Cognitive change 5 years after coronary artery bypass surgery

Interpreting studies of cognitive function following cardiac surgery: a guide for surgical teams

Patients with coronary disease and related health care providers are faced with confusing and often conflicting information with regards to the neurocognitive impact of different strategies for coronary revascularization. Studies involving the measurement of postoperative cognitive deficit (POCD) have significant limitations that may ultimately impact on their interpretation and clinical relevance. In this review, we have described the origin of these tests and delineated the rationale for the design of testing that is commonly used in cardiac surgery patients. In general, neurocognitive tests assess domains of memory/new learning, psychomotor speed/dexterity and attentional capacity/mental control. Pre- and post-intervention tests in each domain can be evaluated either by the measurement of mean change scores (Group Comparison Model) for the entire group as continuous data, or by using categorical or continuous data to examine patterns of individual decline (Individual Comparison Model). This latter approach requires a specific definition of what constitutes a decline, which can be criticized as being arbitrary. There are limitations to each of these approaches that necessitate that critical information in trial design is available to the reviewer to facilitate interpretation. For example, the impact of factors such as test/re-test reliability and practice effect can be mitigated by the use of an appropriately chosen control population. Liberal parlance of neurocognitive outcome as a rationale for therapeutic choice must be tempered by wise interpretation of these tests. It is only through the understanding of their limitations and the implications of trial design that we can translate these results to provide the best therapeutic options for our patients in unbiased manner.

Cognitive outcomes three years after coronary artery bypass surgery: relation to diffusion-weighted magnetic resonance imaging

BACKGROUND

Cognitive decline is well recognized early after coronary artery bypass graft surgery (CABG), but controversy exists regarding the degree and duration of these changes. We investigated the course of cognitive performance during 3 years after surgery and determined whether ischemic brain injury detected by diffusion-weighted magnetic resonance imaging was related to cognitive decline.

METHODS

Thirty-nine patients undergoing on-pump CABG completed preoperative neuropsychologic examination and were followed up prospectively at discharge, 3 months, and 3 years after surgery. Cognitive performance was assessed with a battery of 11 standardized psychometric tests assessing 7 cognitive domains. Cognitive outcome was analyzed by determining (1) mean changes in within-patient scores over time (identifying cognitive functions with decline), and (2) the incidence of cognitive deficit for each individual (identifying patients with decline). Objective evidence of acute cerebral ischemia was obtained by diffusion-weighted magnetic resonance imaging. Prospectively collected data were used to identify predictors of cognitive deficits.

RESULTS

From baseline to discharge, cognitive test scores significantly declined in 7 measures. Most tests improved by 3 months. Between 3 months and 3 years, late decline was observed in 2 measures with persistent deterioration in 1 measure (verbal memory) relative to baseline. Postoperative cognitive deficits (drop of > or = 1 SD in scores on > or = 3 tests) were observed in 56% of patients at discharge, 23% at 3 months and 31% at 3 years. On postoperative diffusion-weighted magnetic resonance imaging, there were new ischemic cerebral lesions in 51% of patients. The presence of cognitive deficit at discharge was a significant univariate predictor of late cognitive decline (p = 0.025). A relation between the presence of new diffusion-weighted magnetic resonance imaging detected lesions and cognitive decline, however, was not found.

CONCLUSIONS

Longitudinal cognitive performance of patients with CABG showed a two-stage course with early improvement followed by later decline. Long-term cognitive deficit was predicted by early cognitive decline, but not by ischemic brain lesions on magnetic resonance imaging.

Evaluation of an alternative S100b assay for use in cardiac surgery: relationship with microemboli and neuropsychological outcome

INTRODUCTION

The aim of the study was to investigate the relationship between S100b release, neuropsychological outcome and cerebral microemboli. Peri-operative assay of the astroglial cell protein S100b has been used as a marker of cerebral damage after cardiac surgery but potential assay cross-reactivity has limited its specificity. The present study uses an alternative enzyme-linked immunoabsorbant assay (ELISA) for serum S100b that has documented sensitivity and specificity data in patients undergoing coronary artery bypass grafting (CABG).

