Download Congenital Complete Heart Block

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Congenital Heart Disease
Congenital Complete Heart Block
a report by
R o b e r t C a m p b e l l , 1 , 2 P e t e r F i s c h b a c h , 2 P a t r i c i o F r i a s 2 and M a r g a r e t S t r i e p e r 1 , 2
1. Sibley Heart Center; 2. Emory University School of Medicine, Atlanta
White and Eustis were the first to document congenital complete heart
patients.5 These antibody-positive infants experienced a higher risk of
block (CCHB) with electrocardiogram in 1921. Until the 1950s, CCHB
developing dilated cardiomyopathy (DCM) with clinical CHF with signs and
without structural heart disease was considered rare and benign. CCHB is
symptoms. CCHB also occurs in the setting of complex structural heart
estimated to complicate one in 15,000–22,000 live births; however, the
disease (most frequently heterotaxy syndromes and/or congenitally
true incidence of CCHB is unknown as there is an association with
corrected transposition of the great arteries). The combination of
structural congenital heart disease (CHD) with a resultant high foetal
heterotaxy syndrome and CCHB has an extremely high mortality rate, even
mortality. Maternal autoimmune disease is often associated with isolated
with pacemaker and surgical treatments.
CCHB (not associated with underlying structural congenital heart defect).
Antibodies cross the placenta and are thought to cross-react with the
Combining several CCHB studies,6–9 risk factors for CHF, Stokes Adams
developing conduction system, leading to injury. Pregnancies complicated
attacks or sudden death include:
2
by mothers positive for anti-Ro/La antibodies result in CCHB in 1–5% of live
infants, with a familial recurrence rate estimated at 15–20%. Some studies
• low newborn ventricular rate (<55bpm);9
have estimated that as many as 20–30% of these infants will suffer foetal
• low foetal atrial rate (<120bpm);9
or neonatal deaths, and an estimated 10% of children with antibody-
• wide QRS complex on electrocardiogram (EKG);10
positive CCHB will be born with hydrops or congestive heart failure (CHF)
• corrected QT interval prolongation >460ms;10
secondary to intra-uterine myocarditis and/or severe brachycardia.1–4 While
• atrial enlargement on EKG or cardiomegaly by chest X-ray (risk factor
CCHB in the absence of immunological exposure is recognised, patients
with antibody-mediated CCHB have been found to require pacing earlier in
life and follow a more malignant disease course than antibody-negative
for CHF);7,11
• ventricular ectopy in combination with a wide QRS complex or
structural heart disease;12 and
• presence of complex structural heart disease.6–9
Robert Campbell is Chief Medical Officer of Children’s Healthcare at Atlanta Sibley Heart
Center, President of Sibley Heart Center Cardiology and Division Director of Cardiology,
Department of Pediatrics, Emory University School of Medicine. He also serves on the Sudden
Arrhythmia Death Syndromes (SADS) Foundation Board. In 2004, he took up the position of
Medical Director for Project SAVE (Sudden Cardiac Death, Awareness, Vision, and Education)
at Children’s Healthcare of Atlanta. Dr Campbell has been a member of the North American
Society of Pacing and Electrophysiology (NASPE)/Heart Rhythm Society (HRS) since 1991 and
a member of the Pediatric Electrophysiology Society (PES) since 1988. He was named
Co-Director of the Pediatric Sudden Cardiac Arrest Task Force through the PES.
Many of these risk factors were defined in an era predating foetal
echocardiography and current surgical and pacemaker therapies;
however, they remain pertinent today for guiding patient care decisions.
The indications for pacemaker implantation continue to be debated, with
practice patterns varying from institution to institution. No large
prospective trials have addressed the ideal timing or indications for device
implantation and recommendations have been forged by consensus
Peter Fischbach is a Clinical Associate Professor at Emory University School of Medicine. He
is a diplomate of the American College of Cardiology (ACC) and the Heart Rhythm Society
(HRS), and has recently been elected Treasurer of the Pediatric Electrophysiology Society
(PES). Prior to joining the faculty at Emory University, he was an Associate Professor and
Director of the Pediatric Electrophysiology laboratory at the University of Michigan.
conferences. The most recent guidelines for pacemaker implantation
published in 2002 by the American College of Cardiology (ACC)/
American Heart Association (AHA)/North American Society of Pacing and
Electrophysiology (NASPE)13 list several indications for pacing in the face
of complete congenital heart block. The class I indications, or those “for
Patricio Frias is a Clinical Assistant Professor at Emory University School of Medicine. He
is a Fellow of the American College of Cardiology (ACC), the Heart Rhythm Society (HRS)
and the American Academy of Pediatrics (AAP). His research focus has been on the
evaluation of alternate pacing modes for children with atrioventricular block. Prior to joining
the faculty of Emory University in July 2000, Dr Frias completed his paediatric cardiology
and electrophysiology training at Vanderbilt University Medical Center.
which there is evidence and/or general agreement that a given procedure
or treatment is useful and effective”, include:
• infants with a ventricular rate <0–55bpm or <70bpm in the face of
congenital heart disease;
• a wide QRS escape rhythm, complex ventricular ectopy or ventricular
Margaret Strieper is Director of Pacing and Electrophysiology at Children’s Healthcare of
Atlanta Sibley Heart Center and an Assistant Professor of Pediatrics at Emory University School
of Medicine. She is a Fellow of the American Academy of Pediatrics (AAP) and the American
College of Cardiology (ACC), and a member of the American Heart Association (AHA), the
North American Society of Pacing and Electrophysiology (NASPE)/Heart Rhythm Society (HRS)
and the Pediatric Electrophysiology Society (PES). Her research interest is in the field of
paediatric electrophysiology, in particular cardiac resynchronisation, ablation and syncope.
