The effect of CABG on neurocognitive functioning.

Post-operative cognitive decline occurs in 20-70% of the coronary artery bypass surgery patients during the first week after surgery. After 6 weeks the incidence declines to 10-40% and remains at this level thereafter.Although the neuropsychological consequences are subclinical, they can interfere with daily life. In this paper, we discuss the impact of surgical factors, with a focus on the use of the heart-lung machine and its intra-operative embolic load. The pre-morbid cardiac condition of the patient as another underlying mechanism for cognitive decline is addressed. We also describe the methodological pitfalls in arriving at an adequate estimation of the prevalence of cognitive decline. Among these are the definition of cognitive decline, testing intervals, the choice of cognitive domains and the appropriate use of control groups.We also pay attention to the relation between cognition, depression and anxiety. Finally, the ecological validity of this study domain is discussed. It is concluded that (1) the literature remains undecided on the role of intra-operative emboli and cognitive decline after surgery. Researchers should focus on the composition, size and location instead of the absolute number of intra-operative emboli; (2) growing awareness of neurocognitive decline in chronic vascular disease patients must challenge both clinicians and investigators.The preoperative cognitive status can increase the risk for post-operative cognitive decline; (3) researchers should include--at the least--the core battery as stated in the Statement of Consensus on assessment of neurobehavioural outcomes after cardiac surgery. They also should work towards a consensus on the definition of cognitive decline and the definition of control groups; (4) depression and anxiety as confounders for postoperative cognitive decline might lead to an overestimation of cognitive decline at least for the majority of neuropsychological domains; (5) much more attention should go to the ecological validity of this research.

Variation in brain lateralization during various language tasks: a functional transcranial Doppler study.

Language dominance has repeatedly been demonstrated by means of functional transcranial Doppler (fTCD) ultrasonography. However, one strongly lateralizing paradigm might be an overestimation of overall language lateralization. We hypothesized that significant differences between hemodynamic patterns could be shown by using multiple language functions (such as productive and receptive tasks). Particularly, we expected more left-hemispheric activity in frontal and productive tasks and we expected less clear left-hemispheric activity in temporal regions and receptive tasks. Thirty healthy volunteers were included in the study. The lateralization index (LI) was measured with transcranial Doppler ultrasonography for each subject during four language tasks: a cued word generation task (WF), a sentence construction task (SENT), a reading task (READ), and a semantic decision task (SEMANT). Left-hemispheric dominance was found in 90%, 80%, 73.3% and 66.7% of the subjects for respectively WF, SENT, READ and SEMANT. A repeated measures analysis of variance revealed significant differences in LIs between the different language tasks (p<.01). Our results showed that productive and syntactic tasks (WF and SENT) lateralize stronger than receptive tasks (READ and SEMANT). The use of a variety of language tasks in the determination of language lateralization therefore appears to be essential in providing a more comprehensive view of language functioning.

Depression, anxiety, and neuropsychological performance in coronary artery bypass graft patients: a follow-up study.

BACKGROUND: Undergoing coronary-artery bypass surgery (CABG) remains a significant life-event, with an important psycho-emotional impact on patients and their families. OBJECTIVE: The authors examined the incidence and course of depression and anxiety in CABG patients before and after surgery. METHOD: The long-term relationship between mood disorders and neuropsychological deficits was studied 1 day before and 6 days (N=53), 6 months (N=37), and 3-5 years (N=43) after the procedure. RESULTS: Before surgery, one-third of the patients showed mild-to-moderate cognitive-affective symptoms of depression. After surgery, one-fourth still showed elevated depression scores, whereas anxiety was significantly decreased at all post-operative time-points. Patients with higher pre-operative symptoms of depression showed sustained feelings of depression after surgery. Visuomotor performance was most affected by mood. CONCLUSION: Data indicated that patients with preoperative moderate cognitive-affective depression could be at risk for sustained feelings of depression even up to 5 years after surgery.

Neuropsychological functioning 3-5 years after coronary artery bypass grafting: does the pump make a difference?

OBJECTIVE: Neurocognitive sequelae after coronary artery bypass grafting (CABG) are frequently reported. The present study investigated the possible difference between on- and off-pump CABG patients in a long-term perspective. METHODS: We administered seven standardized neuropsychological tests 1 day before, 6 days after, 6 months after and 3-5 years after CABG. We measured intra-operative high intensity transient signals (HITS) as a reflection of embolic load by transcranial Doppler ultrasonography. RESULTS: Of the 74 patients originally recruited, 54 of the patients (73%) (mean age 59 years+/-7.5 years) completed the neuropsychological battery. Cognitive decline was defined as 20% decline on two or more tests. Three to 5 years after the operation, 30% of the patients showed neurocognitive problems in domains of non-verbal immediate memory and attention, speed for visual search, visual attention and mental flexibility. Neither difference in frequency of cognitive dysfunction nor a difference in evolution over the 5 year time period between on- and off-pump patients was observed. No significant predictors for cognitive decline were found. CONCLUSIONS: Three to 5 years after the CABG surgery no difference in neurocognitive deficits is found between on- and off-pump CABG patients, indicating that the extracorporeal circulation (ECC) may not be the main cause of late neuropsychological decline.

Relation between neurocognitive impairment, embolic load, and cerebrovascular reactivity following on- and off-pump coronary artery bypass grafting.

