics. Meta-analyses were performed by using a random-effects model.

RESULTS

Twenty-two studies with 2148 patients and 2268 aneurysms were included. The overall incidence of DWI positive for thromboembolic events following endovascular treatment was 49% (95% CI, 42%-56%). Treatment with flow diversion trended toward a higher rate of DWI positive for lesions than coiling alone (67%; 95% CI, 46%-85%; versus 45%; 95% CI, 33%-56%; P = .07). There was no difference between patients treated with coiling alone and those treated with balloon-assisted (44%; 95% CI, 29%-60%; P = .99) or stent-assisted (43%; 95% CI, 24%-63%; P = .89) coiling. Sex, aneurysm rupture status, location, and size were not associated with the rate of DWI positive for lesions.

CONCLUSIONS

One in 2 patients may have infarcts on DWI following endovascular treatment of intracranial aneurysms. There is a trend toward a higher incidence of DWI-positive lesions following treatment with flow diversion compared with coiling. Patient demographics and aneurysm characteristics were not associated with DWI-positive thromboembolic events.

What are the Risk Factors for Cerebrovascular Accidents After Elective Orthopaedic Surgery?

BACKGROUND

Perioperative cerebrovascular accidents (CVAs) are one of the leading causes of patient morbidity, mortality, and medical costs. However, little is known regarding the rates of these events and risk factors for CVA after elective orthopaedic surgery.

QUESTIONS/PURPOSES

Our goals were to (1) establish the national, baseline proportion of patients experiencing a 30-day CVA and the timing of CVA; and (2) determine independent risk factors for 30-day CVA rates after common elective orthopaedic procedures.

METHODS

Patients undergoing elective TKA, THA, posterior or posterolateral lumbar fusion, anterior cervical discectomy and fusion, and total shoulder arthroplasty, from 2006 to 2012, were identified from the American College of Surgeons National Surgical Quality Improvement Program(®) database. A total of 42,150 patients met inclusion criteria. Thirty-day CVA rates were recorded for each procedure, and patients were assessed for characteristics associated with CVA through univariate analysis. Multivariate regression models were created to identify independent risk factors for CVA.

RESULTS

A total of 55 (0.13%) patients experienced a CVA within 30 days of the procedure, occurring a median of 2 days after surgery (range, 1-30 days) with 0.08% of patients experiencing a CVA after TKA, 0.15% after THA, 0.00% after single-level anterior cervical discectomy and fusion, 0.38% after multilevel anterior cervical discectomy and fusions, 0.20% after single-level posterior or posterolateral lumbar fusion, 0.70% after multilevel posterior or posterolateral lumbar fusion, and 0.22% after total shoulder arthroplasty. Independent risk factors for CVA included age of 75 years or older (odds ratio [OR], 2.50; 95% CI, 1.44-4.35; p = 0.001), insulin-dependent diabetes mellitus (OR, 3.08; CI, 1.47-6.45; p = 0.003), hypertension (OR, 2.71; CI, 1.19-6.13; p = 0.017), history of transient ischemic attack (OR, 2.83; CI, 1.24-6.45; p = 0.013), dyspnea (OR, 2.51; CI, 1.30-4.86; p = 0.006), chronic obstructive pulmonary disease (OR, 2.33; CI, 1.06-5.13; p = 0.036), and operative time of 180 minutes or greater (OR, 3.25; CI 1.60-6.60; p = 0.001).

CONCLUSIONS

Numerous nonmodifiable patient comorbidities and increased operative time were associated with CVA after elective orthopaedic procedures. However, the American College of Surgeons National Surgical Quality Improvement Program(®) database does not code for cardiac arrhythmia or atrial fibrillation, which other studies have suggested may be important predictor variables; those may be important risk factors, although we were unable to evaluate them in our study. Surgeons should counsel patients with these risk factors and limit their operative time to reduce the risk of these adverse events, and future studies should examine other patient characteristics such as arrhythmia and noncoronary heart disease and assess the role of pharmacologic prophylaxis in patients with these risk factors.

LEVEL OF EVIDENCE

Level III, prognostic study.

