Risk of seizures in survivors of newborn heart surgery using deep hypothermic circulatory arrest

Inattention, hyperactivity, and school performance in a population of school-age children with complex congenital heart disease

INTRODUCTION

There is a growing interest in characterizing the neurodevelopmental outcomes of school-age survivors of cardiac surgery. The purpose of this study was to examine a population of 5- to 10-year-old children who underwent newborn cardiac surgery for complex congenital heart disease to characterize and assess risk factors for problems with inattention and hyperactivity, as well as the use of remedial school services.

PATIENTS AND METHODS

This study was a cross-sectional analysis of patients who underwent newborn cardiac surgery and were enrolled in a neuroprotection trial conducted at our institution between 1992 and 1997. Parents and teachers completed questionnaires for the school-age child to elicit information pertaining to the child's general health and academic performance. The severity of hyperactivity and inattention were assessed by using 2 standardized questionnaires (Attention-Deficit/Hyperactivity Disorder Rating Scale-IV and Behavior Assessment System for Children). In addition to calculating descriptive estimates of their occurrence, single-covariate logistic regression models were specified and tested by using 3 different outcomes (inattention, hyperactivity, and use of remedial school services) and 14 different covariates representing preoperative, intraoperative, and postoperative factors.

RESULTS

Data were obtained from parents and/or teachers for 109 children. Fifty-three (49%) were receiving some form of remedial academic services, and 15% were assigned to a special-education classroom. The number of children receiving clinically significant scores for inattention and hyperactivity on the Behavior Assessment System for Children was 3 to 4 times higher than observed in the general population. On the Attention-Deficit/Hyperactivity Disorder Rating Scale-IV, 30% of the parents reported high-risk scores for inattention and 29% reported high-risk scores for hyperactivity. No perioperative factors were statistically associated with adverse outcomes.

CONCLUSION

In this cohort of children with complex congenital heart disease, a significant proportion of the children were at risk for inattention and hyperactivity, and nearly half were using remedial school services. We did not identify any perioperative risk factors, which correlated with high-risk scores or the use of remedial school services. Ongoing neurodevelopmental follow-up and screening are recommended in this vulnerable population.

Results with continuous cardiopulmonary bypass for the bidirectional cavopulmonary anastomosis

OBJECTIVE

Some centres have proposed creating the bidirectional cavopulmonary anastomosis without cardiopulmonary bypass, while others continue to use deep hypothermic circulatory arrest. The purpose of this review is to evaluate the results of using continuous cardiopulmonary bypass with moderate hypothermia, perhaps the most commonly used of the three techniques for this procedure.

METHODS

Between 1990 and 2005, 114 patients, having a mean age of 1.58 years, with a median age of 8 months, and ranging from 3 months to 16 years, underwent creation of either a unilateral cavopulmonary anastomosis, in 94 cases, or bilateral anastomoses in 20 cases. All had continuous cardiopulmonary bypass with moderate hypothermia at 32 degrees Celsius, with 24 also having aortic cross-clamping with cardioplegia for simultaneous intracardiac procedures. Interrupted absorbable sutures were used to create the anastomosis in 105 patients.

RESULTS

Perioperative mortality was 5%, with 6 of the patients dying. The mean period of cardiopulmonary bypass for an isolated anastomosis was 91 minutes, with a range from 44 to 160 minutes. In 10 patients (8.8%), it was necessary to place a graft to augment the anastomosis. The average postoperative length of stay was 7.9 days for those undergoing an isolated unilateral anastomosis, and 16.4 days for patients undergoing combined cardiac operations. We have now created the Fontan circulation in 79 of the patients, at an average interval from the bidirectional cavopulmonary anastomosis of 2.1 plus or minus 1.14 years. In 76 patients, we performed postoperative angiograms, and none revealed any stenoses.

CONCLUSIONS

The bidirectional cavopulmonary anastomosis can be performed successfully with continuous cardiopulmonary bypass and moderate hypothermia with a beating heart, avoiding circulatory arrest. The use of interrupted and absorbable sutures was not associated with any late anastomotic stenosis.

