You see an elderly woman who resides in a nursing home for a pressure sore on her left heel that has been present for the past few days. She has advanced dementia and cannot provide any useful history herself. The nursing home reports a history of hypertension and coronary arterial disease.
The patient’s vital signs are normal. Results of the head and neck examination are unremarkable; the lungs are clear and the heart beat is regular, with a 3/6 systolic ejection murmur. The abdominal exam is benign. The extremities show no cyanosis, clubbing, or edema.
The patient has a stage 1 decubitus ulcer on her left heel. Both feet feel cool but are of equal temperature. She has weak but palpable distal pulses on the good foot, but her distal pulses on the left side are not palpable and can only be heard faintly with the handheld Doppler. You note unilateral petechiae on the dorsum of the left foot (Figure). There are no other petechiae.
What’s your diagnosis?