Does everyone's heart rate change when breathing?

Should be: It is a normal condition, called sinus arrhythmia. But if your heart rate changes a lot, you want to check with your doctor.

No: Though most people have at least a very mild fluctuation in heart rate with the respiratory cycle. This is called sinus arrythmia or sinus dysrhythmia--a normal finding. In some people, this can be quite pronounced and seem abnormal, but is perfectly normal.