Role of patient-specific virtual reality rehearsal in carotid artery stenting.

BACKGROUND: Recent advances in simulation science permit patient-specific rehearsal of endovascular stenting procedures. This study aimed to evaluate how effectively real interventions are replicated by patient-specific rehearsal technology, and to assess its value as a preparatory tool for the interventionalist and the operating team. METHODS: All patients deemed candidates for carotid artery stenting procedures with suitable computed tomography images were enrolled. Each team member rehearsed the virtual procedure in the laboratory, simulated operating theatre or angiography suite environment immediately before treating the real patient. Dexterity and qualitative metrics were recorded. Subjective questionnaires used a Likert scale from 1 (poor) to 5 (excellent). RESULTS: Of 18 patients, three were excluded. In 11 of 15 and 13 of 15 patients respectively endovascular tool use and fluoroscopy angles were identical during rehearsal and the real procedure. In a third of patients, the simulator did not adequately predict difficulties in cannulating the stenotic internal or common carotid arteries. The procedure realism, value in evaluating the case, increase in efficiency in tool use, and potential to increase communication, confidence and team performance were all rated highly (4 of 5). CONCLUSION: Patient-specific rehearsal was rated highly for both face and content validity. Access strategy, endovascular material use and angiographic imaging were all replicated effectively, although certain biomechanical vessel properties seemed to be replicated to a lesser degree. Patient-specific rehearsal constitutes a unique tool that may help tailor endovascular material choice, and optimize the preoperative preparation of the interventionalist and team.

Between-task habituation in functional transcranial Doppler ultrasonography.

We investigated the variability of absolute blood flow velocity (BFV) and task-induced BFV change over consecutive cognitive tasks and compared two methods of baseline determination that are used to calculate relative BFV changes. Bilateral transcranial Doppler ultrasonography recordings of BFV in the middle cerebral arteries was performed in 90 right-handed volunteers during 13 cognitive tasks and their preceding rest periods. Both absolute BFV and elicited BFV changes between rest and activation significantly decreased over successive tasks. Instead of calculating an averaged baseline value, our results suggest that the rest phase immediately preceding the activation phase should be selected for baseline measurement. The between-task habituation effect could be due to a fading of attentional resources during the sustained and demanding performance.

Test-retest reliability of functional transcranial Doppler ultrasonography.

The present study evaluates the reproducibility of lateralised blood flow velocity (BFV) changes measured with transcranial Doppler (TCD) ultrasonography during various cognitive paradigms. A total of 20 right-handed volunteers were confronted twice with 13 verbal and visuospatial tasks, with a time interval of 23 to 71 days. No statistically significant differences were found between the lateralisation indices (left BFV change minus right BFV change) on the first and second examinations. Lateralisation indices of eight tasks showed a significant test-retest reliability (r = 0.61 to 0.83). The reproducibility of cognitively induced lateralised BFV changes appears to be task-dependent. The possible influence from technical, physiological, and psychological factors is discussed. We conclude that functional neuroimaging studies based on blood flow data should preferably select cognitive paradigms that demonstrated sufficient test-retest reliability.

Pre-existing cognitive impairment in candidates for cardiac surgery: an overview.

Until now, little attention has been paid to the preoperative status of the patient awaiting cardiac surgery when investigating the effects of cardiac surgery on cognition. However, there is growing evidence that pre-bypass patients show poorer cognitive function than healthy subjects. This article reviews existing published evidence of poor cognitive function in pre-bypass patients by describing patient characteristics, providing an inventory of affected neurocognitive domains, discussing adequate control groups and proposing potential aetiological mechanisms of neuropsychological dysfunctioning. It is concluded that there is a growing need for future research into this important topic on cognitive dysfunctioning in candidates for coronary artery bypass grafting surgery.

