Irregular heart rhythms.

Has anyone else heard or been told their baby has arrhythmia? Went to ER today for torn miniscus and they checked her just in case... An her heartbeat sounded really irregular and it kept dropping drastically and really fast... It'd be 146 and drop to 118 and then bounce back to 130ish for about 30 seconds and it would drop to 109 or so. Did this for two hours... Told me to schedule an app with my OB so I have an app Monday to see if she is still having it... Just wondering if anyone else has experienced or is experiencing this?