Max rate question

max rate

by Tracey_E - 2020-11-23 11:54:24

Not everyone is safe getting their rate up that high. Do you have anything else going on other than the heart block?

It's possible your doctor has mostly sedentary elderly patients and no one needs it that high so that's just a general rule and he's not looking at your specific needs. If that's the case, it's time to find a new doctor, one with other active patients.

Have you had a stress test? Once I passed a stress test and my echo was good,  my ep  turned mine up as high as I needed it to be, 15 over the highest I got on the stress test. My upper limit is 190 and I regularly get to 180. He loves that I am active and does everything he can to make sure I can do what I want to do. Not all doctors have that attitude. 

If you were fit before, if you feel good before you max out, if your echo and stress tests are good, then I would push to raise it, or find a doctor who will. We don't want to compound the problems we already have by not being in shape.  Our heart can limit us, sometimes it's not safe to push hard, but if we are otherwise healthy then the pacer shouldn't limit us. 

Maybe he'd at least turn off the feature that makes it switch to 2:1?

Edited to add,it's really bad for us when it goes into 2:1, as you can tell be how bad you feel. It's important to not push that hard, stop before you get to that point. 

Here goes

by crustyg - 2020-11-23 14:41:08

Heart muscle can only receive oxygenated blood whilst it's relaxed (diastole).  During contraction (systole) there is no blood flowing from the coronary arteries to the heart muscle.

Heart muscle need for oxygen is primarily related to HR => more BPM, more need for oxygenated blood.  See the problem?  As HR goes up, oxygen demand goes up and oxygen delivery goes down.

Where's the breakpoint where demand>supply?  Good question.  It's sort of addressed in the Bruce Protocol treadmill test.  We know from patients with WPW and other recurring SVTs that no matter how young you are as an adult and how healthy your coronary arteries may be, run your heart at 220-230BPM for an hour or so and you can get into real trouble.

Factor in a little more age, slightly less flexible aorta and slightly narrower coronary arteries and you might not enjoy 170BPM for 60min.

What should your maxHR be? Impossible for us to know, and your EP-doc has no desire to face an enquiry if he sets your maxHR too high and you have a fatal MI.  It's a judgement call.  I would *expect* your maxHR to be higher at your age, but I don't know you.  Perhaps more than 150, but probably not as high as 170.  The healthy, athletic heart increases blood supply by increasing stroke volume as well as increasing HR: this is much more sustainable.

Thank you Crustyg

by IAN MC - 2020-11-23 16:29:20

I thought you gave an excellent explanation of the factors which affect one's maximum heart-rate.

I am curious... what is your medical opinion of the value of the  "220 minus your age" formula to calculate maximum safe heart-rate :-

- is it at best a rough estimate ?

- does it have any value, whatsoever, if you have any cardiac condition let alone a pacemaker ?

I am 81 and despite being told that I am  " fit for my age ", I had enormous battles with my EP to persuade him to raise my Max HR to the currrent level of 165 bpm.

I eventually had to perform on a treadmill and do well on the Bruce Protocol before he would even consider raising my max HR from its 135 bpm setting !

Ian

Predicted MaxHR

by crustyg - 2020-11-23 17:25:16

TBH I really don't know Ian.  I probably *should* know the basis behind the predicted maxHR that's used in the Bruce Protocol, but I don't.

I suspect that anything that's used for maxHR prediction is massively out of date - in the sense that our generation (and I'm quite a bit younger than you, so we're about half a generation apart) is based on old levels of nutrition, exercise and near-poisonous foodstuffs (e.g. trans-fatty acids).  It's no longer remarkable to see mentally alert, physically agile ninety-somethings, so it's reasonable to assume that less air pollution, less poisonous foods, more exercise and less exhausting physical labour has had an effect.  What that does to a sensible maxHR is anyone's guess.

Interesting that you had to 'perform' to earn a higher maxHR.  My EP-doc and I were discussing the chance of my having coronary heart disease and he commented dismissively (in a nice way), 'hardly, since you do a Bruce Protocol every weekend'.

I still have direct contemporaries who are practising, and during our earlier years we saw a lot of older men in their early sixties for whom a sustained HR of 160BPM would rapidly prove fatal: two problems with that.  1) it's our parent's generation (see above), 2) ascertainment bias - we weren't seeing non-hospitalised patients and recording their HR and pO2/O2%sat.

