I just started having shortness of breath when exercising and it feels like my heart is fluttering or like my lungs are heavy. My primary doctor ordered a stress and electrocardiogram testing for me. I’m going to be 70 in October. Sounds like I have what you have. My doctor thinks it’s an electrical issue. I’m on zetia and Lipitor and not overweight. I don’t drink or smoke. How painful are the caths?