Neuroprotective effect of diazoxide on brain injury induced by cerebral ischemia/reperfusion during deep hypothermia

OBJECT

The purpose of this study was to determine the effects of diazoxide on apoptosis and the relative mechanisms in a model of brain injury induced by cerebral ischemia/reperfusion (I/R) during deep hypothermia.

METHODS

Three-week-old Sprague-Dawley male rats were randomly and equitably divided into sham-operated group, placebo-treated group and diazoxide-treated group respectively. Specific examination of the regional cerebral blood flow (rCBF) was measured in the three groups continuously during the operation by laser Doppler flowmetry. Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) was showed DNA fragmentation. The mRNA expressions of cytochrome c and full-length caspase-3 were determined by RT-PCR, while the protein expressions of cytochrome c and cleaved caspase-3 were determined by immunohistochemistry at 1 h, 6 h, 24 h, 72 h and 7 days after I/R, respectively. Cytosolic release of cytochrome c at 24 h after I/R was also confirmed by Western blot.

RESULTS

rCBF was significantly decreased in both of placebo-treated and diazoxide-treated group just after ischemia in the time interval 0-5 min, and had no obvious changes in all the time intervals during the operation. Diazoxide preconditioning significantly decreased the percentage of TUNEL-positive staining cells. The mRNA expressions of cytochrome c and full-length caspase-3 in diazoxide-treated group were significantly decreased. In addition, diazoxide provided a significant reduction in the protein expressions of cytochrome c and cleaved caspase-3.

CONCLUSION

These results suggested that the neuroprotective effects of diazoxide against cerebral I/R injury during deep hypothermia correlated with the reduction of DNA fragmentation, prevention of mitochondrial cytochrome c release and inhibition of caspase-3 activation.

Neurology of congenital heart disease: insight from brain imaging

Understanding of the specific pathophysiology of acquired brain injury in infants with CHD will help optimise treatment and brain protection strategies

Off pump repair of aortic arch anomalies with concomitant intracardiac defects via anterior approach

BACKGROUND

The authors evaluated the surgical treatment of aortic arch anomalies associated with intracardiac pathologies, through median sternotomy on beating heart without using cardiopulmonary bypass (CPB).

METHODS

A consecutive series of 10 patients with aortic coarctation were operated upon. Median age at repair was 3.5 months (range, 5 days to 72 months), median weight was 4 kg (range, 2.2 to 30 kg). All aortic obstruction repairs were done via midsternotomy without using CPB and it is used only for repair of intracardiac defects. The aortic reconstruction included resection and end-to-side anastomosis in six patients and pulmonary autograft patch aortoplasty in four patients.

RESULTS

There was no operative mortality. Mean follow-up value was 17.6 +/- 8.07 months. There was no restenosis.

CONCLUSION

Most of the aortic coarctation and interrupted aorta type A can be well-treated surgically through median sternotomy without using CPB. Thus, the need for profound hypothermia and circulatory arrest and its potential neurological and other side effects are removed and CPB is reserved only for associated intracardiac defects, if present.

Complex Neonatal Single Ventricle Palliation Using Antegrade Cerebral Perfusion

BACKGROUND

The efficacy of antegrade cerebral perfusion (ACP) during complex neonatal single ventricle palliation requiring arch reconstruction is uncertain. We adapted the use of ACP in early 2001 in a programmatic effort to minimize the use of deep hypothermic circulatory arrest (DHCA).

METHODS

We retrospectively analyzed data of 126 consecutive patients operated on between 1995 and 2004, including stage-one palliation of hypoplastic left heart syndrome, stage-one palliation for nonhypoplastic left heart syndrome, and Damus-Kaye-Stansel procedures. Patients were divided into two groups: those repaired with prolonged DHCA only (n = 67) and those with ACP (n = 59) and usually a shorter period of DHCA. Risk was further stratified into high risk (weight < or = 2.5 kg or other cardiac lesion) and usual risk for each group.