What can be done for cerebral embolic protection in TAVI? Analysis in the light of 10 years' experience with protected carotid artery stenting

In the last 30 years, development of minimally invasive percutaneous procedures to treat cardiovascular defects has been thriving. Although these techniques present obvious advantages, like avoiding cardiopulmonary bypass, the passage of catheter systems and the deployment of devices in the blood circulation can cause particle embolization that may result in stroke. In carotid artery stenting, cerebral embolic protection devices (CEPD) such as filtering membranes have been available for already 10 years. In transcatheter aortic valve implantation (TAVI), the development of CEPD is starting and three membrane-based devices are in clinical trials. There are controversial discussions about the efficacy of CEPD in TAVI. The experience with CEPD in carotid artery stenting can help to understand some of the technical issues and shortcomings of current devices and thereby ultimately reduce cerebral complication risks during TAVI procedures.

Brain perfusion evaluated by perfusion-weighted magnetic resonance imaging before and after stenting internal carotid artery stenosis in asymptomatic and symptomatic patients

PURPOSE

To evaluate the brain perfusion with MRI perfusion weighted imaging (PWI) before and after ICA stenting in asymptomatic and symptomatic patients.

MATERIALS AND METHODS

PWI was performed 3-21 days before and 3 days after ICA stenting in 31 asymptomatic patients with ICA >70% stenosis - Group I, and in 14 symptomatic patients with ICA >50% stenosis - Group II. PWI was evaluated qualitatively and quantitatively in 5 cerebral territories with: mean transit time (MTT), cerebral blood volume (CBV) and cerebral blood flow (CBF). Mean values of perfusion parameters were measured before and after stenting ΔMTT, ΔCBV, ΔCBF were calculated as subtraction of after-treatment values from those before treatment.

RESULTS

In qualitative evaluation after ICA stenting perfusion was normalized in 21 patients (80.8%) in Group I and in 8 patients (80%) in Group II. In quantitative estimation MTT decreased significantly after CAS on stented side vs. non-stented side in all examined patients regardless of the group, p<0.05. MTT decreased more in Group II than in Group I in all territories (p<0.05) with the exception of temporal lobe. CBV and CBF have shown insignificant differences.

Perioperative stroke in patients undergoing elective spinal surgery: a retrospective analysis using the Japanese diagnosis procedure combination database

BACKGROUND

Although a few studies on perioperative stroke following spinal surgery have been reported, differences in the incidence of perioperative stroke among various surgical procedures have not been determined. The purpose of this retrospective analysis was to investigate the incidence of perioperative stroke during hospitalization in patients undergoing elective spinal surgery, and to examine whether the incidence varied according to the surgical procedure.

METHODS

A retrospective analysis of data from the Diagnosis Procedure Combination database, a nationwide administrative impatient database in Japan, identified 167,106 patients who underwent elective spinal surgery during 2007-2012. Patient information extracted included age, sex, preoperative comorbidity, administration of blood transfusion, length of hospitalization, and type of hospital. Clinical outcomes included perioperative stroke during hospitalization, and in-hospital death.

RESULTS

The overall incidence of perioperative stroke was 0.22 % (371/167,106) during hospitalization. A logistic regression model fitted with a generalized estimating equation showed perioperative stroke was associated with advanced age, a history of cardiac disease, an academic institution, and resection of a spinal tumor. Patients who underwent resection of a spinal cord tumor (reference) had a higher risk of stroke compared with those undergoing discectomy (odds ratio (OR), 0.29; 95 % confidence interval (CI), 0.14-0.58; p = 0.001), decompression surgery (OR, 0.44; 95 % CI, 0.26-0.73; p = 0.001), or arthrodesis surgery (OR, 0.55; 95 % CI, 0.34-0.90); p = 0.02). Advanced age (≥80 years; OR, 5.66; 95 % CI, 3.10-10.34; p ≤ 0.001), history of cardiac disease (OR, 1.58; 95 % CI, 1.10-2.26; p = 0.01), diabetes (OR, 1.73; 95 % CI, 1.36-2.20; p ≤ 0.001), hypertension (OR, 1.53; 95 % CI, 1.18-1.98; p = 0.001), cervical spine surgery (OR, 1.44; 95 % CI, 1.09-1.90; p = 0.01), a teaching hospital (OR, 1.36; 95 % CI, 1.01-1.82; p = 0.04), and length of stay (OR, 1.008; 95 % CI, 1.005-1.010; p ≤ 0.001) were also risk factors for perioperative stroke.