METHODS

Fifty-five consecutive patients undergoing routine CABG surgery received serial venous S100b sampling at five time points: i) Pre-operative, ii) At the end of cardiopulmonary bypass (CPB), iii) 6 hrs, iv) 24 hrs and v) 48 hrs post skin closure. A previously described sandwich ELISA with monoclonal anti- S100b was used. This assay has a lower limit of detection of 0.04 microg/L and < 0.006% reactivity with S100a at a concentration of 100 microg/L S100a. Cerebral microemboli during surgery were recorded by transcranial Doppler monitor over the right middle cerebral artery. Evidence of cerebral impairment was obtained by comparing patients' performance in a neuropsychological battery of 9 tests administered 6-8 weeks post-operatively with their pre-operative scores.

RESULTS

There was a significant increase in S100b only at the end of bypass (mean 0.30 microg/L, SD +/- 0.33 and range .00 to 1.57). S100b levels at the end of bypass did not correlate with neuropsychological outcome or microemboli counts.

CONCLUSIONS

The low levels of S100b detected using the present assay, despite its high sensitivity and despite the routine use of cardiotomy suction, suggest that the assay may have higher specificity for cerebral S100b than previously used assays. There was no evidence that this assay is related to neuropsychological change or cerebral microemboli in cardiac surgery.

Occurrence and clinical impact of microembolic signals during or after cardiosurgical procedures

BACKGROUND AND PURPOSE

Microembolic signals (MESs) are detectable within the transcranial Doppler frequency spectrum downstream from vascular atherothrombotic or cardiothrombotic lesions. A frequent occurrence of MESs has also been shown during bypass surgery or after mechanical valve implantation. We sought to compile the knowledge on MES prevalence, the clinical impact of these cardiogenic MESs, and microemboli composition.

SUMMARY OF REVIEW

We performed a systematic MEDLINE search and summarized the currently available literature about MESs during or after cardiosurgical procedures for this state-of-the-art report.

CONCLUSIONS

The nature of cardiogenic MESs is heterogeneous, and their prevalence is highly variable, reflecting their different origin from a broad spectrum of cardiosurgical conditions. The occurrence and number of MESs during cardiac catheterization and percutaneous coronary angioplasty seem to have a clinical impact but need to be explored further. In patients with prosthetic heart valves, in those with left ventricular assist devices, and during cardiac surgery, the occurrence of MESs has an important clinical impact, and MES monitoring has proven its reliability. Although the data encourage intensifying MES detection in cardiac disorders, their heterogeneous nature does not yet allow the use of MESs as a general surrogate parameter for neuronal damage or cardial thromboembolic risk.

Asymptomatic spontaneous cerebral emboli predict cognitive and functional decline in dementia

BACKGROUND

Spontaneous cerebral emboli (SCE) are frequent in Alzheimer's disease (AD) and vascular dementia (VaD). We investigated the effect of SCE on the rates of cognitive and functional decline in AD and VaD.

METHODS

One hundred thirty-two patients with dementia (74 AD, National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association [NINCDS/ADRDA] criteria; 58 VaD, National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences [NINDS/AIREN] criteria) underwent 1-hour transcranial Doppler for detection of SCE (mean [SD] age 75.5 (7.4) years; 46% female). Neuropsychological tests (Mini-Mental State Examination [MMSE], Alzheimer's Disease Assessment Scale-Cognitive subscale [ADAS-Cog], and Neuropsychiatric Inventory [NPI]) and assessment of activities of daily living (Interview for Deterioration in Daily Living Activities in Dementia [IDDD]) were performed initially and 6 months later. SCE positive (SCE+ve, n = 47) and SCE negative (SCE-ve, n = 85) patients were compared using repeated measures analyses of variance (ANOVAs) adjusted for age, gender, and cardiovascular risk factors.

