Cerebral emboli and serum S100beta during cardiac operations

Effect of bispectral index-guided anesthesia on consumption of anesthetics and early postoperative cognitive dysfunction after liver transplantation: An observational study

The objective of this study was to summarize the incidence of postoperative cognitive dysfunction (POCD) after 7days following liver transplantation (LT), and to evaluate the effectiveness of bispectral index (BIS) guided anesthetic intervention in reducing POCD. Additional serum concentrations of S100β and neuron-specific enolase (NSE) were detected during surgery to determine whether they were reliable predictors of POCD.Patients who underwent LT at Beijing YouAn Hospital Affiliated to Capital University of Medical Science from January 2014 to December 2015 were enrolled. BIS monitor was needed during surgery. Patients who underwent LT without BIS monitoring during August 2012 to December 2014 served as historical controls. A battery of 5 neuropsychological tests were performed and scored preoperatively and 7days after surgery. POCD was diagnosed by the method of one standard deviation (SD). The blood samples of BIS group were collected at 5 time points: just before induction of general anesthesia (T0), 60 minutes after skin incision (T1), 30 minutes after the start of the anhepatic phase (T2), 15 minutes after reperfusion of the new liver (T3), and at 24 hours after surgery (T4).A total of 33 patients were included in BIS group, and 27 in the control group. Mean arterial pressure was different between 2 groups at 30 minutes after the start of the anhepatic phase (P = .032). The dose of propofol using at anhepatic phase 30 min and new liver 15 min was lower in the BIS group than control group (0.042 ± 0.021 vs. 0.069 ± 0.030, P < .001; 0.053 ± 0.022 vs. 0.072 ± 0.020, P = .001). Five patients were diagnosed as having POCD after 7 days in the BIS group and the incidence of POCD was 15.15%. In the control group, 9 patients had POCD and the incidence of POCD was 33.33%. The incidence of POCD between 2 groups had no statistical difference (P = .089). S100β increased at stage of anhepatic 30 minutes (T2) and new liver 15 minutes (T3) compared with the stage of before anesthesia (T0) (1.49 ± 0.66 vs. 0.72 ± 0.53, P < .001; 1.92 ± 0.78 vs. 0.72 ± 0.53, P < .001). NSE increased at stage of anhepatic 30 minutes (T2) and new liver 15 minutes (T3) compared with the stage of before anesthesia (T0) (5.80 ± 3.03 vs. 3.58 ± 3.24, P = .001; 10.04 ± 5.65 vs. 3.58 ± 3.24, P < .001). At 24 hours after surgery, S100β had no difference compared to one before anesthesia (1.0 ± 0.62 vs. 0.72 ± 0.53, P = .075), but NSE still remained high (5.19 ± 3.64 vs. 3.58 ± 3.24, P = .043). There were no significant differences in the serum concentrations of S100β between patients with and without POCD at 5 time points of operation (P > .05). But at 24 hours after surgery, NSE concentrations were still high of patients with POCD (8.14 ± 3.25 vs. 4.81 ± 3.50, P = .035).BIS-guided anesthesia can reduce consumption of propofol during anhepatic and new liver phase. Patients in BIS group seem to have a mild lower incidence of POCD compared to controls, but no statistical significant. The influence of BIS-guided anesthesia on POCD needs to be further confirmed by large-scale clinical study. S100β protein and NSE are well correlative with neural injury, but NSE is more suitable for assessment of incidence of postoperative cognitive deficits after surgery.

A Systematic Approach to the Understanding and Redesigning of Cardiopulmonary Bypass

Cardiopulmonary bypass (CPB) is a highly complex process. We developed a system to capture and study detailed information during cardiac surgery that serves as a framework for understanding variation that occurs during CPB. The system allows the surgical team to link unwanted variation (ie, hypotension) and unwanted events (ie, the production of microemboli) to the processes of care. A more thorough understanding of embolic activity and hemodynamic aberrations, precursors to both stroke and subtle neurologic injury, that occur during CPB, will allow the surgical team to identify high leverage, modifiable aspects of care and abate these precursors to patient injury. Multimodality simultaneous monitoring and recording of physiologic parameters, emboli in the CPB circuit and in the middle cerebral arteries, and cerebral NIRS during surgery was carried out in patients undergoing open heart surgery with CPB. A system was designed that captures physiologic data from the patient monitors and the heart-lung machine at 20-second intervals and time synchronizes all measures with a video recording of the surgical procedure. Emboli counts count in the CPB circuit and right and left middle cerebral arteries were continuously recorded. Video recordings depicting various surgical and perfusion techniques with associated embolic activity were provided to the surgical team. Wide variation in embolic counts, cerebral blood flow velocity, and physiologic parameters were observed. Periods of embolic activity and cerebral desaturation could be related to surgical and CPB processes of care. We have identified increased emboli counts in the CPB circuit and in the middle cerebral arteries related to the method of venous drainage, manipulation of the aorta, and anastomotic techniques. se of this model provides the surgical team detailed information about these precursors to neurologic injury. This system provides a systematic approach to the understanding and redesigning of CPB.

S100 and S100β: biomarkers of cerebral damage in cardiac surgery with or without the use of cardiopulmonary bypass

OBJECTIVE

The present study is to describe the clinical impact of S100 and S100β for the evaluation of cerebral damage in cardiac surgery with or without the use of cardiopulmonary bypass (CPB).

METHODS

Quantitative results of S100 and S100β reported in the literature of the year range 1990-2014 were collected, screened and analyzed.

RESULTS

Cerebrospinal fluid and serum S100 levels showed a same trend reaching a peak at the end of CPB. The cerebrospinal fluid/serum S100 ratio decreased during CPB, reached a nadir at 6 h after CPB and then increased and kept high untill 24 h after CPB. Serum S100 at the end of CPB was much higher in infant than in adults, and in on-pump than in off-pump coronary artery bypass patients. ∆S100 increased with age and CPB time but lack of statistical significances. Patients receiving an aorta replacement had a much higher ∆S100 than those receiving a congenital heart defect repair. Serum S100β reached a peak at the end of CPB, whereas cerebrospinal fluid S100 continued to increase and reached a peak at 6 h after CPB. The cerebrospinal fluid/serum S100β ratio decreased during CPB, increased at the end of CPB, peaked 1 h after CPB, and then decreased abruptly. The increase of serum S100β at the end of CPB was associated with type of operation, younger age, lower core temperature and cerebral damages. ∆S100β displayed a decreasing trend with age, type of operation, shortening of CPB duration, increasing core temperature, lessening severity of cerebral damage and the application of intervenes. Linear correlation analysis revealed that serum S100β concentration at the end of CPB correlated closely with CPB duration.

CONCLUSION

S100 and S100β in cerebrospinal fluid can be more accurate than in the serum for the evaluations of cerebral damage in cardiac surgery. However, cerebrospinal fluid biopsies are limited. But serum S100β and ∆S100β seem to be more sensitive than serum S100 and ∆S100. The cerebral damage in cardiac surgery might be associated with younger age, lower core temperature and longer CPB duration during the operation. Effective intervenes with modified CPB circuit filters or oxygenators and supplemented anesthetic agents or priming components may alleviate the cerebral damage.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

Effects of single aortic clamping versus partial aortic clamping techniques on post-operative stroke during coronary artery bypass surgery

BACKGROUND

The aim of this study was to compare the effects of single-clamping and partial-clamping techniques on postoperative stroke during coronary artery bypass surgery.

METHODS

Between December 2008 and December 2012, 2 000 patients who underwent coronary artery bypass grafting in two hospitals were analysed. Post-operative neurological complications were analysed retrospectively in these patients. The cases were divided into two groups: in group 1, 1 500 patients were analysed, in whom proximal anastomosis was performed with partial clamping in a beating heart (n = 1 500, 846 male, 654 female; mean age 63.25 ± 5.72 years; range 43-78 years). In group 2, 500 patients were analysed, in whom proximal anastomosis had been performed by other surgical teams in another hospital, with cross clamping in a resting heart with cardioplegia (n = 500, 296 male, 214 female; mean age 64.83 ± 8.12 years; range 41-81 years). During 30 days post-operatively, neurological deficits, stroke incidence and the relationship of the clinical situation to mortality were analysed.

