Chronotropic Incompetence - Confused

Can C.I. disappear ?

by IAN MC - 2023-04-24 18:03:24

I imagine that the answer to that question depends on what was causing the C.I. in the first place. I think old age is causing mine, Dammit !

As you know, C.I. is commonly caused by some sort of electrical malfunction of the sinus node. I doubt that this is permanently reversible, other than by pacemaker rate response programs BUT C.I. can have other causes..( Someone much wiser than me will know whether or not appropriate ablations can have a positive outcome for C.I. )

It is well documented that certain drugs can cause C.I. ... Beta blockers, digitalis, and our old friend Amiodarone can all affect the heart's response to exercise.  Stop the drugs and your C.I. may disappear.

All the studies have been done on human beings, it may be different for penguins !

Best of luck

Ian

Chronotropic incompetence.(CI)

by Selwyn - 2023-04-24 18:27:14

Hello Penguin, 

Sorry to hear of your poor exercise tolerance  and communication difficulties with your health professionals. You are certainly in need of some more explanation. 

I think I would want to know what diagnostic criteria is being used when someone first diagnoses you with CI and then what criteria they are using when they tell you that you don't have CI. There are many different criteria for the diagnosis of CI. Confused? So are the physicians.

You could certainly alter the onset and offset of the rate response as these are programmable. This would ensure a slower decline in heart rate, or you could go for a faster onset.  The peak heart rate for the pacemaker is more subject to your demands. You certainly don't want to overdo it, however, you do need a reasonable cardiac output for the exercise you are taking.  The idea is to keep fit, rather than kill yourself!

If you were OK exercising with your old pacemaker settings for rate response, I think I would want these back.  You can always ask for an exercise test if you are struggling so that the experts can see what changes are taking place. 

The other thing to consider is your increasing age ( as cardiac output declines with age) and any other disease affecting cardiac output ( eg. coronary disease, valvular disease, cardiomyopathy, blood pressure, anaemia etc etc.).

My advice is to contact your EP for a further chat. It seems very unlikely that your CI would improve ( look at the definitions  and see what is being used), as pacing itself tends to worsen the problem. 

Ha!

by Penguin - 2023-04-24 18:29:08

Penguins indeed ! Very witty Ian... 

Most studies I've seen are done on human beings for 12 weeks (and rats of course)....not long enough when humans take them for years.

But yes, interesting and perceptive comment about the drugs Ian and coming from you I'm listening. I'm no longer taking any drugs but I was taking a drug with potential impacts on QT intervals and bradycardia earlier on in my pacing journey and one EP did say that temporary pacing would have been more sensible due to this. 

 Can your heart become dependent on too much RR and a.pacing do you think? 8 years is a long time! 

Thank you Selwyn

by Penguin - 2023-04-24 18:47:59

See reply to Ian re: drugs. 

Thanks for the reply Selwyn. 

CI was first proposed during an angiogram and followed up with 2-3 holters / ambulatory monitoring. H/rates with exercise didn't get much above 55 bpm.  CI appeared on my PM card / papers as a 'symptom' being treated by pacing.

I've changed clinic / EP since and had no diagnostics done prior to the 2nd implant to prove / disprove CI.  It has occurred to me that the new PM is allowing my heart more opportunity to kick in and that the previous one jumped in so often that my heart got lazy. 

I'm in my late fifties and not that old yet!  No other health conditions. 

A couple of techs over the last two years have commented that my heart rates (when higher) are due to 'my heart doing it' rather than the PM, so I'm not totally shocked by the EPs comments but would like more info.

I've had a recent exercise test but the emphasis was on AT and provoking symptoms with exercise.  Apparently RR was amended during the test or at some other point, so that it 'came down' more slowly to base rate after exercise. The dramatic fall in h/rate post exercise was presumably a potential cause of AT (?).  I didn't think to ask about whether i needed RR against my background. 

I don't feel as if I can ask for another test. :(

Electrical Disturbances

by Gemita - 2023-04-25 03:20:37

Penguin, I was told during extensive autonomic testing for syncope in 2012 that I had a problem getting my heart rate up during exercise.  This was confirmed by a cardiac technician in July 2022.  I have since been told by another cardiac technician that I do not have CI and that I do not need RR turned on.  Switching it off seems to have improved my overall arrhythmia burden, so I did not question this any further.  Perhaps they are trying this for you?  I was diagnosed with tachycardia/bradycardia syndrome between 2016-2018, getting my pacemaker in 2018.

Yes medication can be the number one culprit for CI, together of course with specific health related issues, of which there are many.  For example, at one time, I was taking Digoxin, Flecainide and Bisoprolol to treat my AF and found this combination of meds to be extremely “pro arrhythmic”, triggering tachycardia, bradycardia and various blocks, but I am not aware that you are on any heart medication at the moment.

I would suggest the other reason for your symptoms might be a new electrical disturbance.  For example, I usually have no difficulty gently climbing stairs or going uphill, unless I am in an arrhythmia like AF when I can really struggle with weakness, breathlessness, increased tachycardia as I try to push through it.  I know you have been having tachycardia/irregular heart rhythms for some time, so that will not be helping you to exert yourself.  Perhaps all your settings should be carefully reviewed again. 

Yes a heart can become lazy and depend on pacing which is why they don’t like to increase the base rate or other settings too much, allowing our own hearts to do the work whenever possible.  However, I am paced at 70 bpm base rate, 100% atrial paced (since 2018).  The higher heart rate is most definitely proving helpful to keep my bradycardia induced arrhythmias under firm control.  My RR is now off and I am reported as having flat histograms, but I am certainly no couch potato.  Not sure what I make of any of this, but as long as I feel okay I am not complaining.  As we always say here it is not about those numbers, those settings, but about how we “feel” that counts.  Since you are not “feeling” right, you need to continue to look for the cause:  ?new pacemaker/new settings/new electrical disturbances?

Gemita - RR

by Penguin - 2023-04-25 05:36:57

Gemita, 

I agree with your last sentence but have grown afraid of further tech interference. Each time I see a tech I come out with a new set of problems. 

Best Wishes