Even if you pass underneith the spine, the aortic artery runs directly underneith it. So, not only are you going to clip the top of the lungs, but chances are youre going to sever this main artery as well.
I hit a buck in the artery about 12 tears ago, nice 8 came in right underneath me. I shot him staright down(I was young) he wheeled around and walk away with the arrow sticking out of his back. 30 yds later he fell over, I was lucky and that was the last time I tried the straight down shot!!
The blood inside the deer was nuts, I have never seen so much!!!