Central nervous system injury associated with cardiac surgery

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.

The effectiveness of the correction of cognitive impairment using computer-based stimulation programs for patients with coronary heart disease after coronary bypass surgery

We evaluated effectiveness of using copyrighted computer-based stimulation programs in the correction of cognitive function in patients with coronary heart disease after coronary bypass surgery.A total of 74 patients were examined, all the patients underwent a course of drug therapy, 37 patients underwent a course of rehabilitation in addition to medical therapy using computer-based stimulation programs (1 time per day for 20 min within 10 days). A course of rehabilitation using computer-based stimulation programs in patients with coronary heart disease after coronary bypass surgery was proved to be an effective way of correcting cognitive function.

Predictors of stroke in patients undergoing cardiac surgery

Objective

To determine the risk factors related to the development of stroke in patients undergoing cardiac surgery.

Methods

A historical cohort study. We included 4626 patients aged > 18 years who underwent coronary artery bypass surgery, heart valve replacement surgery alone or heart valve surgery combined with coronary artery bypass grafting between January 1996 and December 2011. The relationship between risk predictors and stroke was assessed by logistic regression model with a significance level of 0.05.

Results

The incidence of stroke was 3% in the overall sample. After logistic regression, the following risk predictors for stroke were found: age 50-65 years (OR=2.11 - 95% CI 1.05-4.23 - P=0.036) and age >66 years (OR=3.22 - 95% CI 1.6-6.47 - P=0.001), urgent and emergency surgery (OR=2.03 - 95% CI 1.20-3.45 - P=0.008), aortic valve disease (OR=2.32 - 95% CI 1.18-4.56 - P=0.014), history of atrial fibrillation (OR=1.88 - 95% CI 1.05-3.34 - P=0.032), peripheral artery disease (OR=1.81 - 95% CI 1.13-2.92 - P=0.014), history of cerebrovascular disease (OR=3.42 - 95% CI 2.19-5.35 - P<0.001) and cardiopulmonary bypass time > 110 minutes (OR=1.71 - 95% CI 1.16-2.53 - P=0.007). Mortality was 31.9% in the stroke group and 8.5% in the control group (OR=5.06 - 95% CI 3.5-7.33 - P<0.001).

Conclusion

The study identified the following risk predictors for stroke after cardiac surgery: age, urgent and emergency surgery, aortic valve disease, history of atrial fibrillation, peripheral artery disease, history of cerebrovascular disease and cardiopulmonary bypass time > 110 minutes.

Hemoglobin Concentration Affects Electroencephalogram During Cardiopulmonary Bypass: An Indication for Neuro-Protective Values

Hemodilution during cardiopulmonary bypass (CPB) is widely used to decrease transfusion and improve microcirculation but has drawbacks, such as diminished hemoglobin levels. Among others, reduced brain oxygenation accounts for neurological adverse outcomes after CPB. The aim of the present study was to ascertain if and how continuous electroencephalogram (EEG) during CPB is affected by hematocrit level and what should be the minimum value to avoid significant frequency band shifts on the EEG. A comparative study design was used with 16 subjects undergoing elective mitral valve repair/replacement. EEG was continuously recorded during the surgical procedure (from anesthesia induction to 20 min after CPB end). Data were marked at relevant time points (T0: before CPB start; T1: after 30 min from CPB beginning; T2: at CPB end), and the following 2 min EEG analyzed with a fast Fourier transform to obtain relative power for delta, theta, alpha, and beta bands. A general linear model for repeated measure was used to study interactions of time (T0, T1, and T2, EEG frequency band, and topographical distribution. The relative powers for each electrode were calculated and represented using topographic maps. Power spectrum differences between time points (T2-T1; T2-T0; T1-T0) were calculated for each electrode, and differences >10%, considered indicative of neuronal sufferance, were included in further analysis. Cutoff hemoglobin values that maximize the proportion of correctly classified EEG band shifts were obtained by previous definition were obtained. At T2, diffuse EEG slowing in delta and theta bands was detected; a minor slowing over anterior regions was evident at T1 for the theta band. Decrements in EEG power greater than 10% were detected only for the delta band at T2. Hemoglobin concentration levels at which no slowing increase was evident were 9.4 mg/dL (Ht: 28.2%) at T1 and 9.2 mg/dL (Ht: 27.6%) at T2. EEG burst-suppression pattern related to a lesser degree of slowing at T2. In conclusion, we propose hemoglobin cutoff levels that prevent EEG slowing indicative of neuronal sufferance. In addition, burst-suppression EEG patterns offer higher central nervous system protection as measured on EEG.

The Effects of Near-Infrared Spectroscopy on the Neurocognitive Functions in the Patients Undergoing Coronary Artery Bypass Grafting with Asymptomatic Carotid Artery Disease: A Randomized Prospective Study

PURPOSE

The purpose of this study was to research the use of near-infrared spectroscopy (NIRS) on the neurocognitive functions in the patients undergoing coronary artery bypass grafting (CABG) with asymptomatic carotid artery disease.

METHODS

The study design was carried out with the participation of 79 patients in a prospective, randomized and double blind control method. The patients were separated into two groups as NIRS (n = 43) and no NIRS (n = 36). A neurocognitive test was applied preoperatively and postoperatively to all patients before discharge. Cognitive functions were evaluated by applying the Montreal Cognitive Assessment test (MoCA).

RESULTS

The decrease in the postoperative score of mean MoCA in no NIRS group was statistically significant when compared to preoperatively (p <0.001). Postoperative mean MoCA score was found to be significantly higher in NIRS group (NIRS: 26.8 ± 1.9 vs. no NIRS: 23.6 ± 2.5, p <0.001). It has been determined that there was a moderately positive significant correlation between the increase in the NIRS used patients (%) and increase in the MoCA score of the patients (r = 0.59, p <0.001).

CONCLUSION

Intraoperative NIRS usage in the patients undergoing CABG with carotid artery disease might be useful due to its postoperative positive effects on the cognitive functions.

Apolipoprotein epsilon 4 genotype is associated with less improvement in cognitive function five years after cardiac surgery: a retrospective cohort study

PURPOSE

Cognitive performance after cardiac surgery can be impaired, and genetic risk factors have previously been suggested. When compared with other isoforms of the gene, the apolipoprotein epsilon 4 (APOE4) allele is associated with worse outcomes in many neurologic disorders. We hypothesized that the APOE4 allele is associated with less favourable cognitive function five years after surgery.

