Exercise and PM adjustments
I have a dual chamber pacemaker/ICD set for 50 bpm. The EP wanted it set low enough because when it paced I became "symptomatic." He wanted to all but turn it off. So rather than flipping the off switch, so to speak, he put it low enough that I just wouldn't pace.
Since then, I have gradually returned to my cycling and have become as non-competively proficient as I ever was (minus the long six-hour rides). But now I go through definite periods when my breathing is off. I wouldn't call it a shortness of breath, but rather a resistence when I inhale. And it doesn't keep me from continuing whatever I 'm doing. It's just different and annoying.
My question is, should I be adjusting my PM as I become more fit because we know a heart becomes more efficient and the heart rate slows? There may be times during sleep when I drop below 50, as has always happened to me. And that may trigger a disyncrony between the two chambers, thereby sending blood to the lungs througn a closed valve (or pacemaker syndrome).
Some Background (sorry but this is a long story)
In Jan. 2017 I went to the emergency room experiencing erratic heart rate. After 4 days of observation, I received a PM for what was determined to be sick sinus sysndrome. After my release and 8 weeks of recovery, I passed out on my bicycle with a ventricuclar tachycardia. A subsequent heart study showed the origianl SSS diagnosis was wrong. But it also showed no apparent need for a pacemaker. But one was reinstalled with an ICD to protect me if I had another VT. The pacemaker was set with the same settings as the first despite no diagnosis. The thinking was the original doctor saw something at the time and there may be an intermittent incompetance that requires pacing.
After about a year I began having repeated ventricular tachycardias. One would start, the ICD would kick in and stop it before I passed out, but then another would start. There would be four in a row and then the cycles would stop, but start again some other time of the day with no apparent trigger. It was both scary and frustrating to both me and all my cardiologists. I was put on a very powerful anti-arrythmic drug, flecainide which is designed to stop VTs but for temporary use because of its power.. And it worked. But with every powerful drugs there are powerful side effects. Mine included, dizziness, a severe shortness of breath, erratic hearbeats. My loading dose was so strong, that one Sunday I though I was going to die because I couldn't get enough air. I stopped taking the drug for three days, figuring if I went into VT, my ICD would stop it.
During this time my general cardiologist and my EP conducted tests to see what the problem was. They just didn't know and they encouraged me to continue taking Flecainide, which I did in lower dosages. I went to Mayo Clinic. And without conducting their own heart study but conducting an extensive EKG and looking at very good Echo, they diagnosed Left Bundle Branch Block (In all my months and now years, that diagnosis had never come up). I was willing to accept their diagnosis. They were Mayo aferall. They sent me home and told me to wait while they arrange for the procedure.
I couldn't just wait. I was researching as best I could online all of my new heart problems. Up unitl Jan. 2017 I was perfectly fine. There were no issues at all and inside of three years, I was an invalid and no one knew why. I was diagnosed SSS. When that wasn't accurate, every doctor seemed determined to find a reason for my pacemaker. I was diagnosed with heart failure but I didn't have enough of the signs so that was eliminated. Now I was facing Left Bundle Branch Block. But that turned out inaccurate . One of the extreme side affects of flecainide is mimicking LBBB.
In my research I read every paper I could get my hands on. I even ordered a textbook for heart doctor students and read the section on pacemakers. On page 1,048 (or there abouts) I found a description of what is known as pacemaker mediated tachycardia (PMT) That's when the pacemaker creates a dangerous electrical loop that can throw patients into a deadly VT. Bingo.That made sense to me. I have a mechanical mind and always felt the VT cycles I would go into was a electro/mecanical -- sort of like and AC unit or heater short cycling. Starting then stopping; starting then stopping. That led me to research even more. I had all the key search words now. I found paper after paper supporting the concept for. One paper described the death of a youthful, active 50-something man with a PM who dropped dead on a socker field. A review of his PM data showed he had been put into PMT.
With all this information, my doctors wouldn't listen. I was a patient conducting online research. They wouldn't consider it. That made me mad because they were not even looking for an answer and flecainide was diminishing my lifestyle and I knew I was healthy. But I had been put into a category of "heart patient" and every doctor kept me there because the doctor before him/her had put me there.
Fueled further my their inactivity, I found a recently retired PM engineer to work with me. We got all of my settings and we considered every one of my possible conditions regardless of whether I actually had be diagnosed with it. He quickly questioned my need for a PM, but we both agreed from the start he would not provide medical guidance. He would only speak to me about the PM function. He quickly latched onto a setting that was turned on -- rate response. He asked if I had chronotropic incompetence -- that is the diminished capacity for your heart to regulate its rate. I had never heard that before, so NO, I told him. All he said was hmmm. No direction.
I went to my EP and asked him to turn the rate response off. He didn't want to. I said: if it wouldn't kill me, just turn it off. He reluctantly did so but said it wouldn't make a difference. Almost instantly, I felt better. I titrated off of flecainide and haven't had a VT since.
I still have my PM. And I still don't have a diagnosis to go with it. In defference to my EP and cardiologists I'm learning to live with the device. Becasue I had a VT in the past, that makes the ICD important, I suppose. But we have tried to make the PM inconsequential. But as I get more fit, I want to make sure it remains that way.