Actually zac, it won't because the heart is designed to pump blood in only one direction. When you put a hole in the heart you cut the valves and chambers and it no longer is able to pump. It simply sloshes the blood around as it drains from the heart.

It still beats but the blood isn't going anywhere.

A deer will bleed the most if you cut the aorta or pulmanary artery just above the heart as every single drop of blood is pumped into the chest cavity either returning from the body to the lungs, returning to the heart from the lungs, or going to the body from the heart.