Brain damage and neurological outcome after open-heart surgery

Association of Coronary Artery Bypass Grafting vs Percutaneous Coronary Intervention With Memory Decline in Older Adults Undergoing Coronary Revascularization

IMPORTANCE

It is uncertain whether coronary artery bypass grafting (CABG) is associated with cognitive decline in older adults compared with a nonsurgical method of coronary revascularization (percutaneous coronary intervention [PCI]).

OBJECTIVE

To compare the change in the rate of memory decline after CABG vs PCI.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of community-dwelling participants in the Health and Retirement Study, who underwent CABG or PCI between 1998 and 2015 at age 65 years or older. Data were modeled for up to 5 years preceding and 10 years following revascularization or until death, drop out, or the 2016-2017 interview wave. The date of final follow-up was November 2017.

EXPOSURES

CABG (including on and off pump) or PCI, ascertained from Medicare fee-for-service billing records.

MAIN OUTCOMES AND MEASURES

The primary outcome was a summary measure of cognitive test scores and proxy cognition reports that were performed biennially in the Health and Retirement Study, referred to as memory score, normalized as a z score (ie, mean of 0, SD of 1 in a reference population of adults aged ≥72 years). Memory score was analyzed using multivariable linear mixed-effects models, with a prespecified subgroup analysis of on-pump and off-pump CABG. The minimum clinically important difference was a change of 1 SD of the population-level rate of memory decline (0.048 memory units/y).

RESULTS

Of 1680 participants (mean age at procedure, 75 years; 41% female), 665 underwent CABG (168 off pump) and 1015 underwent PCI. In the PCI group, the mean rate of memory decline was 0.064 memory units/y (95% CI, 0.052 to 0.078) before the procedure and 0.060 memory units/y (95% CI, 0.048 to 0.071) after the procedure (within-group change, 0.004 memory units/y [95% CI, -0.010 to 0.018]). In the CABG group, the mean rate of memory decline was 0.049 memory units/y (95% CI, 0.033 to 0.065) before the procedure and 0.059 memory units/y (95% CI, 0.047 to 0.072) after the procedure (within-group change, -0.011 memory units/y [95% CI, -0.029 to 0.008]). The between-group difference-in-differences estimate for memory decline for PCI vs CABG was 0.015 memory units/y (95% CI, -0.008 to 0.038; P = .21). There was statistically significant increase in the rate of memory decline after off-pump CABG compared with after PCI (difference-in-differences: mean increase in the rate of decline of 0.046 memory units/y [95% CI, 0.008 to 0.084] after off-pump CABG), but not after on-pump CABG compared with PCI (difference-in-differences: mean slowing of decline of 0.003 memory units/y [95% CI, -0.024 to 0.031] after on-pump CABG).

CONCLUSIONS AND RELEVANCE

Among older adults undergoing coronary revascularization with CABG or PCI, the type of revascularization procedure was not significantly associated with differences in the change of rate of memory decline.

Direct postoperative protein S100B and NIRS monitoring in infants after pediatric cardiac surgery enrich early mortality assessment at the PICU

BACKGROUND

Neuromonitoring using plasmatic biomarkers such as S100B and near-infrared spectroscopy (NIRS) represents a standard procedure for detecting cerebral damage after cardiac surgery. Their use in pediatric clinical assessment, however, is negligible.

OBJECTIVES

The goal of this study was to evaluate the predictive role of S100B levels and cerebral oxygenation in postoperative pediatric cardiac patients for survival and potential cerebral injuries.

METHODS

A retrospective cohort study of infants after cardiac surgery. Primary outcome was survival until discharge. Intra/postoperative vital signs and laboratory data were measured and statistically analyzed.

RESULTS

Seven out of 226 infants were non-survivors. Non-survivors had significantly lower cerebral saturation than survivors, as well as elevated S100B values at admission, associated with lower arterial pressure and higher serum lactate levels.

CONCLUSION

Although significant differences of S100B and crO₂ values between survivors and non-survivors were found, no critical thresholds could be established from the data. Nevertheless, changes from the norm in these parameters should raise awareness for critical clinical development.

The Effect of Substrate Load and Blood Glucose Management on Cerebral Dysfunction Following Cardiopulmonary Bypass

Seventy patients undergoing elective coronary artery bypass grafting were prospectively randomized into either of two primes: 5% dextrose or Hartmann's solution. The groups were comparable. Neuropsychological assessment was performed before and eight weeks after surgery. During bypass blood glucose concentrations rose to a mean of 26 mmol/L in the 5% dextrose group and 6 mmol/L in the Hartmann's group. No deaths occurred in either group; 2 clinically evident neurological events were noted, both taking place in the hyperglycemic group. Detailed analysis of the results showed differences between the groups. When score changes between tests were assessed it was found that in 17 of the 18 versions of the tests more patients in the hyperglycemic group deteriorated than the normoglycemic controls. With a two-tailed binomial statistic this difference was significant at the 5% level. Learning ability was likewise found to worsen in the hyperglycemic group after surgery.

Hyperglycemia may be a detrimental factor in the development of postcardiac surgical intellectual dysfunction. The authors would advocate the avoidance of glucose-containing bypass primes and the close monitoring of blood glucose during cardiopulmonary bypass.

