I just registered to post this. I'm not a diver though at one point I started to study Scuba with the intent of getting certified in the 1970's. I knew Greg reasonably well as we had common interests outside of Scuba, and I worked under/with him on advanced first aid volunteer work.
This quote is from Gregs wife who posted it on a board she frequents:
"I talked to the coroner. Actually, I think he’s the Jim Brass (CSI reference) of the Monterey County Coroner’s Office. Greg had an undiagnosed congenital heart defect – his tricuspid valve was missing the center cusp. The valve lets the blood flow in and stops it from coming back. The coroner said he didn’t consider this a diving accident. We talked for a while yesterday when I pick up Greg’s stuff. I think I have all my questions answered. No one knows exactly what happened, but we know the time frame and he had problems as soon as he hit the water."
I've looked around the web and this may have been a Bicuspid aortic Valve congenital disorder - if you search on that term you'll get plenty of hits.
When I knew him Greg was strong but also overweight [as am I
]. Pictures of him in his wetsuit reinforce my opinion. I've also found one quote from him on a board somewhere to the effect that 'even us out of shape folks can dive', implying that it wasn't a strenuous hobby. [that quote is heavily paraphrased, and I can't find the exact quote again at this time.] Diving is strenuous. Particularly for us overweight types in our late 40's. This particular problem apparently can become more dangerous as we get older.
I don't know Gregs history of physicals but I'm surprised this wasn't picked up if he had them. It reminds me, and should remind all of you late 40's types, to get a complete physical periodically. Who knows, maybe Greg had experienced some issues and was just too headstrong to admit them to himself. We'll never know.
Greg was a decent guy and leaves behind a bereaved family. Hopefully it will be a reminder to all of you out there to get a physical.
[edit]
Interesting. I just found this quote about the medical condition: "Much of the data relating to its complications derive from necropsy studies since reliable diagnosis has only been possible for the last 15 years or so by two dimensional echocardiography." That would explain it not being found earlier.