Long-term effects of open-heart surgery on intellectual functioning

Neuron Specific Enolase (NSE): A Valuable Prognostic Factor of Central Nervous System Dysfunction Following Cardiac Surgery

Purpose

The aim of this study was to evaluate neuron specific enolase (NSE) as prognostic factor for CNS disorders developed in relation to cardiac surgery.

Patients and methods

A cohort of 92 patients were divided into two groups; the experimental group consisted of patients undergoing open-heart bypass surgery (50 patients) and the control group consisting of 42 patients undergoing general surgery procedures. The blood levels of NSE were measured in both groups before and 24 h after the operation and have been related to the incidence of the postoperative brain damage as well as to the duration of the extracorporeal circulation (ECC).

Results

The analysis of our results showed that the changes of blood NSE levels, before and immediately after ECC in open-heart surgery have been related to the incidence of postoperative brain dysfunction according to a specific mathematical equation. This incidence was raised also in relation to the age of the patient and the duration of ECC. On the contrary, NSE seems to have no prognostic value in general surgery.

Conclusion

NSE can be used in cardiac surgery as a simple and reliable prognostic factor to predict postoperative brain dysfunction.

Postcardiotomy delirium: an overview

Any one of a number of psychologic patterns may appear cardiotomy: (1) Some patients may be elated and confident after awakening from anesthesis and have no severe changes of affect or neurologic deficit. Denial seems to be for them an adequate defense against anxiety. (2) Others are disoriented and manifest neurologic disturbance immediately after awakening, without a lucid interval. The sensorium begins to clear five days after surgery. (3) Some patients go into delirium after being lucid for as long as a week and have hallucinations, illusions, and motor excitation for a few days-or over several weeks. Pathologic brain changes that are apparently anatomical correlates of neurologic deficits in delirium include anoxic lesions of the hippocampus, and infarcted foci. Physiologic factors that contribute to this reaction include: long periods of extracorporeal circulation, arterial hypotension during surgery, emboli, and low postoperative cardiac output. Age, and the type and severity of heart impairment are also factors. Psychologic factors to be taken into account include preexisting psychopathology and the failure of denial under the stress of physical symptoms or hospitalization. Delirium is fostered by sensory overload (or deprivation) in the recovery room and intensive care unit, and by staff tension. Modification of the intensive care unit environment, the administration of antipsychotic drugs, and metabolic correctives are recommended. Preoperative psychologic evaluation, with therapy as needed, preliminary familiarization with perioperative procedures, as well as collaboration between psychiatrist and surgeon, can do much to prevent post-cardiotomy delirium.

Head and Heart: Neuropsychological Reaction and Arterial Line Filtration during Cardiopulmonary Bypass

As part of a prospective study of neuropsychologic reactions after cardiopulmonary bypass and their relation to arterial line filters, 44 patients who underwent elective cardiac operations were randomized into two groups. Group A had a 40-micron nylon screen filter in the arterial line. No arterial filter was used in group B. Neuropsychological examinations of all patients were conducted before and at a mean of 8 days after the operation on a double blind basis by a single trained psychologist. The tests included the Wechsler Memory Scale, the trail-making test, the Hamilton Anxiety Rating Scale, and the Hamilton Rating Scale for Depression. The 2 groups were otherwise similar with respect to preoperative neurologic and intellectual status, anesthetic methods, duration of operation, operative procedures performed, and the time spent in the intensive care unit. Surprisingly, there was a highly significant improvement in all four test scores after surgery. There were no statistically significant differences in the test scores between the two groups but considerable inter-patient performance variability was noted. The arterial line filter did not appear to have an effect on test scores. Routine use of an arterial filter remains questionable.

Neuropsychologic dysfunction after cardiac surgery: what is the problem?

Twenty years ago Aberg published his seminal studies on the neuropsychologic consequences of cardiopulmonary bypass (CPB). Twenty years later, what is the state of current research on the problem of post-CPB neurologic injury, and what different management techniques have been employed to influence this outcome? This article reviews the definition and assessment of postoperative neuropsychologic dysfunction; epidemiologic data and associated risk factors assessing post-CPB neuropsychologic dysfunction are critically appraised.

