What happens when...

I am  CRT-P pending (May 1st).  In my meeting with my EP he said the Medtronic device I'd be getting will have a max of 160bpm.  I didn't think to ask at the time, but what happens if my heart rate exceeds 160?  I ask because for years now if I engage in aerobic activity for more than a few minutes my heart rate regularly pops up to over 160.   I understand that part of the reason is because my EF is below normal so my heart is beating faster trying to get more blood circulating.  And hopefully once CRT-P is placed, my EF will improve so in time my heart won't have to work so hard.  But out of curiosity, what does happy if my HR does exceed 160 after placement?  Do I blow up like some character out of the movie Alien??? (*haha*)


It won't!

by USMC-Pacer - 2024-03-09 20:40:44

It won't blow up :) So many questions as to why you you are getting the device. Is it for heart failure alone? Do you have heart block? Is the device to correct dissynchrony from a branch bundle block? Is your heart failure from a prior heart attack? Is this your first device?

As far as the MTR of 160bpm, the device will only follow you and pace you to 160. If you don't have heart block, it won't stop you from going higher. With heart block, it will stop you at 160bpm and more than likely put you into a 2:1 block and knock you down to 80bpm. It all depends on your condition.. Others will chime in :) 

Answers that I have

by Andiek11 - 2024-03-09 23:48:01

As a newbie i'm still getting used to all of the "details" one must specify...  *insert rolling eyeballs* 

I have had LBBB for over 26 yrs secondary to cardio toxic chemo drug I had way back when.  EF is now down to between 40-45%, and LV is at upper limit of normal.  NO other heart disease or dysfunction.   I guess this is considerd Class 2B Heart Failure w/ reduced Ejection Fration per my EP (if I'm getting the lingo correct).  No meds untill about 5 months ago and then they were started primarily because insurance said I had to try meds before getting approved for CRT-P.  (Metoprolol Succinate and Losartan - both at very, very low doses respectively)  Meds made no difference other than leaving me feeling tired and putting on weight.

I also need you to translate your last paragraph because I've no clue what you've said. :)


by USMC-Pacer - 2024-03-10 03:34:27

LBBB patients have higher success rates with CRT pacing so that's good news for you. I'm assuming your QRSD was wide which can cause ventricular dissychrony.. 

As far as my last paragraph, if you don't have heart block then it is not going to affect you. Heart block is the signal between your sinus node and atrioventricular node is either broken or partially broken (different classes of heart block) With this condition, at least for me, on the treadmill the DR. had me run. I observed that my atrium was at 150bpm, but my ventricles were at 75bpm. At the time, I had intermittent block. <--there's so much more to it but I'm trying to keep this shortish.. So my paragraph above I mentioned MTR with stands for max tracking rate. That's what your DR said your max would be is 160bpm. For you, it won't matter as you don't have heart block. For me, my ventricles would not go over 75bpm without the device. So when they set a max, that is as fast as it will go whatever the MTR is set at. If I go higher, it will put me into a 2:1 block to protect me from what I have no idea :) I'll attach a brief explanation link below.. read #11



Heart block with exercise

by JaneJ - 2024-03-10 04:08:24

This is reallly interesting and now I realize why I can't run for very long.... I have a crt device and atrial asystole as well as complete heart block.  I notice whenever I start running I kind of lose my steam within 2-3 min if starting.  I have plenty of cardiac output initially and then ...bam... I have nothing to keep going.  Hypothesizing it's knocking me back down to 70 when I hit my max tracking rate, which I believe is 130.  Maybe they could increase it?  I'm in fairly good shape and only in my mid 40s.  Will have to bring that up next time I see them.  Best of luck with your crt device Andiek 🙂

If your coronary arteries are clear and heart muscle healthy, ask for a higher maxHR

by crustyg - 2024-03-10 04:38:56

Very few EP-docs have much personal experience of normal maxHR in athletic adults, and even less so for us Seniors.

A maxHR of 130BPM is way too low for healthy heart muscle with a good blood supply *unless* there's a tendency to arrhythmias at higher HR in you.