RESULTS

SCE+ve patients with dementia, both AD and VaD, suffered a more rapid decline in cognitive functioning over 6 months (ADAS-cog, mean increase 7.1 for SCE+ve compared with 3.3 for SCE-ve, p = .006) and activities of daily living (IDDD, mean increase 24.4 for SCE+ve compared with 10.8 for SCE-ve, p = .014).

CONCLUSIONS

Asymptomatic SCE are associated with an accelerated cognitive and functional decline in dementia. SCE may be a potentially treatable cause of disease progression in dementia.

Asymptomatic spontaneous cerebral emboli and cognitive decline in a cohort of older people: a prospective study

BACKGROUND

Asymptomatic spontaneous cerebral emboli (SCE) are common in dementia and are associated with cognitive decline in dementia. The significance of their presence in older people is unknown.

METHOD

We included 96 participants (mean (SD) age 76.8 (6.7) years, 46% female) who were the control group in a case-control study to evaluate SCE in dementia. Cognitive functioning was assessed prospectively over 2.5 years, using the MMSE and CAMCOG.

RESULTS

The mean (SD) MMSE score was 28.7 (1.4) at baseline with an average (SD) drop of 0.79 (0.91) per year. The presence of SCE was not related to the annual drop in MMSE score, nor to the CAMCOG score at follow-up (p = 0.88 and p = 0.41, respectively). Linear regression analyses identified higher age in years (beta = 0.29, p = 0.003), history of stroke (beta = 0.31, p = 0.001) and carotid stenosis (beta = 0.28, p = 0.003) as independent predictors of cognitive decline.

CONCLUSION

We found no association between the presence of SCE and subsequent cognitive decline in older people without dementia.

Neuroprotective effect of mild hypothermia in patients undergoing coronary artery surgery with cardiopulmonary bypass: Five-year follow-up of a randomized trial

OBJECTIVE

In a randomized trial of 223 patients undergoing coronary artery surgery with cardiopulmonary bypass, we have reported a neuroprotective effect of mild hypothermia. To determine whether the beneficial effect of mild hypothermia was long-lasting, we repeated the psychometric tests in 131 patients after 5 years.

METHODS

Patients were cooled to 32 degrees C during aortic crossclamping and then randomized to rewarming to either 34 degrees C or 37 degrees C, with no further rewarming until arrival in intensive care unit. Cognitive function was measured preoperatively and 1 week and 5 years postoperatively with a battery of 11 psychometric tests interrogating verbal memory, attention, and psychomotor speed and dexterity.

RESULTS

Patients who had greater cognitive decline 1 week after surgery showed poorer performance 5 years later. The magnitude of cognitive decline over 5 years was modest. The incidence of deficits defined as a 1 standard deviation [SD] decline in at least 1 of 3 factors was not different between temperature groups. Fewer patients in the hypothermic group had deficits that persisted over the 5 years, but this difference did not attain statistical significance (RR = 0.64, P = .16).

CONCLUSIONS

The effect of surgery on cognitive function observed early after surgery is an important predictor of cognitive performance 5 years later. Although there was evidence of a neuroprotective effect of mild hypothermia early after surgery in the original cohort, the results after 5 years were inconclusive. In general, the magnitude of cognitive changes over 5 years was modest. We believe that further trials investigating the efficacy of mild hypothermia in patients having cardiac surgery are warranted.

Predictive value of IL-18 and SC5b-9 for neurocognitive dysfunction after cardiopulmonary bypass

BACKGROUND

Neurological injury after cardiopulmonary bypass (CPB) continues to be a major problem after cardiac surgery. The aim of this study was to investigate the predictive value of Interleukin-18 (IL-18) and SC5b-9 as biochemical markers of neurocognitive dysfunction after cardiac surgery.