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.

Cognitive function after open-heart surgery: are postoperative neuropsychological deficits caused by cardiopulmonary bypass?

Despite the many technological developments in arterial perfusion and cardiac surgical procedures, open-heart surgery is still believed to pose a significant risk for cerebral injury. There are several potential causes of brain damage during open-heart surgery, including prolonged or severe arterial hypotension, as well as emboli emanating from the cardiopulmonary bypass circuit or the operative field. This article reviews the available neuropsychological studies of outcome following cardiac valve replacement and coronary artery bypass grafting. Because both procedures are life-saving operations, the research in this area has been quasi-experimental and fraught with methodological problems. Nonetheless, the findings converge to suggest that cognitive dysfunction occurs after open-heart surgery, and that the deficits are attributable, at least in part, to factors specific to the operation or to the patient being maintained on cardiopulmonary bypass. Preliminary findings suggest that embolization is the primary cause of perioperative deficits in uncomplicated operations. Studies have also consistently found preoperative deficits in this population, suggesting that neuropsychological dysfunction is caused by severe chronic cardiac disease as well as open-heart surgery.

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.

Cognitive function in patients with symptomatic dilated cardiomyopathy before and after cardiac transplantation

Pre- and postoperative cognitive performance of candidates for heart transplantation was examined by means of an extensive battery of neuropsychological measures. A total of 54 patients completed the preoperative cognitive protocol, 20 of whom also completed postoperative testing. Age (less than 50 or greater than or equal to 50 years of age) and the primary cause of cardiac deterioration (idiopathic, ischemic disease or rheumatic/congenital defects) were the major classification variables. The main findings of this study were: 1) Preoperative neuropsychological measures revealed a high frequency of impaired performance, particularly in measures of memory, higher level processing of information and motor speed. A pattern consistent with diffuse rather than focal or lateralized cerebral deficits was observed. Significant differences were not found on the basis of the cause of cardiac disease, but some were observed for age (the older group was more impaired). 2) A comparison of pre- and postoperative cognitive scores failed to show significant cognitive improvement despite greatly improved physical health. The cause of cardiac deterioration was not differentially associated with postoperative cognitive performance, and there was equivocal evidence for age effects. These findings may have implications for the selection of transplant recipients and the timing of transplantation surgery.

Pupillary signs during cardiac surgery. Their use in the prediction of major cerebral deficit following cardiopulmonary bypass

Pupil sizes and reactions to light were studied in 100 patients who had cardiopulmonary bypass. Behaviour of the pupils was observed at six stages during the operation. Most patients (71) had pupils of equal size and similar reaction to light at all times. Twenty-three patients developed unequal pupils at some stage, while six had equal pupils throughout but exhibited differing reaction to light. Major cerebral deficit was significantly more common after operation in patients who developed inequality in pupil size than those who did not (p less than 0.05). No relationship was seen between dissimilar pupil reaction to light and the development of neurological complications. The clinical estimation of pupil size may help to identify those patients who may exhibit postoperative major neurological dysfunction.

Psychosomatic aspects of coronary artery bypass graft surgery. A prospective study of 101 male patients

