Treadmill Test - experiences?

My EP has suggested a good way forward to check what is going on during exercise is a Treadmill test.

I have so much floating around my head at the moment as I am not sure whether I need more pacemaker support during exercise or less. I desperately need to not go off in the wrong direction after this test.

How will they decide if I need more ventricular intervention or less ventricular intervention?

 


14 Comments

Several factors

by crustyg - 2021-03-26 09:03:33

First is how much you can achieve on the treadmill.  They have predicted maxHR by age/sex and compare that to what you achieved,  they look at your ECG over time/effort and listen to you saying 'this feels easy/I'm about to have to give up' and compare the two.

If you have HB then you need PM support (for exercise at the very least).  The trick, for those who don't have CHB, is to get this support to be as unobtrusive as possible - adding in vent-pacing when your natural pacing from SA-node isn't getting through your AV-node.

The Bruce protocol is open-ended but designed to be 'completed' in a relatively short period - <30min.  The ramp of effort towards the end is increasingly steep, so no-one, not even an Olympian, is going to be saying 'this is easy' at the end.

Don't forget that in all of our discussions, we are using HR as a proxy for cardiac output.  But it's an assumption that can be wrong.  If you lose A=>V synchrony around a certain HR then your cardiac output will actually fall, and that will adversely affect performance.  There are other factors - blood Hb, lung function/oxygenation - which can reduce skeletal muscle performance at any given level of cardiac output - and that's without getting into the small print.  These factors also affect cardiac muscle performance.

You should be good at the treadmill.  For folk with SSS+CI it's slightly cruel without paced support, as we can't get HR up enough to remotely approach max performance.  But, discomfort aside, a treadmill test isn't a competition, it's an exploration.

great idea

by Tracey_E - 2021-03-26 10:18:35

The treadmill is the perfect tool to fine tune your pacer! This is my ep's preferred way of doing it for active patients. They can watch what your heart is doing real time rather than just guessing after the fact, make adjustments immediately and see if it's helping.

Normally on a stress test they increase intensity fairly quickly to see where we max out. I've found that they don't do it like that when they are doing it for the purpose of adjusting the pacer. They slowly got me up to my usual pace and just watched for a bit, made some adjustments to the pacer then had me keep going. Once I had a treadmill in conjunction with an echo (newly paced, wanted to see if function was an issue rather than pacing), the last time was with a pulmonary function test (my heart/pacer wasn't the problem this time, we found asthma), another time was just the treadmill with the pacer rep in the room making changes. I'm congenital, been paced since 1994 so been around this block a few times. 

They'll know if you need more/less intervention because they'll be watching all your numbers- heart rate but also bp, O2 saturation, how you feel, if you are able to continue talking or too breathless. 

I don't know why more ep's don't do this sooner when they have an active patient struggling, it's really the perfect way to see exactly what we need. I had nothing but great results each time. The one time we pinpointed the problem on the stress test but they weren't sure what to do about it (I had two conflicting problems, the fix for one canceled out the fix for the other) so they sent it all to St Judes who made me a case study and sent back recommended settings. That took care of the problem so indirectly, the treadmill was still the answer. I'm a big fan, in case that's not obvious! Good luck.

sounds like it will really help me

by quikjraw - 2021-03-26 12:01:24

It sounds like I can only benefit from this test from your explanations.

I am set at AAI<=>DDD My upper track rate is currently at 150bpm.

If they find that during exercise my intrinsic beats are always present I assume they may even lower my upper track rate.

Conversely if they find that i go into block above 150bpm they might need to increase it.

Does upper tracking rate overide everything, i.e. if i lost a venticular beat at 160bpm would it not be able to do anything?

 

Yes, upper tracking rate is the fastest that your PM will pace you

by crustyg - 2021-03-26 13:29:46

Different vendors have different names but they all have one or two highest pacing rate limits set.  In BostonSci land, MTR is the fastest that the PM will pace the vent-lead after a sensed atrial activation if no vent-activation is sensed within the A-V delay (i.e it tracks atrial activations and watches for vent-activation or delivers vent-activation itself)..  And the MSR is the maximum rate that the PM will deliver pacing outputs driven by the PM's sensor inputs (RR-enabled).  Depending on the present pacing mode, either of these values places an absolute ceiling on the PM's pacing rate.

