HIS-Purkinje Conduction System failure

Hi everyone, I got my Medronic's PM about 8 weeks ago. I have probably been having SVT for years but it was never caught on an ECG. Last April after a day of hiking my HR went up to 158. I was just going to bed and wasn't sure what to do about it. My FitBit caught it and I tested it with BP cuff. it was the same - stayed up for over an hour. I was becoming very anxious as it seemed like a long time for the heart to be beating that fast. They gave me adenosine, which brought it down right away. My cardiologist had me wear a monitor for a few weeks. I had a few episodes of SVT and it corrected itself. In June, while camping, my HR went up to 120 while I was not exerting at all. i stayed back from a hike and as soon as my husband and friends left HR went up to 175. We were high in the mountains and had no cell service. (i know, not very smart) HR stayed up for over 3/5 hours. My watch battery died and when they came back I used my husbands pulse OX and rate was 190. Went to the ER where they were going to cardiovert me, luckily they reached my doc who had them use adenosine again. Hung around for a couple of hours and was discharged. Not an hour later HR back up to 160 with no coming back down. Back to ER and another shot of adenosine. Transported by ambulance to my town a few hours away. My cardiologist referred me to an EP who expained ablation to me and I was all for it. When I asked her about any negatives she said there was only one but it was so rare that she had only seen or heard about it a few times and she didn't want to even discuss it since she was sure I didn't have that. So, went in for the ablation and woke up to find out that they shut down the procedure because I had the thing she said was so rare. Story of my life....the next day she inserted a PM. The DX is HIS-Purkinje Conduction system failure. I had to go back to the ER 2 days  post op for redness and swelling (no infection but a reaction to the glue on the bandage) He spelled out the DX for me as I hadn't really hear it before. He told me to not bother looking it up. He had and couldn't make any sense out of the one article he could find.

SOOOO....sorry for the long story, but I was wondering if anyone out there has this condition. I have a dual pacer set to go off below 60 and above 160. I am 71 years old and very active. We hike, ride bikes and camp a lot. (I did get an ebike before all of this started in June because I was getting so tired on my regular bike-no regrets, I LOVE the ebike) My concern is that by HR will go up to the 150s and not come back down, as it's done in the past and the pacer won't help me. Is that a worry? Should I go to the ER if that does happen? I find that I'm restricing my activities because of my fear. Like not going to high altitudes and hiking. This summer has sucked in so many ways and not spending time in the woods has added to my anxiety. 

Any comments would be appreciated.


HIS-Purkinje Conduction system failure

by AgentX86 - 2020-09-14 17:47:37

The HIS-Purkinje system is just the bundle of nerve fiber below the AV (atrio-ventricular) node, including the right and left bundle branches.  A failure is pretty much results in the same problems as an AV node failure (heart block).  I don't know how they could tell the difference, really.  Is it possible that they damaged this during the ablation?  Sure sounds like it to me.

You wouldn't have tachycardia from an AV node/His/Purkinje failure, rather the opposite (Bradycardia).  My guess is that you had the ablation for your SVTs and they cut the bundle of His by mistake.  It is a relatively rare complication but one nonetheless.

Pretty Picture:


As it relates to EKGs (figure 1):


I'd find a new EP, for sure.  Not because of this complication but because you're being talked to like a child without mommy in the room.  It's not a complicated concept and one I'm sure you're capable of reading up on and understanding.  The fact that she didn't answer your questions directly means that you couldn't have given "informed consent" at the time and it sounds like she's covering tracks now.  I could be all wet here but I'd certainly want to know more of the details, not that it helps you now.  But I'd fire her in a heartbeat, so to speak.

As far as your question goes...  Sure.  A lot of people here have a third-degree heart block. After Sick Sinus Syndrome, it's probably the most common problem around these parts.  I had my AV node and bundle of His intentionally cut (similar to you, but on purpose) about 2-1/2 years ago.  It's hardly rare.


Not enough information for sensible comment...

by crustyg - 2020-09-14 18:01:38

...or perhaps I just don't know enough small-print EP-cardiology.

At my basic level of cardiology, it sounds as though you have/had an aberrant-conduction pathway SVT (e.g. WPW).  An ablation of the aberrant pathway would make sense - often very easy, sometimes very difficult: there's always a small risk of AV-node damage during ablation, largely mitigated by the use of endo-cardial mapping and a skilled and experienced operator.

One would *hope* that a) His-bundle problems might have shown up on one of your many ECGs, b) that ablation of aberrant pathway + discovery of His-bundle problem + PM should have eliminated the SVT.  But perhaps not if they didn't actually ablate anything.  No PM is going to help with an SVT - you can't pace someone out of it.  As you know, IV adenosine is the treatment of choice, but you can't carry that with you.  DC-cardioversion is a very poor second best, and you really don't want repeated crash inductions (of anaesthesia) to render you unconscious for it: DC-cardioversion while you're awake is reach-for-lawyer territory - it really hurts.  Carotid massage / Valsalva manoeuvre are the two common techniques taught to WPW patients to try and control an SVT episode: they sometimes work.  Have they talked about these?