CONCLUSIONS

Perioperative stroke occurred in 0.22 % of patients undergoing spinal surgery. Resection of a spinal cord tumor was associated with increased risk of perioperative stroke as well as advanced age, comorbidities at admission, cervical spine surgery, surgery in a teaching hospital, and length of stay.

The Presence of New MRI Lesions and Cognitive Decline After Cardiac Surgery: A Systematic Review

Patients are commonly reported to experience postoperative cognitive decline (POCD) and new ischemic lesions following surgery, which many researchers have hypothesised to result from emboli entering the cerebral circulation during surgery. Modern magnetic resonance imaging techniques have enabled clear and accurate identification of ischemic lesions. However, difficulties in assessing subtle changes in cognitive impairment clinically remain. The purpose of this systematic review is to discuss the literature that has investigated cognitive outcome in relation to new ischaemic brain lesions after cardiac surgery.

Increased Risk of Cerebral Embolization After Implantation of a Balloon-Expandable Aortic Valve Without Prior Balloon Valvuloplasty

OBJECTIVES

The purpose of this study was to analyze the effect of transcatheter aortic valve replacement (TAVR) without versus with prior balloon aortic valvuloplasty (BAV) on the risk of cerebral embolization in patients who receive a balloon-expandable valve.

BACKGROUND

Avoiding BAV prior to TAVR may simplify the procedure, but the risk of cerebral embolization is currently unknown.

METHODS

A total of 87 consecutive high surgical-risk patients with no contraindications for diffusion-weighted magnetic resonance imaging (DW-MRI) were enrolled. Thirty-two patients received a balloon-expandable aortic valve with and 55 patients without BAV. The incidence, number, and volume of new ischemic lesions in DW-MRI performed 2 to 7 days after TAVI were evaluated.

RESULTS

Mean age (83.8 ± 5.2 years vs. 82.9 ± 6.8 years) and sex (43.8% vs. 52.7% male) of the patients with versus without BAV, respectively, as well as other demographic and hemodynamic data were not significantly different between both groups. The procedural success rate was 93.5% with and 98.2% without BAV, and procedure duration and contrast volume were significantly lower without BAV. The incidence of new cerebral ischemic lesions in the total cohort was 66.7%. Compared with patients with BAV, those without BAV had a significantly higher total volume of cerebral ischemic lesions (235.4 ± 331.4 mm(3) vs. 89.5 ± 128.2 mm(3); p = 0.01).

CONCLUSIONS

The implantation of a balloon-expandable aortic valve without versus with prior BAV, although performed with a shorter procedure time and lower contrast volume, is associated with a significantly higher volume of cerebral ischemic lesions.

Added Value of MRI over CT of the Brain in Intensive Care Unit Patients

BACKGROUND

Intensive care unit (ICU) patients with neurological impairments often require neuroimaging. However, the relative sensitivity of various imaging modalities of the brain has not yet been explored in this population.

METHODS

In this study, we compare the findings of CT and MRI scans in ICU patients to (1) identify the number and rate of clinically relevant lesion detected by MRI while missed by CT and vice versa and (2) determine specific lesion types for which CT versus MRI discrepancies exist. A review of medical records included CT and MRI reports of patients who underwent these procedures while they were patients in our ICUs between July 2004 and July 2009. MRI and CT were compared regarding their ability to detect clinically relevant abnormalities. Odds ratios with 95% confidence limits were calculated to compare diagnostic categories regarding the rate of discrepant MRI versus CT findings, followed by power analyses to estimate sample sizes necessary to allow for further testing in a larger trial.