RESULTS

For both groups, patients were similar in terms of patient characteristics. In group 2, cross-clamp duration and perfusion time were longer; however, time of hospital stay was similar in the two groups. Post-operative stroke was seen in 26 patients in group 1 (1.73%) and in nine in group 2 (1.8%). The difference between the two groups was not statistically significant (p = 0.92). All stroke patients were over the age of 55 years. Seven of the stroke patients died (21.1%). In total, 31 patients died because of multiple organ failure in the postoperative 30 days (group 1: 1.6%; group 2: 1.4%) (p = 0.91). Smoking, diabetes mellitus, hypertension, atrial fibrillation, peripheral vascular disease and hypercholesterolaemia were found to be factors that affected stroke development. Mean duration of hospital stay was 5.1 ± 2.8 days in group 1 and 4.9 ± 3.6 days in group 2 and the difference between the two groups was not statistically significant (p = 0.46).

CONCLUSION

In patients without plaques in the aorta, performing partial clamping did not increase stroke incidence.

Comparing S-100 beta protein levels and neurocognitive functions between patients undergoing on-pump and off-pump coronary artery bypass grafting

BACKGROUND

In the present study, we aimed to investigate the effects of off-pump coronary artery bypass grafting and on-pump cardiopulmonary bypass on the serum S-100 beta (S-100B) protein levels and neurocognitive functions of the patients.

MATERIALS AND METHODS

Sixty-four patients undergoing coronary artery bypass grafting (CABG) were enrolled in the study and were divided into two groups: off-pump (group I, n = 24) and on-pump CABG (group II, n = 40) group. Serum S-100B levels were measured before and 0, 6, and 24 h after the operation. Neurocognitive function tests were done preoperatively and were repeated in the postoperative period as well.

RESULTS

Serum S-100B levels were similar between the two groups preoperatively. However, median S-100B levels at 0, 6, and 24 h after the surgery were found to be significantly lower in the off-pump CABG group than in the on-pump group. The preoperative neurocognitive functions of the patients were similar between the two groups, whereas neurocognitive function was found to be significantly impaired postoperatively in the on-pump group in comparison with the off-pump CABG group.

CONCLUSION

We concluded that off-pump CABG is associated with decreased serum S100 protein levels and less impairment on neurocognitive functions compared with the on-pump group.

Comparison of S100B and NSE between cardiac surgery and interventional therapy for children

This study aimed to compare the release of S100B and NSE between cardiac surgery and interventional therapy for children and to investigate whether S100B serum concentration correlates with cardiopulmonary bypass in children. For this study, 40 children with congenital heart disease were selected and assigned to two groups: group A (20 children undergoing surgical therapy) and group B (20 children undergoing interventional therapy). In group A, blood samples were drawn 10 min after the induction of anesthesia, immediately after aortic cross-clamping, immediately at the end of cardiopulmonary bypass (CPB), immediately at the end of the operation, then 6 and 24 h after the operation. In group B, blood samples were drawn 10 min after the induction of anesthesia, immediately at the end of the procedure, then 6 and 24 h after the procedure. In group A, S100B plasma levels during the perioperative period and 6 h after the operation were higher than the preoperative level (p < 0.05). The NSE plasma concentrations at the termination of CPB and postoperatively were higher than the preoperative level (p < 0.05). Significant correlation was found between the peak value of S100B at the termination of CPB and the durations of both CPB and aortic cross-clamping. In group B, the differences in S100B and NSE between the post- and preoperative levels were not statistically significant (p > 0.05). The perioperative cerebral impairment indirectly evaluated by the release of NSE and S100B protein is greater in children undergoing CPB than in children undergoing interventional therapy. The release of S100B had a strong correlation with the durations of CPB and aortic cross-clamping in children.

Differential Expression in Markers for Thrombin, Platelet Activation, and Inflammation in Cell Saver Versus Systemic Blood in Patients Undergoing On-Pump Coronary Artery Bypass Graft Surgery

OBJECTIVE

Elimination of cardiotomy suction increases reliance on cell-saver blood-conservation techniques. Reinfusion of processed cell-saver blood (PCSB) even without using cardiotomy field suction may contribute to thrombin, cytokines, platelet activators, and hemolytic factors measured systemically.

DESIGN

This study was designed as a prospective, unblinded observational study of patients undergoing first-time, nonemergent on-pump coronary artery bypass graft surgery.

SETTING

A university medical center.

PARTICIPANTS

Fourteen patients were enrolled after informed consent.

INTERVENTIONS

Arterial blood was sampled (1) before cardiopulmonary bypass, (2) immediately after bypass, and (3) 4 hours after bypass. PCSB, using the AutoLog (Medtronic, Inc, Minneapolis, MN), was sampled after bypass.

MEASUREMENTS AND MAIN RESULTS

Blood and PCSB levels of prothrombin fragments 1.2, beta-thromboglobulin, interleukin-6, interleukin-8, polymorphonuclear leukocyte-elastase, neuron-specific enolase, and S-100beta were assayed by using enzyme-linked immunosorbent assay. Paired comparisons were performed by using paired t tests. Compared with postbypass blood, processed cell-saver blood (prepatient infusion) had higher levels of polymorphonuclear leukocyte-elastase, interleukin-8, neuron-specific enolase, and S-100beta (p <or= 0.05).

CONCLUSIONS

Reinfusion of PCSB directly and independently contributes to systemic elevations in interleukin-8, polymorphonuclear elastase, neuron-specific enolase, and S-100beta, augmenting and perhaps accentuating the postoperative inflammatory response. Further evaluation and improvement in cell-salvaging technology and processing techniques are warranted.

Cerebral dysfunction after cardiac surgery--are we moving forward?

This review focuses on the effects of cardiac surgery and cardiopulmonary bypass on the brain, with special emphasis on the results of recently conducted studies. The incidence of postoperative neurological and neuropsychological deficits and risk factors for cerebral injury are reviewed. The relationships between cerebral embolic load, release of biochemical markers of brain injury and cognitive dysfunction after cardiac surgery are also reviewed. Finally, recently gained information on the management of cardiopulmonary bypass is discussed, along with the results of recent pharmacological neuroprotective trials in patients undergoing cardiac surgery.

Prevention of Ischemic Neurologic Injury With Intraoperative Monitoring of Selected Cardiovascular and Cerebrovascular Procedures: Roles of Electroencephalography, Somatosensory Evoked Potentials, Transcranial Doppler, and Near-Infrared Spectroscopy

All neuromonitoring techniques, although imperfect, provide useful information for monitoring cardiothoracic and carotid vascular operations. They may be viewed as providing complementary information, which may help surgical technique and, as a result, possibly improve clinical outcomes. As of this writing, the efficacy of TCD and NIRS monitoring during cardiothoracic and vascular surgery cannot be considered established. Well designed, prospective, adequately powered, double-blind, and randomized outcome studies are needed to determine the optimal neurologic monitoring modality (or modalities), in specific surgical settings.

Elevated serum levels of S-100beta protein and neuron-specific enolase are associated with brain injury in patients with severe sepsis and septic shock

OBJECTIVE

We investigated whether serum levels of neuron-specific enolase (NSE) and S-100beta protein could be used to evaluate cerebral injury and to predict outcome in severe sepsis and severe septic shock.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENTS AND MEASUREMENTS

In 170 consecutively enrolled patients with severe sepsis and septic shock, serum S-100beta and NSE were measured daily during four consecutive days after intensive care unit admission. Admission Glasgow Coma Scale before sedation and daily Sequential Organ Failure Assessment scores were recorded in all patients. Acute encephalopathy was defined as either a state of agitation, confusion, irritability, and convulsions (type A) or characterized by somnolence, stupor, and coma (type B) and persistently observed during 72 hrs after withdrawing sedation. When clinically indicated, contrast computed tomography or magnetic resonance imaging were performed to evaluate brain injury.