Cerebral dysfunction after cardiopulmonary bypass: aetiology, manifestations and interventions

Central nervous system dysfunction following cardiac surgery remains a significant cause of morbidity and mortality, with the reported incidence of dysfunction varying widely between studies. Microemboli and global cerebral hypoperfusion are implicated as the major aetiologies of CNS impairment. Preoperative and intraoperative variables influencing the patient's risk of complications remain controversial. Based on a review of previous studies, this paper outlines the major causes and manifestations of CNS impairment as well as the intraoperative interventions currently advocated to improve the cerebral outcome of cardiac patients.

Neuropsychological and behavioral functioning in children with and without obstructive sleep apnea referred for tonsillectomy

Adenotonsillectomy (AT) is among the most common pediatric surgical procedures and is performed as often for obstructive sleep apnea (OSA) as for recurrent tonsillitis. This study compared behavioral, cognitive, and sleep measures in 27 healthy control children recruited from a university hospital-based pediatric general surgery clinic with 40 children who had OSA (AT/OSA+) and 27 children who did not have OSA (AT/OSA-) scheduled for AT. Parental ratings of behavior, sleep problems, and snoring, along with specific cognitive measures (i.e., short-term attention, visuospatial problem solving, memory, arithmetic) reflected greater difficulties for AT children compared with controls. Differences between the AT/OSA- and control groups were larger and more consistent across test measures than were those between the AT/OSA+ and control groups. The fact that worse outcomes were not clearly demonstrated for the AT/OSA+ group compared with the other groups was not expected based on existing literature. This counterintuitive finding may reflect a combination of factors, including age, daytime sleepiness, features of sleep-disordered breathing too subtle to show on standard polysomnography, and academic or environmental factors not collected in this study. These results underscore the importance of applying more sophisticated methodologies to better understand the salient pathophysiology of childhood sleep-disordered breathing.

Cerebrovascular accidents after cardiac surgery: an analysis of CT scans in relation to clinical symptoms

There is a link between aortic manipulation, particle embolization, and cerebrovascular accidents (CVA) in cardiac surgery. The present aim was to study hemispheric side differences of CVA. Cardiac-surgery patients with CVA and with computer tomography (CT) performed (n = 77) were analyzed within a total group of 2641 consecutive cases. CT data were reviewed for hemispheric and vascular distribution, and compared with CVA-symptom data of immediate and delayed type. Of the included patients, 66% had positive CT. In the group of 'cardiac-type' operations (e.g., routine clamping and cannulation) and having immediate CVA, right-hemispheric lesions were more frequent than of the contra-lateral side (p = 0.005). Patients with aortic dissections had strong dominance of bilateral findings, which was different from the unilateral pattern of 'cardiac-type' operations (p = 0.001). The middle-cerebral artery territory dominated, and when involved showed a significant (p = 0.022) right-sided distribution. Both CT and clinical symptoms confirmed that CVA after cardiac surgery has a right-hemispheric predominance. These observations may imply that aortic manipulation directs embolic material towards the brachiocephalic trunk.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Differential cerebral gene expression during cardiopulmonary bypass in the rat: evidence for apoptosis?

Cardiopulmonary bypass (CPB) is associated with a spectrum of cerebral injuries. The molecular changes in the brain that might contribute to these injuries are not clearly known. We sought to determine whether the expression of apoptotic genes is increased after CPB in the rat. Rats (n = 7) were subjected to 90 min of normothermic CPB. A group of sham-operated rats (n = 7) served as non-CPB controls. After a 3-h post-CPB period of recovery, their brains were removed, homogenized, and processed for messenger RNA (mRNA) extraction. By using a ribonuclease protection assay, the ratios of both pro- and antiapoptotic mRNA (bcl-x, bcl-2, bax, caspase 2, and caspase 3) to the housekeeping glyceraldehyde phosphate dehydrogenase (GAPDH) gene were determined. Additionally, Western immunoblotting was performed to detect the presence of activated caspase 3, a protein central in the apoptotic process. Compared with the non-CPB controls, the CPB group had significantly increased levels of apoptotic/GAPDH mRNA ratios (bcl-x, 0.414 +/- 0.152 CPB versus 0.251 +/- 0.051 non-CPB, P = 0.048; caspase 2, 0.030 +/- 0.014 CPB versus 0.018 +/- 0.005 non-CPB, P = 0.048; bax, 0.106 +/- 0.035 CPB versus 0.066 +/- 0.009 non-CPB, P = 0.009; bcl-2, 0.011 +/- 0.006 CPB versus 0.006 +/- 0.002 non-CPB, P = 0.035). However, no activated caspase 3 protein was detected in either group. Elucidating the molecular biological sequelae of CPB may aid in the understanding of the pathophysiology of cardiac surgery-associated cerebral injury and, in doing so, may be useful in identifying potential therapeutic targets for pharmacologic neuroprotection.

IMPLICATIONS

Cardiopulmonary bypass (CPB) appears to induce transcription of pro- and antiapoptotic genes in the rat brain, but caspase-mediated apoptosis itself does not appear to be activated. Elucidating the molecular biological sequelae of CPB may aid in the understanding of the pathophysiology of cardiac surgery-associated cerebral injury and, in doing so, may be useful in identifying potential therapeutic targets for pharmacologic neuroprotection.

Differential cerebral gene expression during cardiopulmonary bypass in the rat: evidence for apoptosis?

