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Background: Arrythmia is a major cause of cardiovascular morbidity and mortality in patients with congenital heart diseases. It has multifactorial predisposing factor as congenitally malformed or displaced conduction system, hemodynamic, mechanical or hypoxic stress and residual or postoperative sequelae.
Methods: This was a prospective observational study involving all patients who were following up or referred to congenital and structural heart disease unit in our department over a period of 42 months and were discovered to have significant symptomatic cardiac arrhythmia. A detailed custom-made sheet was applied to all eligible patients to collect demographic data, underlying congenital heart disease, type of arrhythmia and possible management and/or outcome.
Results: The study population included 107 patients with different congenital heart diseases with mean age 20.47+/- 13.2. Bradyarrhythmia were more common (67%) than tachyarrhythmia. Post-operative CHB was the most common bradyarrythmia. One third of the patients had atrial or ventricular tachyarrythmia. Post Fallot repair patients developed ventricular tachycardia while patients with Ebstein anomaly more commonly developed atrial tachycardias, flutter or SVT. Patients with CHB were managed with transvenous pacing (51%), epicardial pacing (16%), two patients with CCTGA with impaired RV functions underwent CRT implantation, two patients post Fallot repair underwent ICD implantation.
Conclusion: Patients with CHD are subjected to wide range of arrhythmias. Postoperative complete heart block was the commonest arrhythmia in this registry especially in patients with L-TGA, AVSD and VSD. Tachyarrythmias accounted for one third of the patients. Atriotomy incisions, sutures, and conduit is a major risk factor for post-operative atrial tachycardia. The use of ICDs and CRT in patient with congenital heart diseases have proven relative efficacy.
Congenital heart diseases (CHD) represent 1% of the annual livebirths; arrythmia is a common cause of hospital admission and late mortality in this group of patients . Due to the recent advances in the surgical and interventional cardiovascular management of CHD, the population of the adult patients with CHD exceeded markedly the number of the children . As consequence of these operative repairs and the added longevity, arrythmias are becoming increasingly common . Moreover, arrythmias are poorly tolerated in those with CHD leading to more
hemodynamic compromise and worse cardiovascular outcome .
Arrythmia in congenital heart disease has different etiologies, it may be due to inherent congenital anomaly, however postoperative arrythmia accounts for the majority of these arrythmia . The underlying postoperative mechanisms are multifactorial may be due to direct injury or manipulation to the conduction system, local tissue edema and inflammation to the myocardial tissue adjacent to the conductive system . Other considerable risk factors are the postoperative inotropes and
vasopressors which are highly arrythmogenic, and the electrolyte
imbalances frequently seen after major cardiac surgeries
contributing to the long cross clamping time and cardiac bypass
machine time . Despite the fact that these postoperative
arrythmia are commonly encountered early postoperative, they
are usually transient and recover with proper management .
Our Ain shams congenital heart disease center for both
pediatric and adult population continue to be at the forefront
for multidisciplinary management of these patient with
complex cardiac anatomy and who require multidisciplinary
management strategies including antiarrhythmic therapy, specific
electrophysiological studies, device therapy and catheter ablation.
The current study represents a prospective registery of different
types of arrhythmias encountered in these patients as well as
their management and outcome.
This study was approved by our institutional review board
and informed consent was applied from the enrolled patients or
This was a prospective observational study done in Ain
Shams university hospitals, which a tertiary referral center with a
congenital and structural heart disease unit. The study population
consists of consecutive population of all congenital heart disease
patients who presented to Ain Shams university hospitals, the
structural and congenital heart disease unit for medical treatment
, catheter or surgical interventions or were following up in the
outpatient clinic and suffered from significant symptomatic
cardiac arrythmia from January 1, 2016 till June 30, 2019.
A detailed custom-made sheet was applied to all eligible
patients to collect demographic data, underlying congenital heart
disease, type of arrhythmia and possible management and/or
outcome. All types of significant symptomatic arrythmia were
recorded using a 3channel standard 12-lead electrocardiogram
recorder or 24 or 48 hours Holter when needed. Arrythmias which
were identified by the primary cardiac team were confirmed by
Arrythmia was defined as an abnormal rhythm that was present
for over 30 seconds anytime during the inpatient or postoperative
course. Premature atrial contractions (PACs) or premature
ventricular contractions (PVCs) were not included if they were
infrequent (< 10 per minute). Different types of management
were included as electrical or pharmacological cardioversion,
electrical cardiac pacing, implantable cardiac defibrillator (ICD),
cardiac resynchronization therapy (CRT), overdrive suppression,
transcutanous ablation or pharmacological treatment.
