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Julia K. Gunn
John Beca
Rodney W. Hunt
Monika Olischar
Lara S. Shekerdemian
Perioperative amplitude-integrated
EEG and neurodevelopment in infants
with congenital heart disease
Received: 5 December 2011
Accepted: 13 May 2012
Published online: 1 June 2012
ÓCopyright jointly held by Springer and
ESICM 2012
J. K. Gunn R. W. Hunt M. Olischar
Department of Neonatal Medicine,
Royal Children’s Hospital,
Melbourne, Australia
J. K. Gunn
e-mail: julia.gunn@mcri.edu.au
J. K. Gunn R. W. Hunt
Neonatal Research Group,
Murdoch Children’s Research Institute,
Melbourne, Australia
J. Beca
Paediatric Intensive Care Unit,
Starship Children’s Hospital,
Auckland, New Zealand
R. W. Hunt
Department of Paediatrics,
The University of Melbourne,
Melbourne, Australia
M. Olischar
The Medical University of Vienna,
Vienna, Austria
L. S. Shekerdemian ())
Intensive Care Services,
Texas Children’s Hospital, Houston, USA
e-mail: lssheker@texaschildrens.org
Tel.: ?1-832-8266297
L. S. Shekerdemian
Baylor College of Medicine,
6621 Fannin Street, WT6-006,
Houston, TX 77030, USA
Abstract Purpose: Perioperative
brain injury is common in young
infants undergoing cardiac surgery.
We aimed to determine the relation-
ship between perioperative electrical
seizures, the background pattern of
amplitude-integrated electroencepha-
lography (aEEG) and 2-year
neurodevelopmental outcome in
young infants undergoing surgery
for congenital heart disease.
Methods: A total of 150 newborn
infants undergoing cardiac surgery
underwent aEEG monitoring prior to
and during surgery, and for 72 h
postoperatively. Two blinded asses-
sors reviewed the aEEGs for seizure
activity and background pattern.
Survivors underwent neurodevelop-
mental outcome assessment using the
Bayley Scales of Infant Development
(3rd edn.) at 2 years. Results: The
median age at surgery was 7 days
(IQR 4–11). Cardiopulmonary bypass
was used in 83 %. Perioperative
electrical seizures occurred in 30 %,
of whom 1/4 had a clinical correlate,
but were not associated with 2-year
outcome. Recovery to a continuous
background occurred at a median 6
(3–13) h and sleep–wake cycling
recovered at 21 (14–30) h. Prolonged
aEEG recovery was associated with
increased mortality and worse neuro-
developmental outcome. Failure of
the aEEG to recover to a continuous
background by 48 postoperative
hours was associated with impairment
in all outcome domains (p\0.05).
Continued abnormal aEEG at 7 post-
operative days was highly associated
with mortality (p\0.001). Conclu-
sions: Perioperative seizures were
common in this cohort of infants but
did not impact on 2-year neurodevel-
opmental outcome. Delayed recovery
in aEEG background was associated
with increased risk of early mortality
and worse neurodevelopment. Ongo-
ing monitoring of the survivors is
essential to determine the longer-term
significance of these findings.
Keywords Congenital heart disease
Pediatrics Brain Follow-up
studies Cardiac surgery
Abbreviations
aEEG Amplitude-integrated
electroencephalography
CHD Congenital heart disease
CPB Cardiopulmonary bypass
ECMO Extracorporeal
membrane oxygenation
EEG Electroencephalography
HLHS Hypoplastic left heart
syndrome
SWC Sleep–wake cycling
Intensive Care Med (2012) 38:1539–1547
DOI 10.1007/s00134-012-2608-y PEDIATRIC ORIGINAL
Introduction
Brain injury is a potentially devastating complication of
congenital heart disease (CHD) requiring surgery during
the newborn period [1,2]. The developing white matter is
particularly vulnerable to acute changes in cerebral per-
fusion and oxygenation which are typical during the
perioperative period in young infants with complex CHD.