METHODS

Caucasian patients enrolled in previously reported prospective cognitive trials in both cardiac and non-cardiac surgery participated in this retrospective cohort study. Neuropsychological function was assessed at baseline and five years postoperatively. The relationship between change in cognitive index score and APOE was evaluated using multivariable linear regression. An additive genetic model toward the epsilon 4 allele was applied with adjustment for baseline cognition, years of education, age, presence of diabetes in both cohorts, and presence of coronary artery disease in the non-cardiac surgery cohort.

RESULTS

A total of 357 patients were included in this study. In the cardiac surgery group (n = 233), baseline cognitive index (P < 0.001), years of education (P = 0.04), age at time of surgery (P < 0.001), and the APOE4 allele (P = 0.009), were associated with a five-year change in cognitive index. Patients carrying the APOE4 allele showed less improvement in cognitive index scores five years after cardiac surgery compared with patients without the APOE4 allele. In the non-cardiac surgery (n = 124) group, no association was found between APOE4 allele status and change in cognitive index.

CONCLUSION

We report an association between APOE4 and neurocognitive function five years following cardiac surgery. Preoperative identification of patients with the APOE4 genotype may improve stratification of cardiac surgery patients at risk for a less favourable cognitive trajectory.

A mitral annulus tracking approach for navigation of off-pump beating heart mitral valve repair

PURPOSE

To develop and validate a real-time mitral valve annulus (MVA) tracking approach based on biplane transesophageal echocardiogram (TEE) data and magnetic tracking systems (MTS) to be used in minimally invasive off-pump beating heart mitral valve repair (MVR).

METHODS

The authors' guidance system consists of three major components: TEE, magnetic tracking system, and an image guidance software platform. TEE provides real-time intraoperative images to show the cardiac motion and intracardiac surgical tools. The magnetic tracking system tracks the TEE probe and the surgical tools. The software platform integrates the TEE image planes and the virtual model of the tools and the MVA model on the screen. The authors' MVA tracking approach, which aims to update the MVA model in near real-time, comprises of three steps: image based gating, predictive reinitialization, and registration based MVA tracking. The image based gating step uses a small patch centered at each MVA point in the TEE images to identify images at optimal cardiac phases for updating the position of the MVA. The predictive reinitialization step uses the position and orientation of the TEE probe provided by the magnetic tracking system to predict the position of the MVA points in the TEE images and uses them for the initialization of the registration component. The registration based MVA tracking step aims to locate the MVA points in the images selected by the image based gating component by performing image based registration.

RESULTS

The validation of the MVA tracking approach was performed in a phantom study and a retrospective study on porcine data. In the phantom study, controlled translations were applied to the phantom and the tracked MVA was compared to its "true" position estimated based on a magnetic sensor attached to the phantom. The MVA tracking accuracy was 1.29 ± 0.58 mm when the translation distance is about 1 cm, and increased to 2.85 ± 1.19 mm when the translation distance is about 3 cm. In the study on porcine data, the authors compared the tracked MVA to a manually segmented MVA. The overall accuracy is 2.37 ± 1.67 mm for single plane images and 2.35 ± 1.55 mm for biplane images. The interoperator variation in manual segmentation was 2.32 ± 1.24 mm for single plane images and 1.73 ± 1.18 mm for biplane images. The computational efficiency of the algorithm on a desktop computer with an Intel(®) Xeon(®) CPU @3.47 GHz and an NVIDIA GeForce 690 graphic card is such that the time required for registering four MVA points was about 60 ms.

CONCLUSIONS

The authors developed a rapid MVA tracking algorithm for use in the guidance of off-pump beating heart transapical mitral valve repair. This approach uses 2D biplane TEE images and was tested on a dynamic heart phantom and interventional porcine image data. Results regarding the accuracy and efficiency of the authors' MVA tracking algorithm are promising, and fulfill the requirements for surgical navigation.

Feasibility of near-infrared spectroscopic tomography for intraoperative functional cerebral monitoring: a primate study

OBJECTIVE

The wide-ranging manipulations to the cardiovascular system that frequently occur during cardiac surgery can expose the brain to variations in its blood supply that could prove deleterious. As a first step to developing a resource suitable for monitoring such changes, we detected the hemodynamic events induced in the brain of a primate model, using high-density near-infrared spectroscopy combined with tomographic reconstruction methods and validated the findings using established radiologic and histologic techniques.

METHODS

Continuous monitoring of the relative changes in the components of the cerebral hemoglobin signal was performed using high-density near-infrared spectroscopy (270 source-detector channel array) in anesthetized bonnet macaques with the brain exposed to induced ischemia and other acute events. A comparative analysis (exact binomial test) applied to reconstructed 3-dimensional images before and after the events and between cerebral hemispheres, combined with postprocedure magnetic resonance imaging, and postmortem histopathologic examination of the macaques' brains was performed to document and validate the spatial features revealed by the optical findings.

RESULTS

Relative changes in the measured and calculated components of the hemoglobin signal, in response to the performed manipulations, revealed substantial concurrence among the reconstructed 3-dimensional images, magnetic resonance imaging of the macaques' brains, and postmortem histopathologic examination findings. Concurrence was seen when the manipulated hemoglobin concentration and associated oxygenation levels were either increased or decreased, and whether they were bilateral or restricted to a specified hemisphere.

CONCLUSIONS

Continuous near-infrared spectroscopy tomography has been shown to accurately capture and localize cerebral ischemia, vasodilatation, and hemorrhage in primates in real time. These findings are directly applicable to clinical intraoperative functional cerebral monitoring.

Low incidence of early postoperative cerebral edema after coronary artery bypass grafting

OBJECTIVE

Using magnetic resonance imaging, the authors studied the influence of a single high dose of intraoperative dexamethasone on the severity of cerebral edema that can occur early after coronary artery bypass grafting (CABG). It was hypothesized that high-dose intraoperative dexamethasone reduces cerebral edema after CABG.

DESIGN

Secondary analysis in a subset of participants of the Dexamethasone for Cardiac Surgery (DECS) trial. The DECS trial was a multicenter, randomized, double-blind, placebo-controlled trial in 4,494 cardiac surgery patients, which studied the effect of high-dose dexamethasone on mortality and major complications after cardiac surgery.

SETTING

A large university hospital in The Netherlands.

PARTICIPANTS

Twenty adult patients who underwent CABG with cardiopulmonary bypass (CPB) between March and November 2011.

INTERVENTIONS

Participants received a single intravenous dose of dexamethasone, 1 mg/kg, or placebo, at induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Patients underwent magnetic resonance imaging scanning immediately after surgery. The primary outcome was the severity of cerebral edema. Data from 18 patients (9 in each group, median age 69 years in both groups) could be analyzed. Patients in the dexamethasone group were (median, interquartile range 66 (53-99) minutes on cardiopulmonary bypass v 95 (81-105) minutes in the placebo group (p = 0.11). Only 1 patient in the dexamethasone group had slight cerebral edema (0% v 11%, p = 1.00), and edema severity did not differ between groups (p = 1.00).

