Cerebral Emboli Detected by Transcranial Doppler During Cardiopulmonary Bypass Are Not Correlated With Postoperative Cognitive Deficits

Clinical Study of Symptomatic Nonacute Intracranial Large Arterial Occlusion with Endovascular Recanalization

Objectives  This study reported a single-center clinical trial of endovascular treatment for symptomatic nonacute occlusion of the intracranial large artery (NA-ILAO). The aim of this study was to evaluate the safety, feasibility, and clinical effect of simple balloon dilatation and stent implantation. Methods  The patients diagnosed with symptomatic NA-ILAO were enrolled. A total of 40 cases were included in this study. While recanalization failed in 4 patients, it was successful in 36 patients, who were then divided into two groups for further analysis: balloon dilatation group ( n  = 24) and stent implantation group ( n  = 12). The perioperative complications, clinical outcome, and follow-up results were analyzed. Results  Perioperative complications in the stent implantation group were significantly higher than those in the simple balloon dilatation group ( p  < 0.05). There were 21 and 10 cases of 90-day good clinical outcome (modified Rankin scale [mRS] ≤ 2) in the balloon and stent groups, respectively ( p  = 0.518). All patients with successful recanalization underwent digital subtraction angiography (DSA) or CT angiography (CTA) during an average follow-up of 14 months. There were two cases of restenosis in the balloon dilatation group and one in the stent implantation group ( p  = 1.000). There were two cases of re-occlusion in the stent group and none in the balloon dilatation group ( p  < 0.001). Stroke recurred in two cases in the stent group and in one case in the simple balloon dilatation group ( p  = 0.013). Conclusion  Endovascular recanalization is safe and feasible for patients with symptomatic NA-ILAO. Compared with stent implantation, simple balloon dilation may be a better recanalization method, but larger randomized controlled trials are needed to confirm it.

Clinical relevance of transcranial Doppler in a cardiac surgery setting: embolic load predicts difficult separation from cardiopulmonary bypass

BACKGROUND

During cardiac surgery, transcranial Doppler (TCD) represents a non-invasive modality that allows measurement of red blood cell flow velocities in the cerebral arteries. TCD can also be used to detect and monitor embolic material in the cerebral circulation. Detection of microemboli is reported as a high intensity transient signal (HITS). The importance of cerebral microemboli during cardiac surgery has been linked to the increased incidence of postoperative renal failure, right ventricular dysfunction, and hemodynamic instability. The objective of this study is to determine whether the embolic load is associated with hemodynamic instability during cardiopulmonary bypass (CPB) separation and postoperative complications.

METHODS

A retrospective single-centre cohort study of 354 patients undergoing cardiac surgery between December 2015 and March 2020 was conducted. Patients were divided in tertiles, where 117 patients had a low quantity of embolic material (LEM), 119 patients have a medium quantity of microemboli (MEM) and 118 patients who have a high quantity of embolic material (HEM). The primary endpoint was a difficult CPB separation. Multivariate logistic regression was used to determine the potential association between a difficult CPB separation and the number of embolic materials.

RESULTS

Patients who had a difficult CPB separation had more HITS compared to patients who had a successful CPB separation (p < 0.001). In the multivariate analysis, patients with MEM decreased their odds of having a difficult CPB weaning compared to patients in the HEM group (OR = 0.253, CI 0.111-0.593; p = 0.001). In the postoperative period patients in the HEM group have a higher Time of Persistent Organ Dysfunction (TPOD), a longer stay in the ICU, a longer duration under vasopressor drugs and a higher mortality rate compared to those in the MEM and LEM groups.

CONCLUSION

The result of this study suggests that a high quantity of cerebral embolic material increases the odds of having a difficult CPB separation. Also, it seems to be associated to more complex surgery, a longer CPB time, a higher TPOD and a longer stay in the ICU. Six out of eight patients who died in this cohort were in the HEM group.

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.

