My son is 24. His heart has been ablated twice at 12yrs due to AV nodal re-entry He's been fine up til 1 mo ago he developed an ache in his heart- lasts from 2 to 10 secs an happens throughout the day @ 5 plus xs an hr.Occ SOB. ecg strip an 24 hr halter monitor wr normal. Cardiac stress test- able to get to target heart rate of 179 in 16 mins. was told this ws normal. He proceeded to have echo cardiogram an was told everything looked normal but his ejection fraction ws 50%. What does this mean? The ache continues..