Central nervous system injury associated with cardiac surgery

Height loss caused by bent posture: a risk factor for stroke from ENT clinic - is it time to reconsider the physical examination?

Conclusion. When excessive height loss occurs in the elderly, which may be indicated by a cervical-bent posture, examination of the head and neck should be performed to detect common carotid artery (CCA) and internal carotid artery (ICA) aberration. In such cases brain magnetic resonance imaging (MRI) examination should be conducted to determine whether infarction is present. Objectives. To examine the relationships among bent posture, height loss, aberration of carotid arteries, and ischemic stroke risk with a case-control study. Methods: Controls (n = 163) were selected from among patients who had undergone MRI of the brain because of otolaryngologic symptoms. Case patients (n = 72) were selected from among those whose primary diagnosis was cerebral infarction in the area served by the ICA. Both groups were age-matched between 65 and 84 years old. The neck and pharyngeal cavity in each of the 235 patients were examined to determine whether the carotid arteries exhibited aberration. Patients' current height and greatest lifetime height were recorded, along with presence or absence of bent posture and other stroke risk factors. Results: Height loss alone could predict stroke risk in 79.1% of patients: 90.2% based on carotid artery aberration and 91.4% when all risk factors (aberration of carotid artery, height loss, bent posture) were analyzed.

Multimodal brain monitoring reduces major neurologic complications in cardiac surgery

OBJECTIVE

Although adverse neurologic outcomes are common complications of cardiac surgery, intraoperative brain monitoring has not received adequate attention. The aim of the present study was to evaluate the effectiveness of multimodal brain monitoring in the prevention of major brain injury and reducing the duration of mechanical ventilation, intensive care unit, and postoperative hospital stays after cardiac surgery.

DESIGN

A retrospective, observational, controlled study.

SETTING

A single-center regional hospital.

PARTICIPANTS

One thousand seven hundred twenty-one patients who had undergone cardiac surgery with cardiopulmonary bypass from July 2007 to July 2010. One hundred sixty-six patients with multimodal brain monitoring and a control group without brain monitoring (N = 1,555) were compared retrospectively.

INTERVENTIONS

Multimodal brain monitoring was performed for 166 patients, consisting of intraoperative recordings of somatosensory-evoked potentials, electroencephalography, and transcranial Doppler.

MEASUREMENTS AND MAIN RESULTS

The incidence of major neurologic complications and the duration of mechanical ventilation, intensive care unit, and postoperative hospital stays were considered. Patients with brain monitoring had a significantly lower incidence of perioperative major neurologic complications (0%) than those without monitoring (4.06%, p = 0.01) and required significantly shorter periods of mechanical ventilation (p = 0.001) and intensive care unit stays (p = 0.01) than controls. The length of postoperative hospital stays did not differ significantly between the 2 groups (p = 0.57).

CONCLUSIONS

This preliminary study suggests that multimodal brain monitoring can reduce the incidence of neurologic complications as well as hospital costs associated with post-cardiac surgery patient care. Furthermore, intraoperative brain monitoring provides useful information about brain functioning, blood flow velocity, and metabolism, which may guide the anesthesiologist during surgery.

Effects of surgical stress on long-term memory function in mice of different ages

BACKGROUND

The pathophysiology of post-operative cognitive dysfunction remains unclear and there is no widely accepted animal model that can simulate its occurrence. The purpose of this study was to explore the effects of surgical stress on long-term post-operative memory function in mice of different ages.

METHODS

Healthy C57Bl/6J male mice, of either 4- or 16-month-old, were each randomly divided into three subgroups. (1) CONTROL GROUP: neither anesthesia nor surgery was performed; (2) Anesthesia group: general anesthesia was administrated, surgery was not performed; (3) Surgery group: two-thirds partial hepatectomy was completed in about 15 min under general anesthesia. Morris water maze test was performed after 30 days.