RESULTS

MRI revealed clinically relevant additional abnormalities over CT in 129 of 136 patients (95%) that included the detection of additional finding for 15/27 hemorrhagic lesions (55.6%), 33/36 (92%) ischemic strokes, 19/27 (70%) traumatic lesions, 8/14 (57%) infections, 15/24 (62.5%) metabolic abnormalities, and all seven neoplasms. Odds ratio analysis revealed the added sensitivity of MRI to be greater for ischemic and neoplastic lesions than for trauma, metabolic-related abnormalities, infection, or hemorrhage.

CONCLUSIONS

MRI is more sensitive than CT in identifying clinically meaningful lesions in at least a subset of ICU patients, regardless of pathology.

Evaluation of brain lesions in patients after coronary artery bypass grafting using MRI with the emphasis on susceptibility-weighted imaging

Introduction

Patients undergoing coronary artery bypass grafting (CABG) are at risk of strokes and neurocognitive disorders.

The aim of the study

The aim of the study was to assess the clinical utility of susceptibility-weighted imaging (SWI) MRI in detection of new brain lesions in patients after CABG. We assessed the incidence and types of brain lesions and correlated the data with neurological examinations in groups of patients who underwent on-pump and off-pump CABG.

Material and methods

Patients underwent a neurological examination and MRI before, 6-20 days after and 6 months after the CABG. Fifty-one patients (43 men, mean age 63.12 years) were analyzed.

Results

Fifteen (29.4%) patients underwent on-pump CABG, 36 (70.6%) off-pump CABG. On postoperative scans new lesions were detected in 12 (23.5%) patients. Ischemic lesions (visible on diffusion-weighted imaging [DWI]) were detected in 4 patients, in 6 lesions were visible on SWI, in 1 case lesions were visible on SWI and DWI. Hemorrhagic stroke was observed in 1 patient. In the group of patients who underwent on-pump CABG, new brain lesions were observed in 60.0% of patients vs. 8.3% of those who underwent off-pump CABG (p < 0.0001); these changes more frequently were multiple (p < 0.0013) and located infratentorially (p < 0.0218). Lesions visible on SWI were observed only in patients undergoing on-pump CABG (p = 0.00005). In all patients (except for 1 with stroke), lesions visible in MRI were clinically silent.

Conclusions

The use of SWI enables one to detect lesions occurring in the brain after CABG, invisible in other sequences. On-pump CABG is associated with a greater risk of clinically silent brain damage compared to off-pump CABG.

Cerebral lesions in patients undergoing coronary artery bypass grafting in relation to asymptomatic carotid and vertebral artery stenosis

OBJECTIVES

Carotid artery stenosis (CAS) and vertebral artery stenosis (VAS) are associated with cerebral infarction after coronary artery bypass graft surgery (CABG). It remains unclear whether this association is causal. We investigated the associations between neurologically asymptomatic CAS and VAS and the occurrence of subclinical cerebral lesions after CABG verified by magnetic resonance imaging.

METHODS

CABG patients were included and CAS and VAS were identified by magnetic resonance angiography. Cerebral magnetic resonance imaging was performed to identify new post-operative subclinical cerebral lesions. The associations between CAS/VAS post-operative cerebral lesions were investigated.

RESULTS

Forty-six patients were included in the study. 13% had significant CAS and 11% had significant VAS. Thirty-five percent had new cerebral infarction postoperatively. We found a significant association between the presence of cerebral vessel stenosis and acute cerebral infarction (67% vs. 27%, p = 0.047). However none of the patients with stenosis had isolated cerebral lesions in the ipsilateral vascular territory.

CONCLUSION

Asymptomatic CAS and VAS is common in CABG patients and is associated with an increased risk of postoperative cerebral infarction. Our study suggests that asymptomatic CAS and VAS primarily are risk markers rather than causal factors for cerebral infarction after CABG.

Incidence and risk factors for diffusion-weighted imaging (+) lesions after intracranial stenting and its relationship with symptomatic ischemic complications

BACKGROUND AND PURPOSE

Little is known about high-signal lesions in magnetic resonance diffusion-weighted imaging (DWI [+]) after stenting for intracranial atherosclerotic stenosis. This study aimed to evaluate the incidence, distribution, risk factors, and clinical implications of DWI (+) after intracranial stenting.

