Why doesn't the auto mode switch of my pacemaker prevent all pacemaker medicated tachycardia episodes?

Pacemaker Mediated Tachycardia (PMT) ?

by Gemita - 2024-06-20 17:52:13

Do you mean pacemaker mediated tachycardia?  If so, has this been confirmed?  Your post isn't all that clear.

Mode Switch is a rate control setting designed to prevent the tracking of paroxysmal tachycardias that start in the atria (the upper chambers of the heart).  It works by sensing a fast arrhythmia and then switching to a non atrial tracking mode for the duration of the arrhythmia, thereby helping to prevent a rapid ventricular paced rate in response to the rapid atrial rate which could be dangerous.  Mode Switch cannot however stop the atrial arrhythmia. You may still need other treatments like medication or an ablation if you are having difficult symptoms.

PMT on the other hand does not start in the atria.  Therefore this cannot be helped by the Mode Switch setting.  PMT is a backwards conduction phenomena in the heart, where the conduction comes from the ventricles or from the AV Node and travels upwards into the atria.  This is often caused by a ventricular ectopic beat finding its way upwards through the AV node (or if present, an accessory pathway) which would lead to a mis-timed atrial contraction.  

If you have PMT you will probably need reprogramming of the pacemaker and this may involve lengthening the PVARP setting.  The PVARP is the atrial resting period after the ventricle has contracted known as the post ventricular atrial refractory period.  By increasing the duration of PVARP there is less likelihood that backwards conduction will be sensed and PMT triggered.  Another option might be to change the sensitivity of the atrial lead.

Do you have atrial tachy arrhythmias?  I do and my Mode Switch setting is set to recognise them when they reach a certain heart rate which is set at more than 171 bpm.  Sometimes if you get symptomatic episodes at slower rates, your doctor might want to set your Mode Switch lower to include these as well.  There are other settings that can help too, depending on your make and model of pacemaker.  Your Bio is empty?

It sounds to me as though you need to go back to your doctors and get this sorted as quickly as possible.  I hope they can help with settings adjustments if what you are experiencing is in fact pacemaker mediated tachycardia?  Good luck