RESULTS

In mice of both month-ages, the escape latencies as well as the swimming distances decreased significantly across training days (P<0.001). In 4-month-old mice, there were no significant differences among three subgroups. In 16-month-old mice, the escape latency was significantly less in the surgery group than in the control group (P=0.001), and the swimming distance was significantly shorter in the surgery group than in the control and the anesthesia groups (P=0.001 and 0.047, respectively). In the spatial probe test, time spent in the target quadrant was significantly longer in the surgery group than in the combined control and anesthesia group (P=0.037).

CONCLUSIONS

Partial hepatectomy did not produce significant long-term effects on memory function in 4-month-old mice. However, it significantly improved long-term memory function in 16-month-old mice.

Polymorphisms in complement component 3 (C3F) and complement factor H (Y402H) increase the risk of postoperative neurocognitive dysfunction following carotid endarterectomy

BACKGROUND

Up to 28% of patients undergoing carotid endarterectomy (CEA) are estimated to experience neurocognitive dysfunction following surgery. The complement cascade plays a central role in ischaemia-reperfusion injury. The authors investigated the effect of common polymorphisms in the complement component 3 (C3F) and complement factor H (CFH Y402H) genes on incidence of neurocognitive dysfunction post-CEA.

METHODS

This study examined a nested cohort of prospectively recruited patients receiving elective CEA, who were genotyped for the C3F or Y402H polymorphisms. Each patient underwent a standard battery of eight neuropsychometric tests before, and 1 day and 30 days after, surgery.

RESULTS

57 of 142 (40%) CEA patients had at least one copy of the C3F allele (C3F+), and 17 of 137 (12%) patients had two copies of the CFH Y402H allele (Y402H++). At postoperative day 1, patients were three times (OR 3.05, p=0.045) or six times (OR 6.41, p=0.006) more likely to experience moderate-to-severe neurocognitive dysfunction if they carried the C3F+ or Y402H++ genotype, respectively. Patients with both risk genotypes had an almost eightfold risk of dysfunction (OR 7.67, p=0.046). Right-hand-dominant C3F+ subjects undergoing right-side CEA performed significantly worse on tests of visuospatial function than C3F- subjects. At day 30, C3F+ and Y402H++ genotypes trended towards significance as predictors of dysfunction (p=0.07 and p=0.22, respectively).

CONCLUSION

The C3F and Y402H polymorphisms are strong independent predictors of moderate-to-severe neurocognitive dysfunction at 1 day following CEA. Furthermore, patients undergoing right-sided CEA are predisposed to deficits associated with cortex ipsilateral to the operative carotid artery.

Neurocognitive impairment after off-pump and on-pump coronary artery bypass graft surgery - an Iranian experience

BACKGROUND

Coronary artery bypass graft (CABG) surgery is one of the most commonly performed surgical procedures worldwide, and it may be accompanied by postoperative neurocognitive impairment. Although this complication has been attributed to the use of cardiopulmonary bypass, it is still a matter of debate whether the switch from on-pump to off-pump technique affects the cognitive function.

OBJECTIVE

The aim of this study was to compare the impact of the on-pump and off-pump techniques on neurocognitive impairment in low-risk CABG surgery groups.

METHODS

In a descriptive and analytic study, 201 CABG patients with left-ventricular ejection fraction >30%, and without cardiac arrhythmia were enrolled. Before the elective operation, all patients underwent neurological examination and neurocognitive test, Mini-Mental State Examination (MMSE). Two months following the operation, both on- and off-pump, the patients were re-examined by MMSE to detect any neurocognitive impairment.

RESULTS

Out of 154 patients included in the study, 95 (61.6%) and 59 (38.3%) patients were in off-pump and on-pump groups, respectively. Mean age of the patients was 57.17 ± 9.82 years. A 2-month postoperative neurocognitive impairment was detected among 17 patients of on-pump group (28.8%) and in 28 cases of off-pump group (29.4%) (P = 0.54). The mean postoperative MMSE scores were not comparable between groups (25.01 ± 4.49 in off-pump group versus 23.73 ± 4.88 in on-pump group, P = 0.09).