Statistical analysis was performed using SPSS (statistical
package version sixteen), Categorical variables were expressed as
absolute and relative frequencies (percentage) while continuous
variables were presented as mean values ± standard deviation
(SD). Comparisons were made between the two groups using
t-test for continuous variables and chi-square test and Pearson
correlation coefficient for categorical variables, Difference was
considered statistically significant at a P value < 0.05 and highly
significant at P value < 0.01.
The study population included 107 patients with different
congenital heart diseases, there were 57 males (53%) and 50
females (47%) with mean age 20.47+/- 13.2 with 3 patients ≤ 6
months. Bradyarrhythmia including complete heart block (CHB)
and second degree heart block (2nd HB) were more common (67
%) than tachyarrhythmia. CHB accounted for the most common
arrythmia (66.4%) in the study population. The incidence of
cardiac arrythmia is presented in Table 1.
The most common CHD was ASD (n=31, 29 %), followed by
VSD and AVSD (n= 19, 17.7 %). most of these patients developed
postoperative CHB, however two patients in our study developed
transient CHB after transcatheter ASD closure and 1 patient
developed permanent CHB after transcatheter closure of subaortic
peri membranous VSD.
Symptomatic bradyarrythmia was also significant in patients
with congenitally corrected transposition of the great vessels
(L-TGA) (15.8 %), those with complete transposition of the great
vessels after Senning or Mustrad operation (1.8%) and those who
underwent TV repair (5.6 %) (Table 2).
On the other hand tachyarrythmia accounted for 33 % of the
total population, almost one quarter of them were post fallot repair
patients who developed either atrial or ventricular tachycardia,
similarly Ebstein anomaly accounted for 6.5 % of the patients who
either developed atrial tachycardia, atrial flutter or SVT.
The most common arrythmia in children (< 16 years) was
postoperative CHB (38%), and most common arrythmia in
adulthood was also CHB (28 %) mostly associated with CCTGA
patients followed by atrial fibrillation mostly in patients with ASD
with late presentation older than 25 years.
Postoperative arrythmia was the most common etiology
of arrythmia in the study population (65.4 %), permanent CHB
necessitating pacemaker therapy was frequently seen followed by
atrial tachycardias then atrial flutter. Risk factors which increase
the incidence of postoperative arrythmia was related to younger
age, type of cardiac surgery, long cross clamp time, prolonged
cardiopulmonary bypass time, use of more than one positive
In our study arrhythmia was associated with pregnancy
in 5 patients, two of them with CCTGA developed CHB during
pregnancy, two patient with Ebstein anomaly who developed atrial
flutter and atrioventricular tachycardia (AVRT) and one patient
with single ventricle post Glenn developed atrial fibrillation.
Factors increasing incidence of recurrence of arrythmia was
found to be patient with complex congenital heart disease, history
of previous cardiac surgery, oxygen saturation, pregnancy.
Most of the patients with CHB were managed with transvenous
pacing (51%), few patients managed with epicardial pacing
(16%) , most patients with atrial fibrillation or atrial flutter
were managed conservatively with cardioversion and medical
treatment (16.8%), two patients with CCTGA with impaired RV
functions underwent CRT implantation, two patients post Fallot
repair underwent ICD implantation.
Regarding the cardiovascular outcome, a total of 92 patients
improved, 7 patients underwent successful ablation for AVRT
and AVNRT, 11 patients with atrial fibrillation and atrial flutter
underwent successful electrical cardioversion, 2 patients with
CCTGA were responders to CRT implantation, 1 post Fallot repair
with successful ICD implantation, 49 patients with transvenous
PM either DDD, VVI, VDD or in some cases with complex congenital
heart disease the lead was implanted in the coronary sinus, one
patient underwent simultaneous ASD transcatheter closure and
DDD implantation in one setting.