Continuous electroencephalography (EEG) provides a
real-time picture of the brain’s surface electrical activity
and therefore offers a time-sensitive method of detecting
brain injury [3].
Amplitude-integrated EEG (aEEG) is used in neona-
tal intensive care for assessment of seizures and
background cerebral activity in high-risk neonates [4–9].
As well as providing real-time continuous bedside
monitoring, time-compressed background aEEG patterns
have been shown to correlate with magnetic resonance
imaging changes [5] and neurodevelopmental outcome in
neonatal encephalopathy [7–10]. aEEG has also been
studied in infants undergoing extracorporeal membrane
oxygenation (ECMO) and in infants after the arterial
switch operation [3,11,12]. We recently reported an
association between adverse outcomes (death or impaired
neurodevelopment) and perioperative aEEG abnormali-
ties in a subgroup of these infants undergoing Norwood-
type palliations [13].
Postoperative clinical and electrical seizures, on con-
ventional EEG monitoring, have been shown to correlate
with impaired early neurodevelopment in cohorts of
young infants before and after cardiac surgery [14–16].
Refinements in perfusion techniques, anaesthetic regimes
and surgical approaches, as well as perinatal and post-
operative care have together contributed to improved
survival in recent years. Thus, the findings of historical
studies should only be applied with caution in the current
era.
The aims of this study were to ascertain the typical
period of aEEG recovery in young infants following a range
of cardiac operations, to determine the incidence of peri-
operative seizures using continuous two-channel aEEG
before, during and for 72 h after surgery for CHD and
to relate these findings to 2-year neurodevelopmental
outcome.
Patients and methods
Participants
Between 2005 and 2008, 150 full-term infants scheduled
to undergo surgery for CHD before 2 months of age were
enrolled into a prospective study of brain injury in CHD,
at The Royal Children’s Hospital, Melbourne (centre 1)
and Starship Children’s Hospital, Auckland (centre 2).
Infants were excluded for the following reasons: (1)
gestational age of less than 36 weeks; (2) a genetic
abnormality independently associated with impaired
neurodevelopment; or (3) the need for preoperative
ECMO. The study was approved by both hospitals’
human research and ethics committees and parents of
participants consented to their inclusion.
Amplitude-integrated EEG
aEEG monitoring was performed on each participant
using the BRM2 cerebral monitor (BrainZ Instruments,
Auckland, New Zealand). A two-channel recording of
electrical activity was collected from scalp electrodes
positioned in the C3, P3, C4 and P4 positions of the
international 10–20 EEG system. The monitor used a
computer-generated algorithm to filter and compress raw
data for each cerebral hemisphere. Data were considered
acceptable for analysis according to the following criteria:
impedance of less than 10 kX, absence of movement or
electrocardiographic artefact on the raw trace, and
absence of interference from diathermy or other electrical
devices.
A neonatologist experienced in aEEG interpretation,
and blinded to clinical information, analysed all de-
identified aEEG recordings offline. The complete com-
pressed background recording and the intraoperative raw
trace were assessed. Background traces were classified
according to the dominant pattern at the following pre-
defined phases:
Phase 1 1 h preoperative aEEG.
Phase 2 Intraoperative aEEG: (a) from commencement
of anaesthesia; (b) during cooling and main-
tenance of the target hypothermic temperature;
(c) during rewarming and (d) after cardio-
pulmonary bypass (CPB) until surgery was
completed (or from the time normothermia was
reached if CPB was not used).
Phase 3 Postoperative aEEG: hourly for 6 h then six
hourly until 72 h after the cessation of CPB
(or 1 h post-CPB when CPB was not utilised).
Phase 4 1 h late postoperative aEEG 7 days following
surgery.
Background aEEG activity was classified as continu-
ous (normal), discontinuous or suppressed (burst sup-
pression, low voltage or flat trace), based on a previously
described system [5,17]. The time taken for the aEEG to
‘recover’ to continuous background activity [regardless of
sleep–wake cycling (SWC)] and to SWC were docu-
mented for each patient (up to 72 postoperative hours).