She has published extensively and presented at multiple national meetings, including the
AHA, the ACC, the HRS and the AAP, within the field of paediatric electrophysiology.
dysfunction; and
• age greater than one year with an average heart rate <50bpm, abrupt
pauses in ventricular rate that are two or three times the basic cycle
length or associated symptoms due to chronotropic incompetence.
All of these recommendations are based on the review of small nonrandomised trials. Further evidence for the confusion is the inclusion of the
class IIb indication (usefulness/efficacy is less well established by
© TOUCH BRIEFINGS 2007
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Congenital Heart Disease
evidence/opinion), which reads: “congenital third-degree [atrioventricular
despite the presence of a narrow QRS complex on a surface EKG.
(AV)] block in the asymptomatic infant, child, adolescent, or young adult
Alderson and associates23 demonstrated mechanical dyssynchrony in 11
with an acceptable rate, narrow QRS complex, and normal ventricular
paediatric patients with DCM and a narrow QRS complex.
function, i.e., any patient with congenital heart block”. Despite recent
developments resulting in smaller-diameter pacing leads,14,15 transvenous
While dual-chamber pacing restores AV synchrony and affords
pacing is generally avoided in patients weighing <10kg. For smaller
physiological ventricular rates and variability, RV pacing desynchronises the
patients, or patients with complex congenital heart lesions, epicardial
ventricles. Therefore, the possibility of alternate site and or biventricular
pacing leads are usually placed by way of a limited sternotomy or
pacing in CCHB patients who will require a lifetime of pacing has recently
thoracotomy. Recent data now raise concerns about possible adverse
been raised. For adults with CHF and ventricular dyssynchrony, cardiac
effects of long-term right ventricular (RV) apical pacing. As a result,
resynchronisation pacing has been shown to improve ventricular function,
alternative pacing strategies are now being explored for those children who
decrease symptoms and improve exercise performance. The authors’ group
face a potential life-long pacing requirement. A subset of newborns with
has promoted the term ‘prosynchronisation’24 (dual-chamber biventricular
CCHB may develop DCM during follow-up, despite permanent pacing. A
pacing) as a means of maintaining a more co-ordinated activation pattern
2001 multicentre study14 identified nine patients with isolated CCHB who
in patients with CCHB and possibly preventing the deleterious effects
progressed to DCM out of an initial 111 patients in the retrospective pacing
induced by RV pacing. Acute animal studies,24,25 using a radiofrequency
cohort. Maternal antibodies were present in seven of those nine patients.
ablation-induced AV block model of CCHB, have demonstrated improved
While immunological injury may play the dominant role in myocardial
myocardial performance with biventricular compared with single-site
dysfunction in these patients with CCHB, there is mounting evidence that
ventricular pacing in mature and immature myocardium. Myocardial
chronic RV pacing creates ventricular dyssynchrony and predisposes
performance was assessed using pressure volume loops and tissue Doppler
patients to subsequent ventricular dysfunction. This relationship of
imaging techniques. These animal studies are consistent with a 2006 report
ventricular dyssynchrony to chronic RV pacing and ventricular dysfunction
demonstrating that biventricular resynchronisation pacing can benefit
has been studied extensively in adult patients.16–18
paediatric CCHB patients who develop ventricular dilatation and
dysfunction, with clinical CHF signs and symptoms, following RV pacing.26
Moak et al. reported a group of 16 patients with CCHB who developed
19
ventricular dysfunction (mean left ventricular shortening fraction 9+5%)
Other studies have suggested that pacing from alternate sites in the
following implantation of dual-chamber, single-site ventricular pacing
ventricular myocardium may be more haemodynamically beneficial than RV
systems. Karpawich20,21 reported histological degenerative myocardial
apical pacing. Pacing from the high RV septum has been shown to result in
changes following chronic pacing for CCHB and subsequently reported
acute haemodynamics similar to those seen during sinus rhythm.
decreased systolic and diastolic ventricular performance in 24 patients
Parahisian27 pacing, with the possibility of stimulating the His-Purkinje
who had undergone single-site ventricular pacing for a median of 10
system high in the ventricle, should also result in maintenance of ventricular
years. Newer imaging techniques have been used to assess for
synchrony. While pacing lead placement has proved difficult to date, recent
mechanical dyssynchrony. Cummings et al.22 used tissue Doppler
experience with this approach seems promising.25 Prinzen and colleagues28
imaging to examine the time-course of ventricular dysfunction after the
have proposed left ventricular apical pacing as an optimal strategy. Data
induction of RV pacing in 12 chronically paced patients (mean age 8.5
supporting the long-term benefits of resynchronisation pacing in paediatrics
years; average length of pacing 4.2 years) with CCHB and structurally
are limited. Strieper et al.29 reported a decrease in hospitalisations due to
normal hearts. This study suggested that ventricular remodelling occurs
CHF exacerbation after an upgrade from a conventional pacemaker to a
early and may not initially manifest as decreased ejection fraction. This
resynchronisation device. In this study, seven of nine patients were removed
would support the notion that chronically RV-paced paediatric patients
from transplant consideration due to improved symptoms and cardiac
need close follow-up due to the possibility of developing a clinically
function after the pacing system upgrade. The decision to implant a
significant cardiomyopathy.
prosynchronisation or resynchronisation pacing system, with additional
leads, potential access issues and increased costs, must be carefully
Mechanical ventricular dyssynchrony is not synonymous with a wide QRS
considered. Studies to define the role of prosynchronisation pacing or
EKG complex. Non-invasive diagnostic studies in paediatric patients have
alternate site pacing will be required before these options can be considered
shown that dyssynchrony may be present in patients with isolated DCM
as a clinical standard of care for CCHB patients. ■
1.
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