CONCLUSION

The present study revealed that in low-risk patients undergoing CABG surgery, either the techniques of on-pump or off-pump did not differ regarding the neurocognitive outcome 2 months after the procedure.

Neurocognitive dysfunction following cardiac surgery

Postoperative neurocognitive decline (POCD) is the most frequently reported form of brain injury in the cardiac surgery setting. Even though most patients recover over a period of several months, recovery is variable and often transient, and early decline may be a marker of neurocognitive dysfunction after several years. Recent studies, however, suggest that late neurocognitive decline after coronary artery bypass graft surgery may not be specific to the use of cardiopulmonary bypass. Large prospective, longitudinal trials with appropriate controls remain necessary to identify how patient characteristics, disease progression, and surgical and anesthetic technique contribute to aging-related neurocognitive decline. This article reviews the current literature on the etiology of POCD following cardiac surgery, discusses strategies to reduce patient risk, and provides some insight into some controversies that merit continued investigation.

Cognitive function in congenital heart disease after cardiac surgery with extracorporeal circulation

BACKGROUND

Congenital heart disease (CHD) may cause deleterious effects on cognitive function in children. This study aimed to evaluate the changes of the cognitive and academic functioning in children aged less than 4 years with serious CHD following cardiac surgery with extracorporeal circulation (ECC).

METHODS

A total of 100 children, aged 0-4 years with cyanotic (35) and acyanotic (65) heart diseases who had undergone cardiac surgery with ECC, were subjected to neuropsychological and behavioral evaluation using the Gesell Developmental Schedule (GDS) before operation and at 1 week, and 1, 3 and 6 months after operation.

RESULTS

The GDS scores in the first postoperative week were significantly lower than those before operation, but the scores increased gradually (P<0.01). ECC affected the GDS scores after operation, with the cyanotic children being more significantly affected than the acyanotic children. The GDS scores were negatively correlated with the age at each time point. The GDS scores were significantly lower in the cyanotic children than in the acyanotic children at 1 and 3 months postoperatively (P<0.01), but there was no significant difference at 6 months (P<0.05).

CONCLUSIONS

After cardiac surgery with ECC, the younger the children who have cardiac surgery, the more significantly the GDS score increases. The ECC mainly affects the cognitive ability and academic performance in cyanotic children in one month postoperatively.

The (Un)Importance of Cerebral Microemboli

Background: The use of cardiopulmonary bypass (CPB) is associated with cerebral microemboli. Cognitive decline after cardiac surgery has therefore always been attributed to the use of CPB. However, randomized studies comparing coronary bypass surgery with and without CPB failed to establish a clear cognitive benefit of avoiding CPB. The aim of this analysis was to systematically review the studies that directly assessed the association between cerebral microemboli and cognitive decline after cardiac surgery. Methods: The electronic database of PubMed of the National Library of Medicine from 1980 until 2009 was searched to identify relevant literature. Search terms related to “cardiac surgery,” “microemboli,” and “cognitive decline” were used. Studies were reviewed independently by 2 reviewers and relevant articles were included completely if they matched the selection criteria. This review included studies in adult cardiac surgical patients reporting both a measure of cerebral embolic load and cognitive outcomes. Results: The literature search yielded 423 different titles, of which 22 met the selection criteria. All 22 studies used neuropsychological tests to determine cognitive outcome. Seven studies used postoperative (diffusion-weighted) magnetic resonance imaging (MRI) to detect cerebral emboli and 15 studies used intraoperative transcranial Doppler imaging. In 1 MRI study and 5 Doppler studies, an association was found between the number of cerebral emboli and the risk of postoperative cognitive decline. In 15 studies, such an association could not be established. One study did not assess the direct relation between microemboli and cognitive decline. Conclusion: This systematic review could neither confirm nor rule out a causal link between emboli from CPB and postoperative cognitive decline.

Current state of surgical myocardial revascularization

Despite increasing competition from percutaneous interventions and other novel methods of non-surgical coronary revascularization, coronary artery bypass grafting (CABG) remains one of the most definitive and durable treatments for coronary artery disease, especially for those patients with extensive and diffuse disease. In recent years the CABG procedure itself has undergone innovation and evolution. This review article provides a brief historical perspective on the procedure, and examines the current state of modern variations including off-pump, limited-access, and robotic-assisted CABG.