Cerebral Perfusion and Brain Oxygen Saturation Monitoring with: Jugular Venous Oxygen Saturation, Cerebral Oximetry, and Transcranial Doppler Ultrasonography

Accumulating evidence indicates that cerebral desaturation in the perioperative period occurs more frequently than recognized. Combining monitoring modalities that reflect different aspects of cerebral perfusion status, such as near-infrared spectroscopy, jugular bulb saturation, and transcranial Doppler ultrasonography, may provide an extended window for prevention, early detection, and prompt intervention in ongoing hypoxic/ischemic neuronal injury and, thereby, improve neurologic outcome. Such an approach would minimize the impact of limitations of each monitoring modality, while individual components complement each other, enhancing the accuracy of acquired information. Current literature has failed to demonstrate any clear-cut clinical benefit of these modalities on outcome prognosis.

The Role of Deep Hypothermia in Cardiac Surgery

Hypothermia is defined as a decrease in body core temperature to below 35 °C. In cardiac surgery, four stages of hypothermia are distinguished: mild, moderate, deep, and profound. The organ protection offered by deep hypothermia (DH) enables safe circulatory arrest as a prerequisite to carrying out cardiac surgical intervention. In adult cardiac surgery, DH is mainly used in aortic arch surgery, surgical treatment of pulmonary embolism, and acute type-A aortic dissection interventions. In surgery treating congenital defects, DH is used to assist aortic arch reconstructions, hypoplastic left heart syndrome interventions, and for multi-stage treatment of infants with a single heart ventricle during the neonatal period. However, it should be noted that a safe duration of circulatory arrest in DH for the central nervous system is 30 to 40 min at most and should not be exceeded to prevent severe neurological adverse events. Personalized therapy for the patient and adequate blood temperature monitoring, glycemia, hematocrit, pH, and cerebral oxygenation is a prerequisite and indispensable part of DH.

Neuropsychological Tests in Post-operative Cognitive Dysfunction: Methods and Applications

Post-operative cognitive dysfunction (POCD) is a neurological complication that relatively frequently occurs in older people after anesthesia/surgery, with varying durations and significant differences in the severity of cognitive impairment. POCD is mainly characterized by memory loss mostly without consciousness disorders, accompanied by abnormal emotions, behaviors, and language, mostly without consciousness disorder. The clinical performance of POCD lacks specificity but can reflect the severity of cognitive impairment in patients. The diagnosis of POCD cannot be separated from the evaluation of perioperative cognitive function of patients, and the more popular and accepted method is neuropsychological tests (NPTs).

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.

Considerations for Reduction of Risk of Perioperative Stroke in Adult Patients Undergoing Cardiac and Thoracic Aortic Operations: A Scientific Statement From the American Heart Association

Perioperative stroke is one of the most severe and feared complications of cardiac surgery. Based on the timing of onset and detection, perioperative stroke can be classified as intraoperative or postoperative. The pathogenesis of perioperative stroke is multifactorial, which makes prediction and prevention challenging. However, information on its incidence, mechanisms, diagnosis, and treatment can be helpful in minimizing the perioperative neurological risk for individual patients. We herein provide suggestions on preoperative, intraoperative, and postoperative strategies aimed at reducing the risk of perioperative stroke and at improving the outcomes of patients who experience a perioperative stroke.

The sensitivity and specificity of statistical rules for diagnosing delayed neurocognitive recovery with Montreal cognitive assessment in elderly surgical patients: A cohort study

