Hi, I m a competitive swimmer and this is the second time this is happening to me. ( both times are during intense training weeks). During practice I felt like my heart skipped a beat.My pec moves every heartbeat, I feel like I need to take deep breaths and I have a weird feeling at the side of my left chest/rib cage area. This second time also happened the day after my cat died. I was really upset over that, could that also have something to do with anything ?