RESULTS

Survival at 30 days in the usual-risk groups was 72.0% DHCA and 93.2% ACP (p < or = 0.025), and in the high-risk groups it was 61.5% DHCA and 80% ACP (not significant). One-year survival in the usual-risk groups was 57.4% DHCA and 84.1% ACP (p < or = 0.01), and in the high-risk groups it was 38.5% DHCA and 46.7% ACP (not significant). Overall survival to date is 52.2% DHCA and 71.2% ACP (p < or = 0.5).

CONCLUSIONS

There is a statistically significant survival advantage for usual-risk patients with the use of ACP. Although there is a trend to improved survival in the high-risk groups, it does not reach statistical significance and long-term outcomes in these patients remains disappointing. We continue to use ACP and believe it contributes to an overall survival advantage in our institution.

Proteomics of cerebral injury in a neonatal model of cardiopulmonary bypass with deep hypothermic circulatory arrest

OBJECTIVE

Concern over neurologic injury limits safe duration of deep hypothermic circulatory arrest (DHCA) in surgery for congenital cardiac disease. Proteomics is a novel and powerful technique to study global protein changes in a given protein system. Using a neonatal model of cardiopulmonary bypass with DHCA, we sought to characterize the protein changes associated with DHCA brain injury.

METHODS

Ten neonatal piglets were randomized to cardiopulmonary bypass with DHCA or sham operation. DHCA animals underwent induction of bypass (100 mL x kg(-1) x min(-1)), cooling to 18 degrees C, then DHCA for 60 minutes. Animals were rewarmed to normothermia, weaned from bypass, and harvested after 30 minutes off bypass. Sham animals underwent sternotomy without further instrumentation. Plasma samples were taken before bypass and before harvest. Proteins differentially expressed in the cerebral neocortex between the 2 groups were determined by 2-dimensional differential gel electrophoresis using fluorescent cyanine dyes and mass spectrometry. A second group of 4 piglets were similarly randomized and, after the experiment, tissues underwent perfusion-fixation for histologic examination.

RESULTS

Cardiopulmonary bypass with DHCA caused extensive histologic and ultrastructural cerebral injury. Proteomic analysis of cerebral cortex found 10 protein spots to be differentially expressed; 9 were identified by mass spectrometry to represent 6 proteins, including apolipoprotein A-1, neurofilament-M protein, and enolase. Decreased expression of plasma apolipoprotein A-1 was found in DHCA.

CONCLUSIONS

The acute protein changes associated with cerebral injury in a neonatal model of cardiopulmonary bypass with DHCA have been characterized. These may direct further research aimed at attenuating injury seen from cardiopulmonary bypass with DHCA.

The newborn drug development initiative workshop: Summary proceedings from the neurology group on neonatal seizures

BACKGROUND

The neonatal period eclipses all other epochs of the human life span for the highest incidence of seizures. Neonatal seizures are most commonly incited by serious acute illnesses such as hypoxic-ischemic encephalopathy, birth trauma, or infection.

OBJECTIVE

The goal of this article was to summarize some of the Neurology Group's discussion on neonatal seizures and their treatment with phenobarbital (PB).

METHODS

Information for this article was gathered from a workshop held March 29 and 30, 2004, in Baltimore, Maryland, as part of the Newborn Drug Development Initiative. A group of national experts was invited to form the Neurology Group to review certain aspects of neonatal seizures. Literature reviews were conducted using MEDLINE searches for original research studies, commentaries, and review articles between 1980 and 2004 using the key words neonatal seizures, treatment, and phenobarbital.

RESULTS

It has been empirically established that infants who experience seizures face substantially higher mortality and morbidity rates than those who do not. Basic research indicates that neonatal seizures themselves are not innocuous and actively contribute to adverse neurodevelopmental outcomes. Current worldwide clinical practice most often includes empiric treatment with PB for definite or suspected seizures in the newborn. Unfortunately, this common practice has never been proven by even a single, rigorous, randomized controlled trial. The Neurology Group identified the treatment of neonatal seizures with PB as an important topic in the practice of neonatal neurology for further investigation. Three possible frameworks for ethically acceptable, clinical treatment trials were explored. From these, a suitable scenario was selected-an electroencephalographer-blinded study of PB versus placebo in a homogeneous group of newborns who are at high risk of developing early subclinical electroencephalographic neonatal seizures (ENSs). Prospective video-electroencephalogram monitoring performed immediately after an insult (such as major cardiac surgery for a serious congenital heart defect) would establish the presence and number of subclinical ENSs. For a brief period of time, neonates with subclinical ENSs would be randomized to PB (dosed to match the PB-binding characteristics of the individual) or placebo. Clear criteria for escape from the study to active treatment are defined.

