A patient complaining of substernal chest pain tells you that it feels the same as when he had a heart attack two years ago. He is diaphoretic, nauseated, vomiting, and has a blood pressure of 78/50 mmHg and heart rate of 84. He also is allergic to aspirin. He asks you to assit him in taking one of his nitroglycerin pills. Which one of the assessment findings that follows represents a contraindication to the administration of the nitroglycerin?