CASE REPORT

Successful Implantation of an Intracardiac Defibrillatorin an Infant With Long QT Syndrome and IsolatedNoncompaction of the Ventricular Myocardium

Ozge Surmeli Onay • Isil Yildirim •

Burcin Beken • Sevcan Erdem • Tevfik Karagoz •

Mustafa Yilmaz • Sule Yigit

Received: 3 November 2011 / Accepted: 27 February 2012 / Published online: 23 March 2012

� Springer Science+Business Media, LLC 2012

Abstract Congenital long QT syndrome (LQTS) is an

inherited disorder characterized by QT prolongation and

polymorphic ventricular tachycardia known as torsade de

pointes. The underlying cellular mechanism is prolonged

ventricular repolarization caused by mutations in genes

encoding cardiac ion channels or membrane adaptors. The

disease can be diagnosed at any age and, very rarely, it can

be diagnosed prenatally or in the neonatal period. Isolated

noncompaction of the ventricular myocardium (INCVM) is

defined as the presence of prominent ventricular trabecu-

lations and deep intertrabecular recesses within the endo-

myocardium. This report describes a newborn baby

presenting with polymorphic ventricular tachycardia whose

diagnosis was LQTS and INCVM. Ventricular tachycardia

did not respond to medical treatment, and a transient

epicardial pacemaker was inserted surgically on his 30th

day of life for atrioventricular block and bradycardia. The

transient epicardial pacemaker was upgraded to an epi-

cardial intracardiac defibrillator on his 40th day. The

concomitant occurrence of INCVM, LQTS, and atrioven-

tricular block needs to be evaluated further.

Keywords Atrioventricular block � ICD implantation �Infant � Isolated noncompaction of the ventricular

myocardium � Long QT syndrome

Congenital long QT syndrome (LQTS) is an inherited

disorder characterized by QT prolongation in the electro-

cardiogram (ECG) and polymorphic ventricular tachycar-

dia, known as torsade de pointes (TdP), which may cause

syncope and sudden cardiac death [8]. Isolated noncom-

paction of the ventricular myocardium (INCVM) is defined

as the presence of prominent ventricular trabeculations and

deep intertrabecular recesses within the endomyocardium

[23]. Several electrocardiographic alterations such as ST

depression and flat or negative T-waves, bundle branch

block and Wolff–Parkinson–White (WPW) syndrome

related to INCVM have been reported [15]. We report a

case of a newborn boy with a diagnosis of INCVM, LQTS,

and progressive complete atrioventricular block (AVB)

who had an intracardiac defibrillator (ICD) implanted with

a subcutaneous array system.

Case Report

A 19 day-old, 3,200 g full-term male baby with a diagnosis

of LQTS and polymorphic ventricular tachycardia was

referred to our hospital for ICD implantation. The boy’s

O. S. Onay (&) � S. Yigit

Division of Neonatology, Department of Pediatrics,

Hacettepe University, Faculty of Medicine,

Adnan Saygun Caddesi, Ankara, Turkey

e-mail: ozgesur@yahoo.com

I. Yildirim � T. Karagoz

Division of Pediatric Cardiology, Department of Pediatrics,

Hacettepe University, Faculty of Medicine,

Adnan Saygun Caddesi, Ankara, Turkey

B. Beken

Department of Pediatrics, Hacettepe University, Faculty

of Medicine, Adnan Saygun Caddesi, Ankara, Turkey

S. Erdem

Pediatric Cardiology Unit, Cukurova University,

Faculty of Medicine, Adana, Turkey

M. Yilmaz

Department of Cardiovascular Surgery, Hacettepe University,

Faculty of Medicine, Adnan Saygun Caddesi, Ankara, Turkey

123

Pediatr Cardiol (2013) 34:189–193

DOI 10.1007/s00246-012-0279-7

family history was remarkable for consanguinity of the

parents and early neonatal deaths of the previous three

siblings due to malignant cardiac arrhythmias. Fetal

tachycardia was diagnosed at 6 months of pregnancy, and

beta-blocker was administered to the mother. However it

was discontinued because no response could be achieved.