CONCLUSION

The investigation proposed here could refute or confirm the contemporary practice of PB administration as the first-line treatment of neonatal seizures.

Monitoring the brain before, during, and after cardiac surgery to improve long-term neurodevelopmental outcomes

Innovation in surgical and medical management of cardiac disease has generated a dramatic improvement in operative survival. Along with these favourable results in terms of survival is the heightened awareness of neurologic complications, which often become evident beyond the early postoperative period. A large, multicentre prospective study found serious neurologic injury occurs in about one-twentieth of patients after myocardial revascularization in adults.1More subtle evidence of persistent cognitive decline and functional impairment has been shown to occur in over two-fifths of such patients.2Acute neurologic abnormalities are reported in up to one-fifth of infants and children who undergo cardiac surgery.3–6Lasting impairments in cognitive, motor, and expressive functioning have been reported in up to three-fifths of children who have undergone complex cardiac surgery during infancy.7Specifically, gross and fine motor delays, visual-spatial problems, language deficits and long-term emotional and behavioural problems have been found.8–13

Prolonged electroencephalogram monitoring for seizures and their treatment

This article reviews the diagnosis of neonatal seizures using routine electroencephalogram (EEG) examinations and long-term EEG monitoring. EEG is considered the gold standard for identifying the presence and quantifying the burden of neonatal seizures. The most common medication used to treat neonatal seizures is phenobarbital, although its efficacy has never been demonstrated by a formal, randomized, placebo-controlled drug trial.

Recent developments in the perioperative management of the paediatric cardiac patient

PURPOSE OF REVIEW

Survival of infants born with complex cardiac anomalies has dramatically improved, and the growing population of patients with congenital heart disease reaching adulthood has resulted in an increased incidence of long-term complications related to the perioperative period. This review focuses on recent advances in strategies to prevent, detect, treat, or predict early and late complications arising from open heart surgery for congenital heart disease.

RECENT FINDINGS

Aprotinine and recombinant factor VIIa may effectively reduce the risk of excessive perioperative bleeding, and the use of steroids, complement component C4A, heparin-coated circuits, and modified ultrafiltration may play a role in the control of the postoperative inflammatory response. Milrinone is becoming increasingly popular in the prevention and treatment of the reduced postoperative cardiac output, and extracorporeal life support has become a well established and successful form of support for postoperative myocardial dysfunction, even in the functionally univentricular heart. In recent years interest increased in optimizing myocardial protection using contents-differentiated and temperature-differentiated blood cardioplegia and in optimizing cerebral protection using a higher haematocrit during bypass and by using selective regional perfusion in favour of circulatory arrest.

SUMMARY

Hearts can be mended, but salvation of hearts and brains needs further rigorous attention.

Postmortem intracranial neuropathology in children following cardiac transplantation

At Loma Linda University Children's Hospital, the medical information of 405 pediatric patients who received orthotopic cardiac transplantation were reviewed. Of those who died (n=136), 86% (n=117) underwent postmortem examinations, and the brain was examined in 61% (n=82, male=39). The number and type of intracranial lesions present were compiled, and these were matched to underlying functional cardiac disease categories. Intracranial abnormalities were present in 87%. Infarct was the most common primary central nervous system pathology in hypoplastic left heart syndrome (41%) but was also observed frequently in children with obstructive lesions (37%), cyanotic disease (31%), or cardiac shunting (29%). Secondary findings included extraparenchymal hemorrhage in obstructive lesions (31%); hypoxic changes occurred in 15% of patients with cyanotic disease and in 14% of those with cardiac shunting. Thirty-three percent of children with restrictive lesions had no neuropathology reported. Postmortem examination brain weights were matched against age and sex norms, with 29% of females and 36% of males below two standard deviations. These findings revealed that intracranial pathology was present in the majority of transplanted children who underwent postmortem examination, and that infarctive changes constituted the most common neuropathologic abnormality. Additionally, a number of children had significantly reduced brain weight.