The Erythropoietin NeuroProtective Effect: Assessment in CABG Surgery (TENPEAKS)

Background and Purpose— Neurocognitive dysfunction complicates coronary artery bypass surgery. Erythropoietin may be neuroprotective. We sought to determine whether human recombinant erythropoietin would reduce the incidence of neurocognitive dysfunction after surgery.

Methods— We randomly assigned 32 elective first-time coronary artery bypass graft patients to receive placebo or 375 U/kg, 750 U/kg, or 1500 U/kg of recombinant human erythropoietin divided in 3 daily doses, starting the day before surgery. Primary outcomes were feasibility and safety, and secondary outcomes were neurocognitive dysfunction at discharge and 2 months.

Results— All subjects were male, mean age 60 years (range 46 to 73). No significant differences were found in pump time, cross-clamp time, or hospital length of stay. Mortality and pure red cell aplasia were not observed. One patient in the 375 U/kg group had ST changes compatible with myocardial injury immediately postoperative, but no other thrombotic complications were observed. Neurocognitive dysfunction occurred in 21/32 (66%) of patients at discharge and 5/32 (16%) at 2 months. Neurocognitive dysfunction at discharge by group was: placebo 6/8 (75%), 375 U/kg 4/8 (50%), 750 U/kg 6/8 (75%), and 1500 U/kg 5/8 (63%). Neurocognitive dysfunction at 2 months by group was: placebo 3/8 (38%), 375 U/kg 1/8 (13%), 750 U/kg 1/8 (13%), and 1500 U/kg 0/8 (0%). Neurocognitive dysfunction at 2 months for erythropoietin at any dose was 2/24 (8.3%) versus 3/8 (38%) for placebo ( P =0.085).

Conclusions— This study demonstrates feasibility and safety for the use of human recombinant erythropoietin as a neuroprotectant in coronary artery bypass graft surgery. A trend in the reduction of neurocognitive dysfunction at 2 months was associated with erythropoietin use. A multicenter randomized controlled trial is warranted.

Perioperative hypothermia: use and therapeutic implications

Perioperative cerebral ischemic insults are common in some surgical procedures. The notion that induced hypothermia can be employed to improve outcome in surgical patients has persisted for six decades. Its principal application has been in the context of cardiothoracic and neurosurgery. Mild (32-35 degrees C) and moderate (26-31 degrees C) hypothermia have been utilized for numerous procedures involving the heart, but intensive research has found little or no benefit to outcome. This may, in part, be attributable to confounding effects associated with rewarming and lack of understanding of the mechanisms of injury. Evidence of efficacy of mild hypothermia is absent for cerebral aneurysm clipping and carotid endarterectomy. Deep hypothermia (18-25 degrees C) during circulatory arrest has been practiced in the repair of congenital heart disease, adult thoracic aortas, and giant intracranial aneurysms. There is little doubt of the protective efficacy of deep hypothermia, but continued efforts to refine its application may serve to enhance its utility. Recent evidence that mild hypothermia is efficacious in out-of-hospital cardiac arrest has implications for patients incurring anoxic or global ischemic brain insults during anesthesia and surgery, or perioperatively. Advances in preclinical models of ischemic/anoxic injury and cardiopulmonary bypass that allow definition of optimal cooling strategies and study of cellular and subcellular events during perioperative ischemia can add to our understanding of mechanisms of hypothermia efficacy and provide a rationale basis for its implementation in humans.

[Neuromonitoring and neuroprotection in cardiac anaesthesia. Nationwide survey conducted by the Cardiac Anaesthesia Working Group of the German Society of Anaesthesiology and Intensive Care Medicine]

OBJECTIVE

The primary objective of this nationwide survey carried out in department of cardiac anesthesia in Germany was to identify current practice with regard to neuromonitoring und neuroprotection.

