Try and keep a note of what the latest test results of heart function (e.g. left ventricular ejection fraction, LVEF) were, and what, if any, heart medication your son is on and which cardiologist sees him. This will help the emergency doctors decide if it is likely that the problems they are seeing are due to a problem with the heart.
Awareness of the risk of heart rhythm problems and cardiomyopathy is important.
Anaesthetic risks (see here) need to be taken into account at all times if surgery or sedation is needed.
Information based on consensus statement (published in January 2010)