@bb03 Great description of the adenosine administration. I had it done only once, but the kind nurse explained that it was going to feel awful....for about ten whole seconds....and to just bear with them for that long. Exactly what happened. They said it was coming, and then I felt like my whole body was sinking into the floor and the room closed in on me. I knew what to expect....sort of...and believed them, and sure enough it was over in seconds. Meanwhile, the internist pointed to the monitor over my shoulder and said to everyone looking on, 'See? It's flutter, not AF.' The adenosine, in my case. was meant to stretch out the graphic depiction on the monitor and show more discretely the rhythm. They saw the jagged sawtooth waveform between the QRS complexes which indicate a rapidly fluttering left atrium.

So, call it 'doom', 'dread', foreboding, falling through the floor, the walls closing in on you, everything going dark...it lasts literally 7-12 seconds, depending on how quickly your system can clear it, and it will often, not always, serve its intended purpose.

Incidentally, electrophysiologists routinely use both adenosine and isoproterenol to 'challenge' the patient's heart before they wheel an ablated heart patient out of the cath lab. After all the tissues that need to be ablated have had that done to them, it still makes sense to check, to verify, that they have done a complete ablation before letting the patient begin to recover and to regain consciousness. If one, or both, of those two drugs makes the heart lurch back into arrhythmia, the team knows they have more work to do.