Hello and welcome to our site. A few questions to you: has your son seen a pediatric cardiologist? Has he had his thyroid checked and been seen by an endocrinologist? Patients with fast heart rates, cold hands and feet, fatigue like you are describing are all symptoms of thyroid problems. A fast heart rate of 223 may not be that fast depending on what he was actually doing at the time. It is also important to know if that fast heart rate started and stopped on a dime or if the rate increased and decreased over time. Stabbing chest pains are not indicative of heart disease; it is more a symptom of muscle or cartiledge problems. Truely heart related chest pains are due to a lack of blood flow to the heart muscle and usually children and teens who have this type of RARE symptom, also would have to have very serious forms of heart disease; they certainly would not be able to even attempt at playing a sport such as baseball. Also, these types of problems would not be missed, even on the EKG. The EKG would never be normal, neither would the Echo. Most children and teens refer to palpitations, or an awareness of the heart beating, as having chest pain and this is more likely what your son is actually feeling. It is possible that your son has something called Wolffe-Parkinson-White Syndrome which would cause the fast heart rates, IF those rates were scanned during sleep where he was inactive. The sleeping of 12-14 hours doesn't really make any sense to me as even children and teens who are dying from heart disease do not sleep that many hours. He is a teen and teens often times do not sleep the hours their bodies need to repair themselves; it is much more likely your son is 'catching up on the sleep' his body needs. This really does not sound like a cardiac issue, based on the things you have written here, however, understand that I can only go by what you have written, I am not seeing him myself. based on all of the tests your son has had done, again, this does not sound like a cardiac issue. I would have his thyroid checked, if they haven't done that already.
I just went back and reread your post and wanted to add a couple of other things. If your son is an athlete is it possible that he may have injured his back? That could cause a numbness in his legs. Have you seen a neurologist? That may be something you may want to consider. The other thing I wanted to say was that I do not understand what the nurse was saying about a "pause". A "pause" certainly would have shown up on the EKG because that would have been an electrical issue with the heart and that is the primary thing the EKG is used to diagnose. It can also diagnose certain muscle issues as well. take care