METHODOLOGY

The data are based on a questionnaire sent out to all departments of cardiac anesthesia in Germany between October 2007 und January 2008. The anonymized questionnaire contained 26 questions about the practice of preoperative evaluation of cerebral vessels, intra-operative use of neuromonitoring, the nature und application of cerebral protective measures, perfusion management during cardiopulmonary bypass, postoperative evaluation of neurological status, and training in the field of cerebral monitoring.

RESULTS

Of the 80 mailed questionnaires 55% were returned and 90% of department evaluated cerebral vessels preoperatively with duplex ultrasound. The methods used for intra-operative neuromonitoring are electroencephalography (EEG, 60%) for type A dissections (38.1%), for elective surgery on the thoracic and thoraco-abdominal aorta (34.1% and 31.6%, respectively) and in carotid surgery (43.2%) near infrared spectroscopy (40%), evoked potentials (30%) and transcranial Doppler sonography (17.5%), with some centers using combined methods. In most departments the central nervous system is not subjected to monitoring during bypass surgery, heart valve surgery, or minimally invasive surgery. Cerebral protective measures used comprise patient cooling on cardio-pulmonary bypass (CPB 100%), extracorporeal cooling of the head (65%) and the administration of corticosteroids (58%), barbiturates (50%) and antiepileptic drugs (10%). Neuroprotective anesthesia consists of administering inhalation anesthetics (32.5%; sevoflurane 76.5%) and intravenous anesthesia (20%; propofol and barbiturates each accounting for 46.2%). Of the departments 72.5% cool patients as a standard procedure for surgery involving cardiovascular arrest and 37.5% during all surgery using CPB. In 84.6% of department CPB flow equals calculated cardiac output (CO) under normothermia, while the desired mean arterial pressure (MAP) varies between 60 and 70 mmHg (43.9%) and between 50 and 60 mmHg (41.5%), respectively. At body temperatures less than 18 degrees C CPB flow is reduced below the calculated CO (70%) while 27% of departments use normothermic flow rates. The preferred MAP under hypothermia is between 50 and 60 mmHg (59%). The results of intra-operative neuromonitoring are documented on the anesthesia record (77%). In 42.5% of the departments postoperative neurological function is estimated by the anesthesiologist. Continuing education sessions pertaining to neuromonitoring are organized on a regular basis in 32.5% of the departments and in 37.5% individual physicians are responsible for their own neuromonitoring education.

CONCLUSION

The present survey data indicate that neuromonitoring and neuroprotective therapy during CPB is not standardized in cardiac anesthesiology departments in Germany. The systemic use of available methods to implement multimodal neuromonitoring would be desirable.

Postoperative cognitive decline

Memory loss and lack of concentration are symptoms that frequently occur in patients who have undergone a surgical procedure. Although cognitive function can be assessed using neuropsychological tests, reliable diagnosis of postoperative cognitive decline (POCD) appears to be difficult. Therefore, the true incidence of POCD is unknown. Severe POCD, which is apparent even without neuropsychological testing, is reported most frequently after cardiac and hip-replacement surgery. In these cases, POCD probably reflects microembolic brain injury. Apart from the nature of the surgical procedure, advanced age is the most important risk factor for POCD. The anesthetic technique is not a determinant of POCD: the risk of POCD appears to be similar after both general and regional anesthesia.

Risk factors for neurocognitive dysfunction after cardiac surgery in postmenopausal women

BACKGROUND

Women are at higher risk than men for neurologic complications from cardiac operations. This study identified risk factors for neurocognitive dysfunction after cardiac operations in elderly women.

METHODS

One hundred thirteen postmenopausal women undergoing primary coronary artery bypass grafting, with or without valve operation, underwent psychometric testing and neurologic evaluation the day before operation and 4 to 6 weeks postoperatively. Risk factors assessed for neurologic complications included atherosclerosis of the ascending aorta and apolipoprotein epsilon4 genotype. Postoperative neurocognitive dysfunction was defined as the composite end point of a one standard deviation decrement from baseline on two or more psychometric tests or a new neurologic deficit.

