Congenital heart block

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Contributors: Adam C. Lake

Overview

Congenital heart block is a rare congenital heart disease where a slowed heart rate is caused by defects in the heart conduction system.

Historical Perspective

• [Disease name] was first discovered by [scientist name], a [nationality + occupation], in [year] during/following [event].
• In [year], [gene] mutations were first identified in the pathogenesis of [disease name].
• In [year], the first [discovery] was developed by [scientist] to treat/diagnose [disease name].

Classification

• [Disease name] may be classified according to [classification method] into [number] subtypes/groups:

• [group1]
• [group2]
• [group3]

• Other variants of [disease name] include [disease subtype 1], [disease subtype 2], and [disease subtype 3].

Pathophysiology

Scarring of the conduction system (the heart’s own natural pacemaker), a consequence of inflammation triggered by the mother’s antibodies, damages or even destroys the cells that allow the heart to beat at a normal rhythm.

Neonatal lupus (NL) is the name given to a group of conditions that can affect the babies of mothers who have certain autoantibodies against components of the body’s cells that are called SSA/Ro and SSB/La. Neonatal lupus can appear as a temporary rash that usually goes away by the time the baby is 6 months old, or very rarely an abnormal blood or liver condition that also improves with time or it can cause permanent and often life-threatening damage to the fetal heart, known as congenital heart block (CHB). In women with anti-Ro/La antibodies who are pregnant for the first time, only about 2% of the babies will develop congenital heart block. But for a woman who has already had a child with congenital heart block or neonatal lupus rash, the risk of congenital heart block in her next pregnancy is nearly 20%. Unfortunately, once complete (third degree) heart block has been unequivocally identified in a fetus, it has never been reversed with any of the therapies that have been tried to date. If a child is born to a mother with lupus, there is a chance that the child will develop neonatal lupus, especially if the mother is Anti-Ro (SS/A) positive. In the majority of cases, the mother's antibodies will clear from the child in 6 months, however, in a few cases, the affected child will develop complete congenital heart block.

Causes

The most common cause of congenital complete heart block is neonatal lupus. It accounts for almost all cases presenting in the intrauterine and neonatal period. Other causes include:

• Myocarditis
• Levo transposition of great arteries
• Atrioventricular discordance
• Hurler cardiomyopathy
• Hunter cardiomyopathy
• Polysplenia with atrioventricular canal defect

Differentiating [disease name] from other Diseases

• [Disease name] must be differentiated from other diseases that cause [clinical feature 1], [clinical feature 2], and [clinical feature 3], such as:

• [Differential dx1]
• [Differential dx2]
• [Differential dx3]

Epidemiology and Demographics

• The prevalence of [disease name] is approximately [number or range] per 100,000 individuals worldwide.
• In [year], the incidence of [disease name] was estimated to be [number or range] cases per 100,000 individuals in [location].

Age

• Patients of all age groups may develop [disease name].

• [Disease name] is more commonly observed among patients aged [age range] years old.
• [Disease name] is more commonly observed among [elderly patients/young patients/children].

Gender

• [Disease name] affects men and women equally.

• [Gender 1] are more commonly affected with [disease name] than [gender 2].
• The [gender 1] to [Gender 2] ratio is approximately [number > 1] to 1.

Race

• There is no racial predilection for [disease name].

• [Disease name] usually affects individuals of the [race 1] race.
• [Race 2] individuals are less likely to develop [disease name].

Risk Factors

One form of congenital heart block occurs in babies whose mothers have autoimmune diseases, such as lupus. People who have these diseases make proteins called antibodies that attack and damage the body's tissues or cells.

Natural History, Complications, Prognosis

Prognosis

The damaged heart may beat extremely slowly. In some cases, the heart rate is so slow that it is fatal in nearly 20% of affected babies (with most deaths occurring as fetal demises). Patients presenting as fetuses or at birth have significantly higher morbidity and mortality rates than do patients presenting later in childhood.

• The majority of patients with [disease name] remain asymptomatic for [duration/years].
• Early clinical features include [manifestation 1], [manifestation 2], and [manifestation 3].
• If left untreated, [#%] of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].
• Common complications of [disease name] include [complication 1], [complication 2], and [complication 3].
• Prognosis is generally [excellent/good/poor], and the [1/5/10­year mortality/survival rate] of patients with [disease name] is approximately [#%].