MAIN RESULTS

S-100beta and NSE increased in, respectively, 72 (42%) and 90 (53%) patients. High biomarker levels were associated with the maximum Sequential Organ Failure Assessment scores (p = .001), and the highest values were found in patients who died early, within 4 days of inclusion (p = .005). Low consciousness encephalopathy type B was more frequently observed in patients with elevated S-100beta (p = .004). S-100beta levels of >or=4 microg/L were associated with severe brain ischemia or hemorrhage, and values of <2 microg/L were found in patients with diffuse cerebral embolic infarction lesions. High S-100beta levels were associated with higher intensive care unit mortality (p = .04) and represented the strongest independent predictor of intensive care unit survival, whereas NSE and the Glasgow Coma Scale failed to predict fatal outcome.

CONCLUSIONS

S-100beta and NSE are frequently increased and associated with brain injury in patients with severe sepsis and septic shock. S-100beta levels more closely reflected severe encephalopathy and type of brain lesions than NSE and the Glasgow Coma Scale.

Arterio-jugular Differences in Serum S-100β Proteins in Patients Receiving Selective Cerebral Perfusion

PURPOSE

The early increase in serum S100beta after cardiopulmonary bypass (CPB) seems to be derived from an extracerebral source. To exclude contamination, we investigated the arterio-jugular differences in S100beta levels in patients receiving selective cerebral perfusion (SCP). We also evaluated the brain-protective effect of SCP by comparing the arterial S100beta levels with those in patients undergoing coronary artery bypass grafting (CABG).

METHODS

We measured arterial and jugular venous levels of S100beta in ten patients undergoing aortic arch repair with SCP for up to 12 h postoperatively (SCP group). We also measured arterial levels of S100beta in nine patients undergoing CABG (CPB group).

RESULTS

There was no incidence of hospital death or stroke. The arterial levels of S100beta in both groups were comparable and peaked just after the conclusion of CPB. The arterial and jugular venous levels of S100beta were almost equivalent. The arterio-jugular differences in S100beta levels were negligible, even in our SCP-group patient with postoperative delirium, who had a peak value three times higher than the other patients.

CONCLUSIONS

The arterio-jugular differences in S100beta did not clarify the origin of their increase. Thus, measuring the jugular venous levels of S100beta in patients without postoperative clinical neurological deterioration would be of little benefit. However, SCP seems to protect the brain against S100beta release as effectively as conventional CPB.

Cerebral inflammatory response during and after cardiac surgery

BACKGROUND AND OBJECTIVE

Neurological dysfunction is a common problem after cardiac surgery with cardiopulmonary bypass (CPB). Cerebral ischaemia associated with the use of CPB may result in a release of neuronal-ischaemic markers and a subsequent cerebral inflammatory response which may additionally release inflammatory cytokines. In order to locate the origin and to quantify the release of neuronal-ischaemic markers and cytokines we investigated arterial-cerebral venous concentration gradients during and after CPB in a clinical setting.

METHODS

In twenty-five patients scheduled for coronary artery bypass grafting surgery we measured the plasma concentration of neuron-specific enolase, S-100beta protein as well as interleukins (IL) IL-6, IL-8 and IL-10 from arterial and cerebral venous blood samples prior to surgery (baseline), during hypothermic CPB at 32 degrees C, after termination of bypass, as well as 2, 4 and 6 h after admission to the intensive care unit.

RESULTS

Arterial-cerebral venous concentration gradients of neuron-specific enolase, S-100beta, IL-6, IL-8 and IL-10 were neither detectable during nor after CPB. Compared to the baseline period, S-100beta and neuron-specific enolase significantly increased during hypothermic CPB. After termination of CPB, neuronal-ischaemic markers as well as cytokines were increased and remained elevated during the investigated time course without reaching baseline values.

CONCLUSIONS

Although we found an overall increase in plasma concentrations of neuronal-ischaemic markers, IL-6, IL-8 and IL-10 during and after CPB, arterial-cerebral venous gradients were not detectable for any of these parameters. Our results suggest that the increase of investigated parameters associated with the use of CPB are not primarily caused by a cerebral inflammatory response but rather reflect a release from other sources in the systemic circulation.

Comparison of Hydroxyethyl Starch and Ringer Lactate as a Prime Solution Regarding S-100β Protein Levels and Informative Cognitive Tests in Cerebral Injury

BACKGROUND

Cognitive dysfunction (as an indicator of cerebral dysfunction after open heart surgery) was observed in as many as 70% of patients who underwent cardiopulmonary bypass. S-100beta protein is a sensitive indicator of cerebral injury. We aimed to compare the effects of hydroxyethyl starch and Ringer lactate prime solutions in the protection of cerebral tissue in cardiopulmonary bypass using serum S-100beta protein levels and informative cognitive tests.

METHODS

Patients were randomized into two groups. Open heart surgery was performed by using hydroxyethyl starch solution in group 1 (n = 15) and Ringer lactate solution in group 2 (n = 15). Preoperative, perioperative, and postoperative S-100beta protein levels and informative cognitive test scores, clinical and operational characteristics of the patients were compared.

RESULTS

A significant difference was found only between preoperative and postoperative results of verbal accuracy (human) test in group 1, whereas differences between preoperative and postoperative scores of continuous skill, verbal accuracy (human), verbal accuracy (animal), verbal accuracy (human-animal), go-no-go paradigm, calculation, and abstract thinking tests were significant in group 2 (p < or = 0.05). The S-100beta protein levels were not significantly different between the groups (group p = 0.97).

CONCLUSIONS

Because hydroxyethyl starch prime solution used in extracorporeal circulation had significant positive effects with informative-cognitive tests when compared to Ringer lactate solution, it seems to be a better prime solution to prevent cerebral dysfunction in these patients.

The Impact of Heparin Coated Circuits Upon Metabolism in Vital Organs: Effect Upon Cerebral and Renal Function During and After Cardiopulmonary Bypass

During cardiopulmonary bypass (CPB), the brain and the kidneys may be damaged because of microemboli, ischemia, and inflammation. The latter has been reduced by the use of heparin coated circuits. We questioned whether heparin coated circuits could also reduce cerebral and renal damage and whether inflammatory markers correlate with damage to the brain and the kidneys. Fifty-one patients scheduled for coronary artery bypass grafting were perfused with either a heparin coated or an uncoated circuit. To compare the effect of a heparin coated circuit with an uncoated circuit upon cerebral and renal function in relation to inflammation, we assessed markers of cerebral (S100beta) and renal (N-acetyl-beta-D-glucosaminidase [NAG], creatinine, and urea) function, inflammation, and oxygen metabolism. S100beta levels and NAG levels increased during CPB in both groups as compared with baseline levels (p < 0.01), without differences between the groups. After 15 minutes on CPB, C4b/c levels were significantly higher in the coated group compared with the uncoated group (p < 0.02). C4b/c correlated with S100beta (p < 0.01). Total body oxygen delivery (DO2) and consumption (VO2) decreased significantly in both groups during CPB (p < 0.01), but recovery was better in the coated group. After protamine infusion, total body oxygen delivery and consumption correlated negatively with S100beta levels (both p < 0.05) and with NAG levels (both p < 0.01). This study suggests that, if adequate tissue perfusion is not maintained, the use of a heparin coated circuit gives no additional benefit beyond that of the uncoated circuit. The inverse relationship of both cerebral and renal markers with DO2 and VO2 suggests that increased levels of S100beta and NAG during CPB may primarily be caused by an oxygen deficit and secondary to the inflammatory response.

Neurologic Injury Associated with CABG Surgery: Outcomes, Mechanisms, and Opportunities for Improvement

Neurologic injuries, whether subtle or overt, are a major source of morbidity secondary to coronary artery bypass graft (CABG) surgery. A comprehensive review of research in the area of neurologic injury is provided. We conclude this article by providing insight regarding areas requiring further investigation in order to reduce sustainably the risk of these iatrogenic events among patient undergoing CABG surgery.

Strategies for the reduction of cerebral microembolism during transmyocardial laser revascularization

BACKGROUND AND OBJECTIVES

During transmyocardial laser revascularization (TMLR), multiple microembolic signals (MES) can be detected in cerebral arteries. We sought to characterize composition and clinical relevance of these MES and to evaluate strategies to reduce cerebral microembolization during TMLR.

STUDY DESIGN/MATERIALS AND METHODS

TMLR was performed in pigs. Laser energy was set to 4-10 J (group A) or 80 J (group B). Oxygen concentration was varied between 21 and 100%. MES were recorded in the ophthalmic artery. Brain and spinal cord were investigated histologically after 10 days.

