My 7 year old son has a Cardiac Murmur and Sinus Arrythmia

I took my 7 year old to the Dr. today because he said this throat was hurting and the Dr. listened to his heart and said that he had a heart murmur. Then the Dr. hooked him up to a EKG and said that he also has Sinus Arrhythmia. I know that people can live with a heart murmur and most will grow out of it, and that Sinus Arrhythmia is not very serious, but should I be concerned that he has both? And what should I do?

[Marie M Gleason, M.D.]

Heart murmurs are common in children, and most often represent the sound of blood flow travelling through the normal heart.  Less commonly a murmur is due to a hole in a heart wall, or a leaking or tight valve.  When a child is unwell, flow murmurs are often more easily heard, and this may be the case here.   Sinus arrhythmia is just a slight slowing of the heart rate that links to the breathing of the child.  It is a normal variant in children.  It has nothing to do with the murmur.  Both are likely normal.  What is more important to know is whether or not the rest of the electrocardiogram (ECG) was normal, aside from the sinus arrhythmia.  If normal, then the murmur is likely a flow murmur.  If the ECG was not normal, then follow up may be warranted.