Sudden pulse drop while exercising

I posted this before, thought it was resolved but is returning. The PM was put in 5 years ago to resolve a total blockage of the signal between chambers when at rest.. While exercising, particularly on extended vigorous efforts such as on an elliptical machine, my pulse builds to the 140's (I'm 72 and have never had a high pulse rate). It then may drop suddenly to 100-120 and bounce back after 5-10 seconds. It used to be more dramatic when it would drop to 85 and stay there until I stopped the effort. I traced the trigger to caffiene and the probelm went away for about 18 months after I eliminated caffiene. Recently, it has come back as described above. So far it's an irritant but I'm concerned it will again progress to it's previous level. My PM limits are 60 and 170. Any thoughts?



by Pacer2019 - 2019-12-03 01:45:58

Is 170 considered a high setting ? Sounds higher than average 


by Pacer2019 - 2019-12-03 01:45:59

Is 170 considered a high setting ? Sounds higher than average 

Your PM needs to be checked and adjusted for you

by crustyg - 2019-12-03 03:36:39

If you've complete AV block then your ventricles are being paced all of the time during exercise - although you may not need pacing when resting.

It sounds as though you are activating some sort of protection mechanism (i.e. a limit that the PM has been set for) that reduces pacing rate due to detection of some adverse condition - which as Pacer2019 says is likely to be your ventricular rate.  170bpm is probably unwise at your age.

*IF* your PM is hitting some preset limit it will almost certainly make a record which can be extracted at your next interrogation.  Did you have a chat with your EP doc and team after your last post about this topic?  Was there an entry in your PM log?.

Sounds to me as though your settings need to be adjusted.

Sudden pulse drop while exercising

by Leofred - 2019-12-03 13:14:27

The 170 was arrived at by my cardiologist based on two factors:

1. I have never  had a problem with afib or tachacardia.

2. While exercising, my pulse does get to 150+ occasionally and higher when exercising at elevation where we spend some months in the winter.

When the sudden rate drop occurs, it happens after a gradual heart rate increase (20-25 minutes) of steady exercise and happens when the rate is roughly 135-145, not near 170. The drop is real, not a malfunction in my chest strap rate monitor because I feel the affects shortly before the monitor shows the drop. The events do not show up in myquarterly data, possibly because they are short-lived enough to appear negligible. 


by Tracey_E - 2019-12-03 13:24:00

It doesn't sound like you are bumping your upper limit or setting off the safety mechanisms for afib, two common reasons for sudden drops. It's possible your rate is just dropping on its own. Mine does that, too, I have av block but every once in a while my rate plunges when I'm working out. The pacer was programmed to prevent it. My rate can come down gradually but if it tanks quickly, the pacer kicks in with atrial pacing to keep it up. 

Sudden pulse drop while exercising

by Leofred - 2019-12-03 13:50:19

Thank you Tracey_E , I will talk to my cardiologist to see if my PM can be simiarly programmed. That would make for some concern free exercise.


by AgentX86 - 2019-12-03 17:00:10

You really should be seeing an electrophysiologist for these issues. Cardiologists are plumbers. You really need an electrician.

It’s your settings.

by Pacedmyruns - 2019-12-31 20:41:56

Ask your doctor to calculate your TARP.  This is set by 2 things and can cause your rate to drop 2:1 prior to your max rate. Happened to me. I'm set at 185 and 2:1 block doesn't start until 220. But in the beginning it was set to 2:1 at 120. 😮😮😮 ouch. The TARP should be higher than your 170 max. Hope that helps. 


by Leofred - 2020-01-02 09:20:57

A representative from Medtronic (the manufacturer of my PM) met with me at my cardiopogist's office and, after numerous tests and questions, seems to have resolved the problem, As I understood the explanation, the pacemaker does not recognize effort, only motion so if my pulse goes up while walking up a hill, it's because the normal signal between the chambers is getting through. The PM has a built in pause before sending its signal to allow unaided pacing to occur. That pause can be fixed i.e. the same length of pause regardless of heart rate or it can be dynamic and shorten as the heart rate increases. Apparently, my pause was fixed which is most appropriate for some people  with certain conditions. Luckily, tests and questions convinced him that my PM pause could be switched to dynamic. I've only had 4 workouts since he made the change but, in each case, I have had my pulse in the 140s for extended periods without any significant drops. I don't know how long this will work but it's good for now.


by Leofred - 2020-01-02 09:28:26

Pacedmyruns The Medtronic rep did not use the term TARP but, as I read up onTARP, my lay explanation of what the rep told me seems to fit in with your suggestion about TARP so your suggestion seems to have been right on; thank you.

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