A 13 year old child has bradycardia. There is no obviousshunt. What is the best treatment for a coronary fistula collateral flow in main pulmonary artery, above thepulmonary valve?

None. Most coronary fistulas to the mpa are tiny, and if there there is no obvious shunt it will likely not require rx or cause any problems such as bradycardia. Check with your cardiologist for f/u.
Depends. Depends on the flow through the fistula. If high volume and/or symptoms, the fistula may need to be closed. This could be done either surgically or catheter-based, depending on anatomy.
Please consult. With a pediatric interventional cardiologist for best direction moving forward.