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European Journal of Cardio-thoracic Surgery 39 (2011) 75—80
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Junctional ectopic tachycardia after surgery for congenital heart disease:
incidence, risk factors and outcome§,§§
Leena Mildh a,*, Anita Hiippala b, Paula Rautiainen a, Ville Pettilä a,
Heikki Sairanen c, Juha-Matti Happonen b
a
Department of Anaesthesia and Intensive Care, Helsinki University Hospital, Helsinki, Finland
b
Department of Paediatric Cardiology, Helsinki University Hospital, Helsinki, Finland
c
Department of Paediatric Cardiac Surgery, Helsinki University Hospital, Helsinki, Finland
Received 3 December 2009; received in revised form 9 April 2010; accepted 13 April 2010
Abstract
Objectives: Junctional ectopic tachycardia (JET) is a serious, haemodynamically compromising tachyarrhythmia associated with paediatric
cardiac surgery, with a reported mortality up to 14%. The incidence, risk factors and outcome of this tachyarrhythmia were evaluated in this
population-based, case-control patient cohort. Methods: A total of 1001 children, who underwent open-heart surgery during a 5-year period,
were retrospectively analysed. The patients with haemodynamically significant tachycardia were identified, and their postoperative electrocardiograms were analysed. Three controls matched with the same type of surgery were selected for each patient with JET. Results: JET was
diagnosed in 51 patients (5.0%). These patients had longer cardiopulmonary bypass time (138 vs 119 min, p = 0.002), higher body temperature
(38.0 vs 37.4 8C, p = 0.013) and higher level of postoperative troponin-T (3.7 vs 2.1 mg l 1, p < 0.001) compared with controls. They also needed
longer ventilatory support (3 vs 2 days, p = 0.004) and intensive care stay (7 vs 5 days, p < 0.001) as well as use of noradrenaline (23/51 vs 35/130,
p = 0.019). Ventricular septal defect (VSD) closure was part of the surgery in 33/51 (64.7%) of these patients. The mortality was 8% in the JET
group and 5% in the controls ( p = 0.066). In the logistic regression model, JET was not an independent risk factor for death ( p = 0.557).
Conclusions: The incidence of JETwas 5.0% in this large paediatric open-heart surgery patient group. Compared with controls, these patients had
longer cardiopulmonary bypass time and higher level of troponin-T, possibly reflecting the extent of surgical trauma. However, the tachycardia
was not an independent risk factor for death.
# 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.
Keywords: Arrhythmia; Paediatric cardiology; Congenital heart surgery
1. Introduction
Junctional ectopic tachycardia (JET) is a tachyarrhythmia associated mostly with surgery for congenital heart
disease. It is usually a self-limiting condition, but can cause
serious haemodynamic deterioration in the immediate
postoperative phase [1]. JET is a narrow QRS complex
tachycardia, usually with atrioventricular dissociation and
slower atrial than ventricular rate. It can also present with
1:1 retrograde ventriculoatrial conduction. Haemodynamic
instability is mostly caused by loss of atrioventricular
synchrony and consequent loss of the contribution of atrial
contraction to cardiac output [2,3]. The precise mechanism
of JET is not known, but it is thought to result from
§
Presented at the 43rd Joint Annual Meeting of Association for European
Paediatric Cardiology, Venice, Italy, 21—24 May 2008.
§§
Funding: This study was funded in part by EVO-grant of Helsinki University
Hospital.
* Corresponding author. Address: Helsinki University Hospital, P.O. Box 340,
00029 Helsinki, Finland. Tel.: +358 50 4271641; fax: +358 9 471 78354.
E-mail address: [email protected] (L. Mildh).
mechanical trauma to the proximal conduction tissue
related to suture placement or indirect stretch injury [4].
