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A. Etiology navigator

  1. Autoimmune injury of fetal conduction system most common
  2. Associated with maternal overt or asymptotic SLE
    1. Accounts for 60-70% of all and 80% with structurally normal heart
    2. Positive anti-SSA/Ro or anti-SSB/La present
  3. Other autoimmune associations:
    1. Rheumatoid arthritis
    2. Dermatomyositis
    3. Sjogren syndrome
  4. Congenital heart disease
    1. Abnormal embryonic development of the conduction system
    2. Post-surgical repair involving ventricular septum
    3. Long QT Syndrome
  5. Infections
    1. Myocarditis
    2. Infective endocarditis with myocardial abscess
  6. Kearns-Sayre syndrome

B. Epidemiologynavigator

  1. 1 in 20,000-25,000 live births
  2. Fetal demise of affected infants may result in underestimation of incidence

C. Clinical Findings navigator

  1. Can cause hydrops fetalis in utero
  2. Heart failure within first week of life in most serious cases
  3. Milder cases may present at 3-6 months or remain asymptomatic
  4. Infants may have syncopal episodes
  5. Older children may have night terrors, tiredness, or frequent naps

D. Physical Examination navigator

  1. Prominent pulses
  2. Paradoxical bradycardia
  3. Elevated systolic blood pressure
  4. Irregular jugular venous pulsations due to atrial contraction at different phases of tricuspid valve closure
  5. Exercise or atropine will increase HR only by 20 bpm
  6. Systolic murmurs heard occasionally

E. Laboratory Diagnosis navigator

  1. Electrocardiography (ECG): P waves and QRS complex without constant relationship
  2. Echocardiography
    1. May be detected by fetal US studies
    2. Dissociation between atrial and ventricular contractions
    3. Cardiomegally due to increased diastolic filling time

F. Treatment navigator

  1. Cardiac pacing needed for the following
    1. Significant symptoms
    2. Progressive cardiac enlargement or prolonged pauses
    3. Neonates with HR < 50 bpm, evidence of hydrops or heart failure after birth
  2. Temporally increase heart rate while waiting to arrange pacing
    1. Atropine OR
    2. Epinephrine OR
    3. Isoproternol
  3. Transthoracic epicardial pacers used for infants
  4. Transvenous pacers for older children and young infants
    1. Temporary pacing for post-surgical heart block
    2. infant may recover spontaneously up to 2 weeks post-op

References navigator

  1. Press J, Uziel Y, Laxer RM, et al. 1996. Am J Med. 100(3):328 abstract
  2. Klassen LR. 1999. Neonatal Network. 18(3):33 abstract
  3. Nelson WE. 1996. Textbook of Pediatrics. W.B. Saunders (Philadelphia) p.1342