Delayed neurocognitive recovery (DNR) is common in elderly patients after major noncardiac surgery. This study was designed to investigate the best statistical rule in diagnosing DNR with the Montreal cognitive assessment (MoCA) in elderly surgical patients.This was a cohort study. One hundred seventy-five elderly (60 years or over) patients who were scheduled to undergo major noncardiac surgery were enrolled. A battery of neuropsychological tests and the MoCA were employed to test cognitive function at the day before and on fifth day after surgery. Fifty-three age- and education-matched nonsurgical control subjects completed cognitive assessment with the same instruments at the same time interval. The definition of the international study of postoperative cognitive dysfunction (ISPOCD 1) was adopted as the standard reference for diagnosing DNR. With the MoCA, the following rules were used to diagnose DNR: the cut-off point of ≤26; the 1 standard deviation decline from baseline; the 2 scores decline from baseline; and the Z score of ≥1.96. The sensitivity and specificity as well as the area under receiver operating characteristic curve for the above rules in diagnosis of DNR were calculated.The incidence of DNR was 13.1% (23/175) according to the ISPOCD1 definition. When compared with the standard reference, the 2 scores rule showed the best combination of sensitivity (82.6%, 95% confidence interval [CI] 67.1%-98.1%) and specificity (82.2%, 95% CI 76.2%-88.3%); it also had the largest area under receiver operating characteristic curve (0.824, 95% CI 0.728-0.921, P < .001). The cut-off point rule showed high sensitivity (95.7%) and low specificity (37.5%), whereas the 1 standard deviation and the Z score rules showed low sensitivity (47.8% and 21.7%, respectively) and high specificity (93.4% and 97.3%, respectively).Compared with the ISPOCD1 definition, the 2 scores rule with MoCA had the best combination of sensitivity and specificity to diagnose DNR.

Cognition and Cerebral Infarction in Older Adults After Surgical Aortic Valve Replacement

BACKGROUND

Aortic valve replacement (AVR) for calcific aortic stenosis is associated with high rates of perioperative stroke and silent cerebral infarcts on diffusion-weighted magnetic resonance imaging (MRI), but cognitive outcomes in elderly AVR patients compared with individuals with cardiac disease who do not undergo surgery are uncertain.

METHODS

One hundred ninety AVR patients (mean age 76 ± 6 years) and 198 non-surgical participants with cardiovascular disease (mean age 74 ± 6 years) completed comprehensive cognitive testing at baseline (preoperatively) and 4 to 6 weeks and 1 year postoperatively. Surgical participants also completed perioperative stroke evaluations, including postoperative brain MRI. Mixed model analyses and reliable change scores examined cognitive outcomes. Stroke outcomes were evaluated in participants with and without postoperative cognitive dysfunction.

RESULTS

From reliable change scores, only 12.4% of the surgical group demonstrated postoperative cognitive dysfunction at 4 to 6 weeks and 7.5% at 1 year. Although the surgical group had statistically significantly lower scores in working memory/inhibition 4 to 6 weeks after surgery, the groups did not differ at 1 year. In surgical participants, postoperative cognitive dysfunction was associated with a greater number (p < 0.01) and larger total volume (p < 0.01) of acute cerebral infarcts on MRI.

CONCLUSIONS

In high-risk, aged participants undergoing surgical AVR for aortic stenosis, postoperative cognitive dysfunction was surprisingly limited and was resolved by 1 year in most. Postoperative cognitive dysfunction at 4 to 6 weeks was associated with more and larger acute cerebral infarcts.

Task-related changes in degree centrality and local coherence of the posterior cingulate cortex after major cardiac surgery in older adults

OBJECTIVES

Older adults often display postoperative cognitive decline (POCD) after surgery, yet it is unclear to what extent functional connectivity (FC) alterations may underlie these deficits. We examined for postoperative voxel-wise FC changes in response to increased working memory load demands in cardiac surgery patients and nonsurgical controls.

EXPERIMENTAL DESIGN

Older cardiac surgery patients (n = 25) completed a verbal N-back working memory task during MRI scanning and cognitive testing before and 6 weeks after surgery; nonsurgical controls with cardiac disease (n = 26) underwent these assessments at identical time intervals. We measured postoperative changes in degree centrality, the number of edges attached to a brain node, and local coherence, the temporal homogeneity of regional functional correlations, using voxel-wise graph theory-based FC metrics. Group × time differences were evaluated in these FC metrics associated with increased N-back working memory load (2-back > 1-back), using a two-stage partitioned variance, mixed ANCOVA.