CONCLUSIONS

Relevant degrees of early postoperative cerebral edema were not observed. The present study findings strongly contrasted with older studies showing cerebral edema early after CABG in most patients.

Blood levels of S-100 calcium-binding protein B, high-sensitivity C-reactive protein, and interleukin-6 for changes in depressive symptom severity after coronary artery bypass grafting: prospective cohort nested within a randomized, controlled trial

BACKGROUND

Cross-sectional and retrospective studies have associated major depressive disorder with glial activation and injury as well as blood-brain barrier disruption, but these associations have not been assessed prospectively. Here, we aimed to determine the relationship between changes in depressive symptom severity and in blood levels of S-100 calcium-binding protein B (S-100B), high-sensitivity C-reactive protein, and interleukin-6 following an inflammatory challenge.

METHODS

Fifty unselected participants were recruited from a randomized, controlled trial comparing coronary artery bypass grafting procedures performed with versus without cardiopulmonary bypass for the risk of neurocognitive decline. Depressive symptom severity was measured at baseline, discharge, and six-month follow-up using the Beck Depression Inventory II (BDI-II). The primary outcome of the present biomarker study was acute change in depressive symptom severity, defined as the intra-subject difference between baseline and discharge BDI-II scores. Blood biomarker levels were determined at baseline and 2 days postoperative.

RESULTS

Changes in S-100B levels correlated positively with acute changes in depressive symptom severity (Spearman ρ, 0.62; P = 0.0004) and accounted for about one-fourth of their observed variance (R2, 0.23; P = 0.0105). This association remained statistically significant after adjusting for baseline S-100B levels, age, weight, body-mass index, or β-blocker use, but not baseline BDI-II scores (P = 0.064). There was no statistically significant association between the primary outcome and baseline S-100B levels, baseline high-sensitivity C-reactive protein or interleukin-6 levels, or changes in high-sensitivity C-reactive protein or interleukin-6 levels. Among most participants, levels of all three biomarkers were normal at baseline and markedly elevated at 2 days postoperative.

CONCLUSIONS

Acute changes in depressive symptom severity were specifically associated with incremental changes in S-100B blood levels, largely independent of covariates associated with either. These findings support the hypothesis that glial activation and injury and blood-brain barrier disruption can be mechanistically linked to acute exacerbation of depressive symptoms in some individuals.

Effects of Dexamethasone on Cognitive Decline after Cardiac Surgery

Background:

Cardiac surgery can be complicated by postoperative cognitive decline (POCD), which is characterized by impaired memory function and intellectual ability. The systemic inflammatory response that is induced by major surgery and cardiopulmonary bypass may play an important role in the etiology of POCD. Prophylactic corticosteroids to attenuate the inflammatory response may therefore reduce the risk of POCD. The authors investigated the effect of intraoperative high-dose dexamethasone on the incidence of POCD at 1 month and 12 months after cardiac surgery.

Methods:

This multicenter, randomized, double-blind, placebo-controlled trial is a preplanned substudy of the DExamethasone for Cardiac Surgery trial. A total of 291 adult patients undergoing cardiac surgery with cardiopulmonary bypass were recruited in three hospitals and randomized to receive dexamethasone 1 mg/kg (n = 145) or placebo (n = 146). The main outcome measures were incidence of POCD at 1- and 12-month follow-up, defined as a decline in neuropsychological test performance beyond natural variability, as measured in a control group.

Results:

At 1-month follow-up, 19 of 140 patients in the dexamethasone group (13.6%) and 10 of 138 patients in the placebo group (7.2%) fulfilled the diagnostic criteria for POCD (relative risk, 1.87; 95% CI, 0.90 to 3.88; P = 0.09). At 12-month follow-up, 8 of 115 patients in the dexamethasone group (7.0%) and 4 of 114 patients (3.5%) in the placebo group had POCD (relative risk, 1.98; 95% CI, 0.61 to 6.40; P = 0.24).

Conclusion:

Intraoperative high-dose dexamethasone did not reduce the risk of POCD after cardiac surgery.

Short-term outcome of attention and executive functions from aorta no-touch and traditional off-pump coronary artery bypass surgery

OBJECTIVES

Postoperative cognitive dysfunction (POCD) is an important neuropsychiatric complication of coronary artery bypass grafting (CABG). It is most likely caused by microembolic brain damage and affects domains of attention, memory, executive functions and dexterity. In order to achieve better neuroprotection, surgeons introduced some advantageous operating procedures. Noteworthy among them is a state-of-the-art off-pump CABG aorta no-touch technique ("no touch" OPCABG). The aim of this study was to investigate the short-term effect of "no touch" OPCABG on patients' attention and executive functions.

METHODS

In this prospective, observational, single-surgeon trial, 74 patients scheduled for elective CABG were studied. Thirty-five patients underwent "no-touch" OPCABG and were compared to 39 patients who underwent "traditional" OPCABG. Subjects underwent neurological and neuropsychological evaluation at the time of admission (7 ± 2 days preoperatively) and discharge (7 days postoperatively).

RESULTS

Patients who underwent "traditional" OPCABG showed a significant decline in postoperative performance on 4 neuropsychological tests, while patients treated with "no touch" OPCABG showed a significant decline on 1 test. Twenty patients from "traditional" OPCABG group and ten patients from "no touch" OPCABG group were diagnosed with POCD.

CONCLUSIONS

Use of "no touch" OPCABG was associated with better attention and executive functions 1 week after surgery compared with "traditional" OPCABG.

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.

Influence of intraoperative cerebral oximetry monitoring on neurocognitive function after coronary artery bypass surgery: a randomized, prospective study

OBJECTIVES

Postoperative cognitive decline is common after cardiac surgery, but it is often unrecognized at the time of hospital discharge. However, it has a great impact on patient's quality of life. Cerebral oximetry with the INVOS (IN Vivo Optical Spectroscopy) system provides the possibility of non-invasive, continuous measurement of regional cerebral oxygen saturation (rSO2), which can improve patients' outcome. The aim of this study was to examine whether cerebral oximetry can decrease the incidence of cognitive decline after coronary artery bypass grafting.

METHODS

We have performed a prospective, randomized study with 200 patients enrolled. Patients were divided into INVOS interventional group and CONTROL group without monitoring of cerebral oximetry. A standardized interventional protocol was performed in the INVOS group to maintain rSO2 above 80% of the patient's baseline value or above 50% of the absolute value. Cognitive evaluation was performed in all patients before and 7 days after surgery. Logistic regression was used to reveal predictors of cognitive decline.

