A 55 year old man presents to the emergency department with a two hour history of sudden onset of pain in the right leg and foot. The pain extends from the mid-leg to the entire foot. He says the toes feel "a little numb", but he is able to move the foot normally. He is being treated with anticoagulation (oral warfarin) for chronic atrial fibrillation. His medical history is otherwise normal. Prior to this, he has never experienced any pain in the leg. Specifically, he denies ever having pain in the leg while walking. He does not smoke. On physical examination, he has normal palpable pulses throughout the left lower extremity. On the right, the femoral pulse is palpable, but the popliteal, dorsalis pedis, and posterior tibial pulses cannot be palpated. Sensation and motor function of the right foot are normal.