RESULTS

Neurocognitive dysfunction was present in 25% of the women 4 to 6 weeks postoperatively. Women with a neurocognitive deficit tended to be older than those without a deficit (72.1 +/- 8.1 vs 69.4 +/- 8.9 years, p = 0.144) and were more likely to have mild atherosclerosis of the ascending aorta, a history of congestive heart failure, longer duration of cardiopulmonary bypass (CPB) and aortic cross-clamping, lower nadir blood pressure during CPB, higher rates of postoperative atrial fibrillation, and longer postoperative hospitalization. Mild atherosclerosis of the ascending aorta, duration of CPB, duration of aortic cross-clamping (p = 0.051), and length of postsurgical hospitalization were independently associated with postoperative neurocognitive dysfunction.

CONCLUSIONS

Mild atherosclerosis of the ascending aorta, duration of CPB, aortic cross-clamping time, and length of hospitalization, but not apolipoprotein epsilon4 genotype, identified risk for neurocognitive dysfunction after cardiac operation in postmenopausal women.

Patient Mood and Neuropsychological Outcome After Laparoscopic and Conventional Colectomy

The study was designed to compare patients after laparoscopic and conventional colectomy with regard to early postoperative mood, cognitive function, and neurocognitive variables S100β and neuron-specific enolase (NSE). Forty-five laparoscopic and 25 open colectomies were enrolled into the prospective study. Outcome measurements were positive and negative postoperative mood (BSKE), neuropsychological tests (Trail-Making Test; word reproduction; Stroop Test), and serum biochemical parameters (S100β; NSE). Following laparoscopic procedure, patients described significantly better positive mood ( P < .05), tended to require less time in the Trail-Making Test and Stroop Test, and had lower postoperative serum concentrations of S100β compared to conventional colectomy patients ( P < .01). The current results revealed several group differences, which, in their entirety, seem to represent a more beneficial outcome after laparoscopic colonic surgery.

Toll-like receptor 9: a new target of ischemic preconditioning in the brain

Preconditioning with lipopolysaccharide (LPS), a toll-like receptor 4 (TLR4) ligand, provides neuroprotection against subsequent cerebral ischemic brain injury, through a tumor necrosis factor (TNF)alpha-dependent process. Here, we report the first evidence that another TLR, TLR9, can induce neuroprotection. We show that the TLR9 ligand CpG oligodeoxynucleotide (ODN) can serve as a potent preconditioning stimulus and provide protection against ischemic brain injury. Our studies show that systemic administration of CpG ODN 1826 in advance of brain ischemia (middle cerebral artery occlusion (MCAO)) reduces ischemic damage up to 60% in a dose- and time-dependent manner. We also offer evidence that CpG ODN preconditioning can provide direct protection to cells of the central nervous system, as we have found marked neuroprotection in modeled ischemia in vitro. Finally, we show that CpG preconditioning significantly increases serum TNFalpha levels before MCAO and that TNFalpha is required for subsequent reduction in damage, as mice lacking TNFalpha are not protected against ischemic injury by CpG preconditioning. Our studies show that preconditioning with a TLR9 ligand induces neuroprotection against ischemic injury through a mechanism that shares common elements with LPS preconditioning via TLR4.

Cerebral ischemic lesions on diffusion-weighted imaging are associated with neurocognitive decline after cardiac surgery

BACKGROUND AND PURPOSE

Improvements in cardiac surgery mortality and morbidity have focused interest on the neurological injury such as stroke and cognitive decline that may accompany an otherwise successful operation. We aimed to investigate (1) the rate of stroke, new ischemic change on MRI, and cognitive impairment after cardiac valve surgery; and (2) the controversial relationship between perioperative cerebral ischemia and cognitive decline.

METHODS

Forty patients (26 men; mean [SD] age 62.1 [13.7] years) undergoing intracardiac surgery (7 also with coronary artery bypass grafting) were studied. Neurological, neuropsychological, and MRI examinations were performed 24 hours before surgery and 5 days (MRI and neurology) and 6 weeks (neuropsychology and neurology) after surgery. Cognitive decline from baseline was determined using the Reliable Change Index.

