Evaluation of neurologic assessment and outcomes in cardiac surgical patients

Cognitive Function After Carotid Artery Revascularization

Clinical investigations designed to contrast the efficacy of carotid endarterectomy (CEA) versus best medical therapy and CEA versus carotid artery stenting (CAS) in patients with carotid artery stenosis have been based on the traditional endpoints of stroke, myocardial infarction, and death. Cognitive function is being increasingly recognized as an important outcome measure that affects patient well-being and functional status. However, it has not been evaluated systematically in the context of carotid revascularization. A decline in cognitive function could occur from microembolic ischemia during surgical dissection (CEA) or intravascular instrumentation (CAS). It could also occur from hypoperfusion during clamping (CEA) or balloon dilation (CAS). Conversely, restoring perfusion could improve cognitive dysfunction that might have occurred from a state of chronic hypoperfusion. It is still unclear whether these complex interactions ultimately result in a net improvement or a deterioration of cognitive function. Furthermore, it is not known whether the 2 methods of carotid revascularization have a differential effect on cognitive outcomes. It is becoming increasingly clear, though, that there is a positive relationship between improvement in cognition and improvement in functional outcome of patients. Vascular surgeons will be well served to remain informed and even actively engaged in the development of this field if they wish to continue providing the high-quality, well-informed care they have traditionally offered to patients with carotid stenosis.

Influence of pericardial suction blood retransfusion on memory function and release of protein S100B

Background: To study the influence of pericardial suction blood (PSB) on postoperative memory disturbances and release patterns of protein S100B during and after cardiopulmonary bypass (CPB).

Methods: Sixty male patients admitted for coronary artery bypass surgery were prospectively randomized to receive PSB either by using conventional cardiotomy suction retransfusion or after cell-saver processing.

Results: The concentration of S100B rose during the period of CPB from 0.065±0.004 to 0.24±0.001 mg/L (p<0.001). PSB contained 18.0±1.7 mg/L of S100B. Direct retransfusion from the cardiotomy reservoir made the systemic level increase to 1.42±0.19 mg/L compared to 0.25±0.02 mg/L using a cell-saver. Signs of postoperative memory dysfunction (> 1 SD) were discovered in one of three tests, but were unrelated to technique of retransfusion. No associations were found between serum concentrations of S100B and memory function.

Conclusion: In this study, retransfusion of PSB during cardiac surgery appeared not to cause memory disturbances. PSB contained high concentrations of protein S100B making its use as a marker of cerebral injury unsuitable.

Circulatory bubble dynamics: from physical to biological aspects

Bubbles can form in the body during or after decompression from pressure exposures such as those undergone by scuba divers, astronauts, caisson and tunnel workers. Bubble growth and detachment physics then becomes significant in predicting and controlling the probability of these bubbles causing mechanical problems by blocking vessels, displacing tissues, or inducing an inflammatory cascade if they persist for too long in the body before being dissolved. By contrast to decompression induced bubbles whose site of initial formation and exact composition are debated, there are other instances of bubbles in the bloodstream which are well-defined. Gas emboli unwillingly introduced during surgical procedures and ultrasound microbubbles injected for use as contrast or drug delivery agents are therefore also discussed. After presenting the different ways that bubbles can end up in the human bloodstream, the general mathematical formalism related to the physics of bubble growth and detachment from decompression is reviewed. Bubble behavior in the bloodstream is then discussed, including bubble dissolution in blood, bubble rheology and biological interactions for the different cases of bubble and blood composition considered.

Cognitive changes after surgery vs stenting for carotid artery stenosis

OBJECTIVES

Cognitive function has not been evaluated systematically in the context of carotid endarterectomy (CEA) versus carotid artery stenting (CAS). Cognitive decline can occur from microembolization or hypoperfusion during CEA or CAS. Carotid revascularization may, however, also improve cognitive dysfunction resulting from chronic hypoperfusion. We compared cognitive outcomes in consecutive asymptomatic patients undergoing CAS or CEA.

METHODS

This is a prospective nonrandomized single-center study of patients with asymptomatic carotid stenosis ≥ 70% undergoing CAS or CEA using standard techniques. Neurologic symptoms were evaluated by history, physical examination, and the National Institutes of Health Stroke Scale. A 50-minute cognitive battery was performed 1 to 3 days before and 4 to 6 months after CEA/CAS. The tests (Trail Making Tests A/B, Processing Speed Index (PSI) of the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III), Boston Naming Test, Working Memory Index (WMI) of the Wechsler Memory Scale - Third Edition (WMS-III), Controlled Oral Word Association, and Hopkins Verbal Learning Test) for six cognitive domains (motor speed/coordination and executive function, psychomotor speed, language (naming), working memory/concentration, verbal fluency, and learning/memory) were conducted by a neuropsychologist. The primary analysis of impact of treatment modality was a normalized cognitive change score.