METHODS

A total of 30 patients undergoing elective cardiac surgery using CPB were recruited. Blood samples were obtained for IL-18 and SC5b-9 concentrations before induction, 24, 48, 72, 96 and 120 h post-CPB and 6 weeks after operation. In addition, patients underwent a standard battery of neuropsychometric tests before operation and at day 5 and 6 weeks after operation.

RESULTS

Serum concentration of IL-18, but not SC5b-9, was significantly different between patients with and without neurocognitive dysfunction; serum IL-18 concentration significantly increased in patients with neurocognitive dysfunction (P = 0.018). Neurological outcome was significantly dependent on peak difference in IL-18 concentration at day 5 (P = 0.033), but not on peak difference in SC5b-9 concentration (P = 0.16). Eight patients had neurocognitive dysfunction at day 5 and three had neurocognitive dysfunction at 6 weeks. In a very small number of patients, no significant association was demonstrated between IL-18 or SC5b-9 concentrations and neurocognitive dysfunction at 6 weeks.

CONCLUSIONS

IL-18 has the potential as a useful marker of neurological dysfunction, requiring further investigation.

Piracetam Prevents Cognitive Decline in Coronary Artery Bypass: A Randomized Trial Versus Placebo

BACKGROUND

Coronary artery bypass grafting (CABG) can be associated with postoperative cognitive impairment and ischemic stroke. No effective treatment is currently available. The aim of this study was to evaluate the effectiveness of piracetam to treat the cognitive impairment after CABG in an investigator-initiated, double-blind, placebo-controlled, randomized clinical trial.

METHODS

Patients undergoing CABG (n = 98) were randomized to placebo (n = 48) or piracetam (n = 50). Study drugs were administered intravenously (150 mg/kg daily; 300 mg/kg on the day of surgery) from the day before surgery to 6 days after surgery, then orally (12 g/day) up to 6 weeks after surgery. Cognitive function was assessed before surgery (baseline) and 6 weeks after surgery (outcome) by using a battery of 12 neuropsychologic tests. The Spielberger Anxiety Inventory and the Beck Depression Inventory were also administered. The combined score derived from the standardized neuropsychologic assessments was analyzed by using an analysis of covariance with baseline and education as covariates.

RESULTS

Six weeks after surgery, the combined score indicated a statistically significant treatment effect in the per protocol population (1.848, p = 0.041) and a tendency towards statistical significance in the intent-to-treat population (1.624, p = 0.064) in the group treated with piracetam, but no statistically significant treatment effect was seen in the placebo. The state of anxiety measured by the Spielberger Anxiety Inventory was decreased in both groups (-9.27 and -6.37 in the placebo and piracetam groups, respectively).

CONCLUSIONS

Six weeks after CABG, cognition was significantly improved in patients treated with piracetam. Additional trials are required to confirm these effects.

Central nervous system injury associated with cardiac surgery

Millions of individuals with coronary artery or valvular heart disease have been given a new chance at life by heart surgery, but the potential for neurological injury is an Achilles heel. Technological advancements and innovations in surgical and anaesthetic technique have allowed us to offer surgical treatment to patients at the extremes of age and infirmity-the group at greatest risk for neurological injury. Neurocognitive dysfunction is a complication of cardiac surgery that can restrict the improved quality of life that patients usually experience after heart surgery. With a broader understanding of the frequency and effects of neurological injury from cardiac surgery and its implications for patients in both the short term and the long term, we should be able to give personalised treatments and thus preserve both their quantity and quality of life. We describe these issues and the controversies that merit continued investigation.

Predictors of early neurocognitive deficits in low-risk patients undergoing on-pump coronary artery bypass surgery

BACKGROUND

Postoperative cognitive deficits (POCDs) are a source of morbidity and occur frequently even in low-risk patients undergoing cardiac surgery. Predictors of neurocognitive deficits can identify potentially modifiable risk factors as well as high-risk patients in whom alternate revascularization strategies may be considered.

