The patient is a 62-year-old woman with a chief complaint of fainting. She had been well until one week prior to admission, when she noted rhinorrhea, occasional fever with chills, myalgias, and decreased vigor. She had a history of mild emphysema and her chronic, minimally productive cough had increased slightly and the sputum was green in color. Over the same time period, she noted paroxysms of coughing, which left her feeling faint and from which she recovered with 5 to 10 minutes of rest. She experienced occasional substernal chest burning, which she associated with coughing. The day of admission, the patient climbed two flights of stairs, had a prolonged coughing episode and voluntarily sat down on the landing to keep from fainting and falling. Her husband volunteered that she looked ashen and sweaty, her color improving with approximately 10 minutes of rest. There was no loss of consciousness, nausea, vomiting, or chest or abdominal pain associated with the episode. No focal neurologic deficit or vertigo was described. She had no prior cardiovascular disease, al