Cardiopulmonary bypass (CPB) is associated with a spectrum of cerebral injuries. The molecular changes in the brain that might contribute to these injuries are not clearly known. We sought to determine whether the expression of apoptotic genes is increased after CPB in the rat. Rats (n = 7) were subjected to 90 min of normothermic CPB. A group of sham-operated rats (n = 7) served as non-CPB controls. After a 3-h post-CPB period of recovery, their brains were removed, homogenized, and processed for messenger RNA (mRNA) extraction. By using a ribonuclease protection assay, the ratios of both pro- and antiapoptotic mRNA (bcl-x, bcl-2, bax, caspase 2, and caspase 3) to the housekeeping glyceraldehyde phosphate dehydrogenase (GAPDH) gene were determined. Additionally, Western immunoblotting was performed to detect the presence of activated caspase 3, a protein central in the apoptotic process. Compared with the non-CPB controls, the CPB group had significantly increased levels of apoptotic/GAPDH mRNA ratios (bcl-x, 0.414 +/- 0.152 CPB versus 0.251 +/- 0.051 non-CPB, P = 0.048; caspase 2, 0.030 +/- 0.014 CPB versus 0.018 +/- 0.005 non-CPB, P = 0.048; bax, 0.106 +/- 0.035 CPB versus 0.066 +/- 0.009 non-CPB, P = 0.009; bcl-2, 0.011 +/- 0.006 CPB versus 0.006 +/- 0.002 non-CPB, P = 0.035). However, no activated caspase 3 protein was detected in either group. Elucidating the molecular biological sequelae of CPB may aid in the understanding of the pathophysiology of cardiac surgery-associated cerebral injury and, in doing so, may be useful in identifying potential therapeutic targets for pharmacologic neuroprotection.

IMPLICATIONS

Cardiopulmonary bypass (CPB) appears to induce transcription of pro- and antiapoptotic genes in the rat brain, but caspase-mediated apoptosis itself does not appear to be activated. Elucidating the molecular biological sequelae of CPB may aid in the understanding of the pathophysiology of cardiac surgery-associated cerebral injury and, in doing so, may be useful in identifying potential therapeutic targets for pharmacologic neuroprotection.

Musculoskeletal and neurological complications following coronary artery bypass graft surgery: A comparison between saphenous vein and internal mammary artery grafting

The internal (thoracic) mammary artery (IMA) is currently the vessel of choice for coronary artery bypass grafting (CABG), due to its long term patency. The purpose of this study was to compare the incidence and nature of musculoskeletal and neurological complications following saphenous vein grafting (SVG) and internal mammary artery grafting (IMAG). Ninety-seven patients were screened by a physiotherapist for musculoskeletal and neurological complications three to six weeks following cardiac surgery. The incidence of new musculoskeletal and neurological complications was significantly higher in patients following IMAG (78.5 per cent) than SVG (45 per cent) (p < 0.001, chi2(1) = 17.04). A significant association between musculoskeletal complications affecting the anterior chest and harvesting of the IMA was also demonstrated.

Assessment of perfusion toward the aortic valve using the new dispersion aortic cannula during coronary artery bypass surgery

When there is an echocardiographic diagnosis of severe mobile atherosclerotic plaque in the aortic arch or descending aorta, perfusion toward the aortic arch during cardiopulmonary bypass may create a high risk of embolic neurologic injury. Other perfusion methods, such as cannulation of the femoral or axillary arteries, are not always possible, due to atherosclerosis. The ascending aorta may be an alternative site for perfusion, since it is less frequently diseased. We assessed a new technique of perfusion toward the aortic valve using a new cannula designed for this purpose (Dispersion aortic cannula). Our study included 100 consecutive patients, 72 men and 28 women, with an average age of 68 +/- 1.0 years (range, 39-89 years). There were no complications related to insertion of the cannula or perfusion. The ascending aorta could be cross-clamped and side-clamped without perfusion problems. Three deaths occurred; none was related to the cannulation technique. No intra-operative stroke occurred. Two patients suffered neurologic events, one on day 1 and the other on day 6; both had been fully alert after surgery. Perfusion toward the aortic valve appears to be safe and hemodynamically effective. This cannulation technique appears to be an acceptable alternative to present methods. Comparative studies will be needed to determine whether this alternative technique is effective in patients with severe aortic arch disease.

Neurobehavioural sequelae of cardiopulmonary bypass

The development of coronary artery bypass grafting (CABG) and its effect on angina is the product of a series of technical and scientific advances. Despite these advances, however, adverse neurobehavioural outcomes continue to occur. Stroke is the most serious complication of CABG, but studies that have identified demographic and medical risk factors available before surgery are an important advance. Short-term cognitive deficits are common after CABG, but may not be specific to this procedure. However, deficits in some cognitive areas such as visuoconstruction persist over time, and may reflect parieto-occipital watershed area injury secondary to hypoperfusion or embolic factors. Risk factors for cognitive decline may be time dependent, with short-term studies identifying factors that differ from those of long-term studies. Patients with depression before surgery are likely to have persistent depression afterwards. However, depression does not account for the cognitive decline after CABG. Since CABG is increasingly done in older patients with more comorbidity, the challenge is to identify patients at risk of adverse neurocognitive outcomes and to protect them by modification of the surgical procedure or by effective medical therapy.