I charmed my EP-doc into increasing my maxHR from 160=>165BPM 15months ago.  Gasp!  Not sure that it made *much* difference, but I was pretty sure that a request for 170BPM would have been declined.  I'd think 150BPM is a little too slow for you.  For fun I asked my 30-something son to wear my chest strap up a steep hill: his maxHR was about 174BPM.  I'd imagine that a more realistic maxHR for you would be 160-165BPM - if your coronaries can take it (but I suspect that's not an issue for you).

My cycling mates used to say 'You need a better bike' (looking at my heavy Al-machine) and I'd reply I would *like* a better bike, but what I *need* is better legs.  There's no point in driving our hearts to the absolute limit if legs/glutes/lungs aren't similarly optimised.  And the body mass!  It's not been easy to keep weight under control this last year.

Have fun on the treadmill.

tracking

by Tracey_E - 2021-03-26 13:47:01

If your upper limit is 150 and you got to 160 and dropped a beat, the pacer would just watch. It will only kick in up to the upper limit. 

Even if your heart is going fine on its own when you are pushing hard, I would  want my upper limit set above whatever rate I get to, just in case. It's better to have it too high and rarely use it than need it and not have it. The whole point of having the pacer is to step in when we miss beats. 

After the treadmill, you will know exactly what your upper limit should be because at the end of the test, as crusty described, they basically push us until we can't go another second. Whatever your rate is at this time, they will usually set the upper limit 10--15 above that so we have a nice cushion.  Hitting the upper limit when working out does not feel good!

Caveat, that is as long as everything looks good. If they have a reason for not wanting us to max out, they will set it lower than that, at whatever they feel is safe. I hit 178 on my last stress test so my upper limit is 190. When I was maxed out, my bp and O2 were good, beats were nice and even, I was still chatting with them, so that's why I have an upper limit that is probably considered very high for my age (54). 

So yes, you can only benefit from this! I really don't know why more doctors don't do it on all paced active patients. Absolutely no downsides, it can only give them information to better help you. 

Max heart rate

by quikjraw - 2021-03-26 14:51:12

I learn more everytime I get messages back so I must not forget to keep saying thank you!

So, my max heart rate for many years has been 190, I only get this high running at maximum pace  this is all pre pacemaker of course.

The slight complication with me is that I have such a long PR interval, 400ms. I do not know at this stage whether the long PR interval needs sorting during exercise or being left alone. 

Clearly if I am in 2nd or 3rd degree block i need to be paced, no arguments there but if I've only got a long PR interval during exercise I'm not sure what the best plan will be.

I suppose I will find out soon!

 

SSS+CI

by AgentX86 - 2021-03-27 00:16:16

For Crusty...  My cardiologist said he wants to do a stress test this summer but the process confuses me.  I've had a couple so the mechanics isn't anything new but I haven't had one since getting my PM (five days before but not since)

How do they deal with SSS+CI?  Just use the pacer's RR or externally pace?  Do they contantly tune it during exercise.  Hanging the puck on the PM must be tricky.  Since I not only have SSS+CI but have 100% A/V dyssynchrony (no atrial function).  This doesn't sound fun at all, nor that useful.  My performance is programed right in the pacemaker.  All they have to do is look.  ;-)

Agent

by Tracey_E - 2021-03-27 06:22:01

Your pacer will be working same as always. Unless they're specifically doing the test to fix settings, they probably won't even have you on the pacer computer for the test. Usually the point of a stress test is to see how we handle exertion, not tinker with the pacer. 
 

not sure how they do it on a guy, but  I had the puck tucked in my sports bra. The other time we stopped to make the programming changes, I wasn't actually on the pacer computer for the full test. The pacer was never limited. 

For Agent

by crustyg - 2021-03-27 12:28:46

It's a good question and I suppose the answer depends on what question(s) they are trying to answer.  Certainly *before* PM they want to see the maxHR that the patient can achieve - and this is the slightly cruel part of Bruce for SSS+CI patients.

But a stress test in SSS+CI patient already paced shouldn't need any PM adjustments - the primary assumption being that your PM is already configured/tuned to get you to a sensible max HR.  What they want to see is changes on ECG suggestive of ischaemia, developing HB, extra ectopics, possibly provoke an episode of exercise-induced tachyarrhythmia.  Exactly as Tracey_E says.