Arch reconstruction without circulatory arrest in neonates

Between May 2000 and December 2002, 10 neonates underwent arch reconstruction without circulatory arrest. Age at surgery ranged from 1 to 18 days, and body weight ranged from 1.62 to 3.38 kg. The diagnosis was interrupted aortic arch in 4, hypoplastic left heart syndrome in 3, and coarctation complex in 3. A 3 mm polytetrafluoroethylene graft was anastomosed to the innominate artery, and the brain was perfused via this graft while the aortic arch was reconstructed. Regional cerebral oxygen saturation and the right and left radial artery pressures were monitored. There were 2 deaths: one because of low cardiac output syndrome after a Norwood operation; another from multiple organ failure due to preoperatively undetected congenital biliary atresia. Regional cerebral oxygen saturation was kept constant at over 40% during regional cerebral perfusion. There were no neurologic sequelae observed postoperatively. It was concluded that the regional cerebral perfusion technique can be safely applied during neonatal aortic arch reconstruction, and deep hypothermic circulatory arrest should be avoided.

Neurologic events in neonates treated surgically for congenital heart disease

OBJECTIVE

The incidence of acute neurologic events prior to discharge in neonates with congenital heart disease (CHD) was determined and peri-operative characteristics predictive of a neurologic event were identified.

STUDY DESIGN

A retrospective chart review over 1 year was conducted of infants <1 month of age with a diagnosis of CHD. Outcomes were measured by the occurrence of an acute neurologic event defined as electroencephalogram (EEG)-proven seizure activity, significant hypertonia or hypotonia, or choreoathetosis prior to hospital discharge. Stepwise logistic regression identified variables most likely to be associated with an acute neurologic event.

RESULTS

Surgical intervention occurred in 95 infants who were admitted with a diagnosis of CHD. The survival rate was 92%. Of the survivors, 16 (17%) had an acute neurologic event, with 19% of events occurring preoperatively. Factors associated with neurologic events included an elevated nucleated red blood cell (NRBC) count, an abnormal preoperative brain imaging study, and a 5-min Apgar score <7 (P<0.05).

CONCLUSIONS

Neonates with CHD have a significant risk of neurologic events. Preoperative brain imaging, the 5-min Apgar score, and initial serum NRBC counts may identify infants at highest risk for central nervous system injury.

The relationship of postoperative electrographic seizures to neurodevelopmental outcome at 1 year of age after neonatal and infant cardiac surgery

OBJECTIVE

The occurrence of a seizure after the arterial switch operation is associated with a worse long-term neurodevelopmental outcome. The significance of seizures after neonatal and infant repair of other congenital heart defects is not known.

METHODS

A recent study at our institution demonstrated seizures documented by 48-hour electroencephalographic monitoring in 20 (11%) of 178 neonates and infants after surgery for complex congenital heart defects, including hypoplastic left heart syndrome or variants. The developmental outcomes of this cohort were evaluated at 1 year of age by using the Bayley Scales of Infant Development II, which yields 2 scores: the Mental Developmental Index and the Psychomotor Developmental Index.

RESULTS

Developmental evaluations were performed in 114 (70%) of 164 survivors, including 36 with hypoplastic left heart syndrome. Postoperative electroencephalographic seizures had occurred in 15 (13%) of 114 of the entire group and in 8 (22%) of 36 of those with hypoplastic left heart syndrome. For the entire cohort, the Mental Developmental Index was 92.3 +/- 13.5, and the Psychomotor Developmental Index was 79.9 +/- 18.8 for patients without seizures, compared with 90.3 +/- 10.7 and 74.4 +/- 19.3 for those with seizures (both P > .5). For the hypoplastic left heart syndrome subgroup, the Mental Developmental Index was 92.3 +/- 14.9, and the Psychomotor Developmental Index was 74.8 +/- 19.3 for patients with seizures, compared with 91.9 +/- 12.4 and 73.9 +/- 18.3 for those without seizures (both P > .5). A frontal onset of seizures was predictive of a lower score on the Psychomotor Developmental Index, but not on the Mental Developmental Index.