Stroke Reduction: Diagnosis and Management of the Atherosclerotic Ascending Aorta During Cardiac Surgery

Neurologic injury is the most devastating complication of cardiac surgery, and leads to excessive morbidity, mortality, and increased health care costs. Ascending aorta atherosclerosis is one of the most important risk factors for perioperative stroke, particularly in the el derly. As the number of elderly patients undergoing cardiac surgical procedures continues to increase, it is likely that the frequency of postoperative neurologic complications will increase as well. Strategies aimed toward the identification of high-risk patients include screening for carotid artery disease and ascending aorta atherosclerosis. Epiaortic ultrasound provides high- resolution images of the ascending aorta that allow for evaluation for the presence of atherosclerosis. Minor modifications in the operative technique based on the epiaortic ultrasound findings are easy to perform and require minimal training and relatively inexpensive equipment. Nonrandomized studies that use epiaortic ultrasound have reported perioperative stroke rates that are lower than those in which this approach is not used, suggesting that identification of high-risk patients and minor modifications in the operative technique may lower perioperative stroke rates without increasing operative risk. Prospective, randomized trials are needed to evaluate whether more aggressive changes in surgi cal techniques and/or the use of neuroprotective agents in high-risk patients may prevent neurologic complica tions associated with cardiac surgery.

Influence of Vasodilator Drugs on Perioperative Blood Pressure

Survey results are given of the incidence and the etiology of perioperative hypertension in patients sub jected to coronary artery surgery. Over the years, numer ous types of antihypertensives have been used for intravenous administration with the aim of preventing or treating perioperative hypertension. Nitrovasodilator compounds such as sodium nitroprusside and nitroglyc erin (NTG), a few calcium antagonists (nifedipine, nicar dipine and isradipine), the short-acting β-blocker esmo lol, clonidine, and the multifactorial compounds labetalol and ketanserin are discussed in detail. Perioperatively, there is an increasing level of plasma catecholamines, causing α-adrenoceptor stimulation. This indicates that α-adrenoceptor blockade with appropriate antagonists is a logical approach for the treatment of perioperative hypertension. For this reason, the multifactorial agent urapidil, which is an α-adrenoceptor blocker and a 5-HT1A agonist, is discussed extensively.

Posterior distribution of infarcts in strokes related to cardiac operations

BACKGROUND

Stroke complicates cardiac surgical procedures in a substantial number of patients. The mechanism of stroke is predominantly embolic, although hypoperfusion may play a role. The aim of this study was to determine whether radiologic appearances in this population were consistent with an embolic cause.

METHODS

We reviewed computed tomographic scans and medical records in 24 patients who suffered stroke after cardiac operation. Stroke was evident at 24 hours in 19 patients (79%). Infarcts were multiple in 16 and single in 3 patients (group 1). The remaining 5 patients suffered stroke beyond 24 hours and had single infarcts on computed tomographic scan (group 2).

RESULTS

In group 1, 15 patients (79%) had bilateral cerebellar infarcts, 4 (74%) had posterior cerebral artery infarcts, 10 (53%) had posterior watershed infarcts, and 11 patients (58%) had middle cerebral artery branch infarcts. The mean number of vascular territories involved was 5.1 (range, 1 to 10). Mobile atheromatous plaque was present in the ascending aorta or arch in 5 of 9 patients (56%) in group 1. In group 2, stroke occurred in close association with atrial or ventricular fibrillation in 3 of 5 patients (60%).

CONCLUSIONS

In patients with radiologic evidence of infarction, perioperative strokes after cardiac operation are typically multiple, and involve the posterior parts of the brain, consistent with atheroembolization. Delayed strokes may be attributable to cardiogenic embolism.

Influence of myocardial infarction, coronary artery bypass surgery, and stroke on cognitive impairment in late life

Relations between cognitive test scores in later life and prior myocardial infarction (MI), coronary artery bypass graft surgery (CABG), and stroke were examined for this study. Subjects were 3,734 Japanese-American men (80% of surviving Honolulu Heart Program cohort) aged 71 to 93 years at the time of cognitive testing. Impairment was defined as scoring below the 16th percentile on a validated cognitive assessment scale. Prior MI, stroke, and CABG were established using hospital surveillance, history, and record review. After adjustment for age, years of education, and years of childhood spent in Japan, men with prior stroke were significantly more likely than others to have poor cognitive performance (odds ratio 4.4, 95% confidence limits 3.0 to 6.7). History of > 1 stroke was associated with an odds ratio of 50 (95% confidence limits 10.5 to 238.3). There was no significant association between cognitive performance and > or = 1 prior MI or history of CABG. Time between events and cognitive function testing did not affect results. Analyses support a significant association between clinical stroke and persistent cognitive impairment, but fail to implicate CABG or MI.

Impact of anesthesia on the cognitive functioning of the elderly

Exposure to general anesthesia has been suggested as a possible cause of long-term cognitive impairment in elderly subjects. The present study reviews the literature in this field in order to describe postoperative cognitive impairment in elderly populations, to determine to what extent this may be attributed to anesthetic agents, and to consider evidence of a causal relationship between anesthesia and onset of senile dementia. A systematic literature search was conducted using five bibliographic databases (PASCAL, Medline, Excerpta Medica, Psychological Abstracts, and Science Citation Index). Significant cognitive dysfunction was found to be common in elderly persons 1 to 3 days after surgery, but reports of longer-term impairment are inconsistent due to the heterogeneity of the procedures used and populations targeted in such studies. Incidence rates vary widely according to type of surgery, suggesting that factors other than anesthesia explain a significant proportion of the observed variance. Anesthesia appears to be associated with longerterm cognitive disorder and the acceleration of senile dementia, but only in a small number of cases, suggesting the existence of other interacting etiological factors.

