You had an reaction to the chemical. It happened to my mom also. It is very scary when it does happen. Were they able to get any information on the stress test?
I had my first chemical stress test yesterday and I know how you felt. My main reaction was feeling like my throat had completely closed off and I couldn't get air in. I was terrified! The nurses never prepared me to feel that extreme. They said "some get short of breath". Talk about understatement!! My doctor was right there in the room with me and kept telling me that it was very normal and that my pressure, pulse and ekg were great. That 4 minutes during the injection seemed to be a lifetime. I know from talking to other people that the reactions do vary. Some do just feel a racing heart and others, like us, feel so much more. The nurse told me that they are only concerned that the symptoms subside right away when they stop injecting the chemicals. Did they? Mine were gone within about a minute or so. Not to say that the emotional reaction was gone that soon. Hope this helps ease your mind a bit.