The incidence of JET has been reported to vary from 5.6% to
14% (study samples varying from 343 to 874 patients)
depending on patient selection [2,5—7]. Several risk factors
have been associated with this condition, both surgical and
non-surgical. The surgical risk factors include resection of
muscle bundles, correction of right ventricular outflow tract
and correction of ventricular septum [4]. The non-surgical
risk factors previously reported are young patient age,
longer cardiopulmonary bypass (CPB) time, aortic crossclamp (ACC) time, low level of plasma magnesium, use of
catecholamines and hyperthermia [2,6,7]. Most studies
addressing the incidence and risk factors of JET are based on
selected patient populations, that is, selected surgical
procedures, institution-based patient groups with possible
patient selection or small patient groups. The purpose of this
study was to analyse the incidence, risk factors and outcome
of JET in an unselected population-based patient cohort,
operated upon in the only paediatric cardiac surgery centre
in Finland during a 5-year period.
1010-7940/$ — see front matter # 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.ejcts.2010.04.002
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L. Mildh et al. / European Journal of Cardio-thoracic Surgery 39 (2011) 75—80
2. Materials and methods
This retrospective cohort study was performed at Helsinki
University Hospital for Children and Adolescents, which is the
only centre for paediatric heart surgery and operates all
children born with congenital heart defect in Finland
(population: 5.2 million). The study was reviewed and
approved by the local Human Investigation Committee,
which waived the need for obtain informed consent.
2.1. Subjects and data collection
Data from all patients under 18 years of age, who
underwent heart surgery necessitating CPB between 1
January 2000 and 31 December 2004, were included in the
study. The patients with haemodynamically significant
tachyarrhythmia were identified. The 12-lead electrocardiogram (ECG) and intracardiac atrial and ventricular tracings
from temporary pacing wires were used to divide the patients
into different diagnostic groups according to arrhythmia.
Information describing surgical procedure, duration of CPB as
well as ACC and survival at day 30, postoperatively, were
recorded in specific paediatric heart surgery database
(ProCardio, Melba Group, Finland), which obtains its
information from the Finnish Population Registry Centre
[8]. Surgical procedures were grouped according to the
international congenital heart surgery nomenclature [9—11].
Information on patients’ demographics (sex, weight and
age), intubation time, length of stay at the intensive care
unit (ICU), body temperature, plasma potassium, calcium
and magnesium at tachyarrhythmia onset, the use of
milrinone (yes/no), adrenaline (yes/no) and noradrenaline
(yes/no) as well as first postoperative day troponin-T (TnT)
values were obtained from the intensive care database
(Centricity Critical Care Clinisoft; GE Healthcare, Helsinki,
Finland). Data tables were exported from the intensive care
database, imported into a relational database (Microsoft
Access; Microsoft; Seattle, WA, USA), and combined with the
surgical database.
Patients with solitary atrial septal defect (ASD) closure
received only cold cardioplegia. All other patients
received, in addition to cold cardioplegia, both warm
induction cardioplegia immediately after aortic crossclamp and warm blood cardioplegia before reperfusion.
The CPB circuit was primed with a solution containing
magnesium.
2.4. Postoperative care
Milrinone was used as the first-line inotropic drug. In the
case of insufficient inotropic support (low cardiac contractility evaluated by ultrasound, profound acidosis and
high blood lactate), adrenaline was added to milrinone.
Noradrenaline was used in case of low systemic blood
pressure. The patients were extubated when haemodynamic stability was achieved, gas exchange was satisfactory (arterial blood oxygen and carbon dioxide levels
within normal individual limits according to cardiac defect)
and sufficient muscle strength recovered for airway
patency. Discharge criteria from the ICU included haemodynamic stability with no catecholamine support, normal
sinus rhythm, normal or near to normal renal function and
ability to maintain normal gas exchange with a natural
airway.
2.5. Blood sampling and biochemical analysis
The measurements of plasma potassium and calcium
were obtained at least four times a day and performed with
an ABL 700 series analyser (Radiometer Medical A/S, DK2700; Bronshoj, Denmark). Plasma magnesium was measured daily at 6 a.m. and analysed with spectrophotometric
colour binding (Roche Diagnostic, Mannheim, Germany).