PRINCIPAL OBSERVATIONS

Cardiac surgery patients demonstrated postoperative working memory load-related degree centrality increases in the left dorsal posterior cingulate cortex (dPCC; p < .001, cluster p-FWE < .05). The dPCC also showed a postoperative increase in working memory load-associated local coherence (p < .001, cluster p-FWE < .05). dPCC degree centrality and local coherence increases were inversely associated with global cognitive change in surgery patients (p < .01), but not in controls.

CONCLUSIONS

Cardiac surgery patients showed postoperative increases in working memory load-associated degree centrality and local coherence of the dPCC that were inversely associated with postoperative global cognitive outcomes and independent of perioperative cerebrovascular damage.

Early and long-term cognitive outcome after conventional cardiac valve surgery

Objectives

Adverse cognitive outcome is well recognized after coronary artery bypass grafting (CABG) while little is known about the extent and duration of decline after cardiac valve surgery. We investigated changes in cognitive function following conventional cardiac valve surgery over up to 4 years.

Methods

Among 36 patients (65.2 ± 9.2 years, 36% women) who received valve surgery, we assessed serial cognitive function with a battery of 11 standardized tests across 3-4 years. Cognitive function was analysed to identify: (1) cognitive decline (i.e. within-patient changes in test scores) and (2) cognitive deficit (i.e. drop of score ≥1 SD in ≥3 tests). Diffusion-weighted magnetic resonance imaging (DW-MRI) was applied pre- and post-procedure to detect ischaemic brain injury. Data were compared to a historical cohort of 39 patients undergoing CABG.

Results

After both valve surgery and CABG, a significant decline at discharge was detected in 7 of 11 cognitive tests. The rate of patients with a cognitive deficit after valve surgery vs CABG was 39% vs 56% at discharge, 14% vs 23% at 3 months, and 16% vs 26% at 3-4 years (not significant, [n.s.]). After valve surgery, DW-MRI identified 19 (53%) patients with evidence of 50 new focal ischaemic lesions (CABG: 20 [51%] patients with 42 lesions, n.s.). Cumulative cerebral ischaemic load per patient was not significantly different between the valve surgery group and CABG group (503 ± 485 mm 3 vs 415 ± 234 mm 3 ). After correction for multiple potential risk factors in both groups, reduced verbal memory at discharge could be identified as a predictor of long-term cognitive impairment in CABG patients only ( P  = 0.04). For both the valve surgery and CABG group, no association between cognitive impairment and new ischaemic cerebral lesions was found.

Conclusions

The course of cognitive performance after valve surgery and CABG was similar with early postoperative decline followed by subsequent recovery. Although silent small brain infarcts were present in about half of all patients, they did not impact cognitive performance neither at early nor during long-term follow-up.

Cerebral Microhemorrhage: A Frequent Magnetic Resonance Imaging Finding in Pediatric Patients after Cardiopulmonary Bypass

Objectives:

This study was undertaken to estimate the incidence and burden of cerebral microhemorrhage (CM) in patients with heart disease who underwent cardiopulmonary bypass (CPB), as detected on susceptibility-weighted imaging (SWI), a magnetic resonance (MR) sequence that is highly sensitive to hemorrhagic products.

Materials and Methods:

With Institutional Review Board waiver of consent, MR imaging (MRI) of a cohort of 86 consecutive pediatric patients with heart failure who underwent heart transplantation evaluation were retrospectively reviewed for CM. A nested case–control study was performed. The CPB group consisted of 23 pediatric patients with heart failure from various cardiac conditions who underwent CPB. The control group was comprised of 13 pediatric patients with similar cardiac conditions, but without CPB history. Ten patients in the CPB group were female (age: 5 days to 16 years at the time of the CPB and 6 days to 17 years at the time of the MRI). The time interval between the CPB and MRI ranged from 11 days to 4 years and 5 months. Six patients in the control group were female, age range of 2 days to 6 years old. The number of CM on SWI was counted by three radiologists (PK, EK and DK). The differences in number of CM between groups were tested for significance using Mann–Whitney U-test, α = 0.05. Using the univariate analysis of variance model, the differences in number of CM between groups were also tested with adjustment for age at MRI.