It seems to me that either they abandoned the ablation so you're still at risk of SVT episodes (which could kill you - sorry, but that's the truth) or they actually did the ablation so the SVT is now gone.  Brother of a friend of mine died in a hotel from a WPW-SVT episode, and my EP-doc showed me my worst ECG in AFlut (1:1 conduction at 230BPM - sudden cardiac death territory).

Or there's some third interpretation which I can only guess at...  AgentX86 puts it very well.

In your shoes I would want a good, long conversation with my EP doc - with a friend/supporter/advocate with me to make sure that I capture everything and to help me understand exactly what they did and didn't do, and what name they have for the DX - and the academic paper that describes the condition.  This is serious stuff.


by Gemita - 2020-09-14 22:03:38

SVT was one of my first arrhythmias detected.  I too have had this arrhythmia for years.  On one particularly bad day I went in and out of SVT 18 times and during one of those episodes, the SVT degenerated into an episode of Ventricular Tachycardia and I quickly became very unstable.  I was out at the time and it was a terrifying experience.  The event was confirmed by Reveal Linq Implant.  

I have used vagal manoeuvres in the past to try to stop my SVT but these manoeuvres have only been partially successful since, although they can be very effective at stopping or preventing an attack, they can also trigger attacks or worsen them for me.  I find deep controlled breaths can be very helpful to calm SVT.  I have had an EP study which indicated that there were no accessory pathways.  I was offered an ablation for SVT and other arrhythmias, but because I have several arrhythmias originating from different sites, I knew I was looking at more than one ablation to fix them all - more ablations, greater the surgical risk.  I chose medication and a pacemaker instead.  So far it has been the right choice for me.

My doctors have told me that whenever I feel I need help, to call for an ambulance since high sustained heart rates can weaken my heart and cause heart failure.  I would recommend that you go to hospital or call for help based on your symptoms, not just on high heart rates (e.g. if you become breathless, have chest pain, feel faint/unstable).  I am also 71 years but not as active as you. 

You say you have a dual chamber pacemaker set to go off below 60 and above 160 bpm.  Although your pacemaker can stop your heart rate falling below 60 bpm, it cannot prevent a high heart rate exceeding 160 bpm unless you have a different device like an ICD ?  I am assuming the 160 bpm figure is the upper rate, when your pacemaker is set to trigger an event and store this information for your doctors to download and decide whether any medication given is effective for you.  Too many triggered events above 160 bpm and of long duration may need higher medication doses to control your heart rate.

I too am uncertain what your diagnosis is and what has caused it.  I wonder if they erroneously took out your AV Node to try to stop the SVT.  Unlikely I know, but possible I suppose.  As AgentX86 and crustyg have said, you really need to understand what has happened and whether or not you have had an ablation (and what kind) to stop your SVT?  If not, how will they manage to keep your heart rate under firm control should you have further episodes?  There are just too many questions unanswered but the sooner they are answered and addressed, the sooner you can get on with your life.  I do wish you well.


HIS-Purkinje Conduction System failure

by Sooz - 2020-09-15 16:23:35

Thanks for all of your responses. Though, I will say, they are a little disturbing. I feel pretty confident in my EP - for what it's worth, she was just named top female EP in the country but i guess that doesn't mean she is immune to mistakes. I have sent for my medical records so that I will have a better understanding of what took place during both procedures. I will be talking to her about the top setting as it was both my husbands and my understanding that it would somehow not allow my rate to go higher than 160. I am taking 120mg of Cardizem and my HR hasn't gone over 130 while exercising and it comes right back down, so that makes me feel a little better. It's the high altitudes that worry me. I'll do more research and try to figure this all out. I honestly never thought I'd be dealing with any of this, but then, who does. I'm glad I found this group. Just knowing I can get some answers is helpful.

continued from above

by Sooz - 2020-09-15 16:36:22

My ECG's have shown BBB for a number of years. The cardiologist never seemed concerned, so I wasn't. I had a CABG 20 years ago. Many years ago I taught Lead ll ECG interpretation to medical students so have a pretty good understanding of the conduction system, though I was quite a bit younger and don't remember a lot about the finer issues now. It was difficult while I was in the hospital as my husband was not allowed in due to COVID. He was able to come with me to the follow-up appt. He was a trauma nurse and nursing adminstrator for all of his work life and has been my historian/advocate for years. We went to the follow-up with 3 pages of questions and the doc and then her PA were very happy to answer all of our questions. I'm guessing we didn't ask the ones that would have been most helpful. I'm now starting a new list of questions. Thanks again for your help.

Thank you for the update

by Gemita - 2020-09-15 17:12:41

Well I am totally confident that you will get to the bottom of all this with your background experience.  I am sure you and your husband could teach me a great deal.

I too have bundle branch blocks and my EP was unimpressed.  It takes a lot to excite him (his words not mine).  I don't find my arrhythmias at all exciting !!  

Try not to worry -  Cardizem is a good med and might be all  that is needed to keep your SVT under good control.  Bisoprolol + my pacemaker are working well for me.  

not allow my rate to go higher than 160

by AgentX86 - 2020-09-15 23:29:13

No, a pacemaker won't restrict your heart rate.  It just won't pace it faster.  If you're having an SVT, there is nothing the pacemaker can do but sit back and watch.

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