METHODS AND RESULTS

448 patients undergoing coronary surgery (coronary artery bypass graft [CABG]) underwent standardized preoperative and postoperative neurocognitive testing as part of 2 randomized trials evaluating the effects of mild hypothermia during coronary surgery. Prospectively collected data were used to identify univariate predictors of POCDs and multivariable logistic regression models were constructed. Models were bootstrapped 1000 times. POCDs occurred in 59% of patients. Significant univariate predictors included intraoperative normothermia, impaired left ventricular (LV) function, higher educational level, elevated serum creatinine and reduced creatinine clearance, prolonged intubation time, intensive care unit (ICU) stay, and hospital stay. Advanced age, presence of carotid disease, and cardiopulmonary bypass time were not associated with increased POCDs in this cohort. Multivariable modeling identified intraoperative normothermia (odds ratio [95% confidence interval] -1.15 [1.01, 1.31]), poor LV function (1.53 [1.02, 2.30]), and elevated preoperative creatinine (1.01 [1.00 to 1.03] for every 1 mmol/L increase), prolonged (>24 hours) ICU stay (1.88 [1.27 to 2.79]), and higher educational level (1.52 [1.01 to 2.28]) as independent predictors of POCD occurrence.

CONCLUSIONS

Mild hypothermia, in the intraoperative and perioperative period, may be a protective strategy for the prevention of POCDs. Patients with elevated pre-operative creatinine and poor LV function carry a higher risk of POCDs and may benefit from revascularization strategies other than conventional on-pump CABG.

Quantitative methods for tracking cognitive change 3 years after coronary artery bypass surgery

The analysis and interpretation of change in cognitive function test scores after coronary artery bypass grafting (CABG) present considerable statistical challenges. Application of hierarchical linear statistical models can estimate the effects of a surgical intervention on the time course of multiple biomarkers. We use an "analyze then summarize" approach whereby we estimate the intervention effects separately for each cognitive test and then pool them, taking appropriate account of their statistical correlations. The model accounts for dropouts at follow-up, the chance of which may be related to past cognitive score, by implicitly imputing the missing data from individuals' past scores and group patterns. We apply this approach to a study of the effects of CABG on the time course of cognitive function as measured by 16 separate neuropsychological test scores, clustered into 8 cognitive domains. The study includes measurements on 140 CABG patients and 92 nonsurgical controls at baseline, and at 3, 12, and 36 months. Our "analyze then summarize" method allows us to identify differences between the treatment groups in individual tests as well as in aggregate measures. It takes into account the correlation structure of the data and thereby produces more precise results than summarizing before analyzing. The methods used have application to a wide range of intervention studies in which multiple biomarkers are followed over time to quantify health effects. Software to implement the methods in the R statistical package is available from the authors at http://www.biostat.jhsph.edu/sbarry/software/ATSrcode.pdf.

Use of a large bore syringe creates significantly fewer high intensity transient signals (HITS) into a cardiopulmonary bypass system than a small bore syringe

INTRODUCTION

High intensity transient signals (HITS) have been reported to occur following perfusionist intervention during cardiac surgery. This study investigates the relationship of the syringe bore, injection rate, and HITS created.

METHODS

Syringes (10 mL) with a male luer-lock connection (Large Bore) and Abboject 'jet syringes' with a 20 GA needle and male luer-lock connector (Small Bore) were filled with 10 mL of 0.9 N saline. A perfusionist was randomly assigned a set of four similar syringes followed by the other syringe bore. Each of the four syringes was injected into an in vitro saline-primed cardiopulmonary bypass (CPB) system over 5, 10, 15, or 20 sec. Sixteen randomizations of small and large bore syringes were completed at the four injection times (128 injections). HITS in the CPB arterial line were detected with transcranial Doppler (TCD) probes, were recorded for the 2 min following the injection, and were counted independently off-line by two reviewers.