CONCLUSIONS

The occurrence of a seizure after cardiac operation is a marker of central nervous system injury. However, in this cohort of neonates and infants with complex congenital heart defects, the occurrence of a seizure was not predictive of a worse developmental outcome at 1 year of age as assessed by the Bayley Scales of Infant Development II.

Management of the Pediatric Postoperative Cardiac Surgery Patient

Optimal management of the postoperative pediatric cardiac surgical patient requires a thorough understanding of patient anatomy, physiology, surgical repair or palliation, and clinical condition. This necessitates a dedicated team of clinicians including skilled nurses, physicians, and respiratory therapists specialized in the care of patients who have complex congenital heart disease. This article provides an overview of the multisystemic risk factors and consequences associated with cadiopulmonary bypass and cardiac surgery. An evaluation of cardiac hemodynamics and a review of major organ systems are included. Essential assessment information and interventional strategies for managing the pediatric postoperative cardiac surgery patient are detailed.

Increasing duration of deep hypothermic circulatory arrest is associated with an increased incidence of postoperative electroencephalographic seizures

OBJECTIVE

Electroencephalographic seizures have been shown to occur in 5% to 20% of neonates and infants after biventricular repair of a variety of cardiac defects. Occurrence of a seizure is a predictor of adverse long-term neurodevelopmental sequelae. The contemporary incidence of postoperative seizures after repair of cardiac defects such as hypoplastic left heart syndrome and other forms of single ventricle is not known.

METHODS

A prospective study of 178 patients less than 6 months of age undergoing cardiopulmonary bypass with or without deep hypothermic circulatory arrest (DHCA) was conducted at a single institution from September 2001 through March 2003 to identify postoperative seizures assessed by 48-hour continuous video electroencephalographic monitoring.

RESULTS

Cardiac defects included transposition of the great arteries with or without a ventricular septal defect (n = 12), ventricular septal defect with or without coarctation (n = 28), tetralogy of Fallot (n = 24), hypoplastic left heart syndrome or variant (n = 60), other functional single ventricle (n = 14), and other defects suitable for biventricular repair (n = 40). Median age at the time of the operation was 7 days (range, 1-188 days) and was 30 days or less in 110 (62%) patients. DHCA was used in 117 (66%) patients, with multiple episodes in 9 patients. Median total duration of DHCA was 40 minutes (range, 1-90 minutes). Electroencephalographic seizures were identified in 20 (11.2%) patients. Seizures occurred in 15 (14%) of 110 neonates and 5 (7%) of 68 older infants. Seizures occurred in 1 (4%) of 24 patients with tetralogy of Fallot, 1 (8%) of 12 with transposition of the great arteries, and 11 (18%) of 60 with hypoplastic left heart syndrome or variant. By stepwise logistic regression analysis, once increasing duration of total DHCA (P = .001) was considered, no other variable improved prediction of occurrence of a seizure. Patients with DHCA duration of more than 40 minutes had an increased incidence of seizures (14/58 [24.1%]) compared with those with a DHCA duration of 40 minutes or less (4/59 [6.8%], P = .04). The incidence of seizures for patients with a DHCA duration of 40 minutes or less was not significantly different from those in whom DHCA was not used (2/61 [3.3%], P = .38).

CONCLUSIONS

In the current era, continuous electroencephalographic monitoring demonstrates early postoperative seizures in 11.2% of a heterogeneous cohort of neonates and infants with complex congenital heart defects. Increasing duration of DHCA was identified as a predictor of seizures. However, the incidence of seizures in children with limited duration of DHCA was similar to that in infants undergoing continuous cardiopulmonary bypass alone.

