The heart and blood vessels comprise the two elements of the cardiovascular system that work together in providing nourishment and oxygen to the organs of the body. The activity of these two elements is also coordinated in the body's response to stress.
graft vs fistula. A graft is usually in a horse-shoe or letter C shape, and is normally firmer to the touch. Fistulas usually run up and down and are more squiggly shaped, with bumps (pseudo anurisms) and softer to the touch. Here are some good pics of fistulas. For some reason, I could not find any pics of grafts on the net.
Perianal fistula. A perianal fistula is an abnormal connection between the epithilialised surface of the anal canal and the skin. The causes of perianal fistulas: Primary Obstruction of anal gland which leads to stasis and infection with absces and fistula formation (most common cause).