RESULTS

The incidence of cognitive decline 7 days after surgery was significantly lower (P = 0.002) in the INVOS interventional group (28%) than in the CONTROL group (52%). Intraoperative use of INVOS monitoring was associated with lower incidence of cognitive decline (odds ratio 0.21). In addition, predictors of cognitive decline revealed by multivariate logistic regression were older age, higher EuroSCORE and SAPS II (Simplified Acute Physiology Score) values, lower educational level and persistence of preoperative atrial fibrillation. Patients with prolonged rSO2 desaturation, defined as rSO2 area under the curve (AUC) of more than 150 min% for desaturation below 20% of baseline or AUC of more than 50 min% for desaturation below 50% absolute value, had an increased risk of cognitive decline.

CONCLUSION

Postoperative cognitive outcome was significantly better in patients with intraoperative cerebral oximetry monitoring. Prolonged rSO2 desaturation is a predictor of cognitive decline and has to be avoided.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

Short-term preoperative dietary restriction is neuroprotective in a rat focal stroke model

Stroke is a major complication of cardiovascular surgery, resulting in over 100,000 deaths and over a million postoperative encephalopathies annually in the US and Europe. While mitigating damage from stroke after it occurs has proven elusive, opportunities to reduce the incidence and/or severity of stroke prior to surgery in at-risk individuals remain largely unexplored. We tested the potential of short-term preoperative dietary restriction to provide neuroprotection in rat models of focal stroke. Rats were preconditioned with either three days of water-only fasting or six days of a protein free diet prior to induction of transient middle cerebral artery occlusion using two different methods, resulting in either a severe focal stroke to forebrain and midbrain, or a mild focal stroke localized to cortex only. Infarct volume, functional recovery and molecular markers of damage and protection were assessed up to two weeks after reperfusion. Preoperative fasting for 3 days reduced infarct volume after severe focal stroke. Neuroprotection was associated with modulation of innate immunity, including elevation of circulating neutrophil chemoattractant C-X-C motif ligand 1 prior to ischemia and suppression of striatal pro-inflammatory markers including tumor necrosis factor α, its receptor and downstream effector intercellular adhesion molecule-1 after reperfusion. Similarly, preoperative dietary protein restriction for 6 days reduced ischemic injury and improved functional recovery in a milder cortical infarction model. Our results suggest that short-term dietary restriction regimens may provide simple and translatable approaches to reduce perioperative stroke severity in high-risk elective vascular surgery.

Detection of cerebral arterial gas embolism using regional cerebral oxygen saturation, quantitative electroencephalography, and brain oxygen tension in the swine

BACKGROUND

Cerebral air emboli occur as a complication of invasive medical procedures. The sensitivity of cerebral monitoring methods for the detection of air emboli is not known. This study investigates the utility of electroencephalography and non-invasively measured cerebral oxygen saturation in the detection of intracerebrovascular air.

NEW METHOD

In 12 pigs oxygen saturation was continuously measured using transcranial near-infrared spectroscopy and oxygen tension was continuously measured using intraparenchymal probes. Additionally, quantitative electroencephalography and microdialysis were performed. Doses of 0.2, 0.4, 0.8, and 1.6 ml of air were injected into the cerebral arterial vasculature through a catheter.

RESULTS

Oxygen saturation and electroencephalography both reacted almost instantaneously on the air emboli, but were less sensitive than the intraparenchymal oxygen tension. There was reasonable correlation (ρ ranging from 0.417 to 0.898) between oxygen saturation, oxygen tension, electroencephalography and microdialysis values.

COMPARISON WITH EXISTING METHODS

Our study is the first to demonstrate the effects of cerebral air emboli using multimodal monitoring, specifically on oxygen saturation as measured using near-infrared spectroscopy.

CONCLUSIONS

Our results show that non-invasively measured oxygen saturation and quantitative electroencephalography can detect the local effects of air emboli on cerebral oxygenation, but with reduced sensitivity as compared to intraparenchymal oxygen tension. Prospective human studies using multimodal monitoring incorporating electroencephalography and oxygen saturation should be performed.

Monitoring of central retinal artery and vein with color Doppler ultrasound during heart surgery as an alternative to transcranial Doppler ultrasonography: a case report

Cardiac surgery can have severe neurologic complications. The noninvasive monitoring of intracranial circulation during heart surgery is usually performed with transcranial Doppler ultrasonography. We present the case of a 66-year-old man who underwent elective cardiac surgery for aortic valve replacement and coronary artery bypass graft, in whom monitoring was performed by simultaneously assessing blood flow velocity in the central retinal artery and vein.

Inhibition of Factor XII-Mediated Activation of Factor XI Provides Protection Against Experimental Acute Ischemic Stroke in Mice

Blood coagulation factor XI (FXI) is an established risk factor for acute ischemic stroke (AIS) and thrombosis, but is also needed for normal hemostasis. Contact factor XII (FXII), an upstream activator of FXI, also contributes to experimental stroke, but is not required for hemostasis. We investigated whether selectively inhibiting FXII-mediated FXI activation, while leaving other FXI and FXII functions intact, could improve the outcome of experimental AIS in mice. Twenty-four hours before induction of AIS by placement of a filament into the internal carotid artery for 60 min, mice were anticoagulated with an antibody directed against the apple 2 domain of FXI. This antibody selectively reduces the prothrombotic activation of FXI by FXIIa but does not affect activated FXI or hemostatic activation of FXI by thrombin, thus leaving hemostasis intact in mice and primates. In this model of AIS/reperfusion injury, mice that received the antibody before AIS displayed less ischemic damage, manifested as reduced cerebral infarction and fibrin deposition (thrombosis), increased cortical reperfusion, and improved neurological behavior. Further, the antibody-anticoagulated mice had no detectable hemostasis impairment. Consistent with the neuroprotective phenotype of FXII-deficient mice, our data suggest that a single molecular event, FXII-mediated FXI activation, contributes to the development of experimental AIS.

Influencing factors for early acute cerebrovascular accidents in patients with stroke history following off-pump coronary artery bypass grafting

PURPOSE

To analyse risk factors for early acute cerebrovascular accidents following off-pump coronary artery bypass grafting (OPCAB) in patients with stroke history, and to propose preventive measures to reduce the incidence of these events.

METHODS

A total of 468 patients with a history of stroke underwent OPCAB surgery in Beijing Anzhen Hospital of China from January 2010 to September 2012. They were retrospectively divided into two groups according to the occurrence of early acute cerebrovascular accidents within 48 hours following OPCAB. Multivariate logistic regression analysis was used to find risk or protective factors for early acute cerebrovascular accidents following the OPCAB.

