Pacemaker Mediated tachycardia

Ok, so I saw one of my doctors yesterday, an ENT guy and the conversation went like this.

Me - well I feel like I have POTS but without the tachycardia

Him - that’s probably because of your pacemaker.  I’m going to have to check on this.

So, is it possible to have most of the symptoms of POTS and have a pacemaker that hides or corrects the tachycardia?


PMT or PoTS ??

by Gemita - 2022-06-15 05:46:25

Simon hello, hope you are doing okay.  Can we just clear something up, your headline message says PMT (pacemaker mediated tachycardia) and yet you go on to talk about PoTS (postural orthostatic tachycardia syndrome).  Two completely different matters, or do you have both diagnosed?

I just had a quick glance of your history and see you have a CRT-P.  Your pacemaker won’t stop any tachycardia as could say a CRT pacemaker with a ‘defibrillator’.  Only your medication or an ablation may help to control or to stop any tachycardia caused by an arrhythmia. A simple pacemaker cannot hide or correct an arrhythmia.  

In PoTS, the autonomic nervous system doesn’t always work properly (I attach a link).  There can be a drop in blood supply to the heart and brain when you stand and the heart races to compensate for this.  I can intermittently get either a fall in blood pressure on rising, or an increase.

Unfortunately a pacemaker cannot treat blood pressure falls or increases, so it is possible that PoTS sufferers will still get some episodes of pre-syncope/syncope.  I certainly continue to experience pre-syncope and have had one short syncope episode at home since receiving my pacemaker.

“So, is it possible to have most of the symptoms of PoTS and have a pacemaker that hides or corrects the tachycardia”? you ask. While your pacemaker cannot stop tachycardia caused by an arrhythmia, it may help to mask the symptoms of tachycardia by helping to ease any symptoms you might be getting.  For example, do you have any anti tachycardia pacing programmes set up that you know about?  Many pacemakers have programmes set up to help with arrhythmias.  You should ask your doctors what programmes you have set up, some of which can switch modes to avoid tracking any fast heart arrhythmias and then switch back to your normal pacing mode when the fast arrhythmia ceases. 

For me personally my pacemaker has certainly helped me to correct intermittent PoTS symptoms (as you know I have Ehlers Danlos Syndrome) by maintaining a steady, higher base rate setting.  I had bradycardia induced arrhythmias triggering abnormal heart rhythms which frequently led to atrial fibrillation with a rapid ventricular response rate.  With my pacemaker, my arrhythmias have indeed been tamed.  Quite an achievement I feel and if I am honest Simon, I didn’t really expect this level of success with a pacemaker, since my EP warned me that only a small percentage of patients benefit.  And to think I was heading for an AV Node ablation.

So to conclude, a pacemaker can prevent heart rate falls below our base rate BUT cannot treat heart rate increases due to arrhythmia (unless we have a defibrillator for our arrhythmias or heart condition).  Furthermore, a pacemaker and/or defibrillator cannot control our blood pressure which is why syncope can sometimes be so difficult to manage even with a pacemaker.


by ROBO Pop - 2022-06-15 18:04:00

If it is PMT they can increase your base rste to overcome it. Worked for me


by simonsimon - 2022-06-16 02:42:32

I haven't been diagnosed with either PMT or PoTS, I am trying to determine where my symptoms of imbalance, dizziness and muscle weakness in legs is coming from. Hello Gemita!!    So good of you both to comment, I always admire the feedback i get here

At the risk of revealing too much information, I thought this might be helpful for me to understand from your understandings 

I had a virtual meeting with my electro physiologist here are some notes 

The device is a Medtronic Percepta CRT–P model number RNP 612506S which was implanted on July 12, 2021. The estimated longevity of current settings is 9.4 years.

The atrial lead is a model 5076 with a pacing impedance of 361 ohms, capture threshold 0.75 V at 0.40 ms, and a P wave of 2.9 mV.

The RV lead has a pacing impedance of 418 ohms, capture threshold 0.65 V at 0.40 ms, there were no R waves recorded by the device.

The LV lead has a pacing impedance of 361 ohms, capture threshold 0.0 V at 0.6 ms.

The device is programmed DDDR with a lower rate of 60 and an upper tracking rate of 145 bpm. The device is programmed to nonadaptive mode. The paced AV is 150 ms, sensed AV 120 ms. Mode switch for atrial arrhythmia starts at 171 bpm.

There is a VT monitor zone starting at 150 bpm.

Based on these parameters there were no events. He is active approximately 4 hours/day.

He is paced in the atrium 48.7% of the time and 99.9% paced in the ventricles.

Device shows Excellent parameters

 Source of his hyponatremia which can cause some of the symptoms is being investigated

Despite all of his issues, he continues to walk 1.3 miles per day

Hyponatremia - low sodium

by Gemita - 2022-06-16 05:08:06

Simon, hyponatremia is being investigated and could clearly be the cause for some of your symptoms, as stated.  I would get regular electrolyte checks for magnesium and potassium too especially with your diuretic and other meds.  And if I recall correctly you have right sided heart failure, so a lot going on (not to mention your Marfan's Syndrome).  

I will have a look at your settings and compare them with mine and report back any thoughts when I return home later today.  I am very glad you don't have PMT or PoTS

Just a few thoughts

by Gemita - 2022-06-16 20:19:10

Simon I have had a look at your notes/settings.  I am not a settings expert, so perhaps others can help us out?  The LV lead shows a capture threshold of 0.0 V at 0.6 ms.  You could check this with your cardiac technician to make sure this capture threshold is correct and normal for you personally?