OBJECTIVES: To evaluate the effect of on-pump and off-pump coronary artery bypass grafting (CABG) on postoperative cognitive impairment and cerebrovascular reactivity, with attention for the perioperative high-intensity transient signals (HITS). DESIGN: A prospective comparative study. SETTING: Urban university hospital. PATIENTS: Candidates for cardiac surgery. METHODS: Measurement of HITS as a reflection of embolic load was performed in 50 patients (on-pump CABG, n = 32; off-pump CABG, n = 18). To measure cognitively induced cerebrovascular reactivity, cerebral blood flow velocity (BFV) was measured preoperatively in 66 patients, early postoperatively (after 6 days) in 63 patients, and late postoperatively (after 6 months) in 44 patients during five cognitive tasks. In the same session, seven standardized neuropsychological tests were administered. RESULTS: A higher embolic load was found in the on-pump group (p < 0.01). In the on-pump group, aortic cannulation was the most important HITS-prone surgical maneuver. Repeated-measures multivariate analysis of variance (using surgical technique as between-subjects factor and significant differences between both groups as covariates) on the group data revealed no significant differences in neuropsychological performance and BFV immediately after surgery or at 6 months after surgery, compared with preoperative performance. No main effect of surgery was found for neuropsychological performance and BFV. No significant correlations were found between the number of HITS and the degree of postoperative neuropsychological impairment. Individual comparisons revealed that 60% (59.4% in the on-pump group; 61.1% in the off-pump group) of the patients undergoing CABG showed evidence of cognitive impairment soon after surgery. In 24.2%, the cognitive sequelae persisted at 6 months follow-up (31.8% in the on-pump group; 9.1% in the off-pump group). The cognitive impairment index (sum of impaired neuropsychological tests) showed a significant difference after 6 months between both surgery groups with fewer neurocognitive tests that remained impaired in the off-pump group. CONCLUSIONS: In off-pump surgery, significantly fewer HITS were observed. On an individual level, more favorable results in neuropsychological test performance were demonstrated in the off-pump group after 6 months. The number of HITS showed no correlation with degrees of early and late postoperative neuropsychological impairment.

Cerebral hemodynamics during discrimination of prosodic and semantic emotion in speech studied by transcranial doppler ultrasonography.

Simultaneous measurement of blood flow velocity (BFV) in the middle cerebral arteries was achieved by transcranial Doppler ultrasonography in 36 right-handed volunteers who were instructed to identify the emotion conveyed by prosody or semantics of a number of sentences. The tasks were performed under 2 levels of interference: neutral versus discordant affective value of the modality that had to be ignored. A multivariate analysis of variance showed a significant bilateral increase in BFV during the discordant conditions reflecting increased attentional demand. A significant left-hemispheric lateralization of BFV was observed as emotional semantics were labeled. When attention was shifted to affective prosody, the lateralization effect disappeared as a result of a marked increase in right-hemispheric BFV.

Short-term and long-term neurocognitive outcome in on-pump versus off-pump CABG.

OBJECTIVE: Neuropsychological dysfunctions are considered to be important complications of coronary artery bypass graft surgery (CABG). We examined the frequency of neuropsychological abnormalities occurring in patients undergoing CABG with (on-pump) and without (off-pump) cardiopulmonary bypass. METHODS: Neuropsychological assessment with seven cognitive tasks was performed one day before, 6-7 days after (n=49) and 6 months after (n=35) surgery. The subgroup undergoing on-pump surgery (n=30 at 7 days and n=22 at 6 months) was demographically comparable to the off-pump subgroup. The on-pump group included more multiple vessel disease. RESULTS: Repeated measures multivariate analysis of variance (using surgical group as a between-subjects factor) on the group data revealed no significant differences neither immediately after surgery nor at 6 months after surgery, compared with the preoperative performance. There were no significant differences between the on-pump and off-pump groups in post-operative neuropsychological performance soon after surgery. A significant difference was found between the two groups 6 months after surgery, with more favorable results for the off-pump group. Individual comparisons revealed that 59% of the patients of both groups undergoing CABG showed evidence of cognitive impairment soon after surgery. In 11% of the patients (all on-pump), the cognitive sequelae persisted at follow-up. CONCLUSION: This study showed no short-term difference between the on-pump and off-pump CABG groups. The long-term cognitive outcome revealed more favorable results for the off-pump group. Although a preference to operate multiple vessel disease with classical cardiopulmonary bypass (CPB) has to be considered, the present study shows evidence for a different pattern of early decline and late recovery of cognitive functions in patients undergoing CABG with and without CPB.

Reliability and validity of day-to-day blood flow velocity reactivity in a single subject: an fTCD study.

To evaluate the within-subject variability of repeated task-induced blood flow velocity (BFV) change, we measured the haemodynamics of the anterior and middle cerebral arteries of the same volunteer on 20 consecutive working days during the performance of mental arithmetic with transcranial Doppler ultrasonography. BFV changes with the arithmetic condition were compared against a resting and a counting condition. Absolute BFV data showed equally increased velocities during rest and arithmetic activity as compared to counting. The findings suggest that the resting state might not be the ideal reference paradigm to evaluate task-induced haemodynamic changes. Selecting the counting condition as the more valid baseline measure, we obtained relatively stable lateralisation indices for the MCA with 1 of 10 measurements outside the 95% confidence interval. Reproducibility was poorer in the ACA, with 3 outliers. A strategy that calculates the average of multiple short activation epochs within the same session appears to improve the reliability of the lateralisation index.