Normothermic cardiopulmonary bypass: effect on the incidence of persistent postoperative neurological dysfunction following coronary artery bypass graft surgery

We retrospectively reviewed the records of 250 consecutive patients undergoing coronary artery bypass graft surgery (CABG) from January 1994 through January 1996 to determine the incidence of persistent postoperative neurological dysfunction after CABG and to compare normothermic and moderate hypothermic cardiopulmonary bypass (CPB). Normothermic CPB was used in 128 patients (36°-37°C) and hypothermic CPB (27°-28°C) in 122 patients. Postoperative neurological dysfunction included focal motor deficits, delayed recovery of consciousness (>24h) after surgery, and seizures within 1 week postoperatively. Persistent neurological dysfunction was diagnosed if complete resolution had not occurred within 10 days of surgery. The incidence of persistent postoperative neurological dysfunction was 4.1% in the hypothermic CPB group and 2.3% in the normothermic CPB group. There were no statistically significant differences between the two groups (P=NS). These results suggest that normothermic CPB did not increase the incidence of persistent postoperative neurological dysfunction compared to hypothermic CPB.

Prediction of quality of life after coronary artery bypass graft surgery: a review and evaluation of multiple, recent studies

OBJECTIVE

To review studies predicting psychosocial outcome after coronary artery bypass graft surgery (CABG).

METHODS

Seventeen prospective studies, appearing in the MEDLINE and PsycLIT data bases between 1986 and 1996, were reviewed regarding objectives, methodological issues, results, and clinical relevance.

RESULTS

All studies reported that psychological factors bad predictive value. In particular, preoperative anxiety and depression predicted postoperative psychological maladjustment; social support, preoperative feelings of control, denial, and optimism contributed to psychological adjustment.

CONCLUSIONS

Many specific psychological outcomes seem to be best predicted by preoperative assessment of functions in that specific area, especially in the case of anxiety and depression. Furthermore, personality factors including denial, optimism, control, and the need for support appear to be predictors of psychological outcome. Appropriate identification of predictive factors might improve the development of individually tailored interventions for patients at risk of postoperative psychological problems.

Somatosensory evoked potential monitoring during cardiac surgery: an examination of brachial plexus dysfunction

OBJECTIVE

To observe the effects of the Favoloro and sternal retractors on the ulnar and median nerve somatosensory evoked potentials (SSEPs) and to identify any relationship with postoperative brachial plexus injury.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Twenty cardiac patients.

INTERVENTIONS

SSEPs were studied in patients undergoing cardiac surgery using normothermic cardiopulmonary bypass. Evoked potentials were obtained from bilateral median and ulnar nerves.

MEASUREMENTS

The incidence of nerve-specific SSEP changes and their temporal relationship to retractor usage were determined. The overall incidence of SSEP changes was 75%. There were no differences (p > 0.05) between the group showing changes (n = 15) and the group with no changes (n = 5) with respect to age, body surface area, weight, cross-clamp or cardiopulmonary bypass times. There also were no differences (p > 0.05) between the frequencies of left- and right-sided changes, or in nerve-specific SSEP changes. Seventy-four percent of SSEP changes correlated with retractor usage. No SSEP changes were associated with the Favoloro retractor. Significant SSEP depression, assessed by either percentage reduction in amplitude or persistent amplitude reduction, occurred in the absence of postoperative neurological deficits. There were no detected postoperative brachial plexus injuries.

CONCLUSIONS

SSEP changes correlate with the use of the sternal retractor but not the Favoloro retractor. It was not possible to replicate the results of previous investigators in predicting postoperative neurological deficits based on the SSEP changes, and therefore the routine application of SSEP as a monitor cannot be recommended on the basis on these data.

QEEG and neuropsychological profiles of patients prior to undergoing cardiopulmonary bypass surgical procedures

Within our patient population undergoing cardiopulmonary bypass (CPB) surgery, evidence of pre-existing cortical dysfunction was highly prevalent, with 39.5% displaying QEEG and/or neuropsychological (NP) abnormality. These patients with pre-existing QEEG or NP abnormality were at increased risk for developing both short and long-term postoperative deficits in NP performance. Preoperative QEEG showed increased sensitivity and specificity over preoperative NP performance for predicting NP performance one week after surgery. One week after surgery NP deficits were quite common occurring in 40.6% of the patients. Two to three months after surgery evidence of continued NP performance deficits were still present in 28.1% of the patients. Preoperative NP performance predicted 3 month postoperative NP performance quite well, although preoperative QEEG proved equally effective.

Comparison of serum S-100 beta levels during CABG and intracardiac operations

BACKGROUND

The risk of overt and subtle cerebral injury may be higher in intracardiac operation (ICO) rather than coronary artery bypass grafting (CABG). S-100 protein is a specific astroglial protein whose serum level increases after cerebral injury. Elevated serum levels of S-100 have been detected after adult cardiac operations and correlated with neurologic injury.

METHODS

The level of S-100 protein was measured serially over 24 hours in 40 patients (27 undergoing aortic valve replacement, 9 mitral valve replacement, 4 closure of atrial septal defect) undergoing ICO and 20 patients undergoing CABG.