Results:

There are statistically significant differences in CM on SWI between the CPB group and control group with more CM were observed in the CPB group without and with adjustment for age at MRI (P < 0.001).

Conclusions:

Exposure of CPB is associated with increased prevalence and burden of CM among pediatric patients with heart failure.

Mind Over Matter? The Hidden Epidemic of Cognitive Dysfunction in the Older Surgical Patient

OBJECTIVE

The aim of this study was to highlight the vulnerability of the aging brain to surgery and anesthesia, examine postoperative cognitive outcomes, and recommend possible interventions.

BACKGROUND

Surgeons are facing increasingly difficult ethical and clinical decisions given the rapidly expanding aging demographic. Cognitive function is not routinely assessed either preoperatively or postoperatively. Potential short and long-term cognitive implications are rarely discussed with the patient despite evidence that postoperative cognitive impairment occurs in up to 65% of older patients. Furthermore, surgery may accelerate the trajectory of cognitive decline and dementia.

METHODS

An electronic search was conducted using Pubmed/Medline. References from selected studies were cross-referenced and relevant articles retrieved. Data were summarized in a narrative format.

RESULTS

There is a hidden epidemic of cognitive dysfunction in the perioperative setting. Up to 40% of patients who develop postoperative delirium (POD) never return to their preoperative cognitive baseline. POD can lead to postoperative cognitive dysfunction (POCD), a more prolonged cognitive impairment associated with longer length of hospital stay and cost, premature withdrawal from the workforce, and greater 1-year mortality. Standardized perioperative cognitive assessment is needed to enable progress. Improving outcomes will depend on a multifaceted approach, including correction of modifiable preoperative risk factors and prompt treatment of POD. Risk factors are discussed and possible interventional strategies are presented.

CONCLUSION

Closer preoperative collaboration between surgeons, geriatricians, and anesthetists will enable identification of complex at-risk older patients. A paradigm shift in the approach to management of the older surgical patient is critical to improve postoperative cognitive outcomes in modern surgery.

Perioperative Retinal Artery Occlusion: Risk Factors in Cardiac Surgery from the United States National Inpatient Sample 1998-2013

PURPOSE

To study the incidence and risk factors for retinal artery occlusion (RAO) in cardiac surgery.

DESIGN

Retrospective study using the National Inpatient Sample (NIS).

METHODS

The NIS was searched for cardiac surgery. Retinal artery occlusion was identified by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Postulated risk factors based on literature review were included in multivariate logistic models.

MAIN OUTCOME MEASURES

Diagnosis of RAO.

RESULTS

A total of 5 872 833 cardiac operative procedures were estimated in the United States from 1998 to 2013, with 4564 RAO cases (95% confidence interval [95% CI], 4282-4869). Nationally estimated RAO incidence was 7.77/10 000 cardiac operative procedures from 1998 to 2013 (95% CI, 7.29-8.29). Associated with increased RAO were giant cell arteritis (odds ratio [OR], 7.73; CI, 2.78-21.52; P < 0.001), transient cerebral ischemia (OR, 7.67; CI, 5.31-11.07; P < 0.001), carotid artery stenosis (OR, 7.52; CI, 6.22-9.09; P < 0.001), embolic stroke (OR, 4.43; CI, 3.05-6.42; P < 0.001), hypercoagulability (OR, 2.90; CI, 1.56-5.39; P < 0.001), myxoma (OR, 2.43; CI, 1.39-4.26; P = 0.002), diabetes mellitus (DM) with ophthalmic complications (OR, 1.89; CI, 1.10-3.24; P = 0.02), and aortic insufficiency (OR, 1.85; CI, 1.26-2.71; P = 0.002). Perioperative bleeding, aortic and mitral valve surgery, and septal surgery increased the odds of RAO. Negatively associated with RAO were female gender (OR, 0.77; CI, 0.66-0.89; P < 0.001), thrombocytopenia (OR, 0.79; CI, 0.62-1.00; P = 0.049), acute coronary syndrome (OR, 0.72; CI, 0.58-0.89; P = 0.003), atrial fibrillation (OR, 0.82; CI, 0.70-0.95; P = 0.01), congestive heart failure (OR, 0.73; CI, 0.60-0.88; P < 0.001), DM 2 (OR, 0.74; CI, 0.61-0.89; P = 0.001), and smoking (OR, 0.82; CI, 0.70-0.97; P = 0.02).