RESULTS

More MES could be detected during high- compared to low-energy laser procedures. Ventilation with 100% oxygen reduced the number of MES. No lesions were found on histology.

CONCLUSIONS

The number of MES depends on the laser energy. Laser-induces cavitation-effects lead to an additional release of nitrogen bubbles. Thus, the microembolic load can be reduced by ventilation with 100% oxygen and by decreasing the laser energy.

The dynamic air bubble trap reduces cerebral microembolism during cardiopulmonary bypass

OBJECTIVE

Neuropsychologic disorders are common after coronary artery bypass operations. Air microbubbles are identified as a contributing factor. A dynamic bubble trap might reduce the number of gaseous microemboli.

METHODS

A total of 50 patients undergoing coronary artery bypass operation were recruited for this study. In 26 patients a dynamic bubble trap was placed between the arterial filter and the aortic cannula (group 1), and in 24 patients a placebo dynamic bubble trap was used (group 2). The number of high-intensity transient signals within the proximal middle cerebral artery was continuously measured on both sides during bypass, which was separated into 4 periods: phase 1, start of bypass until aortic clamping; phase 2, aortic clamping until rewarming; phase 3, rewarming until clamp removal; and phase 4, clamp removal until end of bypass. S100 beta values were measured before, immediately after, and 6 and 48 hours after the operation and before hospital discharge.

RESULTS

The bubble elimination rate during bypass was 77% in group 1 and 28% in group 2 (P <.0001). The number of high-intensity signals was lower in group 1 during phase 1 (5.8 +/- 7.3 vs 16 +/- 15.4, P <.05 vs group 2) and phase 2 (6.9 +/- 7.3 vs 24.2 +/- 27.3, P <.05 vs group 2) but not during phases 3 and 4. Serum S100 beta values were equally increased in both groups immediately after the operation. Group 2 patients had higher S100 beta values 6 hours after the operation and significantly higher S100 beta values 48 hours after the operation (0.06 +/- 0.14 vs 0.18 +/- 0.24, P =.0133 vs group 2). Age and S100 beta values were correlated in group 2 but not in group 1.

CONCLUSION

Gaseous microemboli can be removed with a dynamic bubble trap. Subclinical cerebral injury detectable by increases of S100 beta disappears earlier after surgical intervention.

Do S100beta protein level increases due to inflammation during cardiopulmonary bypass occur without any neurological deficit?

PURPOSE

S100beta protein level correlates with the duration of cardiopulmonary bypass (CPB) and aortic crossclamp times, but is different during pulsatile and nonpulsatile CPB. In this study, we investigated the time course of the release of S100beta protein during and after pulsatile and nonpulsatile CPB.

PATIENTS AND METHODS

This is a prospective study. Twenty patients had open-heart surgery with pulsatile flow and 20 with nonpulsatile flow. We compared complement proteins, interleukins, white blood cells and S100beta protein before the initiation of CPB, immediately prior to aortic crossclamping, following unclamping, and at postoperative 1st and 24th hours.

RESULTS

In the pulsatile CPB group following aortic unclamping, S100beta protein (p = 0.028) and C3a (p = 0.011) levels were significantly lower than those of the nonpulsatile group. In the pulsatile CPB group at postoperative first hour, C3a level (p = 0.018) and absolute neutrophil count (p = 0.034) were significantly lower than those of the nonpulsatile group. None of the patients developed a neurological deficit and all of the patients survived after the operation and were discharged from the hospital.

CONCLUSION

During CPB, serum S100beta protein level increases and this increase is higher in the nonpulsatile group. High serum level of S100beta protein is associated with increased levels of serum inflammatory mediators and systemic inflammatory response.

Serial measurement of serum S-100B protein as a marker of cerebral damage after cardiac surgery

BACKGROUND

We used serial measurements of serum S-100B protein to evaluate the time course of serum S-100B protein concentration after cardiovascular surgery and to determine the clinical relevance of its concentration and cerebral damage.

METHODS

We assessed neurologic function in 149 patients undergoing cardiovascular surgery with cardiopulmonary bypass. The patients were classified into three groups according to their early postoperative outcome: those without complications (group A), those having unconsciousness or convulsion or both but no hemiplegia (group B), and those having unconsciousness and hemiplegia either with or without convulsion (group C). Serum S-100B protein concentrations were measured with a commercially available immunoluminometric assay, Sangtec 100 LIA, at seven time-points: before cardiopulmonary bypass, at the end of cardiopulmonary bypass, and at 5, 12, 24, 48, and 72 hours after cardiopulmonary bypass.

RESULTS

At 5 hours after cardiopulmonary bypass, the S-100B values in groups B and C were significantly higher than the value in group A. Although the S-100B level decreased in group C during the first 5 hours after cardiopulmonary bypass, it increased thereafter (12 through 24 hours) and continued at a high level until the final measurement at 72 hours. At 12 hours after cardiopulmonary bypass, S-100B was significantly higher in group C than in group B. This late increase in S-100B was associated with radiologically detected abnormalities and cerebral damage.

CONCLUSIONS

Serial measurement of serum S-100B protein in the initial 12 hours after cardiopulmonary bypass can be used to predict early postoperative brain injury.

S100B in brain damage and neurodegeneration

S100B is a calcium-binding peptide produced mainly by astrocytes that exert paracrine and autocrine effects on neurons and glia. Some knowledge has been acquired from in vitro and in vivo animal experiments to understand S100B's roles in cellular energy metabolism, cytoskeleton modification, cell proliferation, and differentiation. Also, insights have been gained regarding the interaction between S100B and the cerebral immune system, and the regulation of S100B activity through serotonergic transmission. Secreted glial S100B exerts trophic or toxic effects depending on its concentration. At nanomolar concentrations, S100B stimulates neurite outgrowth and enhances survival of neurons during development. In contrast, micromolar levels of extracellular S100B in vitro stimulate the expression of proinflammatory cytokines and induce apoptosis. In animal studies, changes in the cerebral concentration of S100B cause behavioral disturbances and cognitive deficits. In humans, increased S100B has been detected with various clinical conditions. Brain trauma and ischemia is associated with increased S100B concentrations, probably due to the destruction of astrocytes. In neurodegenerative, inflammatory and psychiatric diseases, increased S100B levels may be caused by secreted S100B or release from damaged astrocytes. This review summarizes published findings on S100B regarding human brain damage and neurodegeneration. Findings from in vitro and in vivo animal experiments relevant for human neurodegenerative diseases and brain damage are reviewed together with the results of studies on traumatic, ischemic, and inflammatory brain damage as well as neurodegenerative and psychiatric disorders. Methodological problems are discussed and perspectives for future research are outlined.

Are serum S100beta proteins and neuron-specific enolase predictors of cerebral damage in cardiovascular surgery?

OBJECTIVE

To examine whether serum concentrations of S100beta protein and neuron-specific enolase (NSE) are predictors of cerebral damage in cardiovascular surgery.

DESIGN

Prospective clinical study.

SETTING

University hospital.

PARTICIPANTS

Eighteen patients with conventional cardiopulmonary bypass (CPB), 7 with selective cerebral perfusion (SCP), and 3 volunteers (blood samples).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

S100beta and NSE were measured in the blood obtained at 7 time points during and after operation. The concentrations of these markers in the blood from the surgical field and the cell-saver device, and the influence of graded hemolysis (in vitro) on the concentrations of these proteins were also examined. The mean values of S100beta in the CPB group (2.08 +/- 2.00 ng/mL) and the SCP group (1.46 +/-0.77 ng/mL) were highest after aortic declamping and after termination of SCP, respectively. The mean values of NSE in the CPB group (29.1 +/- 14.0 ng/mL) and the SCP group (31.2 +/- 13.6 ng/mL) were highest after termination of CPB and at the end of the operation, respectively. Three patients suffered from cerebral complications, but the elevation of these markers during operation was indistinguishable from those in the other patients. Peak concentrations of S100beta protein in the CPB group and NSE in the SCP group were correlated with the duration of aortic cross-clamping and CPB, respectively. S100beta protein and NSE concentrations in the blood from the surgical field were significantly larger than those in arterial blood, whereas the concentrations in the blood in the cell-saving device were not elevated. The concentration of S100beta protein was not influenced by the extent of hemolysis, whereas NSE concentration was markedly elevated by hemolysis.