The rest of the info you provided looks within range from my own personal records for my right atrial lead, right ventricle lead capture thresholds and pacing impedance. There is certainly nothing that would give me cause for concern.  I note you are pacing almost 100% in the ventricles and also have almost 50% atrial pacing.

A couple of questions you could ask your EP:-

I see your pacemaker is programmed to a non adaptive mode.  You could ask why and also whether adaptive pacing (synchronising your two ventricles better) might help with your symptoms?  At least get them to explain the benefits of adaptive pacing to see whether it would be suitable or better for you if you have this function available.  

You could ask whether another session working with a cardiac technician to fine tune all your settings while exercising could be arranged?

I would ask whether you are getting any arrhythmias like AF at lower heart rates which could be causing some of your symptoms or worsening your heart failure?  A high burden of arrhythmias, including PVCs may adversely affect CRT pacing.

Have you recently had your Ejection Fraction checked to see whether it is stable, worsening, improving and whether you are on appropriate meds to help with your health condition(s) and symptoms?  I would ask for all your electrolytes to be checked, not only sodium levels and also to look for any other conditions as a cause for your symptoms?

Simon, the good news is that your pacemaker did not show any high heart rate arrhythmia episodes or significant events for either atrial arrhythmias (starting at 171 bpm) or ventricular arrhythmias (starting at 150 bpm), but of course with heart failure, even slower arrhythmias could cause troublesome symptoms so they need to be controlled if present.

Hyponatremia (low sodium levels in the blood) can certainly lead to the symptoms you describe and I am glad this is being properly investigated.  Otherwise, I am uncertain as to the exact cause for your imbalance, dizziness, muscle weakness Simon, other than the latter (generalised muscle weakness) coming from heart failure.  Fine tuning your pacemaker settings to get your ventricles to work well or better together will definitely help and that is what I would try first.  In any event it will do no harm to let your doctors know that you want to make your CRT as effective as possible to help you to manage your condition and to improve your quality of life.  Good luck Simon.  I know you will succeed.


by simonsimon - 2022-06-16 23:55:13

Thanks again that is such helpful inormation, I am definitely going to follow up on your suggestions, they seem like they could be very helpful. I will let you know what happens :))


one more thing

by simonsimon - 2022-06-17 13:47:37

It was noted by the EP that I did have one short run of a fast hearbeat, lasting 7 beats. Given how short this is, they would not want to make any changes.

Please keep us updated

by Gemita - 2022-06-17 16:18:30

Simon, out of curiosity, did your EP disclose whether the fast heartbeat came from the atria or ventricles?  A short run of an atrial tachy arrhythmia of 7 beats wouldn’t be significant, but if it came from the ventricles, a fast 7 beat run of non sustained ventricular tachycardia, although also not serious, may need watching with heart failure.  

Glad you are getting some feedback though Simon.  I sense they don’t feel that your settings are the problem and that your symptoms are probably due to other conditions.  Please keep in touch and update us whenever you can.  I want to hear a happy ending


by simonsimon - 2022-06-23 13:06:07

Gemita -  my EP responded to your thoughts with this -- thorough note by your friend with an excellent assessment. Please let them know, your device is programed to non adaptive because you have high grade AV block and you need to have a PR interval for this algorithm to work, that is why it is off on you.

Your heart rate histograms does not give any evidence of atrial arrhthymias below detection or we would see those beats in a 'bin' recording them.

A comprehensive echo 1.5 years ago showed a normal, low LV function in the 50s.

The device does daily thresholds and all of those are fine.

she also said she wants to hire you!!

Thank you for the update Simon

by Gemita - 2022-06-24 07:22:22

Simon, what a nice response from your EP.  She sounds charming. It is always nice to receive feedback since it is a learning process for all of us. 

You have a CRT which is clearly a more sophisticated system than a dual lead pacemaker (Right Atrium to Right Ventricle) and we will all have our own unique health problems too which will only add to the complexity of our pacing requirements.  Really interesting to read about your high grade AV block and why your device is programmed to non adaptive mode Simon.  Needs further study but I suppose it may not be appropriate or always safe to use AdaptivCRT for all patients, depending on their individual heart condition, see Medtronic Academy link below Simon for further reading:-

I do appreciate all the answers your EP has given.  They are very clear and she seems to be following you most carefully for any serious “events” and deterioration in your condition.  I would be surprised though if your pacing system didn’t record a “percentage figure” for all your arrhythmias, for example, the time you spend out of normal sinus rhythm and in an arrhythmia like Atrial Fibrillation, Atrial Tachycardia, Sinus Tachycardia, Atrial Flutter, SVT etc. irrespective of whether or not your heart rate was below the detection rate for it to be recorded, i.e. (171 bpm for atrial tachy arrhythmias and 150 bpm for ventricular tachy arrhythmias), especially if the arrhythmias were of a long duration.

I see the thresholds set are being monitored daily which is reassuring and that you last had an echo 1.5 years ago.  Of course things can change, so keep an eye on your symptoms and report any new concerning symptoms which might point to a new or a deteriorating existing problem (like for example an arrhythmia).

I think most of us would really benefit from understanding just what has been set up in our pacemakers, what is being monitored, what is being left out, so that we can follow our progress and know what questions to ask in the future, but this will be a lifelong, interesting task.  Good luck Simon and thank you for your great post as always. 

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