Ask for a higher maxHR.  I was given 140BPM at implantation but had it raised to 160BPM five weeks later.  Firm, polite, and determined.

JaneJ - Yes, tell them to raise it!

by USMC-Pacer - 2024-03-10 13:39:19

As Crusty said, barring any other conditions, ask them to raise it. Most devices come default with lower MTRs and if you don't ask or complain, they won't adjust it. Mine has been adjusted a few times and is now at 150bpm. After a few PVARP adjustments, I never hit the MTR anymore (I limit myself). I have my next visit next month and I'll ask them to raise it again because I don't want to limit myself :)

You'll be supercharged and able to run all you want!


higher rate

by Tracey_E - 2024-03-10 16:18:34

I'm not sure about CRT, but there are a few 2-lead pacers that have an upper limit over 160. That said, they may not want your rate going higher than that. I would ask. 

If your rate goes up on its own, the pacer will just sit back and watch. It's a gas pedal, not a brake, so it can't prevent your heart from going up on its own. 

If you are depending on pacing to get your rate up, the pacer will only get you up to 160, assuming that's where they set it. You will only feel good working out up to about 155.

I have complete heart block so my atria beats normally but I depend on the pacer to keep my ventricles in sync. I used to have a pacer that only went to 160. My sinus rate would go higher than that, the pacer would stop at 160, the heart would be out of sync, and it feels a bit like hitting a wall. I got used to backing off whenever I got over 150 so I didn't hit the limit. That was frustrating to me so I eventually went on a low dose beta blocker to keep my rate down. When that one was replaced (I'm on #5), they gave me one that goes to 220 and I stopped the beta blockers. Before they'd let me get higher, they put me on a treadmill to make sure everything looked good when I was over 150, and how high my sinus rate actually got, which is 165-170. So now my upper limit is 190 which means I have a bit of a cushion and don't bump the upper limit.

The first question for your doctor is, is it safe for you to get your rate up over 160. Wtih a low EF, they may not want you working your heart that hard. Second question is, are you pacing when you get up there or is it all you. Third (if the answers to 1 and 2 are yes and pacing) then ask if there is a CRT that goes over 160, and can you pretty please have it. 

Maximum tracking rate

by Repero - 2024-03-10 17:36:55

I guess the appropriate MTR for each of us depends on the condition of our heart, and also our age: something to be discussed with our doctors.

Using the formula (Max HR = 220 - Your Age), which presumably applies to healthy hearts, mine comes out at 145. I have complete heart block and my MTR is set at 130, or 90% of my maximum.

I have hit this a few times when dancing, and I can certainly feel Tracy_E's wall, but I have never exploded. I can live with this and feel reluctant to insist that they raise my MTR: obviously, there isn't that much scope in my case anyway.

Thanks to all....

by Andiek11 - 2024-03-10 19:18:28

Appreciate everyone sharing their expertise and knowledge..  A most interesting learning cuve. :)

I do indeed have increased QRSD >150.  And even my EP and Cardiologist agree *haha* that I am an excellent candidate for CRT-P and they have hopes that i'll respond very well.  All encouraging news and given the wide range of stories from others, I'm very appreciative that this could have been a whole lot worse.

But back to my original question.  I know that I will be 100% paced in that if the unit doesn't send the signal to my LV, it never gets one.  So if my MTR is set at 160 that means my LV will get the "timed" signal at the right moment up to a HR of 160.  But what exactly happens if my heart rate goes above 160?  I gotta feed that techie-geekie side of my brain and understand how my body and the device interact.  

Many thanks to all once again, and mind blowingly good to hear how these devices have helped so many different conditions.  


by USMC-Pacer - 2024-03-10 19:45:22

If you don't have heart block, that number is irrelevent to you. I'm not even sure why your EP mentioned it. 