After delivery, the boy was hospitalized in the neonatal

intensive care unit for 16 days with the diagnoses of con-

genital LQTS and ventricular tachycardia. Propranolol and

lidocain infusions were started, but the ventricular tachy-

cardia could not be controlled, so he was referred to our

hospital for ICD implantation.

At admission, the boy’s physical examination was nor-

mal except for arrhythmia. Echocardiographic evaluation

showed noncompaction involving the left ventricle with an

ejection fraction of 67 % and a patent foramen ovale

(Fig. 1). The patient had a brain natriuretic peptide level of

855.18 pg/ml (range, 0–100 pg/ml), a total calcium level of

10.36 mg/dl (range, 9–11 mg/dl), and a magnesium level

of 1.91 mg (range, 1.4–1.9 mg).

Cardiac and Holter monitoring showed first-degree and

intermittent second- and third-degree AVB with T-wave

alternans, biphasic T-waves, and a corrected QT (QTc)

interval of 630 ms. Holter monitoring further showed TdP

and nonsustained polymorphic ventricular tachycardia

attacks at intervals shorter than 10 s and at a rate of 150 to

200 beats/min (Fig. 2). Diffuse prolongation of both de-

and repolarization intervals also was noted with Holter

monitoring.

Lidocain infusion (30 lg/kg/min), MgSO4 infusion

(0.3 mg/kg/h), and oral beta-blocker (propranolol) (2 mg/

kg/day) were administered. Urine and blood amino acid

paper chromotography, performed to exclude underlying

metabolic diseases, was normal. A transesophageal elec-

trophysiologic study showed a 2:1 AVB, intermittent

complete AVB, nonsustained ventricular tachycardia, a

long QT interval, and electrocardiographic findings con-

sistent with diffuse ventricular transmission defect (Fig. 3).

Although medical treatment decreased the frequency of

the ventricular tachycardia attacks, the patient continued to

have ventricular tachycardia during bradycardia. A tran-

sient epicardial pacemaker was inserted surgically on his

30th day of life for AVB and bradycardia, which was

upgraded to an epicardial ICD on his 40th day.

With the boy under general anesthesia, a short right

lateral paraumblical incision was made for the ICD

implantation. Using the previous subxhyphoid incision

from the pacemaker, both electrodes of the 35 cm bipolar,

steroid-eluting, pace-sensing lead (Bipolar CapsureEpi IS-

1, Model 4968; Medtronic, Minneapolis, MN, USA) were

sutured to the epicardium of the anterior right ventricular

wall. A subcutaneous defibrillation electrode (35 cm, uni-

polar endocardial superior vena cava lead for cardioversion

and defibrillation; Unipolar Transvene-SVC Model 6937,

Medtronic) was passed through the right rectus muscle and

tunneled subcutaneously to a position below the left

scapula. Subsequently, the ICD device (Maximo II VR

D284VRC; Medtronic) was inserted into an abdominal

pocket behind the right rectus abdominis muscle (Fig. 4).

The boy’s postoperative course was uneventful, and he

was discharged 3 days after the operation with propranolol.

During the 6 month follow-up period, the boy had two

attacks of ventricular tachycardia, which were controlled

with antitachycardia pacing, and no attacks of ventricular

fibrillation were determined (Fig. 5).

Discussion

Noncompaction of the left ventricle is classified as a pri-

mary genetic cardiomyopathy [6, 7, 11]. The major clinical

manifestations of INCVM are heart failure, atrial and

ventricular arrhythmias, and thromboembolic events

including stroke [4, 16]. Sinus bradycardia and progressive

AVB in patients with INCVM [3, 17] and LQTS also have

been described [8, 13]. Only one report describes a patient

presenting with INCVM, LQTS, and congenital AVB [6].

The reported patient showed intermittent AVB and

additional electrocardiographic findings in concordanceFig. 1 Left ventricular noncompaction observed with two-dimen-

sional echocardiography

190 Pediatr Cardiol (2013) 34:189–193

123

with diffuse ventricular conduction delay, which is dif-

ferent from the case described by Drago et al. [6]. The

third-degree AVB in our patient may have developed

secondary to LQTS or secondary to antiarrhythmics on

the basis of LQTS and INCVM despite appropriate

dosages.

