A 65-year-old woman has undergone an emergency incision and drainage of a plantar ulcer associated with ascending cellulitis. She has a history of insulin-dependent diabetes, hypertension, and chronic venous insufficiency. On the third postoperative day, the patient complains of severe substernal chest pain radiating to the back. Which of the following is the LEAST likely cause of the pain?
1) Costal chondritis
2) Pulmonary embolism
3) Myocardial infarction
4) Dissecting aortic aneurysm