RESULTS

Fifty-two patients (11.1%) suffered from early acute cerebrovascular accidents in 468 patients, including 39 cases of cerebral infarction, two cases of cerebral haemorrhage, 11 cases of transient ischaemic attack (TIA). There were significant differences between the two groups in preoperative left ventricular ejection fraction ≤ 35%, severe bilateral carotid artery stenosis, poorly controlled hypertension, intraoperative application of Enclose® II proximal anastomotic device, postoperative acute myocardial infarction, atrial fibrillation, hypotension, ventilation time > 48h, ICU duration >48h and mortality. Multivariate logistic regression analysis showed that preoperative severe bilateral carotid stenosis (OR=6.378, 95%CI: 2.278-20.987) and preoperative left ventricular ejection fraction ≤ 35% (OR=2.737, 95%CI: 1.267-6.389), postoperative acute myocardial infarction (OR=3.644, 95%CI: 1.928-6.876), postoperative atrial fibrillation (OR=3.104, 95%CI:1.135∼8.016) and postoperative hypotension (OR=4.173, 95%CI: 1.836∼9.701) were independent risk factors for early acute cerebrovascular accidents in patients with a history of stroke following OPCAB procedures, while intraoperative application of Enclose® II proximal anastomotic device was protective factor (OR=0.556, 95%CI: 0.337-0.925).

CONCLUSIONS

This study indicated that patients with severe bilateral carotid stenosis, the left ventricular ejection fraction ≤35%, the postoperative acute myocardial infarction, postoperative atrial fibrillation and postoperative hypotension were more likely to suffer from early acute cerebrovascular accidents when they received OPCAB. Application of Enclose® II proximal anastomotic device may decrease the incidence of early acute cerebrovascular accidents during OPCAB.

Effect of remote ischemic preconditioning on cognitive function after off-pump coronary artery bypass graft: a pilot study

Background

Several studies have shown in animal models that remote ischemic preconditioning (rIPC) has a neuroprotective effect. However, a randomized controlled trial in human subjects to investigate the neuroprotective effect of rIPC after cardiac surgery has not yet been reported. Therefore, we performed this pilot study to determine whether rIPC reduced the occurrence of postoperative cognitive dysfunction in patients who underwent off-pump coronary artery bypass graft (OPCAB) surgery.

Methods

Seventy patients who underwent OPCAB surgery were assigned to either the control or the rIPC group using a computer-generated randomization table. The application of rIPC consisted of four cycles of 5 min ischemia and 5 min reperfusion on an upper limb using a blood pressure cuff inflating 200 mmHg before coronary artery anastomosis. The cognitive function tests were performed one day before surgery and again on postoperative day 7. We defined postoperative cognitive dysfunction as decreased postoperative test values more than 20% of the baseline values in more than two of the six cognitive function tests that were performed.

Results

In the cognitive function tests, there were no significant differences in the results obtained during the preoperative and postoperative periods for all tests and there were no mean differences observed in the preoperative and postoperative scores. The incidences of postoperative cognitive dysfunction in the control and rIPC groups were 28.6% (10 patients) and 31.4% (11 patients), respectively.

Conclusions

rIPC did not reduce the incidence of postoperative cognitive dysfunction after OPCAB surgery during the immediate postoperative period.

Elimination of gaseous microemboli from cardiopulmonary bypass using hypobaric oxygenation

BACKGROUND

Numerous gaseous microemboli (GME) are delivered into the arterial circulation during cardiopulmonary bypass (CPB). These emboli damage end organs through multiple mechanisms that are thought to contribute to neurocognitive deficits after cardiac surgery. Here, we use hypobaric oxygenation to reduce dissolved gases in blood and greatly reduce GME delivery during CPB.

METHODS

Variable subatmospheric pressures were applied to 100% oxygen sweep gas in standard hollow fiber microporous membrane oxygenators to oxygenate and denitrogenate blood. GME were quantified using ultrasound while air embolism from the surgical field was simulated experimentally. We assessed end-organ tissues in swine postoperatively using light microscopy.

RESULTS

Variable sweep gas pressures allowed reliable oxygenation independent of carbon dioxide removal while denitrogenating arterial blood. Hypobaric oxygenation produced dose-dependent reductions of Doppler signals produced by bolus and continuous GME loads in vitro. Swine were maintained using hypobaric oxygenation for 4 hours on CPB with no apparent adverse events. Compared with current practice standards of oxygen/air sweep gas, hypobaric oxygenation reduced GME volumes exiting the oxygenator (by 80%), exiting the arterial filter (95%), and arriving at the aortic cannula (∼100%), indicating progressive reabsorption of emboli throughout the CPB circuit in vivo. Analysis of brain tissue suggested decreased microvascular injury under hypobaric conditions.

CONCLUSIONS

Hypobaric oxygenation is an effective, low-cost, common sense approach that capitalizes on the simple physical makeup of GME to achieve their near-total elimination during CPB. This technique holds great potential for limiting end-organ damage and improving outcomes in a variety of patients undergoing extracorporeal circulation.

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.

High postoperative serum cortisol level is associated with increased risk of cognitive dysfunction early after coronary artery bypass graft surgery: a prospective cohort study

Context

Stress response induced by surgery is proposed to play an important role in the pathogenesis of postoperative cognitive dysfunction.

Objective

To investigate the association between postoperative serum cortisol level and occurrence of cognitive dysfunction early after coronary artery bypass graft surgery.

Design

Prospective cohort study.

Setting

Two teaching hospitals.

Patients

One hundred and sixth-six adult patients who were referred to elective coronary artery bypass graft surgery from March 2008 to December 2009.

Intervention

None.

Main Outcome Measures

Neuropsychological tests were completed one day before and seven days after surgery. Cognitive dysfunction was defined using the same definition as used in the ISPOCD1-study. Blood samples were obtained in the first postoperative morning for measurement of serum cortisol concentration. Multivariate Logistic regression analyses were performed to assess the relationship between serum cortisol level and occurrence of postoperative cognitive dysfunction.

Results

Cognitive dysfunction occurred in 39.8% (66 of 166) of patients seven days after surgery. Multivariate Logistic regression analysis showed that high serum cortisol level was significantly associated with the occurrence of postoperative cognitive dysfunction (odds ratio [OR] 2.603, 95% confidence interval [CI] 1.371-4.944, P = 0.003). Other independent predictors of early postoperative cognitive dysfunction included high preoperative New York Heart Association functional class (OR 0.402, 95% CI 0.207-0.782, P = 0.007), poor preoperative Grooved Pegboard test score of nondominant hand (OR 1.022, 95% CI 1.003-1.040, P = 0.020), use of penehyclidine as premedication (OR 2.565, 95% CI 1.109-5.933, P = 0.028), and occurrence of complications within seven days after surgery (OR 2.677, 95% CI 1.201-5.963, P = 0.016).