I suspect that there are still plenty of folk of our age for whom a maxHR of 160BPM for any length of time would be most unwise, but there are others who can sustain this sort of rate continously for 30-45min at a time, or even longer.

I think we have to prove ourselves by our actions.  I can't see any investigation which would or could predict that performance - except a static bike session with ECG or Bruce Protocol treadmill test (but it's really unphysiological, and very unkind to patients with SSS+CI).

How to find Max

by bjd00000 - 2020-11-23 18:58:32

Thank you all for this very good information. At least I know why he is hesitant. However, prior to py PM implant I worked pretty hard every day. I can work both of my adult sons into the ground and do so regularly. But since my PM I cant even hike up the hill behind my house without stopping every 100 feet or so to wait for my hear to quit dropping beats.  I used to be able to sprint to the top without panting. I have no idea what my HR used to be but it seems like it must have been something higher than the current Max @ 150. How should I approach my next visit with the EP, any suggestions?

Hitting the brick wall

by AgentX86 - 2020-11-23 23:16:07

Tell you EP what you've told us, then have him explain what happed (don't tell him), why he has your PM set up as it is, and what to do about it.  More training will increase the heart's output, as mentioned above, which will help ut get him to explain exactly what's going on and why.

Ask about max target rate

by PacedNRunning - 2020-11-24 01:55:50

Ask your EP at your next visit the formula 220-your age. This is your target max HR you can get to but not maintain long.  Ask if he could at least put it to that.  Mine was 160bpm at implant. I dropped into 2:1 block, awful feeling. They raised it to 185bpm.  Also ask them to make sure your TARP rate is NOT below your upper rate limit. The issue with TARP is this is your 2:1 block rate and if they change settings and forget to calculate it, you may 2:1 block before your max HR.  I'm guessing for now, you hit over your max HR and into your TARP. Do you know what HR you hit 2:1 block recently? Those of us with heart block our upper rate limit really matters because we can't exceed it without the help of the PM.

"Predicted " Maximum Heart-Rate

by IAN MC - 2020-11-24 06:47:53

Crustyg  ...thanks for your response. It has always seemed to me that HRmax  is a very personal thing as everyone is different

I don't believe it IS possible to meaningfully "predict" it purely on the basis of a formula .Some sort of exercise test is essential .. stationary bike / treadmill etc.

I read somewhere that the 220 minus your age formula has very little scientific basis and was scribbled on the back of an envelope by a medical speaker on his way to a lecture. Apparently he is still alive and is amazed ( and amused ) that it is now taken as gospel around the world !  He never intended this to be the case.

Ian

Some tips ?

by Gemita - 2020-11-24 07:43:56

Hello bjdooooo,

Excellent technical advice from other members and really interesting thread which has helped me a great deal.  Perhaps I can add some practical advice when you next see your EP.

How should you approach your EP?   Well don’t just go in with a list of possible setting adjustments.  I know what my EP would say to me.

I would want to make sure first that you do not have anything else going on to be causing your symptoms, like arrhythmias because they can really throw everything off.  No point in optimising heart rate settings if you have developed an underlying additional electrical disturbance which can play havoc with just about everything they try to set.  And with any heart procedure, the likelihood of developing additional electrical disturbances are of course possible, disturbances that they may unmask by any intervention, including a pacemaker.  Atrial Flutter was unmasked in my particular case which was never detected before my pacemaker.   I am sure though your EP before discussing the details of any further setting changes is going to want further tests arranged to try to find out why you are feeling worse.

When you go in to see him/her, go in with a clear list of your most troublesome symptoms:  like breathlessness, dizziness, weakness and what brings it on?  For example, is it only on exertion, state when, where, how quickly, what makes it better;  or can the same symptoms develop at rest?  Be clear on symptoms and clear on what your options are for treating your symptoms?  Then move to settings. 

Ask what tests he recommends which could help determine what is going on and why you feel worse now than before your pacemaker.

The time for your fine tuned settings will come much later when the EP knows what he is dealing with;  I suggest at the moment, he may not have the full picture?  Good luck

Max rate answers

by bjd00000 - 2020-11-24 18:39:19

Thank you everyone for your thoughtful input. This community is remarkable and has been extremely valuable to me as I'm sure it has been to many others. I hope I can provide help for others in the future.

Brian