RESULTS

The groups were similar with respect to age and cardiopulmonary bypass times. The S-100 level was not elevated before operation in any patient. Peak S-100 levels were reached at skin closure, when 35 of the ICO patients (88%) and 13 of the CABG patients (65%) had elevated S-100 levels. At skin closure peak S-100 levels were significantly greater in the ICO group (median [interquartile range], 0.76 [0.44-1.16] versus 0.3 [0-0.55] microgram/L; p < 0.01). At 5 hours S-100 levels were still elevated in 22 patients in the ICO group compared with 1 patient in the CABG group (p < 0.01), and at 24 hours 17 ICO patients had persistently elevated S-100 levels in comparison with 2 in the CABG group (p < 0.01). One valve patient had a stroke 24 hours after operation accompanied by a secondary increase in the S-100 level. There was no significant difference in postoperative S-100 levels between 5 patients in the ICO group with a prior history of stroke and those without. The peak S-100 level correlated with patient age (r = 0.59; p < 0.001) but not with the duration of cardiopulmonary bypass or core temperature during the operation.

CONCLUSIONS

Intracardiac operation results in a significantly greater elevation in S-100 levels than CABG. Elevated S-100 levels correlate with increasing patient age but not with the duration of cardiopulmonary bypass or intraoperative core temperature. These findings raise the possibility that ICO patients may be more vulnerable to even subtle levels of cerebral injury than CABG patients.

Neuropsychologic change after cardiac surgery: a critical review

Studies that have examined neuropsychologic change after cardiac surgery address three main issues: (1) the incidence of cognitive change; (2) the identification of factors that put patients at higher risk; and (3) the evaluation of interventions to prevent these complications. This review attempts to bring together concerns associated with various study designs and to integrate the conclusions from these studies. Thirty-five studies have been examined in this review. Some of the difficulties encountered when quantifying the degree of cognitive change are related to study design, patient sampling, and deficit definition. Additionally, changing patient populations have influenced results reported from different health care settings. Increasing age and longer cardiopulmonary bypass times have been correlated with cognitive decline in a number of studies. Filtration devices and blood gas management techniques have decreased but not eliminated the number of patients who have cognitive decline. Cognitive change exists following cardiac procedures. Identification of a subgroup of patients at high risk for cognitive change has been difficult, possibly due to issues of study design. Design of future studies, which may include intraoperative or pharmacologic interventions, is dependent on identification of this high-risk group.

Adverse neurologic events: risks of intracardiac versus extracardiac surgery

Intracardiac operations such as valve replacements have typically carried a higher risk (4.2% to 13%) of overt central nervous system outcome, compared with coronary artery bypass grafting (CABG) procedures (0.6% to 5.2%). This is likely owing to the increased risk of macroembolization of air or particulate matter from the surgical field during intracardiac surgery. The periods of highest risk for emboli are during aortic cannulation and especially during release of aortic clamps and weaning from bypass. The number of embolic events measured with transcranial Doppler is significantly higher in patients undergoing valve surgery compared with coronary surgery, particularly during cardiac ejection and immediately after bypass. However, there is current evidence that neurologic risk is increasing in patients undergoing CABG owing to the tendency to operate on older patients with more severe aortic atherosclerosis and cerebrovascular disease. Patients having an intracardiac procedure combined with a CABG procedure may be at particularly high risk for adverse neurologic outcome. For all cardiac surgical patients, there is some cause for optimism in that risk may be minimized by improved assessment (e.g., intraoperative transesophageal or epiaortic echocardiographic scanning of the ascending aorta to identify patients at risk) and monitoring (e.g., detection of embolic phenomena, using transesophageal echocardiography or transcranial Doppler technology). Furthermore, in the future, development and testing of more ideal cerebroprotective drugs may allow amelioration of neurologic injury, either by pretreating all patients at risk, or possibly even by delaying treatment until after the suspected occurrence of an insult.

Long-term neurologic outcome after cardiac operation

Cardiac surgical patients face the threat of neurologic complications in all phases of their disease and its treatment. The incidence of preoperative transient ischemic attacks and stroke ranges from 5% to 14% and from 2% to 11%, respectively. The risk of preoperative cerebrovascular accidents is higher in patients with valvular disease than in those with coronary artery disease. The prevalence of postoperative neurologic disorders varies widely because of differences in defining the clinical criteria, heterogeneity of patient populations, timing of evaluation, follow-up times, study designs, and surgical and anesthesia-related procedures. Fatal cerebral damage is very rare (< 0.1%). Focal cerebral deficits, or definite stroke, are encountered in 1% to 3% of patients and minor clinical abnormalities, in 5% to 10%. Recent studies have shown that contrary to previous concepts, valve replacement does not carry essentially higher neurologic risks than coronary bypass grafting. The most common causes of operation-related neurologic disorders are microembolization or macroembolization and hypoperfusion. Although most disorders resolve early postoperatively, some deficits persist. From the neurologic standpoint, a main objective of a cardiac surgical intervention is to prevent stroke. Today, the incidence of cardiogenic cerebrovascular accidents is very low after reparative cardiac procedures. Despite surgical and anesthesia-related improvements, neurologic complications do occur. Multidimensional investigatory procedures have shown that cardiopulmonary bypass often causes cerebral dysfunction. Whether the harmful consequences are detected depends on the evaluation criteria and the investigatory methods and timing used. Further methods are needed to prevent or treat preoperative cerebrovascular accidents and particularly to improve cerebral protection during operative procedures.

