Cardioverter and defibs

I have a question regarding a patient of mine with medical problem.
He had a Cardioverter defibrillator implanted 2/98 (Meditronic 7223CX) is doing all kinds of sport and now wants do begin scuba diving? What is your opinion in this case.

Cardioverter defibs as well as pacemakers are known to have been dived.
No electrical or physiological problems have been reported. These devices are normally rated to stand increased hydrostatic pressure. For example, modern pacemakers normally can stand pressure up to 3 ATA and there are some models rated for 4 and 5 ATA.
I would base my judgment on two points:
A) that the cardiological situation is not so serious to impair normal response to stress and excercise and not to cause any likely major dysrhythmia or arrhythmia, not immediately correctable by the cardioverter
B) that the cardioverter is rated to stand increased hydrostatic pressure.