Fig. 2 Holter monitoring showing recurrent torsade de pointes (Tdp) and polymorphic ventricular tachycardia attacks

Fig. 3 Simultaneous esophageal and surface electrocardiographic (ECG) recordings demonstrating atrioventricular (AV) dissociation, QT

prolongation, and biphasic T-waves. Eso, esophageal recording; P p-wave; R R-wave; A atrium recording; V ventricle recording

Pediatr Cardiol (2013) 34:189–193 191

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Congenital LQTS is a genetic channelopathy with var-

iable penetrance characterized by abnormally prolonged

ventricular repolarization with an increased propensity to

syncope and polymorphous ventricular tachycardia, which

may lead to ventricular fibrillation and sudden cardiac

death. More than 350 mutations in 12 LQTS-susceptible

genes have been identified, with the majority of the patients

having mutations in one of three genes: KCNQ1 (LQTS1),

KCNH2 (LQTS2), and SCN5A (LQTS3) [8, 20].

Ogawa et al. [14] reported two patients with LQTS and

INVCM whose genetic workup showed two different

mutations in KCNH2. Drago et al. [6] could not identify

any known mutations in their patient, who presented with

LQTS, INCVM, and congenital AVB. Studies have found

SCN5A associated with LQTS, progressive cardiac con-

duction defects, isolated cardiac conduction disease, AV

conduction block, and Brugada syndrome [12, 20, 22].

Recently, mutations in SCN5A also have been identified in

patients with INCVM [24]. Unfortunately, genetic study is

not available at our center, so we can only speculate that

the mutation in our patient may have been in the gene

SCN5A.

Management of patients with ventricular tachycardia

focuses on controlling the tachycardia. The reported patient

presented with prolongation of the QT interval, intermittent

AVB, frequent attacks of polymorphic ventricular tachy-

cardia, and diffuse ventricular conduction delay. Lidocaine

and magnesium infusions and oral beta blocker therapy

were started for rhythm control. The literature contains

limited reports on the use of magnesium for children with

ventricular tachycardia and LQTS [9, 10]. It is thought that

magnesium abolishes triggered activity by inhibiting early

and late depolarizations directly rather than by shortening

action potential duration [10]. Pacing therapy for LQTS

with AVB and pause-dependent TdP has been used pre-

viously. However, it is known that arrhythmic death still

may occur for well-controlled, high-risk patients despite

combined therapy with beta-blocker and pacemakers [5].

For the reported patient, although a transient pacemaker

controlled the ventricular tachycardia attacks, implantation

of an ICD was performed due to the history of three pre-

vious sibling deaths.

Implantation of ICDs in pediatric patients poses several

difficulties. Despite the advancements in technology that

caused the downsizing of pulse generators as well as

improvements in lead design and shock waveforms, pedi-

atric patients present challenges in terms of patient size and

growth and the common coexistence of congenital heart

diseases [1, 2]. Relative to the venous diameter and tho-

racic anatomy of the infants, transvenous leads are large in

caliber and length. Epicardial patches require sternotomy

Fig. 5 Intracardiac electrocardiogram (ECG) showing ventricular tachycardia and antitachycardia pacing showing termination of ventricular

tachycardia (VT)

Fig. 4 Chest X-ray, anteroposterior view. The subcutaneous (SQ)

defibrillation electrode is positioned posterior to the left chest wall

beneath the scapula, with the epicardial pacing leads placed on the

right ventricle and the active generator in the upper right abdomen

192 Pediatr Cardiol (2013) 34:189–193

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or thoracotomy, with higher rates of insulation and con-

ductor fractures as well as the risk for the development of

restrictive pericardial lesions due to the large surface area

of the patches. Implantation techniques using a subcuta-

neous array and an abdominally placed ICD generator have

been described previously [1, 2, 18, 19, 21]. However,

experience with infants younger than 6 months is limited.

The concomitant occurrence of INCVM, LQTS, and

AVB needs to be evaluated further. Meanwhile, echocar-

diographic screening of all patients with LQTS, AVB, or

both, and ECG screening of patients with a diagnosis of

INCVM is of utmost importance and should be adopted as

a clinical policy.

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