Conclusions

High serum cortisol level in the first postoperative morning was associated with increased risk of cognitive dysfunction seven days after coronary artery bypass graft surgery.

Cognitive outcomes 7.5 years after angioplasty compared with off-pump coronary bypass surgery

BACKGROUND

Off-pump coronary artery bypass grafting and percutaneous coronary intervention are both associated with cognitive decline, but limited data are available on long-term outcomes. This study compared long-term cognitive outcomes between patients managed with percutaneous coronary intervention and off-pump coronary artery bypass grafting.

METHODS

A multicenter trial in the Netherlands randomized 280 patients to percutaneous coronary intervention or off-pump coronary artery bypass grafting. Cognitive performance 7.5 years after randomization was assessed through a battery of 9 neuropsychologic tests and summarized into a combined Z-score.

RESULTS

After 7.5 years, cognitive assessment could be performed in 81% of the 249 surviving patients. Better cognitive performance was observed in the off-pump coronary artery bypass grafting group (combined Z-score 0.11 for off-pump coronary artery bypass grafting versus -0.17 for percutaneous coronary intervention; difference 0.28, 95% confidence interval 0.08 to 0.47, p < 0.01). However, this difference became nonsignificant (Z-score difference 0.14, 95% confidence interval -0.01 to 0.29, p = 0.08) after multivariable adjustment for potential confounders.

CONCLUSIONS

At 7.5 years follow-up, off-pump coronary artery bypass grafting patients had a similar or perhaps even better cognitive performance compared with percutaneous coronary intervention patients.

Neurocognitive outcomes after cardiac surgery

PURPOSE OF REVIEW

To summarize recent studies of neurocognitive dysfunction after cardiac surgery, as well as to outline efforts and approaches toward advancing the field.

RECENT FINDINGS

Observational studies have improved our understanding of the incidence and the trajectory of cognitive decline after cardiac surgery; however, the magnitude of this neurocognitive change remains controversial because of the inconsistent definitions and the lack of a gold-standard diagnostic modality. Nonetheless, physicians commonly see patients with functional and cognitive impairments after cardiac surgery, which utilize healthcare resources and impact quality of life. Novel approaches have utilized advanced neuroimaging techniques as well as innovative monitoring modalities to improve the efficiency of neuroprotective strategies during cardiac surgery.

SUMMARY

Adverse cognitive and neurologic outcomes following cardiac surgery range from discrete neurocognitive deficits to severe neurologic injury such as stroke and even death. The elderly are at higher risk of suffering these outcomes and the public health dimension of this problem is expected to accelerate. Future studies should combine advanced neuroimaging with genomic, transcriptional, proteomic, and metabolomic profiling to improve our understanding of the pathophysiologic mechanisms and optimize the diagnosis, prevention, and treatment of neurocognitive injury.

Postoperative neurocognitive dysfunction in patients undergoing cardiac surgery after remote ischemic preconditioning: a double-blind randomized controlled pilot study

Background

Remote ischemic preconditioning (RIPC) has been shown to enhance the tolerance of remote organs to cope with a subsequent ischemic event. We hypothesized that RIPC reduces postoperative neurocognitive dysfunction (POCD) in patients undergoing complex cardiac surgery.

Methods

We conducted a prospective, randomized, double-blind, controlled trial including 180 adult patients undergoing elective cardiac surgery with cardiopulmonary bypass. Patients were randomized either to RIPC or to control group. Primary endpoint was postoperative neurocognitive dysfunction 5–7 days after surgery assessed by a comprehensive test battery. Cognitive change was assumed if the preoperative to postoperative difference in 2 or more tasks assessing different cognitive domains exceeded more than one SD (1 SD criterion) or if the combined Z score was 1.96 or greater (Z score criterion).

Results

According to 1 SD criterion, 52% of control and 46% of RIPC patients had cognitive deterioration 5–7 days after surgery (p = 0.753). The summarized Z score showed a trend to more cognitive decline in the control group (2.16±5.30) compared to the RIPC group (1.14±4.02; p = 0.228). Three months after surgery, incidence and severity of neurocognitive dysfunction did not differ between control and RIPC. RIPC tended to decrease postoperative troponin T release at both 12 hours [0.60 (0.19–1.94) µg/L vs. 0.48 (0.07–1.84) µg/L] and 24 hours after surgery [0.36 (0.14–1.89) µg/L vs. 0.26 (0.07–0.90) µg/L].

Conclusions

We failed to demonstrate efficacy of a RIPC protocol with respect to incidence and severity of POCD and secondary outcome variables in patients undergoing a wide range of cardiac surgery. Therefore, definitive large-scale multicenter trials are needed.

Trial Registration

ClinicalTrials.gov NCT00877305

Histopathology of embolic debris captured during transcatheter aortic valve replacement

BACKGROUND

Recent transcatheter aortic valve replacement studies have raised concerns about adverse cerebrovascular events. The etiopathology of the embolized material is currently unknown.

METHODS AND RESULTS

A total of 40 patients underwent transcatheter aortic valve replacement with the use of a dual filter-based embolic protection device (Montage Dual Filter System, Claret Medical, Inc). Macroscopic material liberated during the transcatheter aortic valve replacement procedure was captured in the device filter baskets in 30 (75%) patients and sent for histopathologic analysis. The captured material varied in size from 0.15 to 4.0 mm. Amorphous calcified material (size, 0.55-1.8 mm) was identified in 5 patients (17%). In 8 patients (27%), the captured material (size, 0.25-4.0 mm) contained valve tissue composed of loose connective tissue (collagen and elastic fibers) with focal areas of myxoid stroma, with or without coverage by endothelial cells and intermixed with fibrin. In another 13 (43%) patients, collagenous tissue, which may represent elements of vessel wall and valvelike structures, was identified. In 9 patients (30%), thrombotic material was intermixed with neutrophils (size, 0.15-2.0 mm). Overall, thrombotic material was found in 52% of patients, and tissue fragments compatible with aortic valve leaflet or aortic wall origin were found in 52% (21/40) of patients.

CONCLUSIONS

Embolic debris traveling to the brain was captured in 75% of transcatheter aortic valve replacement procedures where a filter-based embolic protection device was used. The debris consisted of fibrin, or amorphous calcium and connective tissue derived most likely from either the native aortic valve leaflets or aortic wall.

