(sensation of skipped beats or rapid or forceful beats), symptoms of hemodynamic compromise (eg, dyspnea, chest discomfort, presyncope, syncope), or cardiac arrest.
[merck.com]
Atrial fibrillation without underlying heart disease is extremely rare in children.
[ncbi.nlm.nih.gov]
branch block 左脚ブロック left bundle branch block 完全左脚ブロック complete left bundle branch block 不完全左脚ブロック incomplete left bundle branch block 右脚ブロック right bundle branch block 完全右脚
[jams.med.or.jp]