This was then classified as normal (continuous) or
abnormal at 48 h. Seizures were defined as repetitive
1540
waveforms evolving over a minimum of 10 s on either
hemisphere. Suspected seizures on the amplitude-inte-
grated component were confirmed on the raw EEG and
considered by a second blinded assessor. Seizures iden-
tified acutely were managed at the discretion of the
treating clinical team. A seizure detection algorithm was
not utilised.
Operative management
Anaesthetic management followed institutional cardiac
anaesthesia protocols, with high-dose fentanyl, inhaled
isoflurane and muscle relaxants. Benzodiazepines or
barbiturates were not administered during surgery. For
the infants undergoing CPB, the perfusion strategy
included continuous full-flow CPB at 150 mL/kg/min
with a procedure-specific target temperature during CPB
of 22–34 °C. Alpha-stat acid–base management was
utilised in both centres, with the use of pH-stat at tem-
peratures below 30 °C in centre 2. Antegrade cerebral
perfusion (ACP) was maintained via a Goretex shunt to
the innominate artery in all infants undergoing Nor-
wood-type reconstructions, and infants with biventricular
circulations requiring arch reconstruction in centre 1.
ACP was maintained at flows of 30–40 % of ‘full’ CPB
flow, with flow adjusted to target a right radial arterial
mean pressure of 30–45 mmHg. Brief periods of deep
hypothermic circulatory arrest (DHCA) were used in
centre 2 (but not centre 1) with biventricular circulation
during arch reconstruction, and during surgery to the
atrial septum. Continuous haemofiltration was used in all
patients during CPB, with a target haematocrit of greater
than 30 % during CPB, and 40–45 % at the completion
of CPB.
There were no other differences in perioperative
management between centres. Following selected opera-
tions, including the Norwood procedure, the sternum
was left open with the intention of delayed closure after
a period of haemodynamic stability. Postoperative
analgesia and sedation were achieved with continuous
infusions of morphine (10–40 lg/kg/h) and midazolam
(1–3 lg/kg/min).
Neurodevelopmental assessment
Survivors underwent a neurodevelopmental assessment
by a paediatrician and/or psychologist at 2 years, using
the Bayley Scales of Infant Development (3rd edn)
(BSID-3) for which the normative mean equates to a score
of 100 ±15. Severe neurodevelopmental delay for a
given domain (cognitive, language or motor) was defined
as a score more than two standard deviations (SD) below
the normative mean (\70).
Statistical analysis
Data were analysed using descriptive statistics. Parametric
and non-parametric data are reported using mean ±SD or
median (interquartile range), respectively. aEEG back-
ground recovery was analysed as both a continuous
variable and dichotomous variable (recovery to a contin-
uous background by 48 h). Categorical variables were
analysed using a v
2
test. Ttests, Wilcoxon rank-sum tests
and linear regression were used for analysis of continuous
variables. Statistical significance was determined at a
pvalue of less than 0.05.
Results
Table 1shows demographic and surgical details of the
study participants. Participants were divided into four
preoperative categories, according to a previously descri-
bed classification [18], as follows: two ventricle without
aortic arch obstruction (such as transposition of the great
arteries) 57 (38 %); single ventricle with aortic arch
obstruction [such as hypoplastic left heart syndrome
(HLHS)] 41 (27 %); single ventricle without aortic arch
obstruction (such as pulmonary atresia) 28 (19 %); two
ventricle with aortic arch obstruction (such as coarctation)
24 (16 %).