RESULTS

The use of a large bore syringe compared to a small bore syringe created significantly fewer HITS (29 +/- 6 versus 145 +/- 17 [mean +/- SEM], p<0.001) introduced into the CPB arterial line. Injection over a longer time produced significantly fewer HITS than shorter injection times (p<0.001).

CONCLUSION

Significantly fewer HITS are introduced into the CPB system by using standard syringes and slower injection time.

Cerebral emboli as a potential cause of Alzheimer's disease and vascular dementia: case-control study

OBJECTIVE

To compare the occurrence of spontaneous cerebral emboli and venous to arterial circulation shunts in patients with Alzheimer's disease or vascular dementia and controls without dementia.

DESIGN

Cross sectional case-control study.

SETTING

Secondary care old age psychiatry services, Manchester.

PARTICIPANTS

170 patients with dementia (85 with Alzheimer's disease, 85 with vascular dementia) and 150 age and sex matched controls. Patients on anticoagulant treatment, patients with severe dementia, and controls with marked cognitive impairment were excluded.

MAIN OUTCOME MEASURES

Frequencies of detection of spontaneous cerebral emboli during one hour monitoring of the middle cerebral arteries with transcranial Doppler and venous to arterial circulation shunts by a transcranial Doppler technique using intravenous microbubbles as an ultrasound contrast.

RESULTS

Spontaneous cerebral emboli were detected in 32 (40%) of patients with Alzheimer's disease and 31 (37%) of those with vascular dementia compared with just 12 each (15% and 14%) of their controls, giving significant odds ratios adjusted for vascular risk factors of 2.70 (95% confidence interval 1.18 to 6.21) for Alzheimer's disease and 5.36 (1.24 to 23.18) for vascular dementia. These spontaneous cerebral emboli were not caused by carotid disease, which was equally frequent in dementia patients and their controls. A venous to arterial circulation shunt indicative of patent foramen ovale was found in 27 (32%) Alzheimer's disease patients and 25 (29%) vascular dementia patients compared with 19 (22%) and 17 (20%) controls, giving non-significant odds ratios of 1.57 (0.80 to 3.07) and 1.67 (0.81 to 3.41).

CONCLUSION

Spontaneous cerebral emboli were significantly associated with both Alzheimer's disease and vascular dementia. They may represent a potentially preventable or treatable cause of dementia.

Cognitive and neurobehavioral dysfunction after cardiac bypass procedures

From a cognitive standpoint, CABG as currently practiced appears to be safe for the great majority of patients, but transient changes involving memory, executive functions, and motor speed may still occur in a subset of patients during the first few days to weeks after CABG. The etiology most likely is multifactorial and includes a synergistic effect of microemboli, hypo-perfusion, and other variables associated with major surgery. Older age and degree of pre-existing cerebrovascular disease have been identified as important risk factors. The short-term cognitive changes appear to be reversible by 3 months after surgery for most patients. Late cognitive decline after CABG,occurring between 1 and 5 years after the surgery, has been well documented,but controlled studies demonstrating that this decline is specifically attributable to the use of cardiopulmonary bypass itself rather than to progression of underlying cerebrovascular disease or other age-related changes are pending.

Cardiopulmonary Rehabilitation and Cancer Rehabilitation. 1. Cardiac Rehabilitation Review

Cardiac rehabilitation includes not only the rehabilitation of people with ischemic heart disease but also those with congestive heart failure, heart transplantation, congenital heart disease, and other conditions. New advances in medical treatment have arisen, and there are new approaches in treatment, including alternative medicine and complementary care. New surgical approaches that help restore cardiac function have also been introduced, and rehabilitation professionals must be aware of these advances and be able to incorporate this knowledge into the practice of rehabilitation medicine.

OVERALL ARTICLE OBJECTIVES

(a) To identify major categories of cardiac disease, (b) to elucidate appropriate interventions and support for patients with coronary artery disease, (c) to describe the new interventions available for the treatment of cardiac disease, and (d) to describe the appropriate role of cardiac rehabilitation for people with various forms of cardiac disease.