Upregulation of hypoxia inducible factor is associated with attenuation of neuronal injury in neonatal piglets undergoing deep hypothermic circulatory arrest

BACKGROUND

Prolonged deep hypothermic circulatory arrest is known to cause neurological injury. Hypoxia inducible factor, a transcription factor that mediates adaptive changes during hypoxia, is neuroprotective in models of ischemic brain injury, in part by upregulating erythropoietin. This study tested the hypothesis that upregulation of hypoxia inducible factor and erythropoietin by preconditioning with hypoxia or the hypoxia-mimetic agents deferoxamine and cobalt chloride would be neuroprotective in a piglet model of deep hypothermic circulatory arrest.

METHODS

Anesthetized neonatal piglets were randomized to 4 preconditioning groups (15 per group): hypoxia, deferoxamine, cobalt chloride, or control (NaCl vehicle). Brain hypoxia inducible factor and erythropoietin contents were assessed by means of Western blotting at 3, 8, and 24 hours after treatment (n = 3 per time point). Twenty-four hours after treatment, 6 to 7 animals per group underwent cardiopulmonary bypass and 110 minutes of deep hypothermic circulatory arrest. After recovery, serial neurobehavioral examinations were conducted for 6 days, after which histopathologic brain injury and neuronal apoptosis (cleaved caspase 3) were assessed.

RESULTS

Erythropoietin expression was not significantly increased by any of the pretreatment strategies. In contrast, there was a significant upregulation of hypoxia inducible factor by pretreatment with deferoxamine and cobalt chloride (P = .002). Neurobehavioral measures revealed no significant differences in time to recovery or extent of injury. Examination of histopathologic brain injury in the hippocampus revealed that pretreatment with deferoxamine (0.4 +/- 0.3) and cobalt chloride (0.5 +/- 0.3) were associated with significantly less neuronal loss than pretreatment with hypoxia or control (2.8 +/- 0.5, P = .004). Finally, cleaved caspase 3 (a marker of apoptotic cell death) was also shown to be diminished in the cobalt and deferoxamine groups, but the difference was not significantly different from the value in the control group.

CONCLUSIONS

In contrast to hypoxia, deferoxamine and cobalt chloride preconditioning upregulated hypoxia inducible factor and were associated with histopathologic neuroprotection after exposure to cardiopulmonary bypass and prolonged deep hypothermic circulatory arrest.

Cerebral oxygen saturation and electrical brain activity before, during, and up to 36 hours after arterial switch procedure in neonates without pre-existing brain damage: its relationship to neurodevelopmental outcome

OBJECTIVE

To monitor the pattern of cerebral oxygen saturation (rSat), by use of NIRS, in term infants before, during and after the arterial switch operation and to evaluate its relation to neurodevelopmental outcome.

METHODS

In 20 neonates without pre-existing brain damage hemodynamics and arterial oxygen saturation (AO2-Sat) were monitored simultaneously with rSat and amplitude-integrated EEG (aEEG) from 4 h to 12 h before up to 36 h after cardiopulmonary bypass (CPB) and short duration of cardiac arrest during deep hypothermia (DHCA). The Bayleys developmental scale was performed at 30 months.

RESULTS

Before surgery rSat was <50% in 16 patients. During CPB rSat increased to normal values, with a sharp decrease during brief CA (median 6.5 min). Post-CPB rSat showed a transient decrease (30-45%) despite normal PaO2 with sustained normalization after 6-26 h. Recovery time of the rSat seemed longer when pre-operative rSat was below 35%, and for lower minimum nasopharyngeal temperature and longer duration of CPB and of DHCA. Recovery time of the aEEG varied and did not correlate with normalization of rSat. Neurodevelopmental outcome was normal in all but two patients. Patients with lower pre-operative rSat (<35%) tended to have lower DQ (developmental quotient) scores at 30-36 months. (median: mental 102 and motor 101 (range 58-125) compared with mental 100 and motor 110 (range 83-125))

CONCLUSION

Despite prompt normalization of circulation and oxygenation after surgery, recovery of rSat of the brain took 6-26 h, probably because of higher energy demand after CPB. Pre-operative cerebral oxygenation may be underestimated as a possible cause of adverse post-operative outcome.