Predictors of cognitive decline after cardiac operation

Despite major advances in cardiopulmonary bypass technology, surgical techniques, and anesthesia management, central nervous system complications remain a common problem after cardiopulmonary bypass. The etiology of neuropsychologic dysfunction after cardiopulmonary bypass remains unresolved and is probably multifactorial. Demographic predictors of cognitive decline include age and years of education; perioperative factors including number of cerebral emboli, temperature, mean arterial pressure, and jugular bulb oxygen saturation have varying predictive power. Recent data suggest a genetic predisposition for cognitive decline after cardiac surgery in patients possessing the apolipoprotein E epsilon-4 allele, known to be associated with late-onset and sporadic forms of Alzheimer's disease. Predicting patients at risk for cognitive decline allows the possibility of many important interventions. Predictive power and weapons to reduce cellular injury associated with neurologic insults lend hope of a future ability to markedly decrease the impact of cardiopulmonary bypass on short-term and long-term neurologic, cognitive, and quality-of-life outcomes.

Microemboli during coronary artery bypass grafting. Genesis and effect on outcome

Cerebral dysfunction after coronary artery bypass operations represents some of the most serious and costly complications of cardiac surgery. We used transcranial Doppler ultrasonography to detect and quantify the number of microemboli in the right middle cerebral artery of patients undergoing elective first coronary bypass operations (n = 117) and second coronary bypass operations (n = 10). We hypothesized that total microemboli were related to clinical outcome. A 2 MHz transducer was positioned in front of the ear above the zygomatic arch and depth gated to 50 mm. Microemboli were recorded as perturbations of the blood flow velocity in the middle cerebral artery and aurally monitored. Each episode of microembolism was specified both by clock time and as a perfusion or surgical event. Forty-one patients (32%) completed neuropsychologic evaluation with a battery of tests for cognitive function. Anxiety states and traits were also assessed. The distribution of microembolism showed that there were three groups of patients: < 30 microemboli (n = 83); 30 to 59 (n = 24); and > 60 (n = 20). Seven of 10 patients with cerebral complications (stroke, coma, delirium, aberrant behavior) were in the > 60 microemboli group. Those with cerebral complications had 20.7 +/- 4.5 microemboli from perfusion and 57.4 +/- 15.6 from surgical events. The 13 patients in the > 60 microemboli group without central nervous system symptoms had 95.5 +/- 19.5 microemboli from perfusion and 36.0 +/- 6.9 from surgical events. Neuropsychologic scores were most often depressed for memory (73%), comprehension (49%), attention (46%), and constructional ability (44%). The greatest change was in total score in the > 60 microemboli group (-3.3 +/- 0.6) compared with -1.1 +/- 0.2 and -1.9 +/- 0.2 for the 30 to 59 and < 30 groups, respectively. The incidences of cardiac and pulmonary complications and mortality were different between those patients with < 60 microemboli versus those with > 60 microemboli. Cardiac and pulmonary complications and mortality percentages were 4.7%, 3.7%, and 0.9%, respectively, for the < 60 microemboli group and 20%, 20%, and 15%, respectively, for the > 60 microemboli group. We concluded that transcranial Doppler ultrasonography is a useful technique to quantify and detect the source of microemboli during coronary artery bypass operations and may be useful in assessing new operative strategies, the quality of the perfusion, and potentially as an indicator for pharmacologic therapy in the operating room in patients with high microemboli counts.

Intra- and postoperative cerebral complications of open-heart surgery

A consecutive series of 1400 patients who had undergone open-heart surgery was retrospectively reviewed concerning postoperative cerebral dysfunction. The 30-day mortality was 1.6%. Forty-one patients (2.9%) showed signs of cerebral dysfunction, which proved fatal in seven cases. Neurologic symptoms were observed immediately after surgery in 14 patients, suggesting intraoperative damage. In 20 others there was an interval between surgery and the onset of cerebral symptoms, which in 12 cases were preceded by supraventricular tachycardia. Computed tomographic scans were performed on 27 patients and showed recent brain infarction in 22. No bleeding was found. At follow-up 34 of the 41 patients were alive, 21 of them with neurologic sequelae and 13 reporting complete recovery. Nineteen of the 34 survivors experienced no diminution of quality of life. Since half of the cerebral complications occurred postoperatively, more aggressive prevention and management of supraventricular tachyarrhythmia and anticoagulation therapy should be considered.

Jugular bulb saturation and cognitive dysfunction after cardiopulmonary bypass

Inadequate cerebral oxygenation during cardiopulmonary bypass may lead to postoperative cognitive dysfunction in patients undergoing cardiac operations. A psychological test battery was administered to 255 patients before cardiac operation and just before hospital discharge. Postoperative impairment was defined as a decline of more than one standard deviation in 20% of tests. Variables significantly (p < 0.05) associated with postoperative cognitive impairment are baseline psychometric scores, largest arterial-venous oxygen difference, and years of education. Jugular bulb hemoglobin saturation is significant if it replaces arterial-venous oxygen difference in the model. Factors correlated with jugular bulb saturation at normothermia were cerebral metabolic rate of oxygen consumption (r = -0.6; p < 0.0005), cerebral blood flow (r = 0.4; p < 0.0005), oxygen delivery (r = 0.4; p < 0.0005), and mean arterial pressure (r = 0.15; p < 0.05). Three measures were significantly related to desaturation at normothermia and at hypothermia as well: greater cerebral oxygen extraction, greater arterial-venous oxygen difference, and lower ratio of cerebral blood flow to arterial-venous oxygen difference. We conclude that cerebral venous desaturation occurs during cardiopulmonary bypass in 17% to 23% of people and is associated with impaired postoperative cognitive test performance.