METHODS

A total of 123 patients (male:female=88:35, mean age, 64.1 years) with symptomatic intracranial atherosclerotic stenosis (mean stenosis, 76.1±7.7%) underwent both stenting and poststenting DWI. The incidence, distribution (embolic-alone versus stenosis-associated perforator/mixed), and risk factors of DWI (+) and its relationship with symptomatic ischemic complications (SIC, including stroke or transient ischemic attack) were retrospectively evaluated.

RESULTS

Forty-three patients (35.0%) had DWI (+). Middle cerebral artery, smaller distal parent artery, and treatment-related dissection were independent risk factors for DWI (+) (P<0.05). SIC occurred in 4 patients (3.3%), all of whom had DWI (+). Of the patients with DWI (+), neither the number nor the volume of DWI (+) differed significantly between SIC and asymptomatic patients: median number/patient, 3.5 (range, 2-11) versus 2.0 (range, 1-11) and median volume/patient, 329.8 mm(3) (range, 76-883.5 mm(3)) versus 119.5 mm(3) (range, 32.5-873.0 mm(3)). However, SIC occurred more frequently in the stenosis-associated perforator/mixed type (3/11, 27.3%) than in the embolic-alone type (1/32, 3.1%; P<0.05).

CONCLUSIONS

The incidence of DWI (+) after intracranial stenting for intracranial atherosclerotic stenosis was 35.0%. Middle cerebral artery, smaller distal parent artery, and treatment-related dissection were independent risk factors for DWI (+). SIC occurred more frequently in the stenosis-associated perforator/mixed type than in the embolic-alone type.

Thromboembolic complications in patients with clopidogrel resistance after coil embolization for unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

Antiplatelet resistance is known to be associated with symptomatic ischemic complication after endovascular coil embolization. The purpose of our study was to evaluate the relationship between antiplatelet resistance and clinically silent thromboembolic complications using DWI in patients who underwent coil embolization for unruptured intracranial aneurysm.

MATERIALS AND METHODS

Between October 2011 and May 2013, 58 patients with 62 unruptured aneurysms who were measured for antiplatelet response using VerifyNow assay and underwent elective coil embolization for an unruptured aneurysm with posttreatment DWI were enrolled. Diffusion-positive lesions were classified into 3 groups according to the number of lesions (n=0 [grade 0], n<6 [grade I], and n≥6 [grade II]). The relationship between antiplatelet resistance and diffusion-positive lesions was analyzed.

RESULTS

Sixty-two endovascular coiling procedures were performed on 58 patients. Clopidogrel resistance was revealed in 23 patients (39.7%) and diffusion-positive lesions were demonstrated in 28 patients (48.3%); these consisted of 19 (32.8%) grade I and 9 (15.5%) grade II lesions. Clopidogrel resistance was not relevant to the development of any diffusion-positive lesion (grade I and II, P=.789) but was associated with the development of multiple diffusion-positive lesions (grade II, P=.002). In the logistic regression prediction model, clopidogrel resistance showed significant correlation with the development of grade II lesions (P=.001).

CONCLUSIONS

Multiple diffusion-positive lesions (≥6 in number) occurred more frequently in patients with clopidogrel resistance after endovascular coiling for unruptured aneurysms.

The preoperative neurological evaluation

Neurological diseases are prevalent in the general population, and the neurohospitalist has an important role to play in the preoperative planning for patients with and at risk for developing neurological disease. The neurohospitalist can provide patients and their families as well as anesthesiologists, surgeons, hospitalists, and other providers guidance in particular to the patient's neurological disease and those he or she is at risk for. Here we present considerations and guidance for the neurohospitalist providing preoperative consultation for the neurological patient with or at risk of disturbances of consciousness, cerebrovascular and carotid disease, epilepsy, neuromuscular disease, and Parkinson disease.

