If your breathing is also affected then it goes more in favour of a heart problem rather than costochondritis. And ECG is accurate for diagnosis of heart problems. So since there are no such issues in your case, heart problem is a less likely instance.

my granddaughter has bad chest pains and an increased heart rate at the time so could this be her heart even though test does not indicate any heart problems

thank you very much

Thank you for replying.  I have a heart murmur that the doctor heard through the stethoscope and he said it sounds like a whooshing sound.  Also I noticed with the chest and jaw pain and the pain in both arms and shoulders, neck, and left part of my face, when I take my pulse for a minute and each time my heart skips beats and sometimes I can feel a fluttering in my chest and other times a rapid heartbeat and pounding heartbeat.   My symptoms did get worse