Two-year neurodevelopment
Twenty (13 %) participants died before 2 years, at a
median 55 days (IQR 27–61), eight prior to hospital
discharge. Five (4 %) were lost to follow-up and 125
children (96 % of survivors) underwent neurodevelop-
mental evaluation. Mean cognitive composite scores were
Table 1 Demographic and surgical details of included participants
(n=150)
Male 95 (63 %)
Birth weight (kg) 3.3 ±0.5
Head circumference (cm) 34.5 ±1.8
Gestational age at birth (weeks) 39 ±1.6
Age at surgery (days) 7 (4–11)
Cardiopulmonary bypass used 125 (83 %)
Duration of CPB (min) 184 ±60
Minimum oesophageal temperature
during bypass (°C)
24.5 ±5.3
Aortic cross-clamp time (min) 94 ±40
Circulatory arrest 47 (31 %)
Duration of circulatory arrest (min) 8 (5–17)
Antegrade cerebral perfusion 48 (32 %)
Immediate postoperative lactate (mmol/L) 3.4 (2.0–4.8)
Postoperative ECMO 11 (7 %)
Number (%), mean ±standard deviation or median (interquartile
range) are reported
1541
93.2 ±13.7 and five (4 %) children had severe cognitive
delay (score \70). Mean language scores were 93.5 ±
16.2 and ten (8 %) children had severe language delay.
Mean motor scores were 96.7 ±12.7 and two (2 %)
children had severe motor delay. Mean scores were sig-
nificantly lower than the normative mean in all domains
(cognitive and language p\0.0001; motor p=0.01).
Seizures
Perioperative electrical seizures were identified in 43
(30 %) infants, seven of whom had clinical signs and
were treated with anticonvulsants. There was 100 %
agreement between assessors regarding the presence of
electrical seizures. Preoperative seizures occurred in four
(3 %) infants and intraoperative seizures (Fig. 1) occurred
in 20 (13 %), most commonly during the hypothermic or
rewarming phase of CPB. During the postoperative
recovery period, 27 (19 %) infants displayed electrical
seizures and a further three (2 %) had seizure activity on
the late postoperative aEEG. Minimum core temperature
did not vary between those with or without intraoperative
seizures and there was no relationship between the use of
CPB or circulatory arrest and the occurrence of periop-
erative seizures (p[0.2). There was also no relationship
found between the occurrence of perioperative seizures
and diagnostic group (Table 2), mortality or develop-
mental scores (p[0.10).
aEEG background
Figure 2shows the background aEEG characteristics at
each phase. No relationship was found between preoper-
ative background and 2-year outcome. At or below 28 °C
Fig. 1 Intraoperative aEEG. Ten seconds of raw trace for each
hemisphere (top two traces); and the time-compressed aEEG trace
(bottom two traces) over 5 h. AAnaesthetic induction and
commencement of surgery; Bcooling and maintenance of hypo-
thermia (complete suppression of the background trace);
Crewarming and cessation of CPB; Dconclusion of surgery.
Electrical seizure (orange arrow highlights correlation between
aEEG and raw trace) occurring during rewarming following CPB
and circulatory arrest
Table 2 Relationship between cardiac category and occurrence of electrical seizures and median aEEG recovery time
Preoperative category Any seizures
a
Intraoperative
seizures
Postoperative
seizures
Median (IQR) recovery
time to continuous
background (h)
b
Single ventricle 6 (22 %) 1 (4 %) 3 (11 %) 10 (4–20)
Two ventricle 15 (27 %) 6 (12 %) 10 (18 %) 4 (2–11)
Single ventricle with aortic arch obstruction 13 (33 %) 9 (23 %) 7 (18 %) 16 (4–45)
Two ventricle with aortic arch obstruction 9 (41 %) 4 (18 %) 7 (32 %) 4 (2–13)
Total 43 (30 %) 20 (13 %) 27 (19 %) 8 (3–18)
a
Some infants had seizures within more than one epoch
b
Infants whose aEEG had not recovered by the end of the recording were underestimated to have recovered by 72 h
1542
all intraoperative background traces had either isoelectric
or low voltage activity (Fig. 1B). There was considerable
variability in the degree of background suppression above
28 °C. Recovery to a continuous aEEG background
occurred within 24 h in 112 participants (77 %), by 48 h
in 118 (81 %) and by 72 h in 130 (90 %). Amongst the
130 infants whose background patterns had recovered
within 72 h, the median recovery time was 6 (3–13) h.