RESULTS

Forty-six patients underwent prepost testing (CEA = 25, CAS = 21). Women comprised 36% of the cohort, mean preprocedural stenosis was 84%, and 54% were right-sided lesions. All patients were successfully revascularized without periprocedural complications. The scores for each test improved after CEA except WMI, which decreased in 20 of 25 patients. Improvement occurred in all tests after CAS except PSI, which decreased in 18 of 21 patients. In addition to comparing the changes in individual test scores, overall cognitive change was measured by calculating the change in composite cognitive score (CCS) postprocedure versus baseline. To compute the CCS, the raw scores from each test were transformed into z scores and then averaged to calculate each patient's composite score. The composite score at baseline was then compared with that from the postprocedure testing. The CCS improved after both CEA and CAS, and the changes were not significantly different between the groups (.51 vs .47; P = NS).

CONCLUSIONS

Carotid revascularization results in an overall improvement in cognitive function. There are no differences in the composite scores of five major cognitive domains between CEA and CAS. When individual tests are compared, CEA results in a reduction in memory, while CAS patients show reduced psychomotor speed. Larger studies will help confirm these findings.

[Neurological complications in cardiac surgery post-operative period]

The incidence of neurological complications after cardiac surgery continues to be elevated, although this is variable in the different studies published, fundamentally because of the different populations studied and the different definitions of neurological dysfunction. The etiology of these alterations is attributed to a multifactorial origin, aortic artherosclerosis, cerebral hypoperfusion and inflammatory phenomenon secondary to the technique. This review arises from the recognition of the personal, economic, and socio-health care repercussion entailed by these complications, with high rates of mortality and morbidity recorded, and it tries to give an objective view of the current literature on the subject. Having knowledge of the risk markers and understanding the pathogenesis is important to try to plan strategies that may minimize the appearance and development of these complications and contribute to the decrease of their serious consequences. The data and the experience obtained by our group are shown at the end of the review.

Neurologic complications of cardiac surgery: Current concepts and recent advances

Neurologic complications following cardiac surgery result in increased morbidity and mortality. The incidence of stroke is 2% to 4%, but is substantially higher in patients with a prior history of stroke. The success of off-pump techniques in altering this risk is controversial. The efficacy and safety of simultaneous carotid endarterectomy and coronary artery bypass surgery are still debated. Mechanical clot retrievers may offer new opportunity to treat postoperative large, middle cerebral artery strokes. The risk of cognitive deficits is debatable but may be due to factors other than the use of bypass and may not differ from similar deficits after noncardiac surgery. Short-term cognitive deficits usually resolve by 1 to 3 months. Long-term risks are not clearly established. Novel approaches may decrease the incidence of neurocognitive dysfunction. Postoperative seizures may result from global or focal cerebral ischemia due to hypoperfusion, particulate or air emboli, or metabolic causes. Newer anticonvulsant drugs may offer additional management opportunities.

Stroke After Coronary Artery Bypass Grafting

BACKGROUND

Despite the continuing improvements in surgical and cardiopulmonary bypass techniques during cardiac surgery, stroke remains a devastating complication. This study aimed to identify the preoperative and intraoperative risk factors for developing a perioperative stroke in patients undergoing coronary artery bypass graft surgery on cardiopulmonary bypass.

METHODS

A total of 4,380 consecutive patients who received isolated coronary artery grafting on cardiopulmonary bypass between 1992 and 2002 were included. The sample contained three cardiopulmonary bypass temperature strategies: hypothermic (< 31 degrees C, n = 1,853), tepid (32-35 degrees C, n = 1,088), and normothermic (> 36 degrees C, n = 1,439). Outcome measures reported include stroke incidence, 30-day mortality, and hospital length of stay.

RESULTS

The incidence of stroke was 1.2% (n = 51). Stroke patients were older, were more likely to be diabetic, hypertensive, have creatinine levels greater than 0.12 mmol/L, and have a history of stroke than those who did not have stroke (p < 0.05). Multivariate logistic regressions identified diabetes (p = 0.01), history of stroke (p = 0.04), and older age (p = 0.05) as independent predictors of stroke for all patients. The 30-day mortality for stroke patients was ten times greater than that of those who did not suffer stroke (17.6 vs 1.7%).

CONCLUSIONS

Diabetes, history of stroke, and older age were identified as risk factors for stroke after coronary bypass; the temperature at which cardiopulmonary bypass was performed was not significant.

Side differences in cerebrovascular accidents after cardiac surgery: a statistical analysis of neurologic symptoms and possible implications for anatomic mechanisms of aortic particle embolization

BACKGROUND

Aortic manipulation and particle embolization have been identified to cause cerebrovascular accidents in cardiac surgery. Recent data suggest that left-hemispheric cerebrovascular accident (right-sided symptoms) is more common, and this has been interpreted as being caused by aortic cannula stream jets. Our aim was to evaluate symptoms of cerebrovascular accident and side differences from a retrospective statistical analysis.