Eleven patients developed recurrence post ablation; three
patients with recurrence of atrial flutter after successful ablation,
5 patients with atrial fibrillation and complex congenital heart
disease, 3 patients with Ebstein anomaly with recurrence of AVRT,
one patient died post ICD implantation with malignant ventricular
Atrial and ventricular arrythmias are a major cause of
cardiovascular morbidity and mortality in patients with CHD
[9,10]. Unfortunately most of studies discussed certain type
of arrythmia and its management  or discussed only
postoperative arrythmia in pediatric patients with CHD , there
is a relative paucity in literature for guidelines on management
of arrythmias in CHDs due to the diverse nature of CHDs from
simple to complex lesions and the different types of arrythmias
encountered in these patients .
In the current study we report the incidence and etiology
of different types of arrythmia and the commonly associated
defects. Similar to our study, Edeward P walsh and his coworkers
reported that atrial tachycardia and supraventricular tachycardia
were commonly seen in Ebstein anomaly patients, ventricular
tachycardia mostly seen in post Fallot repair patients, atrial
fibrillation mostly seen in patients with single ventricle physiology
while congenital heart block was frequently reported in CCTGA patients, meanwhile post-operative CHB was seen in patients
after VSD or AVSD closure .
The most common post-operative arrythmia was CHB more
commonly transient due to edema and inflammation of the AV
nodal conduction system , of note that 2.7 % of patients with
CCTGA had CHB after VSD closure, 13.8 % of patient with VSD
had postoperative CHB, 11 % of the patients with atrioventricular
septal defect had postoperative permanent CHB , 4 % of the
patients with ASD had permanent CHB. Moreover Khairy et al.
 and his co-workers reported in their study that 7 % with
AVSD had postoperative CHB, 4% of the patients with VSD had
postoperative CHB, 25 % of the patients with CCTGA developed
CHB after VSD surgical closure . However, in contrast to
ours, J.S Nelson reported that the most common post-operative
arrythmia was the junctional ectopic tachycardia (JET) 6 %
followed by CHB 2.5% . A unique finding in our study is the
recording of postoperative VT in a 5-year-old patient after Ross
procedure mostly due to prolonged cross-clamp time and the use
of more than one postoperative inotrope which was resistant to
medical treatment and responded to lidocaine.
Pregnancy poses a great cardiovascular risk and significant
hemodynamic comprise in patients with CHD especially those
with complex cyanotic CHD . In our study, 5 patients
(4.7%) of the study group had arrhythmia during pregnancy; 3
pregnant ladies who had CCTGA developed CHB , two of them
were presented for the first time during pregnancy, one of them
was associated with impaired RV functions and underwent CRT
implantation, the other two patients with severe TR had DDD
implantation . one patient with severe form of Ebstein developed
atrial flutter who underwent catheter ablation , and 1 patient
with complex congenital heart disease post Glenn who developed
atrial fibrillation was cardioverted successful, meanwhile Tateno
and his coworkers reported that the incidence of arrythmias in
pregnant women with CHD was 20% , including 4 patients with
CCTGA who had CHB, and 15 patient with SVT .
The AV conduction system may be displaced if atrial and
ventricular septa are mal-aligned, AV connections are discordant,
or if the heart is univentricular. As a general rule of thumb, if the
AV conduction system is displaced, it tends to be more susceptible
to degeneration, placing patients at greater risk for AV block .
Regarding the therapeutic options for brady arrythmia, 41% of the
patients had transient CHB which resolved after giving steroids
and atropine mostly due to edema of the conduction system and
32% had permanent CHB which underwent successful either
DDD or VVI implantation, 17% were epicardial and 83% were
transvenous, it is noteworthy that we had successful transvenous
PM implantation in a 6 year old boy weighing 24 kg.
Two patients with Ebstein anomaly and TV valvuloplasty
developed CHB had VVI implantation with fixation of the Lead in
the Coronary sinus due to small RV. Similar to our study Attenhofer
fost et al.  reported 11 patients with Ebstein anomaly needed
permanent pacing for CHB, two of them had transvenous VVI
implanation with placement of the lead in the coronary sinus or
the cardiac vein .
In our study two patients with L-TGA, CHB and impaired RV
functions had successful CRT implantation while Moore JP et al.
 reported successful transvenous CRT implantation in 18
patients with L- TGA and impaired RV functions .
