I am so sorry for your loss Brian, but I feel it's a blessing I landed on your post. I have just been diagnosed with pulmonary hypertension with eisenmegar syndrome. That means the right side of my heart is enlarged and I have a hole in my heart. It's a miracle that something was spotted on a chest x-ray which led to this recent diagnosis. Everyone is born with a hole in the heart and for most, it closes up naturally. Others can go their whole life like that and never know. The rest are at great risk and don't even know something is wrong until a heart attack happens. In my case it is not only herititery, but I also have a heart murmur. I am healthy and 49 yrs old. I was supposed to have my gallbladder removed but was cancelled, but the pre-op physical found this disease. I am in the process of lining up open heart surgery. I don't want to die, but even more I don't want to leave you knowing you just want to know why. There was nothing you could do and no signs of heart problems because your daughter was a healthy young woman. From here on, encourage her blood relatives to get checked out, staring with a chest x-ray. God bless you and know He is with you during this difficult time.