A 15 years old female patient is referred to the pediatric emergency department for dizziness. She was out dancing with friends when she started to feel dizzy and a little bit nauseous. She had been drinking well and did not perform excessive dancing. Also, no trauma, alcohol or drugs involved. History revealed no known prior diseases and no family history of heart disease or SCD.
Her initial ECG:
SR, 84/min, QRS 80°, PR 360ms, QRS 60ms, QTc 415ms (Bazett), R/S transition V4, no PAC/PVC, no signs of ischemia.
Quite long PR interval (PQ in German literature) of 360ms. Such long AV block (AVB) I° usually does not impact on the adolescents wellbeing when at rest. On exertion, however, higher heart rates may lead to functional 2:1 block with insufficient heart rates, for example while dancing.
Usually one would perform stress testing to evaluate for functional 2:1 block and chronotropy associated shortening of PR. Most cases of AVB I° do not require therapy. In certain cases presenting with clearly associated symptoms pacemaker implantation may be indicated.
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