Cycling

Good news day! I had a Guidant pm installed in 2005.
HR had dropped to 30 on a bike ride. Normal resting pulse was about 52. Now participating in veterans' bike races - lowest grade- not too hard. My only slight concern is that during a ride my pulse sometimes goes over 150 (a couple of times at 160). I believe at aged 74 my max should be around 150. Any comments? Matelot

3 Comments

Heart Rate

by SMITTY - 2007-11-20 03:11:26

Hello John,

I take it from your message that you are of the opinion that your pacemaker will hold your heart rate in the range of the settings, without fail. If you have an "on demand" pacemaker, as most of us do, my understanding is that is not exactly the way these things work.

What the settings means it that the PM will come on line should your heart rate drop below the low setting, what ever that may be, and do its best to make your heart beat at that level. If your heart rate goes above that low setting the PM will continue to check your heart beat and help as needed until your heart rate reaches the maximum setting. From that high set point on, your heart is on its own as the PM just monitors your heart beat. According to what the nurse/technician told me, my PM, which is a Medtronic KDR 703 series, will store information on my maximum heart rate that can be downloaded during a checkup.

Now let me preface all this with the statement that I’m not an expert on these things. I’ve had one for almost 8 years, and it has put me through the ringer in more ways than one. Right now my settings are 70 to 110. Just yesterday I was plagued with a HR in the 50s all day. They tell me that this can happen because my hearts natural pacemaker is sending out a signal that it will cause my heart to beat, which my PM sees, but the signal is not strong enough to cause a heart beat, but the PM does not realize that and does nothing. So I end up with skipbeats or PVCs and felling like the devil. At one time I had hope that there were PM settings that could prevent this, and there may be, but not by this bunch I have to see for checkups.

As for what your maximum heart rate should be I will not even venture a guess. However, I would guess that a lot depends on your heart‘s condition and your overall health. Of course the person to give you that information is your doctor. But, I will GUESS that the 160 you saw was due to the physical load from you rexercise and was not caused by your PM.

Good luck,

Smitty

surprised

by gevans - 2007-11-21 10:11:33

Hi John,

I will concur with Smitty except mine has never gone below the lowest setting. That is what the thing is supposed to do for heavens sake. My cardiologist started me at 60 -105, then upped it to 70 - 105 when there was afib still present. I have had it go over the upper limit many times and I've measured it at 160 quite frequently after a brisk run (but now he's discouraging me from pushing too hard because of an unrelated issue).

He said that the built-in computer (on my dual lead St Jude's) will speed up the heart within those parameters when it senses that I'm exerting myself, but once I'm over the upper threshold the heart is "on its own" and I will eventually fatigue from lack of oxygenated blood to the muscles just as it would have prior to my implant.

I have never felt the afibs on the lower end of the spectrum because the PM takes over during those episodes. I am shocked that your PM allowed you to even get below that rate without kicking in.

I'm sure there are many different types of PM so maybe others on this site will be able to clarify this further - but I'm sure glad I have had the proceedure and I'm thankful that I was given a new lease on life.

Gary

Cycling and Pacing

by Cycledoc - 2008-01-02 09:01:13

My pacemaker, also a Boston Scientific/Guidant, was placed in November. I had complete heart block with a rate of about 37 at rest with some increase with exercise to a maximum of about 110. The pacer seems to do fine while being sedentary and doing stationary cycling with a rate increase proportional to my exertion.

On the road I've had a similar experience as you with rates going up rapidly to the max of my pacer which is about 145--your physician can set a maximum pacing rate. Even a relatively modest incline results in a marked increase in rate--and in my case fairly rapid fatiguing--I'm 66.

These are complicated gadgets. The rate response can come from a sensed impulse from the heart's normal pacemaker, the atrium (at the top of the heart). The rate is also augmented (if turned on) by the artificial pacemaker's accelerometer (apparently a sensor that picks up changes in speed) and a measure of your minute ventilation (apparently something to do with the speed of your breathing)

As I understand it, if you simply have heart block without disease of the atrial pacemaker (the one in the top of the heart) then you may not need the augmentation of rate from the accelerometer and minute ventilation--which I think is my problem.

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