FWIW, some of the BostonSci PMs can use a continuous RF-communication for reading PM outputs (real-time EMG, pacing rate, lead impedances) AND make settings changes - but the session must be initiated by the magnetic wand.  Once started, the Zip telemetry takes over, makes a static bike or treadmill tuning session *much* easier - no wand in the way.  In fact, there's a documented issue with BostonSci PMs that have MV - using a magnetic wand for a PM settings change actually disables MV for up to two minutes.  Hardly anyone seems to know this, it's buried as a footnote in their BradyRef manual.  Even worse, each PM set operation discards the MV calibration, which can take ages to complete by itself, or about 2min if they trigger it manually. Means you can't just hop on a bike straight after a settings change and expect it all to work properly - either for another static bike run to test the new settings, or, if you're foolish like me, ride home from the hospital without MV feed into RR.  Not fun.

Treadmill and adjustments

by Persephone - 2021-03-27 13:47:27

I was very happy to get a treadmill test to see where I was and have any PM adjustments that could help address lingering SOB after diagnosis of 2nd-3rd degree HB.  Two things were challenging:  first, the Biotronik rep tested my reaction to turning the pacer all the way down prior to me getting on the treadmill; the effects of that were unpleasant and I think distracted from the evaluation.  If I'd known that was in the cards I would have asked if a different order of events was possible.  The other issue was that the clinic tech wanted to diagnosis me (with the doc's OK, of course) with tachy-brady and prescribe meds based on my initial performance on the treadmill.  I asked about the rate response setting, and the Biotronik rep answered that it wasn't on, even though I am confident that I was told it was on just after implant (so getting as much documentation as possible is the lesson there).  The rep turned on the RR and I got a few more minutes on the treadmill.  I asked if the meds decision could be deferred if I wore a holter monitor, and that was agreed upon.  The results of the monitoring were positive and no additional meds or adjustments were needed.

Edited for clarity: the holter monitoring showed no tachy events.

Treadmill

by AgentX86 - 2021-03-27 22:43:51

Yes, this stress test is intended to find ischemic heart disease.  I had a CABG six years ago so my cardiologist wants a look see. 

My issue is that RR isn't really sensitive to hills (or stairs) so a treadmill isn't going to do much on a treadmill.  Because of the permanent flutter and AV ablation (non-functional atria) they won't let my HR go up very much.  I think I'm limited to 130 (can't find my last pacing report right now) and I've never gotten much above 110, by myself.

My PM runs everything so I'm not sure what they're going to do.  I'm still confused but I guess I'll find out when he puts me on the rack.  I don't see my cardiologist until June, I think.

 

Agent

by Tracey_E - 2021-03-28 09:19:13

They will not push you beyond what your pacer is intended to do. If you aren't programmed to go over 130, they won't push you past that. Also, they'll be able to plainly see if your rate isn't going up with increased exertion and stop the test. I'm surprised they aren't doing it chemical rather than treadmill, that's usually the preferred method with someone who can't get their rate up on a treadmill or bike. (My last one was actually on a bike instead of a treadmill, but that's even worse for getting rate response to kick in.)

Rate limit

by asully - 2021-03-28 13:05:07

When I did my cpet a few weeks ago they had me push past my upper rate limit of 150 (I'm 100% v paced and around 20 a paced) but usually just atrial tracked v paced.  My atria definitely his the max HR for my age but since my upper limit was set at 150 I mode switched at that point to 2:1.  I got a call to come back in to the ep next week and he told me he is going to put my upper limit as high as the pacemaker allows (he didn't know what the max limit was on my medronic crt-p).  Personally I am glad they are finally doing this, I wish 4 years ago when my heart function was still good and I was spending 2 hours at the gym they would have done it, but I had different docs at the time and I could only convince them to put it up to 150 (I was set at 140 in the beginning).  I wouldn't say an exercise test is "hard" it's just what it says it is.  And it usually goes pretty fast, I didn't even have a chance to break a sweat during mine.  I really agree with Tracy that more EPs need to use them!  Anyways an exercise test should really help them see what is going on!  I would recommend them for anyone who can safely do one and is paced just to get settings adjusted.

Do the treadmill

by PacedNRunning - 2021-04-05 00:09:30

Definitely do the treadmill test!  They will see exactly if you need pacing at higher rates.  When mine was programmed to pace specifically during exercise due to intermittent high grade block with exercise it began pacing me 100% once my HR was over 100bpm.  Your MTR will matter because it will only pace up to the MTR.  Also ask about TARP rate! Make sure they calculate your TARP so that you don't go into 2:1 block prior to reaching your MTR.  My guess is once you start exercising your PR intervals will be normal.  Most peoples AV node wakes up with exercise. Mine was the opposite, it decided to block itself in 2:1 or 3:1 block.

 

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