I don'y know if you guy's saw Pat Reeves Buck last Year in Buffalo County WI. I couldn't find the video but I found the story. http://www.wisconsinsportsmanmag.com/hunting/whitetail-deer-hunting/WI_1207_01/

It looked like the same kind of hit you made but it hit a rib and defected under the shoulder blade. Never hit the chest cavity. This might be what happened.