Diagnosis

Diagnostic Criteria

• The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met:

• [criterion 1]
• [criterion 2]
• [criterion 3]
• [criterion 4]

Symptoms

• Signs and symptoms depend on the type of heart block the child has. First-degree heart block rarely causes symptoms.
• Symptoms of second- and third-degree heart block include:
  • Fainting
  • Dizziness or light-headedness
  • Fatigue (tiredness)
  • Shortness of breath
  • Chest pain

Physical Examination

• Patients with [disease name] usually appear [general appearance].
• Physical examination may be remarkable for:

• [finding 1]
• [finding 2]
• [finding 3]
• [finding 4]
• [finding 5]
• [finding 6]

Laboratory Findings

• There are no specific laboratory findings associated with [disease name].

• A [positive/negative] [test name] is diagnostic of [disease name].
• An [elevated/reduced] concentration of [serum/blood/urinary/CSF/other] [lab test] is diagnostic of [disease name].
• Other laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].

Imaging Findings

• There are no [imaging study] findings associated with [disease name].

• [Imaging study 1] is the imaging modality of choice for [disease name].
• On [imaging study 1], [disease name] is characterized by [finding 1], [finding 2], and [finding 3].
• [Imaging study 2] may demonstrate [finding 1], [finding 2], and [finding 3].

Other Diagnostic Studies

• [Disease name] may also be diagnosed using [diagnostic study name].
• Findings on [diagnostic study name] include [finding 1], [finding 2], and [finding 3].

Treatment

Medical Therapy

• There is no treatment for [disease name]; the mainstay of therapy is supportive care.

• The mainstay of therapy for [disease name] is [medical therapy 1] and [medical therapy 2].
• [Medical therapy 1] acts by [mechanism of action 1].
• Response to [medical therapy 1] can be monitored with [test/physical finding/imaging] every [frequency/duration].

Surgery

• Surgery is the mainstay of therapy for [disease name].
• [Surgical procedure] in conjunction with [chemotherapy/radiation] is the most common approach to the treatment of [disease name].
• [Surgical procedure] can only be performed for patients with [disease stage] [disease name].

Prevention

• There are no primary preventive measures available for [disease name].

• Effective measures for the primary prevention of [disease name] include [measure1], [measure2], and [measure3].

• Once diagnosed and successfully treated, patients with [disease name] are followed-up every [duration]. Follow-up testing includes [test 1], [test 2], and [test 3].

References

Electrocardiogram

Electrocardiographic findings in congenital heart block depend on the type of block.

Treatment

Surgery

Treatment depends on the type of heart block.

• First-degree heart block usually needs no treatment.
• For second-degree heart block, patient may need a pacemaker. A pacemaker is a small device that's placed under the skin of your chest or abdomen. This device uses electrical pulses to prompt the heart to beat at a normal rate.
• For third-degree heart block, patient will need a pacemaker.

Nearly all surviving children with congenital heart block require permanent implantation of an pacemaker device.

Prevention

Because it is so difficult to treat or repair the damaged heart, a high-priority strategy is to try to prevent the inflammatory process before irreversible scarring can occur. The mother of the child should consult with a rheumatologist to begin monitoring for possible autoimmune disease. Consultation with a rheumatologist is also advised for the infant, particularly if other manifestations of neonatal lupus erythematosus are present. Genetic consultation is recommended for children with first-degree relatives with structural heart disease or those with storage disorder or cardiomyopathy.

Source

• ClinicalTials.gov

Related Chapters

• Electrical conduction system of the heart
• Electrocardiogram (ECG or EKG)
• SA node
• AV node
• Second degree AV block
• Third degree AV block
• Bundle branch block
• Hemiblock
• Infra-Hisian Block
• Left anterior fascicular block
• Left posterior fascicular block
• Heart block
• Systemic lupus erythematosus
• IVIG