Plasma TnT was obtained on the first postoperative morning
at 6 a.m. and analysed with electrochemiluminescence
immunoassay (Elecsys Troponin T STAT; Roche, Mannheim,
Germany).
2.2. Arrhythmia diagnostics and treatment
2.6. Statistical methods
The ECGs were retrospectively evaluated by paediatric
electrophysiologists (AH, JMH) and patients were grouped
according to JET or other tachyarrhythmia. For each JET
patient, three controls without any arrhythmia and matched
for surgical procedure and age were selected from the whole
patient cohort.
According to institutional treatment protocol, amiodarone was used as the first-line anti-arrhythmic drug for all
patients with haemodynamically compromising tachycardia
[3]. Amiodarone was given as a 5 mg kg 1 loading infusion
in 0.5—1 h followed by a continuous infusion of 10—
20 mg kg 1 d 1 [12]. Other simultaneous treatments
included surface cooling, sedation and, if possible,
decreasing catecholamine dose.
Data are presented as mean SD or median (interquartile
range). Statistical analyses were performed with SPSS
10.1.315 for Windows (SPSS, Chicago, IL, USA). Differences
in continuous variables between patients with JET and their
controls were compared using nonparametric Mann—Whitney
test. Differences in dichotomous variables were compared
with Fisher’s exact test. A p-value less than 0.05 was
considered significant. Univariate analysis regarding diagnosis of JET and relevant variables (CPB, ACC, plasma
magnesium and TnT, use of milrinone, adrenaline and
noradrenaline as well as body temperature at the onset of
tachycardia) was performed with continuous variables
modelled linearly. Thereafter, analysis of an independent
effect of variables on incidence of JET was performed using
backward stepwise logistic regression analysis with p < 0.20
to include and p > 0.10 to exclude covariates from the
model. The influence of JET on 30-day mortality was studied
analysing the whole patient cohort with stepwise forward
multiple logistic regression.
2.3. Myocardial protection
Intermittent antegrade blood cardioplegia enriched
with magnesium was used for myocardial protection.
L. Mildh et al. / European Journal of Cardio-thoracic Surgery 39 (2011) 75—80
Table 1
Tachycardia diagnoses other than junctional ectopic tachycardia among the
103 postoperative arrhythmia patients.
Tachyarrhythmia
Number
of patients
% Of whole
cohort (1001)
Atrial flutter
Atrial tachycardia
Sinus tachycardia
Supraventricular tachycardia
Ventricular fibrillation
Ventricular tachycardia
Other
9
3
13
12
1
1
13
0.9
0.3
1.3
1.2
0.1
0.1
1.3
3. Results
3.1. Patient characteristics
During the study period, a total of 1026 patients
underwent heart surgery with CPB. Patients with heart
transplantation, application of ventricular assist device or
age more than 18 years were excluded from the analysis
(n = 25). The median age of the remaining 1001 patients was
6.7 months (interquartile (IQ) range 2.3—34.3). Of those
1001, 42 (4.2%) died within 30 days after operation. Of all the
1001, 103 (10%) patients were diagnosed with peri- or
postoperative tachyarrhythmia. As many as 51 (5.0 1.36%
of 1001, 95% confidence interval (CI) 3.6—6.4%) patients were
diagnosed with JET, 52 patients had other tachyarrhythmia
(Table 1). JET occurred mostly within 24 h postoperatively.
The median age for JET patients was 3.6 (0.4—10.9) months,
31 were (61%) male and 20 (39%) were female. Of the 51
patients with JET, four (8 7.6%, 95% CI 0—15%) died within
30 days after operation. These four patients were operated
for pulmonary atresia (PA) plus ventricular septal defect
(VSD), tetralogy of Fallot (TOF), total anomalous pulmonary
venous drainage (TAPVD) and hypoplastic left heart syndrome
(HLHS). The surgical procedures associated with JET are
listed in Table 2. VSD closure was part of the surgical
procedure in 33/51 (65%) of JET patients. The median cycle
length of the tachycardia was 325 ms (range, 280—540) and
77
Table 2
Surgical procedures associated with junctional ectopic tachycardia.
