One more tidbit that many of us may not know. When you take your pulse, you are feeling the ventricular rate rather than the atrial rate. The ventricular rate is affected by the atria, but it can't beat as fast when the atria are in flutter, so chooses some fraction of the atrial rate. But after I found out what was going on, I could use my pulse as a an indication that I was in flutter. My normal resting pulse is around 40, but when I was in flutter it was up around 70 to 75. The doctor told me that this was a sign that my atria were in flutter, probably at four times my pulse.
Regarding the heart pounding- I had that sensation just once, but it was only because I was in the water last May. I jumped off the boat and gently finned toward a kelp bed, and I heard this loud rapid booming sound. We were anchored off of a USMC base and my first thought was that it was an automatic weapon, but I soon figured out that it was me. My diving was not affected at all though. My breath hold isn't great, but it was no worse than normal and my strength was normal.
My buddy shot a 59 pound fish that wrapped up in the kelp at about 45 feet, and I spend some time helping him get it out. After we got back to the boat, weighed the fish and took photos, I finally pulled back my hood and took my pulse, and it was about 100 bpm. I was within cell phone service of the coast, so I called my doctor's office and talked to his nurse. It was late on Friday afternoon, so of course she told me that if I had any other problems I should go to the emergency room, but otherwise come in and see the doctor on Tuesday.
I have a heart rate monitor on a stationary bike, so when I got hime that evening I put on the chest strap and stood next to the bike. The rate started showing at around 100, but jumped up and down as if the monitor couldn't get a good reading. The next morning it was more like 60, but still jumping up and down. By that afternoon, it was stable at a normal rate.
When I went to the doctor on Tuesday, my rate was around 40 and it was stable. Based on my description of what I felt and measured, the doctor felt that I was probably in atrial fibrillation rather than flutter, and it had resolved on its own. That is when he decided to implant the heart monitor in my chest. He said that its a brand new gadget that is a game changer for people like me. If a patient is going in and out of a-flutter or a-fib, the doctor can see it in his office even if the patient doesn't feel a thing.
Of course my heart hasn't acted up since the implant, but at least he and I know that.
Not that is has a damn thing to do with fibrillation, but here is the fish my buddy shot while I was fibrillating.