Originally posted by: alchemize
I can't think of the name of this defect off the top of my head, but if it is what I think it is - it gets triggered by physical exertion, often associated with things like swimming. The heart goes into fibrillation and needs zapping to get a regular rythm back.
A friend of mine's daugther has this, they carry a defib everywhere with them and she has to watch her exertion, but otherwise lead a normal life.
I'll see if I can dig this up...
edit: now I remember - it's Long QT syndrome:
http://en.wikipedia.org/wiki/Long_QT_syndrome