What is a normal heat rate for a healthy 12 year old boy?

I have a 12 year old son who has been seen in the ER a couple of times the past 2 months, 3 times for abdominal pain and twice for joint pain. Now we have been admitted to the Hospital for chest pains. When we got here last night he had a heart rate of 47. When he dozed off his heart rate went down to the mid 30's. BP was 85/38. We are not supposed to see the Cardiologist until tomorrow so I am just reaching out for some advice. Thanks