Soft heart murmur and pronounced sinus arrhythmia in child

My 4 year old daughter will be seeing a pediatric cardiologist this Wednesday.  I checked her pulse while she was sleeping (yes, I am neurotic about heart issues and just wanted to check and make sure she is OK since I'm a palp sufferer) and it was irregular.  I mentioned this to her doctor at her checkup last week and he listened to her heart.  He found a soft heart murmur and said her normal sinus arrhythmia is very pronounced - it jumps from 60 bpm on exhaling to 100 when inhaling sometimes.  Does anybody know what this could be?  I am nervous and want her to be OK.  What could cause such pronounced sinus arrhythmia?  She says she can feel her heart beating a lot - I pray she doesn't have something majorly wrong with her.

[G-nat]

You need to ask your question in the doctor's forum.  This is a patient-to-patient forum.  Click on "forums" at the top of the page, then on "yes I agree," then on "post a question."
From what I've heard, and don't take my word for it, but sinus arrhythmias are usually not something doctors worry about.  That's what I've been told by my doctor, anyway.
In any case, try not to make your daughter a hypochondriac until you know for sure if something's wrong.

[notparanoid]

I have the same problem. I was born with it and have no medical problems except from occasional cold extremities due to mild lack of circulation. There is nothing to worry about and your child will live a long and peacefull life.