Procedure
Patients with JET
(% of whole cohort)
No of operations
in whole cohort
Fallot repair
Arterial switch
Arterial switch with VSD closure
VSD closure
TCPC
Rastelli operation
PA + VSD correction
Aortic arch reconstruction + VSD
correction
Norwood I
AVSD correction
PA + Ebstein anomaly correction
BDG
DORV + VSD correction
PA + IVS correction
TAPVD correction
AVR + CABG
9
6
1
11
5
4
3
3
(12%)
(15%)
(4%)
(6%)
(8%)
(44%)
(17%)
(20%)
73
39
25
175
66
9
18
15
2
1
1
1
1
1
1
1
(3%)
(1%)
(100%)
(1%)
(13%)
(10%)
(7%)
(100%)
70
85
1
78
8
11
14
1
In all
51 (5) %
(of 1001)
VSD: ventricular septum defect, ASD: atrial septum defect, TCPC: total
cavopulmonary connection, PA: pulmonary atresia, AVSD: atrioventricular
septum defect, BDG: bidirectional Glenn operation, DORV: double outlet right
ventricle, TAPVD: total anomalous pulmonary vein drainage, AVR: aortic valve
replacement, CABG: coronary artery bypass grafting.
the median atrial cycle length was 380 ms (range, 280—840).
A 1:1 ventruculoatrial (VA) conduction was present in 48% and
VA dissociation in 52% of patients.
3.2. Comparison of JET versus control patients
No differences between JET patients and their matched
controls in age, gender or death within 30 days, postoperatively, could be detected. Patients with JET had longer
intubation time, higher body temperature at onset of
tachycardia, longer CPB time, more frequent use of
noradrenaline and higher postoperative TnT compared with
their matched controls (Table 3). The aim was to select three
matched controls for each JET patient. However, sufficient
Table 3
Patients with junctional ectopic tachycardia and the matched controls (median, interquartile range) (compared by Mann—Whitney test).
Number of patients
Gender (M/F)
Age (years)
CPB time (min)
ACC time (min)
Body temperature (8C)
Troponin-T (mg l 1)
Plasma potassium (mmol l 1)
Plasma calcium (mmol l 1)
Plasma magnesium (mmol l 1)
Intubation time (days)
Use of milrinone number of patients (%)
Use of adrenaline number of patients (%)
Use of noradrenalin number of patients (%)
PICU stay (days)
Mortality (%)
JET
Controls
p-value
51
30/21
0.3 (0.03—0.91)
138 (104—180)
82 (60—107)
38.0 (37.0—38.0)
3.7 (2.2—6.0)
3.4 (3.2—3.7)
1.21 (1.13—1.27)
1.03 (1.03—1.17)
3 (1—6)
41 (80)
38 (75)
23 (45)
7 (5—9)
4 (7.8)
130
70/60
0.3 (0.05—1.00)
119 (79—154)
76 (39—106)
37.4 (37.0—38.0)
2.1 (1.2—3.5)
3.4 (3.0—3.8)
1.21 (1.11—1.29)
1.07 (0.81—1.23)
2 (1—4)
101 (78)
82 (63)
35 (27)
5 (3—7)
6 (4.6)
0.11 a
0.586
0.002 *
0.059
0.013
<0.001 *
0.315
0.901
0.778
0.004 *
0.953
0.238
0.019 *
<0.001 *
0.066 a
ACC: aortic cross-clamp, CPB: cardiopulmonary bypass, PICU: paediatric intensive care unit.
a
Fisher’s test.
*
Due to multiple comparisons p < 0.01 was considered as significant.
78
L. Mildh et al. / European Journal of Cardio-thoracic Surgery 39 (2011) 75—80
Table 4
Backward multiple logistic regression analysis of variables affecting occurrence of junctional ectopic tachycardia (OR with 95% CIs).