CONCLUSIONS

Risk factors for RAO in cardiac surgery include giant cell arteritis, carotid stenosis, stroke, hypercoagulable state, and DM with ophthalmic complications; associated with lower risk were female gender, thrombocytopenia, acute coronary syndrome, atrial fibrillation, congestive heart failure, DM 2, and smoking. Surgery in which the heart was opened (e.g., septal repair) versus surgery in which it was not (e.g., CABG) and perioperative bleeding increased the risk of RAO.

Original Research: Establishment of an early embolus-related cerebral injury model after cardiopulmonary bypass in miniature pigs

Embolus-related cerebral injury is still a serious adverse event after cardiopulmonary bypass (CPB). But there is no stable animal model for basic and clinical research purposes. We chose miniature pig to establish a stable animal model of embolus-related cerebral injury after CPB and verified the validity of results by correlating the histopathological findings with those of diffusion-weighted magnetic resonance imaging (DW-MRI). Based on different treatment regimens, 24 male miniature pigs were randomly assigned into four groups: Control, CPB, embolus, and CPB-embolus groups. DW-MRI was performed before and after surgery to diagnose and locate the brain lesions. Histopathological changes in brain tissues were examined using H&E and Nissl staining. All surgical procedures were uneventful with 100% postoperative survival of pigs. Two animals in the Embolus group and six animals in the CPB-embolus group showed signs of ischemic penumbra on DW-MRI performed 6 h after surgery. Consistent with the results of DW-MRI, histopathological examination showed necrosis and ischemic lesions. In this paper, we demonstrate the feasibility and validity of a pig model of embolus-related cerebral injury associated with CPB. This model may be used in the future for basic and translational research.

Effect of Core Temperature and Embolic Load During Cardiac Surgery on Motion Perception

BACKGROUND

Cognitive decline post-cardiac surgery is of clinical concern. To better understand it a sensitive and specific measure of post-surgery brain impairment is required. The cerebral territory most likely to be adversely affected by surgery is the posterior "watershed" territory.

METHODS

We have designed a psychophysical task involving reading letters defined by motion aimed at measuring the integrity of a cortical area (MT) located in this territory. Patients undergoing coronary artery bypass grafting (CABG) and a healthy control group were given the psychophysical test twice, pre- and post-surgery for the patient group.

RESULTS

There was no overall difference in performance between the surgery group and the control group at either pre- or post-surgery testing. However, multivariate analysis of surgical variables such as body temperature and embolic load to the brain as measured by Transcranial Doppler showed that patients with warmer core temperatures and higher embolic loads performed significantly worse on the motion defined letter reading tasks than those with more favourable surgical variables.

CONCLUSIONS

These results demonstrate that high embolic load and warm core body temperatures lead to poor motion perception post-cardiac surgery, implying damage to the posterior watershed cortex.

