Pediatric Third-Degree Acquired Atrioventricular Block Clinical Presentation

Updated: Dec 23, 2019
  • Author: Charles I Berul, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
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History and Physical Examination

Most pediatric patients with postoperative complete atrioventricular (AV) block (AVB) have had intracardiac surgery for atrial septal defect (ASD) repair, ventricular septal defect (VSD) repair, valve repair or replacements, or other complex congenital heart surgery.

Some patients with surgical complete AV block develop weakness, syncope, or congestive heart failure; others may be asymptomatic. Most of these patients exhibit complete AV block by the time cardiopulmonary bypass ends or during the immediate postoperative period. Fortunately, many recover AV conduction within the first 7-10 postoperative days.

Rarely, postsurgical patients develop complete AV block weeks to months after surgery. Late recovery of AV conduction is less common.

Symptoms and signs

Symptoms consist of dizziness, exercise intolerance, syncope, failure to thrive (in infants), and congestive heart failure. Patients with infranodal block tend to be more symptomatic than those with higher block sites, because low intrinsic escape pacemakers are slower and less reliable than higher-level intrinsic pacemakers.

Typically, patients with complete AV block have bradycardia. However, if the escape heart rate is rapid enough to maintain adequate cardiac output and cerebral perfusion, patients are asymptomatic. These individuals usually present with heart rates of 50-60 beats per minute (bpm).

Conversely, if the heart rate is inadequate to maintain blood flow to the brain (usually < 50 bpm in children) patients may have syncopal episodes. If the escape pacemaker rate is inadequate, sudden death may ensue.

The clinical presentation of newborns with complete congenital AV block may range from hydrops fetalis at birth to asymptomatic presentation with heart rates increasing to 100 bpm upon stimulation (eg, when feeding, crying).