101 consecutive male patients were examined by means of clinical interviews and depression, anxiety, personality, psychometric and life stress tests. The examinations took place preoperatively, on the 9th postoperative day (average) and 7.5 months after surgery. The mean age of the patients was 52.2 years and the mean duration of CHD was 6.7 years. Prior to surgery 77% had experienced myocardial infarction and 85% belonged to NYHA class III or IV. 74% had a 3-vessel disease. When the NYHA classification was used as criterion for rehabilitation the result was excellent. Postoperatively 80% belonged to NYHA class I or II. Hospital mortality rate was 4% and one patient died from myocardial infarction prior to the final follow-up. Preoperatively 17% of the study group were working. 87% of the patients experienced negative effects on work life, caused by CHD. Postoperatively 33% worked regularly. The postoperative work situation correlated with the duration of preoperative unemployment (p less than 0.0001), the patient's own opinion about work return (willingness/unwillingness to return to work) (p less than 0.01), as well as with the amount of negative life stress experienced preoperatively (p less than 0.01). Only 13% of the series experienced positive effects on work life, caused by CABG surgery. The majority of the patients had experienced negative effects on social and economic life (51%), as well as on sexual life (70%), caused by CHD. After surgery improvements were noted by 36% on social life and by 27% on sexual life. 15% experienced impairment of sexual life postoperatively. According to the Beck Depression Inventory 29% showed depression preoperatively, and 10% postoperatively. The difference is significant (p less than 0.0001). Clinically the figures tended to be higher. The same tendency holds for anxiety scores as measured by the Hamilton anxiety scale. The incidence of postoperative psychoses was 35%. Higher age (p less than 0.01) and/or absence of psychosomatic diseases (p less than 0.05) correlated with higher frequency of psychoses. Even though cardiological rehabilitation according to the NYHA classification was excellent, 22% of the series did not think their expectations were fulfilled. Psychic and social rehabilitation was in several aspects unsatisfactory, and the patients did not seem prepared for this. The importance to consider rehabilitation from a psychosomatic standpoint is clearly shown. To predict the result of rehabilitation preoperatively is not possible.

Long-term cerebral outcome after open-heart surgery. A five-year neuropsychological follow-up study

A prospective 5 years' neuropsychological, neurological, cardiological and electroencephalographical follow-up study was carried out in 44 patients who had undergone open-heart surgery for valve replacement. A distinct interrelationship was found between the clinical outcome immediately after operation and the neuropsychological long-term course despite the rapid recovery of occasional clinical disorders related to operative procedures. In fact, the psychometric performance scores of those who did not develop clinical signs of cerebral dysfunction induced in operation showed a significant difference only years after operation. Similarly, the harmful effects of long perfusion time (extracorporeal circulation) in operation were reflected in the long-term neuropsychological performance. Some evidence seemed to suggest that the correction of the prolonged circulatory disorder might possibly afford real enhancement of higher cerebral functions. The long-term results not only emphasize the importance of a careful clinical evaluation but also emphasize the necessity of considering the subclinical level of events both before and after operation when assessing the overall outcome and cerebral safety of cardiac surgery patients.

Brain oedema and blood-brain barrier permeability in pulsatile and nonpulsatile cardiopulmonary bypass

In pigs subjected to pulsatile or nonpulsatile cardiopulmonary bypass (CPB) at normothermia for 3 hours, evaluation was made of water content in brain tissue (specific gravity measurements), blood-brain permeability to serum proteins (immunocytochemical demonstration of extravasated proteins, using peroxidase-antiperoxidase technique) and histopathology (paraffin sections). The specific gravity in parietal cortex was higher after pulsatile than after nonpulsatile CPB or in control pigs, the change corresponding to a 6.3% water increase. The tissue water content was unchanged in the internal capsule, basal ganglia and nucleus accumbens after CPB. The vascular permeability to serum proteins was unchanged after nonpulsatile CPB, but after pulsatile CPB minute foci of extravasated serum proteins appeared. All the animals showed dark neurons in cortical and subcortical regions, but these could have been artefacts in immersion-fixed tissue. There were no other signs of ischaemic tissue damage. The study indicated that cortical oedema may follow pulsatile CPB, the cause being altered permeability of the blood-brain barrier to serum proteins.