Postoperative Cognitive Dysfunction: Minding the Gaps in Our Knowledge of a Common Postoperative Complication in the Elderly

Postoperative cognitive dysfunction (POCD) is a common complication associated with significant morbidity and mortality in elderly patients. There is much interest in and controversy about POCD, reflected partly in the increasing number of articles published on POCD recently. Recent work suggests surgery may also be associated with cognitive improvement in some patients, termed postoperative cognitive improvement (POCI). As the number of surgeries performed worldwide approaches 250 million per year, optimizing postoperative cognitive function and preventing/treating POCD are major public health issues. In this article, we review the literature on POCD and POCI, and discuss current research challenges in this area.

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 microemboli and neurocognitive change after carotid artery stenting with different embolic protection devices

OBJECTIVES

Proximal cerebral protection devices have been developed as an alternative to filter protection devices for reducing neurological complications during carotid artery stenting (CAS). The aim of the present study was to evaluate the frequency of silent cerebral embolism after CAS using different cerebral embolic protection devices and the impact of silent cerebral embolism on neurocognitive function.

METHODS

One hundred consecutive patients who underwent CAS were enrolled. The patients were randomized to either proximal balloon occlusion or filter protection. Neurocognitive tests were performed before and six months after CAS. Cerebral embolisms were evaluated with diffusion-weighted magnetic resonance imaging (DW-MRI).

RESULTS

The number and volume of new ischemic lesions found with DW-MRI were higher in the filter protection group than in the proximal balloon occlusion group. According to our definition, nine (21%) patients in the balloon occlusion group and 16 (36%) patients in the filter protection group showed neurocognitive decline, and ten (23%) patients in the balloon occlusion group and four (9%) patients in the filter protection group showed neurocognitive improvement (NS). Regarding the group of patients with new cerebral ischemic lesions on DW-MRI, neurocognitive decline occurred in 14 (31%) of 45 patients with DW-MRI lesions and 11 (26%) of 43 patients without DW-MRI lesions (NS).

CONCLUSION

Neurocognitive outcome after CAS is unpredictable; both neurocognitive decline and improvement can occur. In this study, the proximal balloon occlusion system significantly decreased cerebral microemboli during CAS compared to filter protection. Cerebral microembolism was not found to be associated with neurocognitive decline.

Perioperative management of combined carotid and coronary artery bypass grafting procedures

The objective of this review is to provide a high level overview on current thinking for treatment of patients with combined carotid and coronary artery disease given that these patients are at higher risk of adverse cardiac events, stroke, and death. This review discusses (1) the current literature addressing perioperative stroke risk in the setting of coronary artery bypass graft, (2) the literature regarding different surgical approaches when both carotid and coronary revascularization are being considered, and (3) the data available to guide optimal management of this complex patient population to minimize complications regardless of the surgical approach taken.

Single aortic clamping in coronary artery bypass surgery reduces cerebral embolism and improves neurocognitive outcomes

Aortic manipulation releases embolic material, thereby enhancing the probability of adverse neurologic outcomes following coronary artery bypass grafting (CABG). We prospectively evaluated 59 patients undergoing CABG. Patients in the single (SC, n = 37) and multiple clamp (MC, n = 22) groups were comparable in relation to age and operative risk (p > 0.05). Neurocognitive evaluation consisted of the Auditory Verbal Learning Test (AVLT), Color Trails Test A, the Grooved Pegboard test and the Mini-Mental State Examination. Data acquisition was performed preoperatively, early postoperatively and at the 4-month follow-up. Intraoperative transcranial Doppler (TCD) monitoring was used to quantify the embolic load in relation to different aortic clamping strategies. Preoperative neurocognitive results were similar between the groups (p > 0.05). The incidence of postoperative delirium was greater in the MC group but this failed to reach statistical significance (23% vs 8%, p = 0.14). SC patients had fewer embolization signals (270 ± 181 vs 465 ± 160, p < 0.0001). Early postoperative neurocognitive results were depressed in comparison to preoperative values in both groups (p < 0.05 for multiple comparisons). The magnitude of this cognitive depression was greater in the MC group (p < 0.05 for multiple comparisons). Preoperative levels of neurocognition were restored at follow-up in the SC group in all tests except the AVLT. A trend towards improvements in neurocognitive performances at follow-up was also observed in the MC group. Residual attention, motor skill and memory deficits were, however, documented with multiple tests. In conclusion, the embolic burden was significantly lower in the SC group. This TCD imaging outcome translated into fewer early cognition deficits and superior late restoration of function.