Use of ketanserin in the treatment of hypertension following coronary artery surgery

Ketanserin, a selective S2-serotonin receptor blocker with alpha 1-adrenergic blocking effects, may be a suitable antihypertensive medication after coronary artery surgery and lacks side effects seen with other vasodilators. Fifty patients with systolic blood pressures greater than 150 mmHg after coronary artery surgery were given, in a randomized double-blind fashion, either ketanserin (K) or saline (S). Each patient received six successive boluses of 1 mL of S or 1 mL of K (5 mg) at 2-minute intervals. After the last injection, sodium nitroprusside was started whenever the systolic blood pressure exceeded 150 mmHg. In the K group, the following significant (P < 0.05) changes occurred: systolic and diastolic arterial pressure -12% and -11%, respectively; heart rate -3%; systolic and diastolic pulmonary artery pressure -5% and -6%; central venous pressure -5%; pulmonary capillary wedge pressure -5%; systemic vascular resistance -16%; pulmonary vascular resistance -8%; stroke index +6%. None of these parameters changed significantly in the S group. There was no change in pulmonary shunt fraction in either group. In the K group, five patients did not require any further antihypertensive therapy during the 120 minutes following the last bolus injection. Twenty patients needed sodium nitroprusside during this period. This occurred 37 minutes (+/- 17 min) after the last bolus. In conclusion, after coronary artery bypass surgery, K is an effective antihypertensive medication, which does not cause reflex tachycardia or an increase in pulmonary shunt fraction. Exceeding the recommended dose of 10 (or 20) mg, as done in this study, does not seem to improve effectiveness or prolong the duration of action.

Neuropsychiatric complications of cardiac surgery

Historically, intracardiac operations have carried a higher risk of neurologic complications than coronary artery bypass grafting (CABG) procedures, although the incidence of such complications has been increasing after CABG in recent years. In both intracardiac and extracardiac surgery, macroemboli from the surgical field cause most neurologic complications. The periods of highest risk for emboli are during aortic cannulation, onset of bypass, and weaning from bypass. Risk factors include atherosclerosis of the ascending aorta, advanced age, presence of concomitant cerebral vascular disease, previous neurologic abnormality, duration of surgery, diabetes, and history of failure of the native circulation. Although hypothermia is beneficial in elective circulatory arrest, its usefulness in reducing postoperative central nervous system deficits during routine cardiac operations may be limited. Studies suggest a role for barbiturate protection in intracardiac but not in extracardiac surgery. Studies have not shown better neurologic or neuropsychological outcome with the use of membrane oxygenation and arterial filtration. Recent studies suggest no correlation of neurologic injury with serum glucose levels during CABG, with either duration or severity of hypotension during hypothermic CABG, or with blood gas management during hypothermic CABG.

Does hypothermia or hyperventilation affect enflurane MAC reduction following partial cardiopulmonary bypass in dogs?

This study in dogs determined the effect of systemic cooling and arterial hypocarbia during cardiopulmonary bypass (CPB) on the requirements for enflurane anaesthesia (MAC) before and after CPB. Twelve mongrel dogs were each anaesthetized with enflurane in oxygen on two separate occasions. End-tidal enflurane concentration was measured with a Puritan-Bennett Anaesthesia Agent Monitor. Using the tail-clamp method, MAC was determined twice with a one-hour interval between measurements (MAC 1 and MAC 2). Partial CPB was then initiated using femoral arterio-venous cannulation and maintained for one hour. Following separation from CPB, MAC was again determined twice with a one hour interval between measurements (MAC 3 and MAC 4). Dogs were randomly assigned according to PaCO2 management during CPB (low, 17.6 +/- 8.6 mmHg vs high, 38.9 +/- 11.5 mmHg), and then subjected to two experimental conditions. The first experiment on each dog was undertaken using normothermia during CPB (warm, 35-37 degrees C) while the second experiment (at least two weeks later) was conducted using hypothermia during CPB (cold, 30 degrees C). Analysis of the data, using ANOVA for repeated measures, revealed MAC 3 (1.95 +/- 0.33%, post-CPB) to be reduced when compared with MAC 1 (2.18 +/- 0.28%, P < 0.01) or MAC 2 (2.10 +/- 0.22%, P < 0.01), determined before CPB. Multivariate repeated measures analysis revealed no independent effects of hypothermia or arterial hypocarbia during CPB, on MAC reduction. By the time of the second experiment in each dog (two weeks later), MAC had returned to baseline levels.(ABSTRACT TRUNCATED AT 250 WORDS)

A critical review of cognitive and memory assessment tools:

A small percentage of cardiac clients experience cognitive and memory disorders after surgery. Since these disorders could limit a client's ability to function independently in daily activities, it would seem imperative that occupational therapists be able to examine the cognitive and memory dysfunctions of their cardiac clients. This paper presented information on the reliability and validity of a number of tools that have been administered by researchers and rehabilitation professionals to assess cognition. A critique of the information on assessment instruments and screening tools suggested that several tools could provide therapists with valuable diagnostic material on cognition. Promising screening tools and assessments appeared to require further research with a cardiac population.