Early neurological complications of coronary artery bypass surgery

A prospective study of 312 patients undergoing elective coronary artery bypass surgery was undertaken to determine the incidence, severity, and functional impact of postoperative neurological complications. Detailed evaluation of the patients showed that neurological complications after surgery were common, occurring in 191 of the 312 patients (61%). Although such a high proportion of the total developed detectable changes, serious neurological morbidity was rare. Neurological disorders resulted in death in only one patient (0.3%) and severe disability in only four (1.3%). Forty eight patients were mildly disabled during the early postoperative period, and the remaining 138 with neurological signs had no serious functional disability. The postoperative neurological disorders detected included one death from cerebral hypoxic damage. Prolonged depression of conscious level was observed in 10 patients (3%) and definite stroke in 15 (5%); 78 (25%) developed ophthalmological abnormalities and 123 (39%) primitive reflexes; postoperative psychosis was observed in four (1%); and 37 (12%) developed disorders of the peripheral nervous system. The incidence of serious neurological problems such as fatal cerebral damage, stroke, and brachial plexopathy is in accordance with experience elsewhere. Lesser abnormalities, whose detection required detailed neurological examination, were much commoner than expected from previous reports.

Five-year neurological and EEG outcome after open-heart surgery

A five-year neurological and EEG follow-up was carried on 55 patients who had undergone open-heart surgery for valve replacement in order to investigate the long-term results of the treatment. The five-year survival rate was 89%. The prevalence of permanent neurological abnormalities after operation was 9%. Transient ischaemic attacks occurred in five patients but no more severe cerebrovascular accidents were encountered. The rate of embolic events was 2.8 per 100 patient-years. Various subjective symptoms and complaints showed a highly beneficial outcome. Also the five-year EEG outcome was encouraging; the prevalence of abnormal EEG had fallen from the value before operation of 45% to 25%. The harmful influence of long perfusion time (extracorporeal circulation) during operation was found to be reflected in the long-term EEG outcome and, significantly, not only in the patients who had, but also in those who had not developed clinical abnormalities complicating the immediate course after operation. Although a valvular surgery patient faces a number of CNS problems before, during and after operation, the overall long-term outcome of successful surgery seems highly beneficial in neurological terms.

Neuropsychological status of patients with congenital and rheumatic heart diseases: preoperative and postoperative comparison

Thirty surgical patients receiving surgery for congenital heart or rheumatic heart disease were compared with a match control group on a battery of neuropsychological tests. Subjects were examined prior to surgery, 4 weeks post- and again 6 months postsurgery. Preoperative surgical subjects showed a generalized impairment in functioning suggestive of brain dysfunction secondary to hypoxia. Improvement following surgery was attributed to practice effects.

Effect of open heart surgery on intellectual performance

The interrelationship between postoperative psychosis, neurologic symptoms, and changes in tests of cognitive performance have been studied in a series of 60 cardiac valvular patients who underwent open heart surgery. The effects of preoperative psychological, psychiatric, and cardiologic factors on postoperative cognitive changes were analyzed. The investigation period was from five months before up to five months after the operation. There was a general trend towards improvement in intellectual performances. The psychotic group, however, still showed a persisting impairment in some visual and psychomotor tests several months after the surgery. The group with neurologic symptoms showed impairment in one visual test. Of the preoperative variables, mitral valve disease, a high level of hypochondriasis and anxiety, and poor performance in some visual and psychomotor tests predicted postoperative intellectual impairment. The results suggest two types of cerebral complications of open heart surgery. Postoperative psychosis reflects diffuse brain dysfunction manifesting itself in psychological tests long after the clinical symptoms have resolved. The presence of neurologic symptoms refers to a focal or lateralized injury. Both the neurologic and neuropsychologic findings indicate that the right hemisphere may be prone to dysfunction than the left hemisphere.

Effects of cardiac surgery with extracorporeal circulation on intellectual function in children

The effect of extracorporeal circulation during open heart surgery on changes in intellectual function was studied in 18 children. A group of patients undergoing such surgery was compared to a control group undergoing cardiac surgery without extracorporeal circulation. The Wechsler Intelligence Scale for Children was used to evaluate the patients. No significant differences were found in either the performance IQs, verbal IQs, or full scale IQs by comparing the postoperative scores to the preoperative scores either within each group or between the groups. Extracorporeal circulation during open heart surgery does not appear to alter intellectual functioning in the pediatric age group.