Tachycardia while exercising

PM is about 3 months old. Saturday I was on elliptical at gym and 1st 15 min or so I had what I call tachycardia - hard, heavy palpitations. This has never happened to me while exercising nor for this amount of time. It started when I began using the arm part of the machine but continued whether I was using arms or just resting them. I did not feel pain. Kept going so I could see my heart rate. 1st reading was 144 then it went to 169. I stopped after that. Any clues what might have been happening? Should have I stopped when it happened? Should I call my doctor? Thank you.

2 Comments

minute ventilation sensor

by golden_snitch - 2009-10-26 01:10:58

Hi!

One explanation could be that your pacemaker has a so-called minute ventilation sensor for rate adaptation. It's a physiologic sensor and generally really good, but there is one problem with it: when you are using your arms, the sensor somehow "thinks" that you are breathing faster and hence increases the rate. It's difficult to explain, has something to do with impedance in the chest. I asked my pacer manufacturer about it because the doctor didn't have a proper explanation and rather thought that the accelerometer (another sensor for rate adaptation) is causing the problem. But no, manufacturer said it's the minute ventilation. So I have this problem, too. I can even provoke it while being at rest just doing something with my left arm (pacer in on the left, when I do something with the right arm only, I don't have this problem).

However, when I use the crosstrainer for example, everything's ok. It's really just when I do things like taking a ball in one hand and then passing it to the other hand, back and forth, again and again. Or when I stretch my left arm out, then touch my sternum with the left hand, then stretch the arm out again, and so on.

The rate response feature can be programmed not to increase the heart rate too fast. There is a setting that's called something like "level of activity". When this is programmed to "low", the pacer will increase the rate pretty fast because it thinks that you are not well trained. I have mine set at "high level of activity", and this has helped a bit.

Best wishes
Inga

Pacemaker induced tachycardia

by Drin6969 - 2009-10-27 09:10:33

I had a long talk with my cardiologist about the upper limit setting on my pacemaker because I really did not understand it. I cannot explain it well but basically my understanding is that if the Minute ventilation and accelerometer are set to continue to pace at a higher rate (up to your upper limit) you can develop a pacemaker induced tachycardia. The electrical impulses from the lower chamber (ventricles) travel up into the atrium and depolarizes the atrium before the next atrial-paced beat, the impulse can then trigger the pacemaker to repeatedly pace the ventricle causing tachycardia. This can only occur with a dual lead pacer. My particular pacemaker has a feature that can safegaurd against it if enabled. (mine is not currently).

Here is the definition of pacemaker mediated tachycardia from Boston Scientific: "PMT is initiated when ventricular activity is conducted retrograde to the atria, resulting in premature atrial depolarization. The pacemaker senses the retrograde-induced atrial event and paces the ventricle following the programmed A-V Delay. If the ventricular event is again conducted retrograde to the atrium, the cycle may develop into what is known as pacemaker-mediated tachycardia (PMT), which often drives the ventricular rate to the Maximum Tracking Rate (MTR).
Retrograde conduction pathways (and the potential for associated PMT) are often enabled by the loss of A-V synchrony. Loss of A-V synchrony may be caused by premature ventricular contractions, atrial oversensing/undersensing and/or loss of atrial capture"

Agian, I am awful at explaining things but hopefully that makes sense.

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