Pediatric Third-Degree Acquired Atrioventricular Block Differential Diagnoses

Updated: Dec 23, 2019
  • Author: Charles I Berul, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
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Diagnostic Considerations

Atrioventricular (AV) dissociation may be secondary to sinus or atrial bradycardia with a faster ventricular or junctional escape rhythm, in which appropriately timed atrial impulses conduct to the ventricles. The R-R interval changes when a sinus/atrial beat is conducted, as opposed to complete AV block (AVB) where R-R intervals do not vary.

AV dissociation with second-degree AV block varies from occasionally dropped sinus/atrial beats to occasionally conducted beats. In this last example, it may be hard to distinguish from complete AV block.

Transient postsurgical complete AV block is caused by edema of adjacent tissues. This resolves after 1-2 weeks.

Other conditions to consider when evaluating a child with suspected third-degree acquired AV block include rheumatic fever, Rickettsial Infection, Rocky Mountain Spotted Fever, and Tuberous Sclerosis.

Differential Diagnoses