I went to my pacemaker doctor (cardiologist) for a checkup, on Friday. I think he was worried because I was out of the country for such a long time. Everything checked out fine. Under his questioning I finally confessed that I had had a couple of incidents when my heart was beating too fast (one of the symptoms that won me the pacemaker), and another occasion when I felt funny, like maybe short of breath, but I didn't really know what short of breath meant. We had quite a long discussion about all of this, the question being, when should I call him, or when should I go to the hospital. He told me that the fast heart rate wasn't important if it didn't last too long. What is too long? I was thinking three days. He said ten minutes, thirty minutes and I should get to the hospital. He urged me to call and come into the office if I have another "shortness of breath" incident. I guess that makes the whole thing somewhat clearer, but the truth is I still don't understand what constitutes an emergency. Obviously none of these incidents qualifies; it's been many days and he thought I was just fine.