eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Atrioventricular Block, Third Degree, Congenital: Differential Diagnoses & Workup

Author: Monesha Gupta, MD, MBBS, FAAP, FACC, Assistant Professor, Division of Pediatric Cardiology, University of Texas Medical School, Children's Memorial Hermann Hospital
Coauthor(s): Robert Murray Hamilton, MD, MSc, FRCPC, Section Head, Electrophysiology, Director, High-Risk Hereditary Heart Conditions Clinic, Labatt Family Heart Centre; Professor, Department of Pediatrics, Associate Scientist, Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, University of Toronto, Canada
Contributor Information and Disclosures

Updated: Feb 2, 2009

Differential Diagnoses

Atrioventricular Block, Third Degree, Acquired
Myocarditis, Viral
Transposition of the Great Arteries

Other Problems to Be Considered

Heterotaxia
Atrioventricular septal defect
Myopathies
Metabolic disorders
Infections

Workup

Laboratory Studies

In patients with congenital atrioventricular block, routine electrolyte assays should be performed to assess for metabolic derangements (especially hyperkalemia), and a CBC count should be obtained to assess for anemia, neutropenia, or thrombocytopenia.

  • Neonatal Lupus: Neonatal assessment should include a measurement of anti-Ro and anti-La antibody levels, preferably using an enzyme-linked immunosorbent assay (ELISA) in the mother. Assessment for other organ and/or tissue damage should include a platelet assessment to rule out thrombocytopenia and an assessment of liver enzymes to rule out alloimmune hepatitis.
  • Myocarditis: If inflammatory disease is suspected, workup for various infectious etiologies (eg, human immunodeficiency virus [HIV]) should be performed. Cardiac troponins and pro-brain natriuretic peptide (BNP) levels can be helpful in assessing the severity of the disease.
  • Cardiomyopathy: If hypertrophic cardiomyopathy is suspected, evaluation for lysosomal storage diseases should be included.
  • Congenital heart defects: Pre-ductal and post-ductal saturations by pulse oximetry should be performed. Check for hypoxemia and acidosis using ABG findings. Also check lactic acid for perfusion. A hyperoxia test is very helpful in differentiating lung disease related hypoxemia versus due to a cyanotic heart disease. One can evaluate for Heinz bodies on peripheral smear for evaluation of asplenia that is seen with Heterotaxia syndromes.

Imaging Studies

  • Echocardiography should be performed initially and in periodic follow-up care in affected fetuses, infants, and children to assess ventricular function and size and to rule out congenital or acquired cardiac malformations or valve dysfunction.
  • Children of mothers with the anti-Ro and anti-La antibodies should undergo regular fetal ultrasonographic assessments, including detailed fetal echocardiography to identify conduction delay, bradycardia, and ventricular function. All children, regardless of fetal findings, should undergo an ECG after birth to check the conduction intervals. Children with first-degree or second-degree atrioventricular (AV) block have been known to progress to CAVB.
  • Mothers with the autoimmune antibodies or those with one affected child should undergo regular fetal ultrasonographic assessments, including detailed fetal echocardiography to identify subsequent affected pregnancies starting early, at 16 weeks' gestation. Fetal echocardiography can reveal the complete AV block. Fetal monitoring should be performed to look for bradycardia, fetal distress and hydrops fetalis. Fetal echocardiography is geared towards looking for early heart block, bradycardia, arrhythmias, pericardial effusion, cardiomegaly, valvular insufficiency (especially tricuspid regurgitation), decreasing contractile function, and abnormal venous and arterial pulsations. 

Other Tests

  • Chest radiography can reveal cardiomegaly and pleural effusions. Heterotaxia can be suspected in presence of visceroatrial discordance. One should look for a midline liver, rightward stomach bubble, and dextrocardia. Looking at lead placement in temporary and permanent pacemakers is helpful.
  • After birth, ECG is recommended to assess for CAVB and to assess the QT interval that can be prolonged. ECG and Holter ambulatory ECG monitoring are routinely performed initially and periodically in patients with complete CAVB.
  • Holter monitoring (ambulatory electrocardiography) is recommended to determine if the AV block is intermittent or persistent and to evaluate for associated arrhythmias.
  • Exercise testing is performed on a regular basis in patients who are capable, usually in patients older than 7 years.