CONCLUSION

A large part of the increases in S100beta protein and NSE during CPB and SCP is not attributed to neuronal damage, but to contamination with the blood from the surgical field. To determine whether these markers are useful to predict neurologic complications, it will be necessary to exclude contamination from the surgical field as observed in the present study.

Vascular dementia may be the most common form of dementia in the elderly

Cerebrovascular lesions, mainly lacunes and white matter ischemia, are common in elderly patients with dementia. Vascular dementia (VaD) is the second most common cause of dementia, after Alzheimer's disease (AD). However, lacunar strokes have become an important factor in the clinical expression of AD. Also, population-based studies indicate that vascular risk factors increase the risk of developing AD. It is postulated here that the two main causes of VaD-stroke and ischemic heart disease (IHD)-may be responsible for the majority of cases of dementia in the elderly. STROKE RELATED VaD: Cerebrovascular disease (CVD) is the second leading cause of death worldwide. About 1/3 of stroke survivors [range: 25-41%] 65 years old and above develop VaD within 3 months following the ictus. In the USA alone, 125,000 new cases/year of VaD occur after ischemic stroke (about 1/3 of the 360,000 incident cases of AD). Therefore, more than 1 million elderly people are currently affected by poststroke VaD in the USA. Since current criteria identify "pure" cases of AD and VaD, it is likely that "AD plus CVD" ("mixed" dementia) could be responsible for a large number of cases currently diagnosed as probable AD. CARDIOGENIC VAD: By 2020, IHD leading to congestive heart failure (CHF) will become the leading cause of disability worldwide. Vascular cognitive impairment occurs in 26% of patients discharged from hospitals after treatment for CHF. Cognitive dysfunction correlates with left ventricular dysfunction and systolic blood pressure below 130 mm Hg. CHF is a leading cause of hospital admissions in Western nations (4.5 million cases in the USA alone) and is a growing problem in developing countries. Furthermore, over 800,000 patients/year undergo coronary artery bypass graft (CABG) surgery worldwide, including 300,000 patients in the USA. Measurable cognitive dysfunction occurs post-CABG in 80-90% of patients at hospital discharge. Long-term (5 years) incidence of cognitive defects is 42%. Finally, an international study found short-term postoperative cognitive dysfunction in 26% of patients (>60 years) after abdominal or orthopedic surgery; most of them may be instances of VaD. In conclusion, VaD may be the most underdiagnosed and undertreated form of dementia in the elderly.

Early elevation of S-100B protein in blood after cardiac surgery is not a predictor of ischemic cerebral injury

BACKGROUND

We hypothesized that early changes in S-100B levels after cardiac surgery are nonspecific and mostly reflect damage to tissues outside the brain rather than ischemic brain damage.

METHODS

We measured serum levels of S-100B at several times perioperatively in 21 patients undergoing cardiac surgery. In addition, we measured levels of neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP), creatine kinase (CK), the cardiac isoenzyme of CK (CK-MB), and myoglobin (MB) in these patients.

RESULTS

Early increases in serum S-100B concentration were significantly (p<0.01) correlated with increases in markers of tissue injury outside the brain: S-100B/CK: r(2)=0.69; S-100B/CK-MB: r(2)=0.64; S-100B/myoglobin: r(2)=0.60; S-100B/NSE: r(2)=0.51; CK/NSE: r(2)=0.60; CK-MB/NSE: r(2)=0.59; and myoglobin/NSE: r(2)=0.54.

CONCLUSIONS

Our findings indicate that increases in S-100B in the early phase after cardiac surgery are not due to release of S-100B from brain alone but also from tissue outside the brain.

Clinical significance of serum S-100 beta protein level after pediatric cardiac surgery

OBJECTIVE

The serum S-100 beta protein level is a specific marker of damage to the central nerve system (CNS). We studied its significance in pediatric cardiac surgery as a possible marker of CNS damage.

METHODS

Subjects were 18 consecutive pediatric patients aged 12 days to 13 years (mean: 2.8 years) undergoing open-heart surgery. We measured the serum S-100 beta protein level using ELISA (SRL Co. Ltd., Tokyo) immediately after inducing anesthesia and immediately, 12 hours, and 24 hours after weaning from cardiopulmonary bypass (CPB).

RESULTS

None had postoperative neurological symptoms. The prebypass serum S-100 beta protein level showed a significant logarithmic correlation with patient age. All patients showed increased S-100 beta protein immediately after weaning from CPB, and multiple regression analysis showed that bypass time and cyanosis were significant factors in such as increase. Cyanosis was the only factor in increased S-100 beta protein levels 12 and 24 hours after weaning from CPB. The peak S-100 beta protein level showed a significant exponential correlation with bypass time.

CONCLUSION

Serum S-100 beta protein elevated immediately after weaning from CPB correlated with bypass time but not with neurological symptoms. Physiological changes other than substantial brain damage caused by CPB may increase the serum S-100 beta protein level. Prebypass data on neonates and infants showed serum S-100 beta protein increased without brain damage supporting this hypothesis.

Biochemical markers for brain damage after cardiac surgery -- time profile and correlation with cognitive dysfunction

BACKGROUND

Cerebral dysfunction is common after cardiac surgery and may be reflected in increasing blood concentrations of neuron specific enolase (NSE) and S-100 beta protein. The aim of the study was to determine the optimal timing of blood sampling.

METHODS

We studied 15 patients undergoing coronary artery bypass grafting. Serum concentrations of NSE and S-100 beta protein were measured before surgery and after 12, 18, 24, 30, and 36 h. Neuropsychological testing was performed before surgery, at discharge from hospital and after 3 months.

RESULTS

Serum concentrations of both NSE and S-100 beta protein increased significantly. At the first postoperative test, seven patients had cognitive dysfunction and a significant correlation was found between the composite z-score and the increase in the NSE level after 36 h (R = 0.76, P=0.001). The median increase in NSE after 36 h was 4.1 microg/l in patients having cognitive dysfunction and 0.9 microg/l in the remaining patients (P<0.05). No significant correlation was found between cognitive dysfunction and the increase in S-100 beta protein. After 3 months, no statistically significant correlation was found between either NSE or S-100 beta protein and cognitive dysfunction.

CONCLUSION

NSE seems to be a useful blood marker for early cognitive dysfunction after coronary artery bypass grafting, optimal timing of blood sampling being at approximately 36 h postoperatively.

Serum concentration of S-100 protein in assessment of cognitive dysfunction after general anesthesia in different types of surgery

BACKGROUND

S-100 protein serum concentration (S-100) serves as a marker of cerebral ischemia in cardiac surgery, head injury and stroke. In these circumstances S-100 corresponds well with the results of neuropsychological tests. The aim of the present study was to investigate the value of S-100 and neuron specific enolase (NSE) in reflecting postoperative cognitive deficit (POCD) after general surgical procedures.

METHODS

One hundred and twenty patients undergoing vascular, trauma, urological or abdominal surgery were investigated. Serum values of S-100 and NSE were determined preoperatively and 0.5, 4, 18 and 36 h postoperatively. Neuropsychological tests for detecting POCD were performed preoperatively and on day 1, 3, and 6 after the operation. A decline of more than 10% in neuropsychological test results was regarded as POCD. Furthermore, we retrospectively compared the S-100 in patients with and without POCD in different types of surgery.

RESULTS

According to our definition, forty-eight patients had POCD (95% confidence interval: 37.5-58.5). These patients showed higher serum concentrations of S-100 (median 024 ng/ml; range 0.01-3.3 ng/ml) compared with those without POCD (n=69; median 0.14 ng/ml; range 0-1.34 ng/ml) 30 min postoperatively (P=0.01). Neuron specific enolase was unchanged during the course of the study. Differences of S-100 in patients with and without POCD were found in abdominal and vascular surgery but not in urological surgery.

