You are seeing a 66-year-old male patient who has a history…

You are seeing a 66-year-old male patient who has a history of dyslipidemia, hypertension and myocardial infarction five years ago. He is in today complaining of pain in his foot. “It hurts all the time, but especially at night.” On exam you notice he has no hair on his lower extremities, his right foot is pale, and you cannot find his posterior tibial pulses. You try to use the pulse oximeter, but it will not register. There is a 3 mm punctate-appearing ulcer on the lateral aspect of his foot. Which of the following is the best assessment and plan for this patient?