Like Tracey_E said: "If your rate goes up on its own, the pacer will just sit back and watch. It's a gas pedal, not a brake, so it can't prevent your heart from going up on its own." 



by Andiek11 - 2024-03-10 20:10:08

Tracey_E and USMC-Pacer, thanks for your clarifications.  My geeky brain is at peace now.  My personal hope is that with improved EF which is their goal and mine, perhaps my heart won't need to work so hard during exercise / physical activity, so maybe the 160 limit won't be an issue.  And as for "pretty please - ing" my EP, I have absoluely no hesittions is broaching this topic (*Evil Grin*).  They always say they like it when patients have questions, so I'm taking them at their word - perhaps a bit to their consternation.... *lol*  

We're a different breed..

by USMC-Pacer - 2024-03-10 22:45:08

I was 47 when I got my 1st device and my NPs weren't used to my demands of more, more, and more. They abliged but it took some convincing with the EP to get them to raise my MTR from 125 (default) to finally 200 :) That and a few avdelay adjustments and I was good to go for over 10 years until the battery ran out :(.. that is another story. I think most EPs aren't prepared for the physically fit individuals that aren't okay with slowing down and being sedentary. I know I was a learning curve for my NP.. She has been great though!

Great info!

by JaneJ - 2024-03-11 02:22:47

This has been super interesting and helpful post to follow.  I hope all goes well for you Andiek!  I actually don't have a low ef whatsoever, it's completely normal, so I doubt that would be an issue with raising the max tracking.  They put a crt in based solely on the fact that I pace a large percent in the ventricle and had concerns about potential pacemaker induced heart failure.  To be honest, in retrospect, I really wished they would of just gone with the traditional dual chamber.  All the leads stuck in my veins set off a massive cascade of blood clots throughout my innominate, subclavian and even clotted into my internal jugular veins.  Consequently we found out after the procedure that I have a clotting disorder.  Fingers crossed during my battery change this year things won't go to bad with blood clots.  Anyone else have a crt device put in just based on high percentage of v pacing?  I feel like that's not a super common thing to do....


by Gemita - 2024-03-11 06:51:47

Jane, I think your question

"Anyone else have a CRT device put in just based on high percentage of ventricular pacing?  I feel like that's not a super common thing to do….”

would make an excellent new post?  If you don't do one, I might.

No it would not be a super common thing to do.  It would certainly not be an indication in the UK for CRT on its own.  An indication for CRT would generally be evidence of a failing heart with an Ejection Fraction of less than 35% especially if medication and lifestyle changes had first been tried and failed. 

Let us face it, any procedure carries some risk, even pacemaker implant or upgrade and if something isn't broken, why try to fix it.  Many of us do exceedingly well with a high burden of RV pacing if they need it and never go on to develop heart failure.  My EP stated should I ever show signs of developing heart failure in the future from a high degree of RV pacing, I would of course be upgraded to a CRT device and would be monitored more closely with frequent echocardiograms.  Fortunately I am mainly atrial paced, so I have no concerns at present


by Tracey_E - 2024-03-11 09:30:17

No, it's not common and doctors are mixed on if it prevents heart failure. It's a new enough idea that (as far as I know) there are no studies.


by USMC-Pacer - 2024-03-11 14:26:03

On a positive note, with regular dual chamber devices, you have a 20-40% chance of developing Pacing Induced Cardiomyopathy (PICM) <-- ME - As I said above, my device worked great for over 10 years until my battery change. During procedure prep, they noted my EF went from 65 down to 35, enlarged ventricle and atrium = heart failure! With your current device they can run it as a dual chamber until if / when you develop PICM.. not everyone does. Doctors don't know who, what, or why it happens and can't even seem to agree on the percentages. At least now, for you, that is covered. Typically as stated above, they are implanted for low ejection fraction and dissynchrony in the ventricles with QRSD >120ms and up. Mine at the time was <200ms. Just some random thoughts... stick around, I'm full of them :)

Thanks for input!

by JaneJ - 2024-03-11 23:55:13

Thanks for comments and input everyone.  Interesting and super helpful info!  I didn't think many without heart failure and good ef would have a crt.  They did initially put in a his bundle pacemaker but a couple months later they had to pull it and put in the crt due to very high threshold readings and loss of capture at times.  Take care all!

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Hi, I am 47 and have had a pacemaker for 7 months and I’m doing great with it.