How does rate response work

I have an ICD and have problems with getting the rate response settings adjusted correctly. A small level of activity or road vibration results in my heart rate increasing significantly and I feel pretty awful. Could someone please advise how an ICD works, in particular the sensing of activity and how it increases your heart rate. Thank you


1 Comments

Rate Response

by SMITTY - 2008-08-10 12:08:43

Hi Steve,

If I understand rate response as well as I think I do, it works in the following manner:

The rate response in some pacemakers (which one depends on the make and model) is controlled by an accelerometer. An accelerometer is basically a tiny electronic component that senses the degree of vibration in the body (when you move, it causes the tissues of the body to vibrate) and increases the heart rate in proportion to the amount of vibration (and hence the amount of movement). More specifically, an accelerometer is a transducer which converts mechanical motion into an electrical signal that is proportional to the acceleration value of the motion.

In other words, this is a very simple process. One way to test the competence of the "motion sensor" is simply to tap the pacemaker itself with your finger. The heart rate should noticeably increase. If not, then there's very likely a pacemaker malfunction or an adjustment is needed.

The sensitivity on the rate response part of my Medtronic is adjustable. The first settings I had would increase my heart rate with almost any physical movement. That sensitivity level was reduced, but it is still a pretty sensitive setting. Like you, when I drive over a rough road where the hjostling lasts for more a few seconds, my heart rate will increase, even though I am sitting perfectly still.

Smitty

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So, my advice is to go about your daily routine and forget that you have a pacemaker implanted in your body.