Brain emboli distribution and differentiation during cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass (CPB) is a lifesaving practice in cardiac surgery, but its use frequently is associated with cerebral injury and neurocognitive dysfunctions. Despite the involvement of numerous factors, microembolism occurring during CPB seems to be one of the main mechanisms leading to such alterations. The aim of the present study was to characterize the occurrence of cerebral microembolism with reference to microembolic amount, nature, and distribution in different combinations of cardiac procedures and CPB on the microembolic load.

DESIGN

A retrospective observational clinical study.

SETTING

A single-center regional hospital.

PARTICIPANTS

Fifty-five patients undergoing elective cardiac surgery with CPB.

INTERVENTIONS

Bilateral detection of the patients' middle cerebral arteries using a multifrequency transcranial Doppler.

MEASUREMENTS AND MAIN RESULTS

Patients were divided into 3 groups depending on the CPB circuit used (open, open with vacuum, or closed). There was a significant difference between the number of solid and gaseous microemboli (p<0.001), with the solid lower than the gaseous ones. The number of solid microemboli was affected by group (p< 0.05), CPB phase (p<0.001), and laterality (p<0.01). The number of gaseous microemboli was affected only by group (p<0.05) and CPB phase (p<0.001). Generally, the length of CPB phase did not affect the number of microemboli.

CONCLUSIONS

Surgical procedures combined with CPB circuits, but not the CPB phase length, affected the occurrence, nature, and laterality of microemboli.

Impact of the intensity of microemboli on neurocognitive outcome following cardiopulmonary bypass

BACKGROUND

This study aimed to determine whether there was any association between the intensity of intraoperative gaseous microembolic signals (GME), neuropsychological testing and clinical outcome in high-risk patients undergoing coronary artery surgery (CABG).

METHODS

Over a 6-month period, GME activity was monitored in 102 Euroscore 6+ patients during cardiopulmonary bypass (CPB) with a conventional 32-micron arterial filter by non-invasive, real-time ultrasonic device. Cognitive tests; line bisection, the Stroop test, finger tapping, and the Rey Auditory Verbal Learning Test were performed at baseline, postoperative one week and postoperative one month.

RESULTS

The distribution of GME activity showed that there were three groups of patients: >500 total emboli (n = 38); 250 to 500 emboli (n = 30) and <250 emboli (n = 34) at a detection level of 2% of the circuit diameter on the arterial side. Line bisection, the Stroop test and finger tapping were impaired significantly in >500 emboli patients versus control (<250 emboli) in postoperative week one, but resolved in one month.

CONCLUSIONS

Correlation between intraoperative GME intensity and neurocognitive tests suggests that the level of GME might have a role in determining the psychological outcome after CABG with CPB.

Can postoperative cognitive dysfunction be avoided?

Postoperative cognitive dysfunction (POCD) refers to a postoperative decline in cognitive function compared with preoperative cognitive function. Diagnosis requires pre- and postoperative testing, the latter of which is usually performed both 7 days and 3 months postoperatively. Although several risk factors for POCD have been described, age is the only consistently reported risk factor. Postoperative cognitive dysfunction is often transient. It may last several months, and is associated with leaving the labor market prematurely and increased mortality. As the pathophysiology of POCD is still a matter of debate and is likely to be multifactorial, there are no widely accepted prophylactic and therapeutic interventions. In this article, we discuss POCD's definition, risk factors, long-term significance, and pathophysiology. We also present data on prophylactic interventions that have been investigated in clinical trials.