Neural correlates of cognitive dysfunction after cardiac surgery

Patients who underwent cardiac surgery and their relatives often complain on postoperative memory impairment. Most prospective neuropsychological studies also found postoperative cognitive decline early after surgery. Nevertheless, recently several reports questioned the existence of long-term brain alterations in these patient cohorts. The present review was aimed to clear up the true cardiac surgery effects on brain and cognitive functions. The reviewed data evidence that cardiac surgery interventions induce persistent localized brain ischemic lesions along with rapidly reversing global brain swelling and decreased metabolism. A range of studies showed that left temporal region was especially prone to perioperative ischemic injury, and these findings might explain persistent verbal short-term memory decline in a considerable proportion of cardiac surgery patient cohorts. Speed/time of cognitive performance is commonly decreased early after on-pump surgery either. Nevertheless, no association between psychomotor speed slowing and intraoperative embolic load was found. The rapid recovery of the latter cognitive domain might be better explained by surgery related acute global brain metabolism changes rather than ischemic injury effects. Hence, analyses of performance on separate cognitive tests rather than summarized cognitive indexes are strongly recommended for future neuropsychological studies of cardiac surgery outcomes.

Cognitive Outcomes Three Years After Coronary Artery Bypass Surgery: A Comparison of On-Pump Coronary Artery Bypass Graft Surgery and Nonsurgical Controls

BACKGROUND

Coronary artery bypass grafting has been associated with both early and late postoperative cognitive decline, but interpretation of previous studies has been limited by lack of appropriate control groups. We compared changes in cognitive performance from baseline to 3 years in patients undergoing coronary artery bypass grafting with those of a control group of patients with known risk factors for coronary artery disease but without surgery.

METHODS

Patients undergoing coronary artery bypass grafting (n = 140) and a demographically similar nonsurgical control group with coronary artery disease (n = 92) completed baseline neuropsychological assessment and were followed up prospectively at 3, 12, and 36 months. Cognitive performance was assessed with a battery of neuropsychological tests, measuring the cognitive domains of attention, language, verbal and visual memory, visuospatial, executive function, and psychomotor and motor speed. The statistical analyses were performed in two ways: using data from all tested individuals, and using a model imputing missing observations for individuals lost to follow-up.

RESULTS

Both the coronary artery bypass grafting and nonsurgical control groups improved from baseline to 1 year, with additional improvement between 1 and 3 years for some cognitive tests. The coronary artery bypass grafting group had statistically significantly greater improvement than the nonsurgical controls for some subtests, and had a comparable longitudinal course for the remainder of the subtests. Both study groups had a trend toward nonsignificant decline at 3 years on some measures, but the overall differences between groups over time were not statistically significant.

CONCLUSIONS

Prospective longitudinal neuropsychological performance of patients with coronary artery bypass grafting did not differ from that of a comparable nonsurgical control group of patients with coronary artery disease at 1 or 3 years after baseline examination. This finding suggests that previously reported late cognitive decline after coronary artery bypass grafting may not be specific to the use of cardiopulmonary bypass, but may also occur in patients with similar risk factors for cardiovascular and cerebrovascular disease.

Perioperative Microembolism is not Associated with Cognitive Outcome Three Months after Carotid Endarterectomy

OBJECTIVE

To investigate the association between perioperative microembolism and cognitive outcome 3 months after carotid endarterectomy (CEA).

DESIGN

Prospective study.

MATERIALS AND METHODS

Patients were tested 1 day before and 3 months after surgery with neuropsychological tests measuring a wide range of cognitive functions. Number of microemboli was monitored with transcranial Doppler ultrasonography in 58 patients during the operation and in a random subgroup of 27 patients directly following the procedure.

