I have had several stress tests due to a heart attack after a surgery when I was 30. In addition my mom who had COPD like symptoms also had one. For me, the stress test was an injection of something that made my heart rate increase and then they measured the results with a scan. Ironically, when I had the stress test before that procedure that gave me the heart attack, I got the all clear. Oh well! For me it was a little scary for that 30 seconds I felt like I couldn't catch my breath but it was all under the direct supervision of the doctor and they counteracted it right after by giving me a caffeine drink. Let us know if you have any other questions! Keep on keepin' on, DPM