Tachycardia and Pacemaker

I know my PM causes my heart to beat 60bpm when it slows down. But does it slow your heart down when it is beating too fast? Thanks.


In general no...

by crustyg - 2020-03-14 05:58:27

A pacemaker, as the name implies, drives or paces the heart.  In the motoring metaphor it's an accelerator not a brake.

For a few patients with tachycardias from the atria, a PM *can* be programmed to increase the atrial pacing rate (for a short while) so that not every electrical activation from the atria reaches the ventricles.  It does this by pushing the atrio-ventricular node (AV) into a 2:1 or 3:1 block so that the ventricles actually beat less often even though the atria may be running at 150bpm or faster leaving the ventricles running at 75bpm or so.  This programmed behaviour doesn't last for long and it's not a common action, but it has its uses.



by TimMcCoy - 2020-03-14 12:10:16

What a great way to explain it... it's an accelerator, not a brake. Thanks HTH. 


Another perspective

by Gemita - 2020-03-14 12:55:20

Hi Tim, 

From personal experience I am finding that by my pacemaker pacing me at a steady rate (70 bpm)  day and night (which is a much higher rate than my norm), this often prevents my arrhythmias, including tachycardia, from taking a hold.  It was the slow, irregular, pausing heart beats which were leading to many of my arrhythmias and this “over pacing” is proving a real winner in helping to stop, or lessen the duration of these unwanted episodes.

With regard to Atrial Tachycardia in particular and whether a pacemaker alone has the ability to stop attacks or reduce rates, I have to agree with Crustyg this is not possible, unless we were to take out the AV node and prevent any atrial rhythm disturbances from passing through the AV Node to affect our ventricles and then just pace our ventricles.  However should we have a dangerous arrhythmia which starts in the ventricles like Ventricular Fibrillation or sustained Ventricular Tachycardia, a Defibrillator would also be required to shock the heart back into a normal rhythm and terminate the tachy arrhythmia to hopefully prevent sudden cardiac arrest.

I have a dual chamber Medtronic pacemaker and when it detects a high heart rate in the atria it will automatically switch modes and pace me in the right ventricle, so as not to track any atrial tachy arrhythmia which would cause high rate ventricular pacing.  When the atrial tachy arrhythmia terminates, my pacemaker senses this and automatically switches back to tracking the atria again.  Mode switch is triggered when an atrial tachy arrhythmia is detected at a certain speed (set by your EP).  So for instance, if my heart rate reaches 130 bpm  (or the set upper tracking rate) my mode switch would come on and pace me in the right ventricle instead, rather than tracking the chaos going on in my atria.  I have SVT, AF, Flutter, Atrial Tachycardia and I can have really high ventricular response rates, so obviously switching modes will be helpful.  Even though the atrial tachy arrhythmias are still getting through the AV node to affect the ventricles, our AV node does slow this process down and then with AV nodal blocking medication like a beta blocker, our heart rates can be better controlled.  So that is my understanding of what the mode switching facility does.

I would ask your EP what programmes and settings you have to help prevent and/or slow down your tachycardia.  There is so much that can be done to make us more comfortable

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The pacer systems are really very reliable. The main problem is the incompetent programming of them. If yours is working well for you, get on with life and enjoy it. You probably are more at risk of problems with a valve job than the pacer.