METHODS

During a 2-year period, 2641 consecutive cardiac surgery cases were analyzed. Patients positive for cerebrovascular accident were extracted from a database designed to monitor clinical symptoms. A protocol was used to confirm symptom data with the correct diagnosis in patient records. Patients were subdivided into 3 groups: control, immediate cerebrovascular accident, and delayed cerebrovascular accident.

RESULTS

Among pooled patients, immediate and delayed cerebrovascular accidents were 3.0% and 0.9%, respectively. The expected predisposing factors behind immediate cerebrovascular accidents were significant, although the type of operation affected this search. Aortic quality was a strong predictor ( P < .001). The rate of delayed cerebrovascular accident was unaffected by surgery group. Left-sided symptoms of immediate cerebrovascular accident were approximately twice as frequent ( P = .016) as on the contralateral side. This phenomenon was observed for pooled patients and for isolated coronary bypass procedures (n = 1882; P = .025).

CONCLUSIONS

Immediate cerebrovascular accident and aortic calcifications are linked. The predominance of left-sided symptoms may suggest that aortic manipulation and anatomic mechanisms in the aortic arch are more likely to cause cerebrovascular accidents than effects from cannula stream jets.

Preoperative high leukocyte count: a novel risk factor for stroke after cardiac surgery

BACKGROUND

Stroke after cardiac surgery is a devastating complication. The relationship between white blood cell count (WBC) and perioperative cerebrovascular accident (CVA) has not been investigated. An effort was made to identify how preoperative WBC may relate to CVA development during or after cardiac surgery.

METHODS

Prospective data were collected from 7,483 patients who underwent coronary artery bypass grafting or valvular surgery or both. WBC was determined preoperatively and postoperatively. Differentiation of WBC was examined only preoperatively.

RESULTS

There were a total of 125 CVAs (10 transient ischemic attacks [TIAs], 115 strokes). WBC was significantly higher preoperatively and directly postoperatively in patients with stroke. Qualitative changes in preoperative WBC were also found in these patients (chi2; p < 0.001). The predictive power of the stepwise logistic regression model for CVA was greater when preoperative WBC was included. The risk for perioperative CVA increased starting at preoperative WBC of 9 x 10(9)/L (p = 0.044) and progressed in higher WBC ranges. WBC had a significant impact on CVA outcome (analysis of variance, p = 0.001).

CONCLUSIONS

Our studies have established the correlation between high preoperative WBC and stroke during or after cardiac surgery. Furthermore, elevated preoperative WBC was related to the clinical outcome of CVA. Preoperative measures aimed at preventing or treating conditions such as infections that may cause elevated WBC may be beneficial in the prevention of stroke during or after cardiac surgery.

Is there any impact of the shape of aortic end-hole cannula on stroke occurrence? clinical evaluation of straight and bent-tip aortic cannulae

OBJECTIVE

To compare the impact of straight and bent-tip aortic cannulae on stroke occurrence, location, and severity.

METHODS

Prospective data were collected on 8,129 patients (coronary artery bypass grafting (CABG) and/or valvular surgery). 'Bent-tip' aortic cannulae were used in 15.6% of cases and 'straight' end-hole cannulae in 84.4% of cases.

RESULTS

There were a total of 137 strokes: right anterior 52, left anterior 39, bilateral 23, posterior 18, and location not established 5. With the use of bent-tip cannulae, the incidence of strokes was 0.9% versus 1.8% with straight cannulae (chi2, p = 0.026). Bilateral and posterior strokes occurred more often with the use of straight cannulae (chi2, p = 0.015). Straight cannulae also related to the severity of strokes (chi2, p = 0.003).

CONCLUSIONS

There is an influence of the type of cannula on the occurrence, location, and severity of strokes. Straight cannulae cause significantly more often and more severe bilateral and posterior strokes than bent-tip cannulae.

Outcome of cardiac surgery patients with complicated intensive care unit stay

Risk stratification has become an essential element in the practice of cardiac surgery. Several studies have identified preoperative risk factors for adverse outcome. However, outcome is mostly defined by 30-day mortality and morbidity. These data reflect poorly the benefit for the patient. Long-term survival, quality of life, and functional status should be included in a more global analysis of the outcome, particularly in patients with complicated ICU stay. By reviewing the recent data reported in the literature, we can identify a number of preoperative predictive factors for complicated ICU stay, including advanced age, chronic obstructive pulmonary disease, preoperative low ejection fraction, previous myocardial infarction, reoperation, renal failure, combined surgery (coronary artery bypass grafting plus valve surgery), low hematocrit, and neurologic impairment. Short- and long-term outcomes are dependent on the type of postoperative complication. Unfortunately, data regarding the long-term outcome in these situations are very scarce.