Cognitive dysfunction after on-pump operations: neuropsychological characteristics and optimal core battery of tests

Postoperative cognitive dysfunction (POCD) is a mild form of perioperative ischemic brain injury, which emerges as memory decline, decreased attention, and decreased concentration during several months, or even years, after surgery. Here we present results of our three neuropsychological studies, which overall included 145 patients after on-pump operations. We found that the auditory memory span test (digit span) was more effective as a tool for registration of POCD, in comparison with the word-list learning and story-learning tests. Nonverbal memory or visuoconstruction tests were sensitive to POCD in patients after intraoperative opening of cardiac chambers with increased cerebral air embolism. Psychomotor speed tests (digit symbol, or TMT A) registered POCD, which was characteristic for elderly atherosclerotic patients. Finally, we observed that there were significant effects of the order of position of a test on the performance on this test. For example, the postoperative performance on the core tests (digit span and digit symbol) showed minimal impairment when either of these tests was administered at the beginning of testing. Overall, our data shows that the selection of tests, and the order of which these tests are administered, may considerably influence the results of studies of POCD.

Perioperative stroke: risk assessment, prevention and treatment

OPINION STATEMENT

Numerous risk factors for perioperative stroke have been identified and many are modifiable. Surgical patients with a history of cerebrovascular disease should be evaluated by a neurologist. Cardiac and cerebrovascular testing is critical in identifying patients at high risk for perioperative stroke. The identification and treatment of carotid disease in the context of upcoming surgery has been a source of controversy. Routine carotid revascularization performed with coronary artery bypass graft (CABG) surgery for incidentally discovered carotid stenosis is not recommended. Prior to aortic manipulation during CABG, epiaortic ultrasound should be performed to identify aortic atheromatous plaques. If possible, preoperative aspirin, beta blocker, statin, and angiotensin converting-enzyme (ACE) inhibitor therapy should be continued in the perioperative period. Patients who are prescribed anticoagulation at high risk of thromboembolism should receive bridging anticoagulation during the perioperative period. The identification and prevention of postoperative atrial fibrillation (AF) is central to stroke prevention. CABG patients should be initiated on beta blockade +/- amiodarone to prevent postoperative AF. Many practitioners have been traditionally nihilistic towards acute perioperative stroke treatment. Given the narrow therapeutic window of treatment options, candidacy is dependent on timely recognition. Intravenous and endovascular thrombolysis/therapies are viable options in selected patients under the guidance and expertise of a neurologist. This article will present the epidemiology of perioperative stroke, the pathophysiology, risk assessment and stratification for common surgeries. The article will additionally focus on treatment options including modifiable risk factor reduction and the perioperative management of medications.

Cognitive Trajectory After Transcatheter Aortic Valve Implantation

Background—

Transcatheter aortic valve implantation (TAVI) is known to be associated with silent cerebral injury, which could contribute to cognitive impairment. Considering its increasing use, thorough longitudinal investigation of cognitive trajectory after TAVI is pivotal.

Methods and Results—

Repeatable battery for the assessment of neuropsychological status was performed before (E1), 3 days (E2), 3 months (E3), 1 (E4) year, and 2 years (E5) after TAVI. Baseline characteristics, procedural data, imaging parameters of brain injury (diffusion-weighted MRI), and the use of conceivable neuroprotective approaches were investigated for their effect on cognitive function. Cognitive performance was investigated in 111 patients (mean log EuroSCORE, 30±13%). Global cognitive function (repeatable battery for the assessment of neuropsychological status total score) increased transiently at E2 ( P =0.02) and was comparable with baseline levels at E3, E4, and E5. Six patients (5.4%) demonstrated early cognitive decline. Persistence and late onset were seen infrequently (n=3, 2.7% and n=4, 3.6%, respectively). Hence, early cognitive decline was ruled out in 105 patients (94.6%), and a majority of patients (91%) demonstrated sustained cognitive performance throughout all investigated time points. Interestingly, only patient age ( P =0.012), but not prior cerebrovascular events, cognitive status, direct TAVI, cerebral embolism in diffusion-weighted MRI, or the use of a cerebral embolic protection device was found to be independently associated with cognitive decline, linking higher age to cognitive impairment along the first 2 years after TAVI.