CONCLUSION

When all patients are pooled, S-100 appears to be suitable in the assessment of incidence, course and outcome of cognitive deficits. We suspect that in some surgical procedures, such as urological surgery, S-100 appears to be of limited value in detecting POCD. Neuron specific enolase did not reflect neuropsychological dysfunction after noncardiac surgery.

Limitation of thrombin generation, platelet activation, and inflammation by elimination of cardiotomy suction in patients undergoing coronary artery bypass grafting treated with heparin-bonded circuits

OBJECTIVE

Reports evaluating the efficacy of heparin-bonded circuits to blunt inflammation, platelet dysfunction, and thrombin generation in response to cardiopulmonary bypass have varied. We hypothesized that this variability may in part be related to the use of cardiotomy suction, which has been demonstrated to reintroduce procoagulant and proinflammatory factors into the systemic circulation during cardiopulmonary bypass. A prospective, randomized study was undertaken to evaluate the specific effects of cardiotomy suction.

METHODS

Thirty-six patients undergoing first-time, nonemergency coronary artery bypass grafting with cardiopulmonary bypass were randomly assigned to one of three treatment groups: group I, non-heparin-bonded circuits with the use of cardiotomy suction (n = 12); group II, Duraflo II (BCR-3500; Jostra Bentley Corp, Irvine, Calif) heparin-bonded circuits with cardiotomy suction (n = 12); and group III, Duraflo II heparin-bonded circuits without cardiotomy suction (n = 12). Thrombin generation, neutrophil activation (polymorphonuclear elastase), platelet activation (beta-thromboglobulin), and neuronal injury (neuron-specific enolase) were analyzed by enzyme-linked immunosorbent assays after cardiopulmonary bypass and compared with prebypass levels. Results are presented as mean +/- SEM.

RESULTS

Prebypass levels of all markers were similar among treatment groups. However, postbypass levels were significantly and consistently highest in group I relative to groups II and III. Thrombin generation levels were 5.0 +/- 0.9 nmol/L in group I, 3.0 +/- 0.6 nmol/L in group II, and 1.5 +/- 0.1 nmol/L in group III (P <.05 vs group II and P <.001 vs group I). Polymorphonuclear elastase levels were 307 +/- 64 microg/L in group I, 128 +/- 24 microg/L in group II (P <.05 vs group I), and 75 +/- 14 microg/L in group III (P <.001 vs group I). beta-Thromboglobulin levels were 2692 +/- 401 IU/mL in group I, 912 +/- 99 IU/mL in group II (P =.001 vs group I), and 646 +/- 133 IU/mL in group III (P =.001 vs group I). Neuron-specific enolase levels were 9.8 +/- 0.9 ng/mL in group I, 10.5 +/- 1.6 ng/mL in group II, and 4.2 +/- 0.5 ng/mL in group III (P =.001 vs groups I and II).

CONCLUSIONS

Use of cardiotomy suction resulted in significant increases in thrombin, neutrophil, and platelet activation, as well as the release of neuron-specific enolase, after cardiopulmonary bypass. Limiting increases in these markers would be best accomplished by eliminating cardiotomy suction and routinely using heparin-bonded circuits whenever possible.

Complete Myocardial Revascularization in Severe Arteriopathy

Multivessel coronary revascularization was successfully performed in a 75-year-old man with severe atherosclerosis of the ascending aorta and aortic arch, significant stenoses in the right subclavian, innominate, and aortoiliac arteries, renal impairment, and conduit shortage, by combining the beating-heart approach with aorta-sparing pedicled arterial and venous grafts. No postoperative complications were encountered.

Normothermic versus hypothermic cardiopulmonary bypass during repair of congenital heart disease

OBJECTIVE

To compare normothermic cardiopulmonary bypass (CPB) versus hypothermic CPB in pediatric patients undergoing repair of congenital heart disease with focus on biochemical markers for brain damage.

DESIGN

Prospective randomized interventional study.

SETTING

Postgraduate teaching hospital.

PARTICIPANTS

Twenty patients undergoing repair of congenital heart disease.

INTERVENTIONS

Patients were randomized to normothermic (36 degrees C) versus hypothermic (25 degrees C) CPB. Serum levels of neuron-specific enolase (NSE) and S-100beta protein were measured in all patients before surgery, immediately after CPB, and 12 and 24 hours after surgery. Blood loss and time for extubation of the trachea were recorded.

MEASUREMENTS AND MAIN RESULTS

Before operation, the S-100beta protein and NSE levels were similar in the 2 groups. The S-100beta protein serum level increased significantly after CPB in both groups, whereas no change was found in the NSE level. There was no difference in the change of NSE and S-100beta protein levels between normothermic and hypothermic CPB. Blood loss was significantly less after hypothermic CPB (25 mL/kg/24 h v 42 mL/kg/24 h). Time for extubation was similar.

CONCLUSION

No difference was found in the release of brain-specific proteins between normothermic and hypothermic CPB, but blood loss was higher after normothermic CPB.

S100beta correlates with neurologic complications after aortic operation using circulatory arrest

BACKGROUND

Astrocyte protein S100beta is a potential serum marker for neurologic injury. The goals of this study were to determine whether elevated serum S100beta correlates with neurologic complications in patients requiring hypothermic circulatory arrest (HCA) during thoracic aortic repair, and to determine the impact of retrograde cerebral perfusion (RCP) on S100beta release in this setting.

METHODS

Thirty-nine consecutive patients underwent thoracic aortic repairs during HCA; RCP was used in 25 patients. Serum S100beta was measured preoperatively, after cardiopulmonary bypass, and 24 hours postoperatively.

RESULTS

Neurologic complications occurred in 3 patients (8%). These patients had higher postbypass S100beta levels (7.17 +/- 1.01 microg/L) than those without neurologic complications (3.63 +/- 2.31 microg/L, p = 0.013). Patients with S100beta levels of 6.0 microg/L or more had a higher incidence of neurologic complications (3 of 7, 43%) compared with those who had levels less than 6.0 microg/L (0 of 30, p = 0.005). Retrograde cerebral perfusion did not affect S100beta release.

CONCLUSIONS

Serum S100beta levels of 6.0 microg/L or higher after HCA correlates with postoperative neurologic complications. Using serum S100beta as a marker for brain injury, RCP does not provide improved cerebral protection over HCA alone.

Increase in serum S100A1-B and S100BB during cardiac surgery arises from extracerebral sources

BACKGROUND

Elevated levels of serum S100B after coronary artery bypass grafting may arise from extracerebral contamination. Serum S100B content was analyzed in several tissues, and the two dimers S100A1-B and S100BB were analyzed separately in blood.

METHODS

Serum, shed blood, marrow, fat, and muscle were studied in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass using suction either to the cardiotomy reservoir (group 1, n = 10) or to a cell-saving device (group 2, n = 10), or operated on off-pump (group 3, n = 10).

RESULTS

Serum S100B was sixfold higher in group 1 than in groups 2 and 3, which were identical. The same ratio between S100A1-B and S100BB was found in all groups. When compared with serum, S100B was 10(2) to 10(4) times higher in marrow, fat, muscle tissue, and shed blood.

CONCLUSIONS

Separate analysis of S100A1-B and S100BB did not distinguish between S100B of cerebral and extracerebral origin. The concept that S100B only originates in astroglial and Schwann cells is wrong. Fat, muscle, and marrow in mediastinal blood contain high levels of S100B. Cardiopulmonary bypass caused no increase in S100B.

Single aortic cross-clamp technique reduces S-100 release after coronary artery surgery

BACKGROUND

Neurologic impairment after coronary artery bypass grafting is associated with cerebral embolization. An important cause of embolism is aortic manipulation. Constructing both distal and proximal anastomoses during a single period of aortic cross-clamping avoids this source of embolism and may reduce neurologic injury after coronary artery bypass grafting.

METHODS

Fifty consecutive patients undergoing coronary artery bypass grafting were prospectively randomized to group 1, in which a single aortic cross-clamping was used to construct distal and proximal anastomoses, or to group 2, in which the proximal anastomoses were each constructed with a partial occluding aortic clamp. Levels of S-100 and troponin-T release were measured preoperatively and postoperatively.

RESULTS

Aortic cross-clamp time was significantly longer in group 1, but other preoperative and intraoperative variables were equally represented in both groups. Control group levels of S-100 and troponin-T were similar. Postoperative S-100 levels were significantly higher in group 2 than in group 1 (p < 0.015). No significant difference was found between the groups in postoperative troponin-T levels.

