depending on the heart condition, you may be at a higher risk for developing a clot. circulation in your lower appendages is under the influence of gravity. meaning its harder to pump the blood out of there. swelling is a sign of inadequate heart function. as blood pools, it can clot. the pain in your calf is known as "homan's sign" and is a crap way to diagnose a possible clot in your lower leg. people still use this old method to check for clots, even though research evidence has debunked its accuracy. basically, your MD checks your calf b/c it makes him feel better. the swelling, however, can be a cheap, but accurate to measure heart function.