RESULTS

Forty patients (69%) had intraoperative embolism, varying from 1 to 33 isolated microemboli and/or 1 to 11 embolic showers. Postoperative emboli were present in 22 of the 27 patients (81%), ranging from 1 to 142 isolated microemboli. More than 10 microemboli (including showers) were detected in 13 patients (22%) intraoperatively and in 6 patients (22%) postoperatively. Twenty-two patients (38%) showed deterioration in three or more cognitive function variables at 3 months. There were no significant associations between any cognitive change or deterioration score and presence or number of intraoperative and/or postoperative emboli.

CONCLUSIONS

The degree of microembolism during and immediately following CEA is generally small and seems to be of no significance with respect to postoperative cognitive functioning. Future research should include a larger group of patients to allow reliable subgroup analysis.

Neurocognitive outcomes: the year in review

PURPOSE OF REVIEW

This review is a survey of the recent literature investigating the etiology and the relative incidence of postoperative neurological and cognitive dysfunction after cardiac surgery.

RECENT FINDINGS

Several studies reviewed here have employed transcranial Doppler for detection of cerebral emboli and compared results between patients undergoing beating-heart versus conventional cardiopulmonary bypass. A transcranial Doppler device ostensibly discriminating between particulate and gaseous emboli has additionally been employed, yet despite a consistently lower incidence of cerebral emboli associated with avoidance of cardiopulmonary bypass, several groups have reported similar incidences of cognitive dysfunction across these procedures, suggesting other, potentially more important, factors. Two recent studies have focused on the hazards associated with perioperative anemia in both infants and older patients, and which can result in developmental delay or profound changes in cerebral blood flow. A further study has identified an adverse interaction with postoperative hypoxia. The use of intraortic filtration for capture and removal of particulate macroemboli has been associated with a reduction in the incidence of clinically apparent central-nervous-system injury and should be further investigated. Several other studies identify pre-existing levels of central-nervous-system impairment prior to surgery, underscoring the confounding issues introduced by the failure to include a non-surgical comparator group.

SUMMARY

While further evidence of cerebral embolization continues to accrue, several studies suggest that other factors may be of equal or greater importance in cognitive dysfunction. Further investigations into the role of perioperative anemia, co-incident hypoxemia and other aspects of perioperative care, e.g. hyperglycemia and postoperative hyperthermia, are warranted.

Neurocognitive complications after coronary artery bypass surgery

Both short- and long-term cognitive changes continue to occur after coronary artery bypass grafting (CABG), but the pathophysiology of these neurobehavioral changes remains incompletely understood. The persistence of mild postoperative neurocognitive changes despite multiple improvements in the cardiopulmonary bypass procedure may be partially because of surgical populations being older and having more prevalent comorbid disease. The cause of the early postoperative changes is most likely multifactorial and may include ischemic injury from microemboli, hypoperfusion, and other factors resulting from major surgery. Several lines of evidence suggest that the late cognitive decline between 1 and 5 years after surgery may be secondary to high rates of cerebrovascular disease among candidates for CABG. A history of hypertension and other risk factors for vascular disease is known to be associated with increased risk for long-term cognitive decline in community-dwelling elderly individuals. Cerebrovascular risk factors are also associated with silent magnetic resonance imaging abnormalities in patients undergoing CABG. Thus, whereas both short- and long-term postoperative cognitive changes have been associated with CABG, only the short-term, transient changes appear to be directly related to the use of cardiopulmonary bypass.

Introduction to the Special Section on Health and Cognitive Function

Numerous factors related to health and diseases have been studied in relation to cognitive function. It has been shown that across the life span, systemic medical diseases can negatively impact cognitive function. Factors that influence the development of medical diseases, such as poor health habits, biological risk factors, hormones, genetic factors, exposure to environmental toxins, and certain treatments for disease, can also have an adverse effect on cognitive function. Conversely, factors such as high levels of education, good health habits, and some treatments for disease can be protective. Included in this special section are 6 empirical articles that examine the relation of health or disease to cognitive function.