Conclusions—

Long-term cognitive performance was preserved in the great majority (91%) of patients throughout the first 2 years after TAVI, despite the high intrinsic risk for cognitive deterioration.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00883285.

Risk factors for early postoperative cognitive dysfunction after non-coronary bypass surgery in Chinese population

Background

The present study was performed to investigate the incidence of early postoperative cognitive dysfunction (POCD) after non-coronary bypass surgery and the potential risk factors in Chinese population.

Methods

We performed a prospective study in a teaching tertiary hospital from May 2012 to August 2012. One hundred and seventy-six adult patients undergoing non-coronary bypass surgery were recruited. Mini-Mental State Examination (MMSE) score was evaluated before and 3 to 5 days after surgery. Patients with a MMSE score reduction of 2 was diagnosed with POCD.

Results

The general incidence of POCD was 33.0%, with no significant difference between the types of surgeries. In the univariate analysis, POCD associated factors included age, duration of surgery, anesthesia, cardiopulmonary bypass (CPB), cross-clamp and rewarming, and sevoflurane concentration. However, only age, cross-clamp duration and sevoflurane concentration were demonstrated to be independent risk factors for POCD.

Conclusion

Incidence of early POCD after non-coronary bypass surgery was relatively high in Chinese population. Advanced age, longer aortic cross-clamp duration and lower sevoflurane concentration was associated with a higher incidence of POCD.

Impact of bubble size in a rat model of cerebral air microembolization

Background

Cerebral air microembolization (CAM) is a frequent side effect of diagnostic or therapeutic interventions. Besides reduction of the amount of bubbles, filter systems in the clinical setting may also lead to a dispersion of large gas bubbles and therefore to an increase of the gas–liquid-endothelium interface. We evaluated the production and application of different strictly defined bubble diameters in a rat model of CAM and assessed functional outcome and infarct volumes in relation to the bubble diameter.

Methods

Gas emboli of defined number and diameter were injected into the carotid artery of rats. Group I (n = 7) received 1800 air bubbles with a diameter of 45 μm, group II (n = 7) 40 bubbles of 160 μm, controls (n = 6) saline without gas bubbles; group I and II yielded the same total injection volume of air with 86 nl. Functional outcome was assessed at baseline, after 4 h and 24 h following cerebral MR imaging and infarct size calculation.

Results

Computer-aided evaluation of bubble diameters showed high constancy (group I: 45.83 μm ± 2.79; group II: 159 μm ± 1.26). Animals in group I and II suffered cerebral ischemia and clinical deterioration without significant difference. Infarct sizes did not differ significantly between the two groups (p = 0.931 u-test).

Conclusions

We present further development of a new method, which allows reliable and controlled CAM with different bubble diameters, producing neurological deficits due to unilateral cerebral damage. Our findings could not display a strong dependency of stroke frequency and severity on bubble diameter.

Review of transcranial Doppler ultrasound to detect microemboli during orthopedic surgery

Transcranial Doppler ultrasonography has been used to detect microemboli in the middle cerebral artery during orthopedic surgery. We conducted a comprehensive systematic literature review of transcranial Doppler ultrasonography in orthopedic surgery to evaluate its status in this setting. Fourteen studies were selected for qualitative analysis. The highest number of patients studied was 45; emboli were detected in all studies, occurring in 20%-100% of patients. Most embolic counts were below 10, but some high counts were noted. No study reported all the technical parameters of the transcranial Doppler ultrasonography. All studies assessed neurologic status, and 6 studies evaluated cognitive function postoperatively. No study identified an association between postoperative cognitive function and embolic count. Six studies sought the presence of right-to-left shunts.

Ascertainment of any and all neurologic and myocardial damage in carotid revascularization: the key to optimization?

The majority of carotid revascularization procedures performed at present are in asymptomatic patients. Since such procedures convey no immediate benefit, but rather protect from future hazard, optimization of procedural safety is mandatory. The authors focus their discussion on the methodologies that assess periprocedural myocardial damage and brain injury, as used in past clinical trials, from the fields of perioperative medicine and neurovascular imaging, and discuss methodologies to reduce both events in carotid revascularization.