SWC was established by 72 h in 118 infants at a median
21 (14–30) h. Intraoperative seizures were associated
with a 10.6 [95 % CI 1.1, 20.1] h delay in aEEG recovery
to a continuous background (p=0.03) but not to return
of SWC (p=0.46). Postoperative seizures did not impact
on the recovery time of the background activity.
Prolonged recovery to a continuous background was
associated with lower mean cognitive scores (Coeff 0.14
[95 % CI 0.01, 0.28]; p=0.03) and motor scores (Coeff
0.17 [95 % CI 0.05, 0.30]; p=0.008) (Table 3). Delayed
recovery of SWC was associated with lower cognitive
scores (Coeff 0.17 [95 % CI 0.05, 0.28]; p=0.006).
Participants with a cognitive or language score below 70
had mean recovery times to continuous background which
were 16.6 [95 % CI 0.5, 32.8] h (p=0.04) and 14.8
[95 % CI 3.2, 26.3] h (p=0.01) longer than those with a
score within two SDs of the normative mean. Likewise,
recovery to normal SWC was 32.5 [95 % CI 14.0,
30.9] h, 14.5 [95 % CI 0.8, 28.3] h and 42.8 [95 % CI
13.6, 72.1] h later in those who subsequently had
respective cognitive (p=0.007), language (p=0.04) or
motor (p=0.004) scores below 70. Death before 2 years
was associated with a 19.4 [95 % CI 9.3, 29.0] h increase
in postoperative recovery time to a continuous back-
ground compared with survivors (p=0.0001) and a 14.8
[95 % CI 4.3, 25.3] h increase in time to return of SWC
(p=0.006).
Postoperative ECMO was associated with delayed
aEEG recovery—50 % of those on ECMO failed to
recover background aEEG by 48 h compared with 10 %
of those without ECMO (v
2
=12.8, p\0.0001). Seven
of the 11 children who had required ECMO died and one
declined follow-up. Removal of the remaining three
children from outcome analysis did not alter the impact of
delayed aEEG recovery on outcome. Eight infants had
persisting discontinuous or low voltage background pat-
terns 1 week after surgery, of whom five had required
ECMO and subsequently died (v
2
=16.4, p\0.001).
Time of recovery to a continuous background was
longer in those with single-ventricle physiology (with
either obstruction to the systemic or pulmonary circula-
tion) compared to those with two-ventricle physiology
preoperatively (p=0.0002) (Table 2), but there was no
significant prolongation of recovery time specifically
related to delayed chest closure (p=0.051). Mean cog-
nitive (p=0.028) and motor (p=0.002) scores were
also lower in those with single-ventricle physiology and
80 % of the deaths occurred in this group. However, time
to return of SWC was not related to preoperative cardiac
anatomy (p=0.20).
Discussion
This is the first cohort study to report on perioperative
aEEG monitoring across a range of congenital heart
lesions. Moreover, this is the first study which links
postoperative aEEG recovery with neurodevelopmental
Fig. 2 Predominant background aEEG pattern at each phase of
recording. The reduction in data available for all recording phase,
especially during surgery (phase 2), is related to artefact-affected or
missing intraoperative data
Table 3 Impact of delay in recovery of aEEG beyond 48 h postoperatively on 2-year outcome
Two-year outcome aEEG recovery by 48 h post-CPB Abnormal aEEG at 48 h post-CPB pvalue
Mean cognitive score 94.3 (95 % CI 91.8, 96.8) 83.5 (95 % CI 72.2, 94.8) 0.017
Cognitive score \70 3/111 (3 %) 2/10 (20 %) 0.008
Mean language score 94.3 (95 % CI 91.3, 97.4) 81.3 (95 % CI 70.9, 91.7) 0.016
Language score \70 7/111 (6 %) 3/10 (30 %) 0.009
Mean motor score 97.7 (95 % CI 95.4, 100.1) 85.9 (95 % CI 75.6, 96.2) 0.005
Motor score \70 1/111 (1 %) 1/10 (10 %) 0.031
Two-year mortality 12/126 (10 %) 8/19 (42 %) \0.001
Postoperative ECMO 5/121 (4 %) 5/19 (26 %) \0.001
1543
performance in this population. Subclinical perioperative
seizures were common during the perioperative period,
but these were not related to 2-year outcome. However,
postoperative aEEG recovery time was related both to
impaired neurodevelopment and increased mortality.