A 5 year old patient with large Secundum ASD and CHB
underwent simultaneous ASD closure and VVI implantation in one
setting, which was not reported in literature except in a medical
center in India by Raghu Cherukupalli .
In the current study two patients had transient CHB after
transcatheter ASD closure which recovered spontaneously after
the first 24 hours. Nonetheless, Nehgme reported a 2-year-old
patient recovered from second degree Mobitz type II AV block
after initial corticosteroid treatment [21,22]. Even though there
was no conduction disturbance initial after device implantation,
late-onset complete AV block requiring permanent pacemaker
might still occur 4 years later  In the current study one patient
had CHB 6 months post transcatheter VSD closure necessitating
transvenous PM implantation.
The management of patients with tachyarrhythmias include
pharmacological therapy, catheter ablation, ICD implantation and
surgical interventions . Pharmacological therapy is often not
well tolerated in patients with CHD due to systemic ventricular
dysfunction, sinus node disease, negative inotropic effect, hypoxic
stress which increases the incidence of pro-arrythmia . Due
to the limited data on the dosage and toxicity of anti-arrhythmic
drugs for the various age group with CHD , medical treatment
was used only in 17% of patients, 12% of them developed atrial
fibrillation and underwent successful cardioversion followed by
anti-arrythmic drug (mostly amiodarone), 5% with atrial flutter
and atrial tachycardia received betablockers most of them regained
their sinus rhythm, and one patient who developed ventricular
tachycardia and prolonged QT mostly due to amiodarone toxicity,
responded dramatically to lidocaine.
Anatomical complexities and difficult vascular accesses pose
a challenge to catheter based interventions in CHD patients.
Ablation is specifically difficult too because of the hypoxia of
the tissue and the hypertrophy which makes difficult to make
a transmural scar . With the advent of three-dimensional
electroanatomic mapping and advances in catheter technology
permitting larger and deeper lesions, transcatheter ablation
has emerged as a promising alternative for many patients with
tachyarrhythmias . In our study 9.3% (10 patients), patients
underwent successful conventional ablation. 8 patients with
Ebstein anomaly and right sided accessory pathway underwent
successful ablation with rate of recurrence reaching up to 25% the cases. Meanwhile Reich JD et al.  reported 65 patients
with Ebstein anomaly and right sided accessory pathway with
short term ablation success rate reaching up to 90% with late
recurrence reaching up to 32% . Mapping and ablation can
be challenging as signals in the atrialized portion of the right
ventricle may be complex and the true AV groove, along which
accessory pathways are targeted, may not be readily apparent
which increases the incidence of recurrence .
It is noteworthy to say that a 17-year-old patient with
CCTGA had right sided accessory pathway underwent successful
conventional ablation, another 14year old D-TGA patient post
intra-atrial baffle repair (mustard) operation who underwent
successful ablation of atrial arrythmia of the pulmonary venous
Sudden cardiac death is the most common cause of mortality
in post Fallot repair patients. Monomorphic ventricular
tachycardia occurs in 10 % of post Fallot repair patients due to
reentry tachycardia . Risk factors include QRS interval > 180
ms, presence of RVOT patch, older age at repair. In our study 3
post Fallot repair patients underwent ICD insertion two of them
survived cardiac arrest, another patient with high risk criteria
who utilized it for primary prevention who had non-sustained VT
with QRS > 180 and RVOT transannular patch.
The last decade has witnessed major advances in our
understanding of arrhythmia mechanisms and therapeutic
option. CHB commonly occurs in patients with L-TGA, AVSD
and VSD. Atriotomy incisions, sutures, and conduit may lead to
development of scar-based macro-reentrant atrial circuit. The use
of ICDs and CRT in patient with congenital heart diseases have
proven relative efficacy.
We still need more use of the 3D anatomical mapping and
growing advances in the use of catheter technology (thermal, cryo
and laser ablation) for treatment of many patients with complex
anatomy and tachyarrythmia together with further analysis for
risk factors of recurrence.
We need thorough risk stratification for patients with
congenital heart disease presented with significant arrhythmia.
Long term follow up with special attention to issues related to
sudden death, ICDs, catheter ablation and surgical therapy are