References

• Figa FH, McCrindle BW, Bigras JL, et al. Risk factors for venous obstruction in children with transvenous pacing leads. Pacing Clin Electrophysiol. Aug 1997;20(8 Pt 1):1902-9.
• Michaelsson M, Jonzon A, Riesenfeld T. Isolated congenital complete atrioventricular block in adult life. A prospective study. Circulation. Aug 1 1995;92(3):442-9. [Full Text].
• Boutjdir M, Chen L, Zhang ZH, et al. Arrhythmogenicity of IgG and anti-52-kD SSA/Ro affinity-purified antibodies from mothers of children with congenital heart block. Circ Res. Mar 1997;80(3):354-62.
• Boutjdir M, Chen L, Zhang ZH, et al. Serum and immunoglobulin G from the mother of a child with congenital heart block induce conduction abnormalities and inhibit L-type calcium channels in a rat heart model. Pediatr Res. Jul 1998;44(1):11-9.
• Claus R, Hickstein H, Kulz T, et al. Identification and management of fetuses at risk for, or affected by, congenital heart block associated with autoantibodies to SSA (Ro), SSB (La), or an HsEg5-like autoantigen. Rheumatol Int. Aug 2006;26(10):886-95.
• Copel JA, Buyon JP, Kleinman CS. Successful in utero therapy of fetal heart block. Am J Obstet Gynecol. Nov 1995;173(5):1384-90.
• Costedoat-Chalumeau N, Amoura Z, Villain E, et al. Anti-SSA/Ro antibodies and the heart: more than complete congenital heart block? A review of electrocardiographic and myocardial abnormalities and of treatment options. Arthritis Res Ther. 2005;7(2):69-73.
• Costedoat-Chalumeau N, Georgin-Lavialle S, Amoura Z, et al. Anti-SSA/Ro and anti-SSB/La antibody-mediated congenital heart block. Lupus. 2005;14(9):660-4.
• Cutler NG, Karpawich PP, Cavitt D, et al. Steroid-eluting epicardial pacing electrodes: six year experience of pacing thresholds in a growing pediatric population. Pacing Clin Electrophysiol. Dec 1997;20(12 Pt 1):2943-8.
• Friedman DM, Kim MY, Copel JA, et al. Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study. Circulation. 2008;117:485-93.
• Friedman DM, Zervoudakis I, Buyon JP. Perinatal monitoring of fetal well-being in the presence of congenital heart block. Am J Perinatol. 1998;15(12):669-73.
• Hamilton R, Gow R, Bahoric B, et al. Steroid-eluting epicardial leads in pediatrics: improved epicardial thresholds in the first year. Pacing Clin Electrophysiol. Nov 1991;14(11 Pt 2):2066-72.
• Hamilton RM, Chiu C, Gow RM, Williams WG. A comparison of two stab-on unipolar epicardial pacing leads in children. Pacing Clin Electrophysiol. Mar 1997;20(3 Pt 1):631-6.
• Jaeggi ET, Hornberger LK, Smallhorn JF, Fouron JC. Prenatal diagnosis of complete atrioventricular block associated with structural heart disease: combined experience of two tertiary care centers and review of the literature. Ultrasound Obstet Gynecol. Jul 2005;26(1):16-21.
• Karpawich PP, Stokes KB, Proctor K, et al. "In-line" bipolar, steroid-eluting, high impedance, epimyocardial pacing lead. Pacing Clin Electrophysiol. Mar 1998;21(3):503-8.
• Karpawich PP, Walters H, Hakimi M. Chronic performance of a transvenous steroid pacing lead used as an epi- intramyocardial electrode. Pacing Clin Electrophysiol. Jul 1998;21(7):1486-8.
• Miranda-Carus ME, Boutjdir M, Tseng CE. Induction of antibodies reactive with SSA/Ro-SSB/La and development of congenital heart block in a murine model. J Immunol. Dec 1 1998;161(11):5886-92.
• Moak JP, Barron KS, Hougen TJ, et al. Congenital heart block: development of late-onset cardiomyopathy, a previously underappreciated sequela. J Am Coll Cardiol. Jan 2001;37(1):238-42.
• Neiman AR, Lee LA, Weston WL, Buyon JP. Cutaneous manifestations of neonatal lupus without heart block: characteristics of mothers and children enrolled in a national registry. J Pediatr. Nov 2000;137(5):674-80.
• Rao V, Williams WG, Hamilton RH, et al. Trends in pediatric cardiac pacing. Can J Cardiol. Dec 1995;11(11):993-9.
• Suarez-Penaranda JM, Munoz JI, Rodriguez-Calvo MS, et al. The Pathology of the heart conduction system in congenital heart block. J Clin Forensic Med. Aug-Nov 2006;13(6-8):341-3.
• Weng KP, Chiou CW, Huang SH, et al. The long-term outcome of children with isolated congenital complete atrioventricular block. Acta Paediatr Taiwan. Sep-Oct 2005;46(5):260-7.