i do kinda understand how it couldve missed the vitals. it looks like a good shot if the deer was quartered more. i shot a doe last week and hit her in the same spot as you did but the exit came out in the front of the other shoulder. i got the liver with one blade, and both lungs. you could have probably put the arrow a little closer to the shoulder and gotten better results. either way good kill.
Derek

Between and under the lungs and behind the heart. When the arrow peirced the diaphragm the vaccum that holds the lungs open was last and immediately collapsed them. A good cough and they can reinflate at least partially. As the hole fills with blood or other organs the vaccum is re-established and lungs reinflate. That is how deer can look so bad and suddenly straighten up and leave never to be seen again. A 3bld wound is much less likely to seal as easily. It can happen on low broadside chest hits, below the collapesed lung tissueas well. When you really drop them is when you can punch the center to top 1/3 of the lung that is where they go when they collapse or the air escapes them...the tissuegoes upward and is aprox 1/3 the size of a resting lung with air inside.

How do I know? I am a CCRNC Crititical Care RN Cert. And Spent 5yrs working as assistant to the chief of cardiology at a regional med center. Worked heart surg and trauma. Seen it happen in humans more than I care to recall. Talked to many docs when I was younger as newbie nurseabout how deer could survive such hits. They were not at all suprised when I showed them my Bear Razorheads. Did I just give my age away????

Anyway the more blades and more ragged a cut the less likelythe chestwall ordiaphragmwill seal. Also a sharp edge will cut vessels more cleanly and not allow platelets to stick and form clots as easily.

Hope this helps understand why the survive what should be a lethal hit.