Impact of concomitant coronary artery disease on atherosclerotic plaques in the aortic arch in patients with severe aortic stenosis

BACKGROUND

Coronary artery disease (CAD) often occurs concurrently in patients with severe aortic stenosis (AS). However, the influence of concomitant CAD on the presence of atherosclerotic complex plaques in the aortic arch, which is associated with increased stroke risk, has not been fully assessed in patients with severe AS.

HYPOTHESIS

We hypothesized that concomitant CAD would be associated with the presence of complex arch plaques in patients with severe AS.

METHODS

The study population consisted of 154 patients with severe AS who had undergone transesophageal echocardiography (TEE) and coronary angiography (71 male; mean age, 72 ± 8 years; mean aortic valve area, 0.67 ± 0.15 cm(2) ). Aortic arch plaques were assessed using TEE, and complex arch plaques were defined as large plaques (≥4 mm), ulcerated plaques, or mobile plaques.

RESULTS

The prevalence of aortic arch plaques (87% vs 70%; P = 0.03) and complex arch plaques (48% vs 20%; P < 0.001) was significantly greater in AS patients with CAD than in those without CAD. After adjustment for traditional atherosclerotic risk factors, we found that concomitant CAD was independently associated with the presence of complex arch plaques (odds ratio: 2.86, 95% confidence interval: 1.23-6.68, P = 0.01).

CONCLUSIONS

In patients with severe AS, concomitant CAD is associated with severe atherosclerotic burden in the aortic arch. This observation suggests that AS patients with concomitant CAD are at a higher risk for stroke, and that careful evaluation of complex arch plaques by TEE is needed for the risk stratification of stroke in these patients.

Normothermic cardiopulmonary bypass increases cerebral tissue oxygenation during combined valve surgery: a single-centre, randomized trial

OBJECTIVES

In cardiac surgery, the choice of temperature regimen during cardiopulmonary bypass (CPB) remains a subject of debate. Hypothermia reduces tissue metabolic demands, but may impair the autoregulation of cerebral blood flow and contribute to neurological morbidity. The aim of this study was to evaluate the effect of two different temperature regimens during CPB on the systemic oxygen transport and the cerebral oxygenation during surgical correction of acquired heart diseases.

METHODS

In a prospective study, we randomized 40 adult patients with combined valvular disorders requiring surgical correction of two or more valves into two groups: (i) a normothermic (NMTH) group (n = 20), in which the body core temperature was maintained at 36.6°C during CPB and (ii) a hypothermic (HPTH) group (n = 20), in which the body was cooled to a core temperature of 32°C maintained throughout the period of CPB. The systemic oxygen transport and the cerebral oxygen saturation (SctO2) were assessed by means of a PiCCO2 haemodynamic monitor and a cerebral oximeter, respectively. All the patients received standard perioperative monitoring. We assessed haemodynamic and oxygen transport parameters, the duration of mechanical ventilation and the length of the ICU and the hospital stays.

RESULTS

During CPB, central venous oxygen saturation was significantly higher in the HPTH group but SctO2 was increased in the NMTH group (P < 0.05). Cardiac index, systemic oxygen delivery and consumption increased postoperatively in both groups. However, oxygen delivery and consumption were significantly higher in the NMTH group (P < 0.05). The duration of respiratory support and the length of ICU and hospital stays did not differ between the groups.

CONCLUSIONS

During combined valve surgery, normothermic CPB provides lower central venous oxygen saturation, but increases cerebral tissue oxygenation when compared with the hypothermic regimen.

Cognitive dysfunction after cardiac surgery: Pathophysiological mechanisms and preventive strategies

Despite improvements in surgical techniques and the implementation of effective brain protection strategies, the incidence of brain injury after cardiac surgery has remained relatively constant over the years as patients have become older and sicker. Cognitive dysfunction is the most common clinical manifestation of brain injury after cardiac surgery. Its occurrence is related to a combination of three factors that are often associated with cardiopulmonary bypass (CPB): embolism, hypoperfusion, and the inflammatory response. However, such factors and their potential cerebral consequences are not exclusive to CPB. Postoperative cognitive dysfunction also afflicts patients who undergo cardiac surgery without CPB as well as nonsurgery patients who undergo transcatheter interventions. There is growing evidence that patient-related factors such as the presence of (cerebro)vascular risk factors play an important role in both early and late postoperative cognitive dysfunction.

Open-heart surgery increases cerebrospinal fluid levels of Alzheimer-associated amyloid β

BACKGROUND

Neurocognitive dysfunction occurs frequently after open-heart surgery. It has been suggested that cognitive decline after cardiac surgery with cardiopulmonary bypass (CPB) could be a functional consequence of Alzheimer's disease (AD)-like neuropathological changes. The aim of the present study was to evaluate the cerebrospinal fluid (CSF) levels of amyloid β peptide (Aβ(1-42) ) and soluble fragments of amyloid precursor protein (sAPP) as well as the cerebral inflammatory response to open-heart surgery.

METHODS

Ten patients undergoing aortic valve replacement with CPB were included. CSF was obtained the day before and 24 h after surgery for assessment of CSF levels of Aβ(1-42) α-cleaved sAPP and β-cleaved sAPP (sAPP-β). Furthermore, CSF and serum levels of the inflammatory cytokines: tumour necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) were also assessed.

RESULTS

Cardiac surgery with CPB increased CSF levels of Aβ(1-42) from 447 ± 92 to 641 ± 83 ng/l (P = 0.011), while CSF levels of sAPP-β decreased from 276 ± 35 to 192 ± 21 ng/ml (P = 0.031). CSF levels of TNF-α increased from ≤ 0.60 to 0.79 ± 0.26 ng/l (P = 0.043), IL-6 from 1.89 ± 0.53 to 22.8 ± 6.9 ng/l (P = 0.003) and IL-8 from 39.8 ± 7.8 to 139 ± 18.3 ng/l (P < 0.001).

CONCLUSIONS

Cardiac surgery with CPB causes a profound cerebral inflammatory response, which was accompanied by increased post-operative CSF levels of the AD biomarker Aβ(1-42) . We hypothesize that these changes may be relevant to Alzheimer-associated amyloid build-up in the brain and cognitive dysfunction after cardiac surgery with CPB.

