A method of using a staple for joining first and second blood vessels. A staple having an open center is provided to staple the two vessels together. One end of the first blood vessel is placed through the staple and then pierced by an end of the staple. An opening in the side of the second blood vessel is formed and the pierced end of the first blood vessel is inserted into the hole. A second end of the staple is then deflectively bent and pierces the outer wall of the second vessel to staple the two vessels together.