CONCLUSIONS

The results of this trial suggest improved cerebral protection is associated with the single aortic cross-clamp technique for coronary artery bypass grafting with no increase in myocardial damage. The single aortic cross-clamp technique is simple and inexpensive. We recommend its wider use.

S-100beta protein levels do not correlate with stroke in patients undergoing carotid endarterectomy under general anesthesia

OBJECTIVE

To establish the S-100beta protein profile during carotid artery surgery to show a possible correlation between postoperative stroke and this biochemical marker.

DESIGN

Prospective, nonrandomized study.

SETTING

Departments of anesthesiology, biochemistry, and vascular surgery in a single university hospital.

PARTICIPANTS

One hundred patients consecutively scheduled for carotid endarterectomy.

MEASUREMENTS AND MAIN RESULTS

Postoperative neurologic complications were defined as major, occurrence of a postoperative permanent stroke, or minor, occurrence of a new postoperative transient ischemic attack lasting < 2 hours. Serum samples were obtained before induction, before carotid artery cross-clamping, after declamping, at the end of surgery, during recovery, and on the first postoperative day. Concentrations of S-100beta were analyzed using a commercially available kit (LIA-mat S300 analyzer, Byk-Sangtec Medical, Bromma, Sweden). Ninety-five patients awoke without a neurologic defect. Three patients experienced a permanent stroke, and 2 patients had a transient ischemic attack. S-100 basal values were unrelated to preoperative status, including hypertension, neurologic status, renal function, and degree of the carotid lesion. S-100 concentration increased slightly but significantly at the end of surgery and remained stable until the first postoperative day. S-100 profile during the procedure was independent of the duration of carotid artery cross-clamping and the need for a shunt. S-100 serum level was not significantly different in the patients with a postoperative ischemic event in comparison with the entire group. The S-100 profile was not increased in 2 of 3 patients with a permanent stroke and in 1 of 2 patients with a transient ischemic attack in comparison with the 95 patients with uneventful recovery.

CONCLUSION

S-100 concentration slightly increased at the end of surgery and remained high until the first postoperative day in all patients. S-100 was not significantly different in the patients with postoperative stroke. S-100 did not serve as a marker for postoperative stroke after carotid artery surgery. This fact must be taken into account during further investigations of S-100.

Blood S-100 protein concentration in children undergoing cardiac surgery

OBJECTIVES

To investigate plasma levels of the betabeta isomer of S-100 protein and to assess the relationship between post-cardiopulmonary bypass (CPB) levels of this marker and a variety of perioperative and patient factors in children undergoing cardiac surgery.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Twenty-five children.

INTERVENTIONS

Blood samples (2 mL) for S-100 determinations were collected after the induction of anesthesia, 30 minutes after aortic cross-clamping, 1 hour after the termination of CPB, and 5 and 24 hours after the operation. Electroencephalogram activity was recorded, and neurologic examination was performed on all children 1 day before and 10 days after the operation. Lowest values of nasopharyngeal temperature, mean arterial pressure, arterial carbon dioxide tension (PaCO2), pH, and hematocrit during CPB were recorded.

MEASUREMENTS AND MAIN RESULTS

The overall change in S-100 during the study period was found to be statistically significant (p < 0.0001). Correlation between deltaS-100 and age (r = -0.45; p = 0.04), body surface area (r = -0.63; p = 0.002), nasopharyngeal temperature (r = -0.55; p = 0.01), and PaCO2 (r = -0.55; p = 0.009) was statistically significant in infants and children. Multivariate regression analysis indicated significant effects of PaCO2 and body surface area on deltaS-100 levels and area under the curve values.

CONCLUSION

In contrast to newborns, infants and older children showed prominent increases in S-100 protein concentration. Lack of pathologic electroencephalogram findings and neurologic signs in the postoperative period precludes the clinical use of S-100 protein concentration as a sensitive marker of cerebral injury.

Serum S-100beta protein predicts brain injury after hypothermic circulatory arrest in pigs

OBJECTIVE

Serum S-100beta protein is suggested to be a neurobiochemical marker of brain injury after cardiac and aortic arch surgery. The aim of the present study was to investigate the predictive value of S-100beta protein with respect to histopathological analysis of the brain after a prolonged period of hypothermic circulatory arrest (HCA).

METHODS

Eighteen pigs (21 to 31 kg) underwent a 75 min period of HCA at 20 degrees C. Serum concentrations of S-100beta were assayed in mixed venous blood before and 2, 4, 7 and 20 h after HCA. A semiquantitative post-mortem histopathological analysis scoring all main regions of the brain was carried out in every animal.

RESULTS

All animals were stable during and after cardiopulmonary bypass (CPB) and survived at least to the first postoperative day. Ten of the 18 animals survived 7 days after surgery and were electively sacrificed. Animals with severe histopathological injury showed higher serum S-100beta protein levels at every time point after HCA. The strongest correlation between the total histopathologic score and serum S-100beta levels was found at 7 h after HCA (tau = 0.422 and p = 0.023).

CONCLUSION

Serum S-100beta protein levels correlate with histopathological injury after a prolonged period of HCA in pigs. This finding supports the results of previous studies suggesting the potential accuracy of S-100beta in the prediction of brain injury after cardiac surgery.

Serum S100 protein as a marker of cerebral damage during cardiac surgery

The identification of a serum marker to assist in the diagnosis of cerebral injury after cardiac surgery is potentially useful. S100 protein is an early marker of cerebral damage. It is released after cardiac surgery performed under cardiopulmonary bypass (CPB). Its level is correlated with the duration of CPB, deep circulatory arrest and aortic cross-clamping. Increased levels of S100 protein are correlated with the age of the patient and the number of microemboli, especially during aortic cannulation. Perioperative cerebral complications such as stroke, delayed awakening and confusion are associated with increased levels of S100 protein directly after bypass and from 15 to 48 h after it. In addition, increased levels of S100 protein are related to neuropsychological dysfunction after cardiac surgery. S100 protein has early and late release patterns after CPB; the early pattern may be due to sub-clinical brain injury. The late release pattern may be due to perioperative cerebral complications. Patients undergoing intracardiac operations combined with coronary artery bypass surgery are more susceptible to brain injury and have higher levels of S100 after CPB. Furthermore, adults and children undergoing deep circulatory arrest are more susceptible to brain injury, in terms of higher S100 protein release after CPB. Serum S100 protein levels are reduced after using arterial line filtration and covalent-bonded heparin to coat the inner surface of the CPB circuit.

Early release pattern of S100 protein as a marker of brain damage after warm cardiopulmonary bypass

Warm blood cardioplegia may be more beneficial to the heart than cold cardioplegia, but the effects of warm cardiopulmonary bypass and warm blood cardioplegia on the brain are controversial. S100 protein is an early marker of brain damage and has been detected after cold cardiopulmonary bypass. We studied S100 concentrations in 20 patients undergoing coronary artery bypass surgery before and after warm cardiopulmonary bypass (34-37 degrees C) using warm blood cardioplegia (37 degrees C) for all patients. The peak level of S100 protein occurred immediately after warm cardiopulmonary bypass, then decreased progressively until the last measurement at 4.5 h after bypass. The peak level appears to be dependent upon the age of the patient, with the following regression equation: y = -3.2 + 0.08x, where y is S100 protein concentration in microg.l-1 and x is patient age in years. Further studies are needed to investigate the clinical significance of this early release pattern. Patient age should be taken into account when studying S100 protein levels after cardiopulmonary bypass.

Subtle brain damage cannot be detected by measuring neuron-specific enolase and S-100beta protein after carotid endarterectomy

OBJECTIVE

To assess whether subtle brain damage after carotid endarterectomy could be detected using serum levels of neuron-specific enolase (NSE) or S-100beta protein.

DESIGN

Prospective noninterventional study.

SETTING

University hospital.

PARTICIPANTS

Twenty-two patients undergoing carotid endarterectomy and 16 patients undergoing repair of abdominal aortic aneurysm.