Variable
Univariate
analysis p value
Multivariate
analysis p value
OR
95% CI for OR
95% CI for OR
Postoperative TnT (mg l 1)
CPB time (min)
Temperature (8C)
ACC time (min)
Plasma magnesium (mmol l 1)
Use of milrinone
Use of adrenaline
Use of noradrenalin
0.041
0.028
0.06
0.038
0.93
0.91
0.51
0.09
0.037
0.032
0.050
ns
ns
ns
ns
ns
1.214
1.007
2.187
1.012
1.001
1.000
1.456
1.013
4.783
ACC: aortic cross-clamp, CI: confidence interval, CPB: cardiopulmonary bypass, OR: odds ratio, TnT: troponin-T, ns: not significant. p < 0.05 considered as statistically
significant.
amount of operations was not performed for certain surgical
groups and, therefore, fewer controls were selected for
these groups (Rastelli, PA + Ebstein and AVR + CABG).
3.3. Variables affecting the incidence of JET
The stepwise backward multiple logistic regression
analysis revealed longer CPB time and higher postoperative
TnT to be significant prognostic factors for the incidence of
JET (Table 4). Higher body temperature at the onset of JET
nearly reached statistical significance (Table 4). JET was not
an independent prognostic factor for death in the whole
cohort of 1001 patients ( p = 0.557).
4. Discussion
In this study of a nationwide paediatric cardiac surgery
patient population, the incidence of postoperative JET was
5% (95% CI 3.6—6.4%). This is in accordance with recent
smaller studies where the incidence has varied from 5% to
14%, depending on patient selection and study setting
[2,5,7,13,14]. JET has been previously associated with
several risk factors as well as with increased morbidity and
mortality. Risk factors associated with JET include younger
patient age, duration of CPB and ACC, electrolyte disturbances, use of inotropes and type of surgery [2,5,13—15].
Many of the earlier studies differ in their setup and thus
cannot always be compared with each other.
In our study, JET patients had longer CPB time, higher
body temperature at the onset of JET, more frequent use of
noradrenaline, higher postoperative TnT release, longer
ventilator time and longer ICU stay compared with the
matched controls. Most of these factors may reflect the fact
that JET patients are overall more sick than their controls as
speculated in the previous reports [3]. However, in the
logistic regression model, only longer CPB time and higher
postoperative TnT were identified as independent risk
factors. Further, higher body temperature at the onset of
arrhythmia was found to be nearly significant ( p = 0.050).
Longer CPB time, as well as higher postoperative TnT, is
probably a result of more difficult surgical correction and
larger surgical trauma. In two previous case-control studies
[5,7], younger patient age [5], more frequent use of
inotropes [5,7], duration of CPB and elevated postoperative
creatine kinase MB isoenzyme (CK-MBm) [7] were associated
with JET. In these two studies, control patients were selected
according to the date of surgery and could therefore include
totally different type of patients and surgery, which makes
the comparison of patients and the conclusion made more
difficult. In our study, the use of milrinone and adrenaline did
not affect the occurrence of JET. Noradrenaline was used
more often in JET patients compared with their controls, but
the logistic regression model was not an independent risk
factor for JET. The fact that higher body temperature is
associated with the occurrence of JET supports the rationale
for avoiding hyperthermia in the immediate postoperative
period.
We matched the controls according to surgical procedure
and age. This eliminates surgical risk factors, which in some
studies have affected the occurrence of JET [4]. However, in
our study, patients with surgery in the vicinity of atrioventricular node and bundle of His, frequently developed JET.
VSD closure was part of the surgical procedure in 35/51 (65%)
of JET patients. Further, almost half (44%) of Rastelli patients
developed JET. This operation frequently involves extensive
manipulation and resection of ventricular septum and, in our
material, occasionally mandated operating through tricuspid
valve annulus. The Rastelli operation is thus surgically
challenging requiring long CPB times and producing high
postoperative TnT values. Interestingly, 15% of patients with
arterial switch operation, which does not include surgery
near the conduction system, developed JET. This same
phenomenon has been detected in other studies also
[3,6,7,13,14] and indicates that direct manipulation of the
conduction system is not always the triggering cause of JET.