RESULTS

Two of 40 (5%) patients had perioperative strokes and 22 of 35 (63%) tested had cognitive decline in at least one measure (range, 1 to 4). Sixteen of 37 participants (43%) with postoperative imaging had new ischemic lesions (range, 1 to 17 lesions) with appearances consistent with cerebral embolization. Cognitive decline was seen in all patients with, and 35% of those without, postoperative ischemic lesions (P<0.001), and there was an association between the number of abnormal cognitive tests and ischemic burden (P<0.001).

CONCLUSIONS

We have provided a reliable estimate of the rate of stroke, postoperative ischemia, and cognitive impairment at 6 weeks after cardiac valve surgery. Cognitive impairment is associated with perioperative ischemia and is more severe with greater ischemic load.

Pulse pressure is an age-independent predictor of stroke development after cardiac surgery

Chronologic age is a strong predictor of adverse outcomes after cardiac surgery. The variability in age-related cardiovascular changes suggests that age may not be the most accurate predictor of adverse perioperative outcomes. Vascular stiffness has emerged as an important surrogate of vascular aging. In a retrospective review, we investigated the value of vascular stiffness, as assessed by brachial pulse pressure (PP) measurements, in predicting stroke in 703 patients (63.4% men and 36.6% women). Patients were followed for 348+/-215 days after cardiac surgery. We used a multivariable logistic model and unadjusted and adjusted Cox proportional-hazard models to assess the probability of stroke and the hazards of stroke over time. Stroke patients had a significantly higher PP (81.2 mm Hg versus 64.5 mm Hg; P=0.0006). In the logistic regression model, PP was an independent predictor of stroke development (unadjusted odds ratio: 1.35; 95% CI: 1.13 to 1.62, for every 10-mm Hg increase in PP; P=0.001). In the unadjusted and adjusted Cox models, PP again predicted stroke (hazard ratio: 1.32; 95% CI: 1.12 to 1.57; hazard ratio: 2.62; 95% CI: 1.49 to 4.60, respectively; P=0.001 for both) for every 10 mm Hg increase in PP. Age, gender, and diabetes were not independent predictors of stroke. Ejection fraction was inversely related to stroke in the adjusted model. Kaplan-Meier estimates and corresponding log-rank test indicated that the probability of stroke-free survival function was significantly lower (P=0.0067) in patients with PP >72 mm Hg versus <72 mm Hg. This analysis suggests that indices of vascular stiffness could be important predictors of neurologic complications.

Prolonged deep hypothermic circulatory arrest in rats can be achieved without cognitive deficits

Cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) enable surgical repair of cardiovascular defects. However, neurological complications can result after both CPB and DHCA. We sought to investigate if 75 min of CPB or DHCA caused motor, cognitive or histological deficits in rats. Three groups were studied: DHCA, CPB, and sham. Rats in the DHCA group were subjected to 75 min DHCA at 15 degrees C, with a total CPB duration of 75 min. Rats in the CPB group were subjected to 75 min of normothermic CPB. Shams received the same anesthesia, cannulations and infusions. Motor function was assessed using beam testing on days 3-13. Cognitive performance was evaluated using Morris water maze tasks on days 7-13. Overall Performance Category (OPC) and Neurologic Deficit Score (NDS) were assessed daily. Histological Damage Score (HDS) was assessed in survivors on day 14. Sustained deficits on beam testing were seen only in the CPB group. Rats in the CPB and DHCA groups exhibited similar cognitive performance vs. sham. There were no differences in OPC or NDS between groups. Neuronal degeneration was present only in small foci in rats after DHCA (n=4/7). However, HDS was not different in individual brain regions or viscera between DHCA or CPB vs. sham. Surprisingly, CPB, but not DHCA was associated with motor deficits vs. sham, and no cognitive deficits were seen in either group vs. sham. Future studies with longer DHCA duration will be necessary to provide targets to assess novel preservation strategies.

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.