Timing

My PM is set to "help out" at 45. But what about the pauses that I still get? While at the Dr.'s visit yesterday we saw a premature beat, a little extra beat and then a quick pause. Does the PM wait until my resting heart rate is at 45 to work or does it also help out when I get these pauses? Is there a timing interval of some sort?

I have a printout from yesterday but not sure what it all means and forgot to ask her about it when I saw it happening...her only response was that "everyone has them, nothing to worry about."

Thanks

6 Comments

timing

by Tracey_E - 2010-05-20 06:05:13

I'm going to use 60 for my example because the math is easier! If you are set at 60, it's really set for one beat per second, not 60 beats per minute, so it will not let you go a second without a beat. They can program how long the ventricle waits to pace after an atrial beat and all sorts of other stuff so it's not that cut and dried, that that's the gist of it. Two regular beats, a premature beat, then a regular beat will feel like a pause. Or, if you're going at 90 and pause, for a quick second you'll be paced at 60 so that will feel like a pause also. Clear as mud? LOL

Irregular Heart Beat

by SMITTY - 2010-05-20 06:05:27


Hello Wendit,

Yes, your heart rate should drop to 45 or below before your pacemaker will come in and try to maintain that rate, or one higher. The ringer in that statement is "try to maintain that rate." Our pacemakers can be fooled I found out the hard way. I'll try to explain that in my own words.

The pacemaker may let your heart rate drop below the lowest set point before it helps but it doesn't always happen that way. (My low set point was 70 and it let my HR go into the mid 40s many times) Even with skip beats, PVCs or PACs the heart's natural pacemaker may be sending an impulse to make the heart beat but those impulses are too weak to do the job. However, our pacemaker doesn't count heart beats, it monitors our heart function for electrical impulses that should make the heart beat. When one of these weak impulses from the heart's natural pacemaker are sent the manmade PM doesn't send an impulse and the result is usually a skip beat. On the premature beats, the PM can sense them and will not send an impulse, but one is not needed for a preemie as that is a heart beat but not a good one. The result is these weak impulses from the heart's natural pacemaker is fooling the pacemaker.

When arrhythmia such skip beats, PVCs or PACs are taking place our doctors will often times prescribe medications that will slow the heart's natural pacemaker to a point below the lowest set point on the pacemaker and let it bring the heart rate back to at least the low set point.

As for timing settings on a pacemaker there are such settings, along with about a jillion other settings. A couple I have heard about are the ones that tell the pacemaker how often to send an impulse to make the heart beat and the ones that determine how long the electrical impulse from the PM will last.

My suggestion is that if you are having this problem continue to contact your doctor and let him know things are not quite right yet. Otherwise he may think everything is perfect.

I wish you the best,

Smitty

Wow

by Pookie - 2010-05-20 09:05:35

what a great explanation smitty. thanks. I always learn something from you.


Wenditt....why is your pacemaker set so low??? 45 was my sleep mode. Just curious.


Pookie

Sleeping

by wenditt - 2010-05-20 11:05:41

It was set at 50 but while laying down to sleep, my regular heart rate was hanging out at 56, 54, 52, 51 and I could feel it kick in. I told her I didn't like the feeling so she said because my heart muscle is healthy she could turn it lower so that maybe I wouldn't feel it as much.

She said I use it so little that I shouldn't feel any symptoms but we'll see.

A Cardiologist's Explanation

by Genie - 2010-05-21 08:05:06

This is a long post...

I once asked a friend of mine who his training to be a cardiologist (he's been a doctor for 7 years, but is just starting to specialise) a similar question: I wanted to know if the pacemaker would stop missed beats if my heart was above the PM setting. This is what he said. It's very technical (at least to me) and is talking about my type of heart block (Wenckebach), but might be useful:

"The two leads each have a sensing and pacing function. The atrial lead will
obviously sense the atria and pace the atria, and the ventricular lead does
the same with the ventricle.
The atrial lead will therefore look out for atrial electrical activity (the
P wave on ECG) and if this does not occur at an appropriate time then it
will pace the right atrium. If it does sense electrical activity then there
will be no pacing in the atrium.

The ventricular lead will look at the ventricles (QRS complex on ECG). The
pacemaker device knows when electrical activity has occurred in the atria.
It will track this activity (i.e. wait and see) to the ventricle. If
electrical activity has not occurred in the ventricle when it should then
the ventricle will be paced. If electrical activity does occur in the
ventricle then it will not be paced.

Wenkebach phenomenon is a prolonging electrical interval between atria and
ventricles in each successive cardiac electrical cycle until such time when
there is no electrical activity in the ventricle (i.e. a dropped ventricular
beat). The cycle starts again.
In terms of electrical activity - prolonging interval is seen as a
lengthening PR interval (PR is delay between atria (P wave) and ventricle
(QRS complex)). The dropped beat is seen as a P wave but no following QRS
complex.

So what does the pacemaker mean for you?

Atrial lead will sense the P wave. It won't pace the atria. The ventricular
lead will track this electrical activity and wait for the ventricles to
react (QRS complex). If this does not happen within a pre-programmed
interval then the ventricular lead will pace the ventricle. The
pre-programmed interval (i.e the max PR interval) is not long. This will
mean that the dropped beat (or pause as you refer to it) will not occur.
Whether or not the PR interval prolongs depends on what is the max PR
interval allowed. So the PR interval might get slightly longer but when it
is getting too long then the ventricular lead paces the ventricle. The cycle
resets. But a dropped beat or pause will not occur.

In the situation you describe ("But the scenario is: I am awake, my pulse is
going steadily at 80bpm and then pauses for 2 secs."):

1. a pause like this is not necessarily abnormal
2. if it is wenkebach the pacemaker will react as above
3. if it is a failure of atrial activity (P wave) - i.e. atrial activity
does not occur when it should (i.e. long pause between QRS and P this time)
then the atrial lead will pace the atrium. When this occurs depends on what
has been set as the baseline atrial rate in the pacemaker. (NB this is not
the same as your pulse rate as the pulse is generated by the ventricle
contracting)."

Almost right

by ElectricFrank - 2010-05-22 12:05:18

Cabg,
It's actually the reverse. Us electronicers use a mirror to see where the smoke is coming from. That got exciting back when I worked on missles. LOL

frank

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