Delores Smith was a former patient of House. She was an unseen character. Delores had a heart condition. Normally, she would have been given nitroglycerine. However, she also had low blood pressure and since nitroglycerine quickly dilates the blood vessels, using it would be dangerous. Instead House prescribed Viagra, which acts much more slowly to the dilate the blood vessels. He then billed the matter to Medicare and thought nothing more of it.