Seizures
Perioperative seizures were observed in 30 % of our
cohort. Preoperative epileptiform activity may have
been underestimated compared with a previous study
which included a more prolonged preoperative recording
period and detected seizures in 19 % of infants [19].
Intraoperative seizures were observed in 13 %. This
phenomenon has been reported as rare during adult car-
diac surgery, but has rarely been studied in infants [20]. In
the Boston Circulatory Arrest study, conventional multi-
channel EEG recording continued during surgery, and
intraoperative seizures were not observed. However per-
fusion strategies in that cohort included hypothermia to no
greater than 18 °C in all patients, and anaesthetic man-
agement included routine administration of thiopentone at
the nadir of body temperature (10 mg/kg), which could
suppress intraoperative electrical activity.
Postoperative electrical seizures were identified in
19 % of our participants. Similar rates of electrical sei-
zures have been reported in other postoperative cohorts
including clinical seizure rates of 16–17 % after surgery
for HLHS [21–24]. Immature brains are less likely to
exhibit clinical manifestations of seizures despite their
increased frequency [25]. This reflects the typical
‘uncoupling’ of clinical and electrical seizures commonly
seen in neonates, which are further masked by pharma-
cotherapy [26]. Andropoulos et al. [27] recently reported
postoperative seizures in only 3 % of neonates undergo-
ing single-ventricle palliation, but all patients in that
sample had received intravenous midazolam throughout
their surgery as well as boluses during their postoperative
recovery. Though this may have increased the seizure
threshold, it will be essential to determine whether this
difference in seizure occurrence translates into improved
outcomes. While in the Boston cohort, postoperative
electrical seizures were associated with impaired neuro-
development at 1, 4 and 16 years of age, but not at
8 years [15,28,29], we did not demonstrate a relationship
at 2 years of age using the BSID-3 assessment.
Postoperative aEEG
Failure of the aEEG background to recover to a continuous
pattern within 48 h after CPB was highly correlated with
increased mortality and worse 2-year neurodevelopment in
survivors. There is limited literature regarding EEG
recovery in infants after cardiac surgery. In the Boston
cohort, background EEG had not yet returned to baseline
at 48 h in the study participants, which may reflect a dif-
ference in anaesthetic and postoperative strategies. In a
cohort of infants followed up after the arterial switch
operation, there was a wide variability in time to recovery
of background aEEG and 18/20 participants had normal
neurodevelopment at 30 months [3]. We have previously
reported an association between delayed postoperative
aEEG recovery and motor delay in a subgroup of these
infants undergoing the Norwood procedure [30]. Corre-
lation between aEEG and neurodevelopmental outcome
has not previously been reported in broader cohorts of
infants with CHD. Importantly, our findings are consistent
with studies of neonatal encephalopathy, in which time to
recovery of aEEG background, and return of SWC, is
correlated with outcome [7,31]. These data suggest that
postoperative aEEG monitoring may have a role to play in
identifying children at higher risk of a poor outcome.
The finding that aEEG background, but not seizures,
was related to neurodevelopmental impairment may
reflect the accuracy of a two-channel tool designed to
examine background patterns rather than seizures. It may
also reflect the nature of cerebral injury in this population,
namely the dominance of white matter injury rather than
localized cortical injury, which is more likely to present
with seizures.