Procedures

  • Electrophysiologic testing is not routinely performed in patients with CAVB, although it occasionally provides information regarding pathophysiology and prognosis in certain cases.

Histologic Findings

  • Myocardial biopsies are not routinely performed in patients with CAVB. However, histologic findings have been reported from experimental studies and autopsy specimens; these findings demonstrate various stages of fibrosis and calcification of the AV conduction area, depending on the timing of the specimen. Immune deposition is also a frequent finding, although whether this is specific for the conduction system or occurs throughout the myocardium in general is unclear. The mechanisms of cell death and fibrosis are unclear. Hypotheses include alloimmune-mediated inflammatory responses and immune-triggered apoptosis.
  • In some cases, the sinoatrial node has also been found to be affected and may be hypoplastic, fibrotic, or completely absent.

More on Atrioventricular Block, Third Degree, Congenital

Overview: Atrioventricular Block, Third Degree, Congenital
Differential Diagnoses & Workup: Atrioventricular Block, Third Degree, Congenital
Treatment & Medication: Atrioventricular Block, Third Degree, Congenital
Follow-up: Atrioventricular Block, Third Degree, Congenital
References
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References

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  3. 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. [Medline].

  4. 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. [Medline].

  5. 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. [Medline].

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Further Reading

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Keywords

third degree congenital atrioventricular block, third-degree congenital atrioventricular block, CAVB, congenital heart block, congenital complete heart block, congenital complete atrioventricular block, atrioventricular, AV, congential complete AV block, congential complete A-V block, autoimmune complete heart block, 3° atrioventricular block, 3° AV block, 3° A-V block, collagen vascular disease, systemic lupus erythematosus, Sjogren syndrome, Hunter syndrome, Hurler syndrome, myocarditis, hydrops fetalis, endocardial fibroelastosis, L-transposition of the great arteries, ventricular septal defect

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Contributor Information and Disclosures

Author

Monesha Gupta, MD, MBBS, FAAP, FACC, Assistant Professor, Division of Pediatric Cardiology, University of Texas Medical School, Children's Memorial Hermann Hospital
Monesha Gupta, MD, MBBS, FAAP, FACC is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Society of Echocardiography, Medical Council of India, and Society of Pediatric Echocardiography
Disclosure: Nothing to disclose.

Coauthor(s)

Robert Murray Hamilton, MD, MSc, FRCPC, Section Head, Electrophysiology, Director, High-Risk Hereditary Heart Conditions Clinic, Labatt Family Heart Centre; Professor, Department of Pediatrics, Associate Scientist, Physiology and Experimental Medicine, The Hospital for Sick Children and Research Institute, University of Toronto, Canada
Robert Murray Hamilton, MD, MSc, FRCPC is a member of the following medical societies: American Heart Association, Canadian Cardiovascular Society, Canadian Medical Association, Canadian Medical Protective Association, Cardiac Electrophysiology Society, Heart Rhythm Society, Ontario Medical Association, Pediatric Electrophysiology Society, Royal College of Physicians and Surgeons of Canada, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Medical Editor

Charles I Berul, MD, Associate Professor of Pediatrics, Harvard Medical School; Senior Associate, Department of Cardiology, Children's Hospital of Boston
Charles I Berul, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, Heart Rhythm Society, and Society for Pediatric Research
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Alvin J Chin, MD, Professor of Pediatrics, Division of Cardiology, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine
Alvin J Chin, MD is a member of the following medical societies: American Association for the Advancement of Science and American Heart Association
Disclosure: Nothing to disclose.

CME Editor

Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College
Gilbert Herzberg, MD is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Chief Editor

Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Associate Professor, Department of Pediatrics, Baylor College of Medicine
Steven R Neish, MD, SM is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, and American Heart Association
Disclosure: Nothing to disclose.

 
 
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