Clinical implications for diffusion-weighted MRI brain lesions associated with transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) is increasingly used to treat patients with aortic stenosis deemed high or extreme surgical risk candidates. Despite improved survival and quality of life following the procedure, TAVR is not without its complications. Stroke is a major source of morbidity and mortality in patients undergoing the procedure, with rates similar to and often higher than those associated with surgery. Most studies show a consistent link between TAVR and embolic lesions visualized on diffusion-weighted magnetic resonance imaging. The question of whether these lesions lead to long-term cognitive consequences remains open, but given the large literature on silent strokes and cognition, this association is probable. Initial studies implementing cerebral embolic protection devices in TAVR have yielded promising results with decreased neurological complications and appearance of new lesions on imaging. In this article, we will review the evidence linking silent stroke with cognitive decline, and potential therapeutic options to prevent stroke related to TAVR, including cerebral protection devices currently under investigation.

Risk factors predictive of carotid artery stenting-associated subclinical microemboli

Subclinical microemboli documented on diffusion-weighted magnetic resonance imaging (DWI) are common following carotid artery stenting (CAS) procedures despite absence of neurological symptoms. This study was to evaluate risk factors predictive of microemboli in patients undergoing protected CAS with a distal embolic protection device. All CAS patients who received pre- and postprocedural magnetic resonance imaging (MRI) evaluations for carotid interventions at a single academic institution from July 2004 to December 2008 were examined. Microemboli were defined by new hyperintensities on postoperative DWI with corresponding decreased diffusion. Risk factors including patient demographics, medical comorbidities, clinical symptoms, lesion morphologies, and perioperative information were examined, and logistic regression analyses were utilized to determine predictors of CAS-related microemboli. A total of 204 patients underwent carotid interventions (76 CAS and 128 carotid endarterectomies) during the study period; 167 of them, including 67 CAS patients, received both preoperative and postoperative MRIs. Among those who underwent protected CAS, the incidence of microemboli was 46.3% despite a relative low incidence of associated neurological symptoms (2.9%). Univariate and multivariate regression analyses showed that date of procedure (odds ratio [OR] 30.6 and p = 0.019) and preoperative transient ischemic attack symptoms (OR 9.24 and p = 0.009) were independent predictors of developing postoperative changes on DWI in the ipsilateral hemisphere, and age >76 years was predictive of having new lesions on DWI in the contralateral hemisphere (OR 6.11 and p = 0.026). Our study underscores that certain risk factors are significantly associated with CAS-related microemboli and that physician experience and patient selection are essential in improving outcome of CAS procedures.

Blood-brain barrier disruption after cardiac surgery

BACKGROUND AND PURPOSE

CNS complications are often seen after heart surgery, and postsurgical disruption of the BBB may play an etiologic role. The objective of this study was to determine the prevalence of MR imaging-detected BBB disruption (HARM) and DWI lesions after cardiac surgery.

MATERIALS AND METHODS

All patients had an MRI after cardiac surgery. For half the patients (group 1), we administered gadolinium 24 hours after surgery and obtained high-resolution DWI and FLAIR images 24-48 hours later. We administered gadolinium to the other half (group 2) at the time of the postoperative scan, 2-4 days after surgery. Two stroke neurologists evaluated the images.

RESULTS

Of the 19 patients we studied, none had clinical evidence of a stroke or delirium at the time of the gadolinium administration or the scan, but 9 patients (47%) had HARM (67% in group 1; 30% in group 2; P = .18) and 14 patients (74%) had DWI lesions (70% in group 1; 78% in group 2; P = 1.0). Not all patients with DWI lesions had HARM, and not all patients with HARM had DWI lesions (P = .56).

CONCLUSIONS

Almost half the patients undergoing cardiac surgery have evidence of HARM, and three-quarters have acute lesions on DWI after surgery. BBB disruption is more prevalent in the first 24 hours after surgery. These findings suggest that MR imaging can be used as an imaging biomarker to assess therapies that may protect the BBB in patients undergoing heart surgery.