FRIEND OF MINE JUST DIED FROM AN "ANEURYSM BEHIND THE HEART" WHICH WAS
WHAT THE AUTOPSY REPORT SAID.   I HAVE A FEW QUESTIONS ABOUT THIS:  1.
  ACCORDING TO THE ANATOMY BOOKS THERE IS NOTHING BEHIND THE HEART BUT
THE BACK OF THE HEART ITSELF;  THE BOOKS ALSO SAY THAT WITH AN
ANEURYSM OF THE HEART DEATH IS INSTANTANEOUS;  HOW COME IT TOOK HIM
OVER 2 HOURS TO DIE?
2.  DURING THESE 2 HOURS HE EXPERIENCED AGONIZING PAIN IN THE HEAD,
THE CHEST AND THE ABDOMINAL AREA.   WHY?  WHAT  EXACTLY CAUSED THIS
PAIN?   WAS IT THE FACT OF BLOOD FILLING UP SPACES WHERE THERE WAS NO
ROOM FOR IT....KIND OF LIKE A BLOOD BLISTER?   AND WHY IN THESE 3
AREAS....?   ALL IN FRONT OF THE BODY!

Perhaps this illustration and explanation will be helpful to you.  I'm
sorry about your friend.

http://www.doereport.com/generateexhibit.php?ID=3749

Slosid7, I am very sorry for your loss.

An aneurysm is a weak spot in a blood vessel.  It may be entirely
asymptomatic for a prolonged period.  It starts becoming symptomatic
when there is a tear in the inner lining of the vessel (this is
painful).  Once a tear exists, it can expand slowly, expand rapidly,
or potentially it could seal itself off.  Death could be
instantaneous, but it also could take minutes, hours, or in fact never
occur.  There is no way to say a priori whether an aortic aneurysm (or
a ventricular aneurysm --- an aneurysm of the heart) will be fatal or
not, or how fast.

The pain comes from the tearing of the lining of the blood vessels. 
Pain is our body's way of telling us that there is something wrong, of
course, and the mechanism works quite well.  If blood was accumulating
in extravascular spaces, this could of course cause pain as well, but
dissecting (expanding) aneurysms of the aorta that are not currently
leaking blood are nonetheless extremely painful.

I can't say for sure why he had pain in his head, but it is possible
that the tearing spread from the aorta up into the carotid arteries
that lead to the brain.  Often the pain felt from internal structures
seems to be coming from places distant from the actual structure, a
phenomenon known as "referred pain".  This is because the nerves to a
particular internal structure may share a pathway with a nerve from a
particular external structure that is distant from it.  Injury or
damage to the heart can result in pain in the left arm, shoulder, and
left side of the jaw, for example.  Hypothetically, injury to the
carotid arteries could result in headache (although I am unaware that
this is a well-described phenomenon).

Once again, I am very sorry for your loss.

sorry to hear about our friend.being a medical student all i can pin
point to is an entity called "dissecting aortic aneurysm" which in
your friend's case might be in descending aorta (lies behind the
heart)& it's aggravation causes excruciating pain in the chest with
radiation to head & abdomen.it's a weakness in blood vessel & it tears
apart in it's lining & blood enters that.it's etiology can be tracked
down to few conditions like hypertension,atherosclerosis,weakness due
to connective tissue disorders like marfan's and post-syphilitic
aneurysm.
may god rest your friend's soul in peace.