INTERVENTIONS

Serum levels of NSE and S-100beta protein were measured in all patients before surgery and postoperatively at 12, 24, 36, and 48 hours. In patients undergoing carotid endarterectomy, neuropsychologic testing was performed before surgery and postoperatively at discharge from the hospital and after 3 months using a neuropsychologic test battery.

MEASUREMENTS AND MAIN RESULTS

Compared with abdominal aortic surgery patients, the preoperative serum concentration of NSE was significantly higher in carotid artery surgery patients. Postoperatively, the NSE serum level decreased significantly after uncomplicated carotid artery surgery, and the level was then similar to that in the aortic surgery patients. Before operation, the S-100beta protein levels were similar in the two groups, but a significant increase was seen in aortic surgery patients postoperatively. Neuropsychologic testing after uncomplicated carotid artery surgery revealed cognitive dysfunction in 2 of 20 (10%) of the patients after 5 days and 3 of 16 (19%) of the patients after 3 months. There was no correlation between the change in cognitive function and the changes in blood levels of either NSE or S-100 protein.

CONCLUSIONS

Subtle brain damage after carotid artery surgery could not be detected by measuring blood levels of NSE and S-100beta protein. The NSE level was significantly higher before carotid artery surgery and decreased postoperatively to the level observed in aortic surgery.

The effect of cardiotomy suction on the brain injury marker S100beta after cardiopulmonary bypass

BACKGROUND

An increase of S100beta in serum during cardiopulmonary bypass (CPB) has been interpreted as a sign of brain injury. Cardiotomy suction may cause fat embolization, and its role in the S100beta increase was examined.

METHODS

Twenty coronary artery operation patients were randomly assigned to two groups, 10 with suction during CPB to cardiotomy reservoir (CR), 10 to cell saving device (CS). S100beta was measured (immunoassay) in blood from the patients and from cell saving device after processing. In 7 additional patients S100beta was measured in the cell saving device before processing and directly from the wound at sternotomy.

RESULTS

Before anesthesia, serum S100beta was 0.03+/-0.06 microg/L. At the end of CPB it was 2.47+/-1.31 microg/L and 0.44+/-0.27 microg/L (CR vs CS; p < 0.001). S100beta was 33+/-12 microg/L in CS reservoir and 42+/-18 microg/L in blood from the wound.

CONCLUSIONS

Most serum S100beta after CPB with cardiotomy suction may be of extracerebral origin. S100beta after CPB with cell saving device was the same as after off-pump operation. The interpretation that an increase in S100beta during CPB in patients reflects cerebral injury must be questioned.

Is there a relationship between serum S-100beta protein and neuropsychologic dysfunction after cardiopulmonary bypass?

OBJECTIVES

Over the past decade, the glial protein S-100beta has been used to detect cerebral injury in a number of clinical settings including cardiac surgery. Previous investigations suggest that S-100beta is capable of identifying patients with cerebral dysfunction after cardiopulmonary bypass. Whether detection of elevated levels S-100beta reflects long-term cognitive impairment remains to be shown. The present study evaluated whether perioperative release of S-100beta after coronary artery operations with cardiopulmonary bypass could predict early or late neuropsychologic impairment.

METHODS

A total of 100 patients undergoing elective coronary bypass without a previous history of neurologic events were prospectively studied. To exclude noncerebral sources of S-100beta, we did not use cardiotomy suction or retransfusion of shed mediastinal blood. Serial perioperative measurements of S-100beta were performed with the use of a new sensitive immunoluminometric assay up to 8 hours after the operation. Patients underwent cognitive testing on a battery of 11 tests before the operation, before discharge from the hospital, and 3 months later.

RESULTS

No significant correlation was found between S-100beta release and neuropsychologic measures either 5 days or 3 months after the operation.

CONCLUSION

Despite using a sensitive immunoluminometric assay of S-100beta, we found no evidence to support the suggestion that early release of S-100beta may reflect long-term neurologic injury capable of producing cognitive impairment.

A contrastive analysis of release patterns of biochemical markers of brain damage after coronary artery bypass grafting and valve replacement and their association with the neurobehavioral outcome after cardiac surgery

OBJECTIVE

The present study aimed at a comparative analysis of neurobiochemical markers of brain damage and the neurobehavioral outcome in patients undergoing either valve replacement (VR) or isolated coronary artery bypass surgery (CABG). In order to control for well known risk factors both samples were strictly matched according to age, sex and preoperative neuropsychological performance.

METHODS

We analysed neurone-specific enolase (NSE) and protein S-100B (S-100B) concentrations in serial venous blood samples taken preoperatively and 1, 6, 20 and 30 h postoperatively in 36 patients undergoing VR (N = 18) or isolated CABG surgery (N = 18). Mini Mental State Examination (MMS) was performed preoperatively, 3 and 7 days after surgery and 0.5 years later. Neuropsychiatric assessments were based on the diagnosis of postoperative delirium according to DMS-IIIR criteria and the Brief Psychiatric and the Delirium Rating Scale.

RESULTS

VR and CABG patients, respectively, showed an increase of both S-100B (exact two-tailed Wilcoxon signed ranks test: P = 0.0001) and NSE (P = 0.0001) concentrations followed by a decrease during the next 30 h. Whereas S-100B values did not differ between patients groups subjects undergoing VR surgery exhibited higher NSE values during the postoperative course. Furthermore, VR patients showed a higher decline in cognitive performance which was also detectable 0.5 years after surgery. We found a weak association between the degree of individual postoperative decline of cognitive performance and S-100B area under curve values.

CONCLUSIONS

Our data indicate that--apart from patients' age and preoperative neuropsychological performance--type of surgery remains a risk factor for postoperative neurobehavioral disorders. The different vulnerability of neurobehavioral disorders might be mirrored in different postoperative release patterns of NSE. We assume that both, NSE release and neurobehavioral disorders might be caused by a higher amount of intraoperative cerebral embolic events in VR patients.

Neurophysiologic monitoring and outcomes in cardiovascular surgery

The first step to make in improving neurologic outcome is to recognize and accept neurologic injury occurs in all patient groups undergoing CPB. Fortunately, that stage has now been passed. Accurate detection and documentation of the incidence of brain injury is the next progression. At the same time, the cause of the injury needs to be established. Since the introduction of CPB, numerous improvements and refinements have been achieved, making it the acceptable, everyday clinical tool that has enabled the development of cardiac surgery. Despite these improvements, CPB-related morbidity persists. The advent of new technologic advances drives the quest for new techniques. New protective strategies for many end organs, including the heart, kidney, and brain, are evolving. No organ system should be viewed in isolation; otherwise, organ-specific protective strategies may arise in conflict. A strategy that confers absolute myocardial protection would be ideal, but at what cost to the protection of the kidneys, intestines, and brain? A neuroprotective strategy would ideally eliminate brain injury and be beneficial for all organs. The only way to continue to make progress is by the scientific evaluation of new techniques. The use of appropriate monitoring and outcome measures is fundamental to this process.

Release of S100B during coronary artery bypass grafting is reduced by off-pump surgery

BACKGROUND

S100B, a plasma marker of brain injury, was compared after coronary artery bypass grafting with and without cardiopulmonary bypass (CPB).

METHODS

Fourteen patients with off-pump operations and 18 patients with CPB were compared. Seven patients in the off-pump group underwent a minithoracotomy and received only an arterial graft, whereas 7 patients underwent sternotomy and received both an arterial and one or two vein grafts. S100B was measured in arterial plasma using an immunoassay with enhanced sensitivity.

RESULTS

S100B before the operation was 0.03 microg/L. At wound closure, S100B in patients of the off-pump and CPB groups reached a maximum level of 0.22 +/- 0.07 and 2.4 +/- 1.5 microg/L, respectively (p < 0.001). No strokes occurred. Patients without CPB receiving arterial and vein grafts released slightly more S100B (p < 0.05) than patients with only arterial grafting. In patients undergoing CPB, S100B increased slightly before aortic cannulation (p < 0.001), to the same level as the maximum reached for the non-CPB group.

CONCLUSIONS

Coronary artery bypass grafting with CPB caused a 10-fold greater increase in S100B than off-pump grafting. S100B release after off-pump sternotomy with vein grafting was slightly greater than in arterial grafting through a minithoracotomy.