Monitoring of selective antegrade cerebral perfusion using near infrared spectroscopy in neonatal aortic arch surgery

BACKGROUND AND OBJECTIVE

To prevent neurological complications, low-flow antegrade cerebral perfusion (ACP) is used during repair of complex congenital heart defects. To overcome technical problems, continuous monitoring of cerebral blood flow and oxygenation is mandatory. The aim of the study was to evaluate the effect of different ACP flow rates on cerebral oxygen saturation obtained by near infrared spectroscopy.

METHODS

Ten consecutive neonates undergoing Norwood stage I were included. In addition to near infrared spectroscopy (Invos 5100; Somanetics Corp., USA) on both hemispheres, mean arterial pressure and transcranial Doppler flow velocity were measured continuously and arterial and jugular venous oxygen saturation intermittently. Cerebral oxygen extraction ratio was calculated. Measurement points were obtained after starting bypass, during ACP with flow rates of 30, 20 and 10 mL kg(-1) min(-1) and immediately after ACP. ANOVA and Tukey-Kramer multiple comparison test were used for statistics.

RESULTS

The near infrared spectroscopy signal could be obtained in all children at all measurement points, whereas transcranial Doppler failed in 1 neonate at a flow rate of 30 mL kg(-1)min(-1), in 3 neonates at 20 mL kg(-1) min(-1) and in 4 neonates at 10 mL kg(-1)min(-1). With the reduction of flow there was a significant decrease of cerebral oxygen saturation on both hemispheres (right: 78+/-8 to 72+/-9 and 66+/-8, P < 0.001; left: 71+/-7 to 65+/-7 and 60+/-7, P < 0.001), of jugular venous oxygen saturation (94+/-6 to 89+/-13 and 83+/-15, P < 0.001) and a significant increase in oxygen extraction ratio (9.1+/-8 to 14.8+/-14 and 21+/-16, P < 0.001) respectively, for 30, 20, 10 mL kg(-1)min(-1).

CONCLUSION

Near infrared spectroscopy reliably detects flow alterations during ACP with profound hypothermia.

Electrographic Neonatal Seizures after Infant Heart Surgery

PURPOSE

Neonatal seizures are relatively common and an important early sign of acute encephalopathy in those who survive infant heart surgery. The contemporary occurrence of seizures in this setting is not fully known, and their electrographic characteristics are incompletely described. This study describes the characteristics of electrographic neonatal seizures (ENSs) in contemporary infants with congenital heart disease (CHD) surgically repaired by using cardiopulmonary bypass, with or without deep hypothermic circulatory arrest.

METHODS

Consecutive infants undergoing heart surgery were monitored by video-EEG for 48 h postoperatively to establish the time of first seizure, total number of ENSs, site(s) of ENS(s) origin and other characteristics.

RESULTS

ENSs occurred in 21 (11.5%) of 183 infants. None had clinically visible seizures. The mean time to the first ENS was 21 h (range, 10-36 h). The total number of ENSs among the entire cohort was 1,429. Mean total number of ENSs per patient over a 48-h period was 72 (range, 1-217). Phenobarbital administration was associated with a > or =50% reduction in seizure counts in five (41.7%) of 12 subjects.

CONCLUSIONS

ENSs were relatively common in a large, contemporary cohort of infants after infant heart surgery. A wide variation was noted in seizure burden, but many experienced numerous seizures. Electrographic neonatal seizures are a candidate outcome end point in future neuroprotection trials in this patient population.

Critical care in cardiovascular medicine

The field of cardiac intensive care is rapidly evolving with nearly simultaneous advances in surgical techniques and adjunctive therapies, respiratory care, intensive care technology and monitoring, pharmacologic research and development, and computing and electronics. The focus of care has now shifted toward reducing morbidity and improving "quality of life" while the survival of infants and children with congenital heart defects, including those with univentricular hearts has dramatically improved during the last three decades. Despite these advances, there remains a predictable fall in cardiac output after cardiopulmonary bypass. This article focuses on early identification and aggressive treatment of the low cardiac output syndrome peculiar to these patients. The authors also briefly review the recent advances in the treatment of pulmonary hypertension, mechanical support, and neurologic surveillance after cardiac surgery.