Limitations
The first, and probably most important limitation to our
study, relates to our modality of cerebral monitoring. We
applied two-channel aEEG during the study, and did not
have access to continuous conventional multichannel
EEG monitoring for the extensive period of monitoring.
In terms of seizure identification, while it is possible that
the aEEG may have missed occasional seizures, particu-
larly pertaining to the frontal regions, it is generally
accepted that there is good correlation between the
two methods when interpreted by experienced clinicians
[32,33]. The investigator assigned to interpretation of the
aEEG was experienced in this, having been trained by
colleagues who have extensively published in the field
[34–37]. Seizures may also have been missed in the phase
1 and 4 components of recording due to the short time
period over which monitoring was applied at these points.
Less evidence is available regarding the accuracy of
aEEG in interpretation of the background activity in
infants after heart surgery. Clancy et al. [38] described
good correlation between single-channel aEEG and con-
ventional multi-lead EEG at the two extreme categories
(normal and markedly abnormal) but significantly weaker
correlation in the intermediate categories. Those investi-
gators used single-channel aEEG, and did not have access
to ‘raw’ aEEG traces and the authors acknowledged that
the agreement between the two modalities could be
1544
enhanced with two-channel recording [39], examination of
the raw trace (particularly by an experienced aEEG reader)
and interpretation of background patterns according to the
Hellstrom-Westas classification [17]. All of these potential
factors were used or incorporated in our study.
A second limitation relates to the potential contribution
of sedative and analgesic drugs to the interpretation of
aEEG. While it is generally believed that these agents
suppress aEEG background activity, there is little pub-
lished evidence to support this, particularly in full-term
neonates without significant acute diffuse brain injury, or
refractory seizures [40]. All infants in our study received
weaning doses of morphine and midazolam during the
postoperative period, which could influence aEEG
recovery, particularly as the sickest infants are more likely
to require longer periods of such agents. However, in a
subgroup of this cohort, we found no relationship between
postoperative aEEG background pattern and infusions of
morphine or midazolam [41]. All infants in this study
received similar anaesthetic regimens, but there remains
the potential for effects on the aEEG of agents such as
fentanyl and isoflurane, which require further elucidation.
Finally, inclusion of a control group with this cohort
would have strengthened the assessment of neurodevel-
opmental impact on these children. Previous assessments
of cardiac children have not incorporated the BSID-3
which may overestimate abilities compared with previous
versions of the test [42].
Conclusions
Electrical seizures are common in young infants under-
going surgery for CHD, both during and after surgery, but
do not predict 2-year neurodevelopmental outcomes.
A prolonged aEEG recovery phase after surgery is asso-
ciated with both increased mortality and impaired
neurodevelopment in all domains at 2 years of age in
survivors. Perioperative neuromonitoring is essential in
these high-risk infants. Further follow-up will determine
the longer-term significance of these findings.
Acknowledgments Thank you to the following people for their
assistance with data collection (the Hearts and Minds Study
research nurses in Melbourne and Auckland, particularly Michelle
Goldsworthy, Laura-Clare Whelan, Stephen McKeever and Carmel
Delzoppo) and for their support of our study (the cardiac surgeons,
anaesthetists, perfusionists and paediatric intensive care staff of
both hospitals). We are also appreciative of Prof Terrie Inder for
her involvement in the original study design. Funding support was
received from the National Heart Foundation (Australia), Heart
Foundation of New Zealand, Auckland Medical Research Fund,
Green Lane Research and Education Fund, Australian and New
Zealand Intensive Care Foundation, Murdoch Childrens Research
Institute (MCRI) and the Victorian Government’s Operational
Infrastructure Support Program. Dr Gunn received a postgraduate
health research scholarship from National Health and Medical
Research Council (NHMRC) and MCRI.
Conflicts of interest The authors have no financial disclosures or
conflicts of interest to declare.
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