Clinical, methodological and theoretical issues in the assessment of cognition after anaesthesia and surgery: a review

As people live longer, the burden of cognitive impairment to elderly patients, their families and society becomes increasingly common and important. The loss of independence, a reduction in the quality of life and increased mortality are possible correlates to the mental disintegration. Cognitive dysfunction following major surgery on the elderly is a significant problem which adds to other cognitive impairments caused by neurodegeneration, cerebrovascular impairments and other causes. There are challenges in reviewing the literature because of many methodological concerns. There is no standard definition; the diagnosis is made only by the results of neuropsychological tests which are not standardised for this purpose; test results are analysed by different statistical methods (some of them inappropriate); controls are often absent or poorly matched; and pre-existing mild cognitive impairment, which affects 10 to 20% of people older than 65 years and is similar to the subtle cognitive impairment following surgery, is not sought for and recognised. Reviews of the subject have varied from descriptions such as 'a well recognised and significant problem' to 'a hypothetical phenomenon for which there is no International Statistical Classification of Disease (ICD-9) code, and no Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) code'. This article examines both sides of the spectrum in a detailed review which explains the necessary psychological 'jargon', discusses the methods used and points to areas of future research.

Cognitive function after transapical aortic valve implantation: a single-centre study with 3-month follow-up

OBJECTIVES

Reports on adverse neurological events following transcatheter aortic valve implantation (TAVI) have focused on strokes, while more subtle postoperative cognitive decline has not yet been systematically investigated. In this study, we prospectively examined neurological and cognitive outcomes in patients undergoing transapical (TA) and surgical aortic valve replacement (AVR).

METHODS

A total of 64 patients with severe symptomatic aortic stenosis were investigated between January 2008 and July 2009. Clinical neurological examination and comprehensive neuropsychological testing were performed before and after the procedure, at discharge and at 3-month follow-up. Diffusion-weighted magnetic resonance imaging (DW-MRI) was applied to detect morphological brain injury.

RESULTS

TA-TAVI patients (n = 27) were older and at higher surgical risk compared with surgical AVR patients (n = 37; mean age 82.2 ± 4.7 vs 67.5 ± 8.9 years; log EuroSCORE 36.4 ± 13.2 vs 2.6 ± 8.5%, both P <0.001). There was one stroke in each group (3.7 vs 2.7%, P = 0.49), both classified as embolic based on imaging characteristics. After TA-TAVI, cognitive tests showed no decline during follow-up, while, after AVR, 7 of 11 tests showed a decline early after surgery. Similarly, with-in patient analysis showed that the rate of individuals with clinically relevant cognitive decline was increased early after AVR (TA-TAVI vs AVR: 18 vs 46% at discharge [P = 0.03]; 28 vs 6% at 3 months [P = 0.04]). New focal ischaemic cerebral lesions were detected on DW-MRI in 58% (7 of 12) of patients after TA-TAVI vs 34% (12 of 35) after AVR (P = 0.13). The number of brain lesions per patient and cumulative embolic load per patient were similar between groups. An association between postoperative cerebral ischaemia and cognitive dysfunction was not found (odds ratio 2.37, 95% confidence interval 0.05-113.75, P = 0.66).

CONCLUSIONS

Cognitive function was only mildly impaired after TA-TAVI when compared with a marked, albeit transient, decline after surgical AVR. Focal embolic brain injury tended to occur more frequently after TA-TAVI, but this was not related to cognitive decline during the 3-month follow-up.

Review article: cerebral near-infrared spectroscopy in adults: a work in progress

Near-infrared spectroscopy (NIRS) has potential as a noninvasive brain monitor across a spectrum of disorders. In the last decade, there has been a rapid expansion of clinical experience using NIRS to monitor cerebral oxygenation, and there is some evidence that NIRS-guided brain protection protocols might lead to a reduction in perioperative neurologic complications after cardiac surgery. However, there are no data to support the wider application of NIRS during routine surgery under general anesthesia, and its application in brain injury, where it might be expected to have a key monitoring role, is undefined. Although increasingly sophisticated apparatuses, including broadband and time-resolved spectroscopy systems, provide insights into the potential of NIRS to measure regional cerebral oxygenation, hemodynamics, and metabolism in real-time, these innovations have yet to translate into effective monitor-guided brain protection treatment strategies. NIRS has many potential advantages over other neuromonitoring techniques, but further investigation and technological advances are necessary before it can be introduced more widely into clinical practice.

Risk of Stroke After Coronary Artery Bypass Grafting

Background and Purpose—

The risk of stroke after coronary artery bypass grafting (CABG) is known to increase dramatically with age. During recent years, the age of patients operated on has increased and concomitant therapy has changed. Therefore, we have re-evaluated the risk of stroke after CABG.

Methods—

Through the Danish National Hospital Register, we identified all 25 159 patients with isolated CABG from 1997 through 2006. Stroke, comorbidities, and medication were further obtained. Risk factors of stroke were determined through regression models.

Results—

Overall, 1901 patients (7.6%) suffered a stroke after surgery, 477 patients (2.0%) within 30 days after CABG. Rates of stroke per 100 person-years (95% CI) within 30 days after surgery increased with age: <60 years, 10.1 (7.8–13.0); 60 to 64 years, 18.4 (14.3–23.5); 65 to 69 years, 27.7 (23.0–33.3); 70 to 74 years, 36.0 (30.4–42.6); 75 to 79 years, 36.1 (29.1–44.7); ≥80 years, 38.0 (25.2–57.1). Risks of stroke within 30 days after surgery adjusted for age (reference: age <60 years), sex, relevant comorbidities, and selected medication included: 60 to 64 years: HR, 1.7 ( P =0.005; 95% CI, 1.2–2.4), 65 to 69 years: HR, 2.4 ( P =0.001; 95% CI, 1.7–3.3), 70 to 74 years: HR, 2.8 ( P =0.001; 95% CI, 2.1–3.8), 75 to 79 years: HR, 2.8 ( P =0.001; 95% CI, 2.0–4.0), ≥80 years: HR, 3.0 ( P =0.001; 95% CI, 1.8–4.9), previous stroke: HR, 4.2 ( P =0.001; 95% CI, 3.3–5.4), diabetes: HR, 1.3 ( P =0.019; 95% CI, 1.1–1.7), hypertension: HR, 1.4 ( P =0.003; 95% CI, 1.1–1.7), peripheral vascular disease: HR, 1.6 ( P =0.001; 95% CI, 1.3–2.1), renal failure: HR, 1.7 ( P =0.012; 95% CI, 1.1–2.5), statins: HR, 0.8 ( P =0.049; 95% CI, 0.7–1.0), clopidogrel: HR, 0.6 ( P =0.032; 95% CI, 0.4–1.0).

Conclusions—

The increase in stroke with age after CABG is moderate and the relation uncertain in ages older than 70 years. Declining CABG in elderly patients because of risk of stroke purely on the basis of high age is debatable.