To avoid JET, surgery should be performed as gently as
possible, especially in the vicinity of the conduction system,
and unnecessary stretching of the tricuspid valve should be
avoided. However, this cannot always be avoided and, if high
postoperative TnT is detected, the patient should be kept
normothermic and monitored carefully for the occurrence of
JET.
Plasma magnesium, calcium and potassium values did not
differ between JET patients and the controls. In our study,
plasma potassium was below (3.2—3.7 mmol l 1) the recommended levels at the onset of JET [3], but plasma magnesium
level (1.03—1.07 mmol l 1) was within normal values. We
added magnesium to our perfusion prime as well as
cardioplegia solution and this could be the reason for
magnesium not affecting the occurrence of JET. Both
hypomagnesaemia and hypokalaemia have been reported
L. Mildh et al. / European Journal of Cardio-thoracic Surgery 39 (2011) 75—80
to be risk factors for developing JET [2,16,17]. In the study of
Manrique et al., magnesium supplementation decreased the
incidence of JET in a dose-related manner [18]. However, in
some other studies, hypomagnesaemia has not had any effect
on the occurrence of JET [5,13,14].
JET has been associated with worse outcome and
increased death rate compared to non-JET patients [3,7].
Again, patients with JET are possibly sicker and younger and
require more extensive surgery and therefore are at higher
risk of increased morbidity and mortality. In our study, there
was no significant difference in mortality between JET
patients and their matched controls. Due to a relatively small
sample size and a nearly significant p-value, we cannot rule
out the possibility of a b-type error. However, using multiple
regression analysis, JET was not found to be an independent
risk factor for death in the whole patient population, which
supports our conclusion. Contrary to mortality, JET did affect
the morbidity of these patients. JET patients had increased
ventilator time and longer ICU stay, which has been shown by
previous studies [2,6,7]. This can be explained by the
treatment protocol for haemodynamically unstable JET
patients, which include also sedation, muscle paralysis and
ventilator therapy. The patients cannot be transferred to
regular ward until JET has subsided. Both longer ventilator
time and longer ICU stay increase other possible complications, that is, infections, and also increase the cost of
treatment.
In JET, ventricular rate usually exceeds that of atrial rate
and there is atrioventricular dissociation. In our study, 1:1
ventriculoatrial conduction was noted in 48% of JET patients,
a number exceeding the results in the study of DodgeKhatami et al. [2] JET was the most frequent tachycardia in
the postoperative setting and occurred within the first 24 h
after operation, which is in accordance with previous studies
[3,6,13,14].
The rationale for amiodarone use differs in previous
studies for treatment of JET [2,7,13,14,19]. Some institutions, like ours, use amiodarone as a primary treatment [6],
because of the good response to intravenous amiodarone in
patients who failed to respond to conventional therapies or
are haemodynamically unstable. It has also been recommended as an early first-line treatment for JET [12,20].
There are some limitations in the present study. First, as a
retrospective cohort study, no perfect standardisation of
anaesthesia, cardioplegia, CPB or postoperative care could
be done. However, all these procedures were performed
according to the institutional protocol, which limits the
patient-to-patient variation.
In addition, due to a quite large sample size, we find the
incidence and outcome of JET to be reliable with narrow
confidence intervals. Due to continuous postoperative ECG
monitoring, the number of patients with no detection of JET
is supposed to be low. Yet, the exact incidence of JET might
be slightly higher than 5%.
This single-centre case-control study showed JET to be
the most frequent haemodynamically significant tachyarrhythmia in the early postoperative period after congenital
heart surgery. A prolonged CPB, high postoperative TnT and
increased body temperature are independent risk factors
for JET. When JET has developed, it increases ventilator
time and ICU stay and, thus, hospital costs. With the current
79
recommended treatment protocol [12] with early amiodarone use, JET does not have independent impact on
mortality.
Acknowledgements
We would like to thank Sirpa Savolainen for her expertise
and help in collecting the data from electronic databases.
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