Exceeding PM upper setting during exercise

Hi all,

First off, I'm thrilled to find out about the PM Club, which I just joined today; it seems like a very supportive and friendly group of folks.

I'm 43 and had my first PM implanted ~ 6 weeks ago. Prior to that, I was an avid (and sometimes competitive) cyclist and runner. I resumed running ~ 4 weeks ago (with my doctor's blessing) and it is going pretty well. I started off easy at first and have worked up to where I now include one speed/interval workout a week, in preparation for some races in a few weeks. During these sometimes intense intervals, my HR gets as high as 175. Based on my pre-PM training, this is a pretty normal HR for me during such intervals.

So far, I've tolerated this type of training pretty well with no bad effects during or after these intense efforts. However, my question/concern is the following: Some of the posts and comments here have lead me to believe you shouldn't exceed your upper limit set on your PM. My lower/upper settings for the PM are 40/140.

However, I haven't felt any ill effects of going above 140. In addition to interval training, many of the more steady and easier paced runs are still above 140 for most or all of the run, and again I've never felt anything funky when I get above 140. Given this, should I be concerned about where my upper limit is set?

Thanks!
Tim

9 Comments

why did you get it?

by Tracey_E - 2008-09-04 06:09:11

What condition did you get the pm for? It sounds like your rate goes up on its own. As long as you feel good, go for it. The set limit is just the max the pm will go, it has nothing to do with how fast your heart can/will go when your heart is beating normally on its own. For me, my ventricular rate is completely dependent on the pm so if I get my atrial rate over the set limit when I'm working out, the pm won't let my ventricular rate keep up with the atria so I get dizzy and tired and have to slow down my workout until I get back under the limit again.

Regardless, you might want to ask about having it turned up higher when you have your next check. 140 is pretty low for someone athletic and otherwise healthy. It doesn't sound like you need it, but it doesn't affect anything else to have it higher.

Follow-up to Tracey's Question

by tjkirk - 2008-09-04 06:09:23

Hi Tracey,

Thanks for the reply; your explanation makes good sense.

To answer your question, I had an episode back in April in which I almost passed out, then a more serious syncope in July for which I wound up in the ER and which ultimately led to the PM implant. In both cases, the syncopes occured when I was at rest; either sitting in my office or at home.

The official diagnosis was 'AV node block', or something like that.I never had any of the tired or dizziness episodes while exercising, so I'm assuming the PM only really needs to kick in when my HR gets too low. I had asked one of the doctors why it was set at 140, and the answer was that the PM can't really pace higher than that.

blocks

by Tracey_E - 2008-09-04 09:09:03

They can definitely go higher! 130 or 140 is the factory setting. Most doctors don't have many patients that need them higher. I've been seeing the same doctor for 15 yrs and I'm still his only patient that's not retired and actively works out! (I'm 41) My pm can go as high as 180, and my doctor mentioned finding me another type that'll do higher than that next time I get it replaced because I still max out sometimes when I work out.

AV block means the message isn't getting from the atria (SA node) to the ventricle (AV node). It sounds like yours is not a 3rd degree block because you do just fine on your own some of the time, apparently at higher rates. I have the same condition but it's a complete block and my pm works more than 99% of the time because the message never gets through.

EP Nurse follow-up

by tjkirk - 2008-09-05 03:09:05

Thanks for everyone's advice; I'm starting to understand thing much better thru these discussions. I spoke with the EP Nurse who programmed my PM and she explained my situation quite well. She basically said the PM is activated with an upper threshold of 140, even though I don't have a condition such as third degree block that requires an upper threshold. It's there as a safeguard, so that in the event I had atrial high rates or complete heart block the upper rate would keep my heart rate from beating too fast. Makes sense to me now.

I also learned that my official diagnosis is "symptomatic bradycardia with syncope". While the doctors initially suspected some form of AV block, none of the EKGs or tests supported this.

do you need an upper limit?

by ixdes - 2008-09-05 04:09:07

HI,

I was given my PM back in may after passing out and a few dizzy spells (I am 39). I have carotid sinus hypersensitivity, and so only need the PM for when my hr drops. My bottom limit is set at 40, but I was told I did not have an upper limit set when I had my 6 week checkup.

If that is the case, maybe it would be an option for you.

Simon.

It is unfortunately common

by johnc_19 - 2008-09-05 04:09:57

I've also been a poster child for this problem for many years. The upper rate threshold is limited by the FDA device approval -- since device manufacturers aren't interested in proving the safety of the device behavior above that.

It is possible to get the rate limit raised on certain, not all, pacemakers. Some devices are limited by hardware and some are limited by software, so you need to find out which you may have.

If you have a SW limit, then it is possible although not guaranteed that your doctor can sponsor an exemption for you with the device manufacturer.

By the way, your peak natural heart rate is probably getting very close to the SW limit right now, so if you are unable to obtain the exemption you can essentially wait until your max heart rate slows naturally, and meanwhile, make sure your PM is adjusted properly to avoid "Wenckebach" 2:1 block, in which case your PM will intentionally skip beats after the peak rate limit is reached.

A good PM programmer is hard to find, and most cardiologists cannot program these types of special device behaviors (avoiding the Wenchkebach 2:1 block), so read-up and be patient.

If you are not PM dependent, you would probably prefer to track your atrial rhythm rather than use the sensor -- so if that is your situation make sure not to fall for that because it is cluge that causes more problems than it helps -- in my opinion.


Pacing upper limit ?

by johng - 2008-09-05 10:09:20

Tim,
TALK TO YOUR EP. OR YOUR PACEMAKER TECHNICIAN.
The upper limit setting may not be activated.
If your heart is otherwise sound, there is no problem in going to your natural limit, (remember you CAN overdo it ).
On a recent Stress Test, my heart rate was over 185 b.p.m. for about 2 minutes.
The Cardiologist made no reference to this until I asked if it would be a problem. He said that my problem was 2nd. deg. A/V. block, and the Rate Response was not activated.
Over 60 b.p.m. my heart is on it's own.
Hope things go well.
John

makes more sense

by Tracey_E - 2008-09-06 07:09:08

Bradycardia means your heart rate drops. That fits with your symptoms better than a block. With a block, the pm helps your heart when it wants to go faster. With bradycardia, the pm prevents it from getting to low and the upper limit is irrelevant because you're beating on your own when you get your rate up.

Hitting your upper limit

by W1LL14D - 2008-10-08 03:10:12

I recently got the go ahead to run also and the second time I ran I hit my upper limit unknowingly and started feeling a little sick which was from the PM trying to pace me back down then I got shocked. I went to the ER and they checked everything out and simply raised the upper limit to 210. I've ran everyday this week with no problems.

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