Rate below threshold

Hello folks, I'm new to the forum, but am a veteran to the pacemaker world, having had my third device fitted two years ago at the age of 37. I suffered from SVT amongst other things, so the PM seemed like the way to go. In the fourteen years since I've had the PM I've had a good unrestricted life. I lift weights and drink beer without side effects.

Anyway, over the last month, I've started to see some of the old symptoms. SVT and missed beats. I've had two incidents where by pulse has fallen to around thirty-five, yet my lower threshold is sixty, leaving me feeling pretty drained. The device has been checked and it's A1. Ive had some ectopic beats and arrested during the last implant as a result, but these aren't excessive in number, so basically I'm confused! Why has this happened? The pacing technician mentioned something about the pacing rate being halved when my heart exceeds the upper threshold. She increased this from 140 to 160. Could this be the reason? Any comments or intelligence appreciated :-)

1 Comments

svt

by Tracey_E - 2012-07-24 08:07:46

My first comment is the technician has probably never seen this before and is stumped. Raising the limit may help but I doubt it. It will only help if when you race you don't get over 160.

The pm is set to watch for afib, which to the pm looks a lot like svt sometimes, it's a safety feature. When it senses the atria is going too fast, it puts us into an artificial 2:1 block and paces half, so if you were at 140 and it put you in a block, it would be pacing you at 70, at least that's how I understood it when it happened to me. Key word here is PACING, if you are beating on your own faster than that the pm will just watch. For me, it mostly happened when I worked out. I'd max out the pm (svt, atria took off faster than my upper limit) and it would suddenly make me plummet. I was set at 160 so it would start pacing me at 80 until my atrial rate came down under 160. Way to kill a workout!

Since I have no history of afib, they turned this feature off. They also set something I think is called rate drop response so if I suddenly plummet on my own, it kicks in and paces atrial to keep my hr level, or at least come down more slowly. This helped as long as my atria didn't go over 160, but it did so I eventually had to go on beta blockers. Now I never get over 140, thanks to atenolol. I'm more tired and don't have quite the stamina, but I don't have the racing or plummets so I get by. It took a lot of months and a lot of patience from my dr and tech to do all this, it was all done in baby steps rather than sudden big changes.

Now that I've rambled on, I'll point out that it doesn't sound like that's what's happening to you. If your lower limit is 60, you should never ever get below 55 or so, paced or not. And half of 140 is not 35 last I checked. If you took note of the date and time, they should have been able to see what the pm was doing at that time. Are they sure the leads are good?? Were they able to find the episodes on the pm report?

We can't do much about ectopic beats.

Good luck figuring it out! Hope this helps.

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