Getting technical...

artist credit: Dr. Howard Reichman medium: light blue hospital flat sheet 

To the left is pictured an example of a normal functioning blood line including artery, capillaries, veins, with pressure amounts. Right is an example of what happened in mom's case. Due to the malformation the pressure was at 50% instead of 4% and hemorrhaged. I really don't know what I'm talking about so visit http://en.wikipedia.org/wiki/Cerebral_arteriovenous_malformation. 
Thank you for the prayers!