You are called to a supermarket for a 70-year-old male complaining of chest pain. Your patient describes his pain as a sudden onset with excruciating pain between the shoulder blades and stabbing pain in his chest. He has a history of high blood pressure and recently stopped taking his meds because they made him feel strange. You suspect he may have a dissecting aortic aneurysm. What might you find in his vital signs that will differentiate an aortic aneurysm from an acute myocardial infarction (AMI)?