Lateralization of cerebral blood flow velocity changes during cognitive tasks. A simultaneous bilateral transcranial Doppler study.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasonography (TCD) permits the assessment of cognitively induced cerebral blood flow velocity (BFV) changes. We sought to investigate the lateralization of BFV acceleration induced by a variety of cognitive tasks and to determine the influence of age, gender, IQ, and quality of the performance on the relative BFV changes. METHODS: Simultaneous bilateral TCD monitoring of BFV in the middle cerebral arteries (MCAs) was performed in 90 normal right-handed volunteers during 13 verbal and visuospatial tasks and their preceding rest periods. RESULTS: All tasks induced a significant bilateral BFV increase in the MCAs compared with the preceding rest periods. Five verbal tasks showed a significant left-hemispheric BFV acceleration. Linguistic tasks that required active or creative processing of the verbal stimuli, such as sentence construction or word fluency, elicited the most asymmetric response. Five visuospatial tasks revealed a significant right-hemispheric BFV shift. Paradigms that combined visuospatial attention and visuomotor manipulation showed the most lateralized acceleration. Older volunteers (aged >50 years) showed higher relative BFV changes, but lateralization was not influenced by age. Gender, IQ, and performance quality did not reveal significant effects on BFV change. CONCLUSIONS: Bilateral TCD is a noninvasive technique that has the potential to connect the particular change in flow pattern of the MCA distribution with selective cognitive activity and thus offers specific functional information of scientific and clinical value.

Transcranial Doppler ultrasonography monitoring of cerebral hemodynamics during performance of cognitive tasks: a review.

The examination of blood flow velocity (BFV) changes during the performance of mental tasks is one of the applications of transcranial Doppler (TCD) ultrasonography. The purpose of this review is to summarize the results of the functional TCD literature, to investigate the effects of methodological differences between studies, and to provide guidelines for future research. It is concluded that larger series of more homogeneous groups concerning age and handedness, and stricter criteria for subject selection and laboratory setting are required. The implication of quantitative and qualitative performance measures and psychological parameters (motivation, anxiety, and task anticipation) could also yield important information. We recommend future agreement upon a more standardized methodology. TCD promises to be a useful tool to provide further insight into the cerebral organization and temporal reactivity of the human brain.

Effect of cardiovascular disease on hemodynamic response to cognitive activation: a functional transcranial Doppler study.

We compared the cerebrovascular response to various cognitive tasks of cardiovascular patients and healthy controls by using transcranial Doppler ultrasonography (TCD). Cognitive task-induced cerebral blood flow velocity (BFV) changes in 66 candidates for coronary artery bypass graft surgery (mean age 59.4 +/- 7.5) were compared with the functional BFV measurement of 60 healthy controls (mean age 58 +/- 7). Absolute BFV values during baseline and activation were monitored with TCD. Relative increase of the BFV was calculated from the immediately preceding rest period to the following activation. A manova with group (patients versus controls) as between-subjects factor showed no differences in absolute BFV during the rest period. For absolute BFV during activation, a significant difference between the two groups was found. Although for each test the percentage change was smaller in the cardiac group, the difference just failed to reach significance. An explorative multivariate linear regression analysis with the absolute activation and percentage change as dependent variables and coronary risk factors as independent variables revealed no significant predictors. Using functional TCD we found that BFV values during activation were significantly lower in cardiac patients compared with healthy controls. Future research should focus on the possible explanations of this phenomenon.

Personality as independent predictor of long-term mortality in patients with coronary heart disease.

BACKGROUND: Emotional distress has been related to mortality in patients with coronary heart disease (CHD), but little is known about the role of personality in long-term prognosis. We postulated that type-D personality (the tendency to suppress emotional distress) was a predictor of long-term mortality in CHD, independently of established biomedical risk factors. METHODS: We studied 268 men and 35 women with angiographically documented CHD, aged 31-79 years, who were taking part in an outpatient rehabilitation programme. All patients completed personality questionnaire at entry to the programme. We contacted them 6-10 years later (mean 7-9) to find out survival status. The main endpoint was death from all causes. FINDINGS: At follow-up, 38 patients had died; there were 24 cardiac deaths. The rate of death was higher for type-D patients than for those without type-D (23 [27%]/85 vs 15 [7%]/218; p < 0.00001). The association between type-D personality and mortality was still evident more than 5 years after the coronary event and was found in both men and women. Mortality was also associated with impaired left ventricular function, three-vessel disease, low exercise tolerance, and the lack of thrombolytic therapy after myocardial infarction. When we controlled for these biomedical predictors in multiple logistic regression analysis, the impact of type-D remained significant (odds ratio 4.1 [95% CI 1.9-8.8]; p = 0.0004). In this group of CHD patients, type-D was an independent predictor of both cardiac and non-cardiac mortality. Social alienation and depression were also related to mortality, but did not add to the predictive power of type-D. INTERPRETATION: We found that type-D personality was a significant predictor of long-term mortality in patients with established CHD, independently of biomedical risk factors. Personality traits should be taken into account in the association between emotional distress and mortality in CHD.