Trying to be active

It is confusing

by IAN MC - 2017-01-08 16:00:27

But, they are totally different :-

UPPER TRACKING RATE :  As you know, the upper chambers ( the atria) pack the lower chambers ( the ventricles ) full of blood before they contract and pump blood around the body

If your atria beat at say 70bpm the PM will "track" this and make sure that the ventricles also empty at around 70 bpm. But what if you had atrial flutter and the upper chambers go crazy. You could end up with the PM causing the ventricles to contract at say 300bpm and your health would be at serious risk . For this reason there is a maximum tracking rate

It is an adjustable setting that controls the absolute quickest that the PM will pace the ventricles.

UPPER SENSOR RATE :  Some people need Rate Response switching on; this is only people who are " chronotropically incompetent " i.e. their heart-rates don't increase as they should when they exercise.  

If you have RR switched on, your Medtronic PM will put in extra beats when it detects vibration and assumes that you are exercising.  BUT it could be dangerous if it puts in more & more beats without any limits. So the inbuilt sensor, which detects vibration, stops working when you reach the pre-set maximum sensor rate.

Hope this is clear

Ian

Upper Tracking Rate vs Upper Sensor Rate

by RvC - 2017-01-09 23:31:56

Thanks Ian.  Unfortunately, it is about as clear as mud................I have 3rd degree heart block and am therefore chronotropically incompetent.  I only just (last month) had my rate response turned on despite the fact that I'm 49 and very active (I've had the pm for 26 months).  My upper tracking rate is newly set at 180, and my upper sensing rate is set at 150.  I'm wondering if that upper sensing rate is "holding me down" at 150 and not even allowing me to hit the 180 tracking limit.  I guess I'm wondering if the tracking and the sensing rate should be set at the same number (180)?   

I'm having major issues when exercising.  I have an appointment with the PM Clinic on the 16th, so I'm trying to learn as much as humanly possible before I go because to date they haven't been able to help me.

Upper Tracking Rate vs Upper Sensor Rate

by RvC - 2017-01-09 23:41:31

I re-read my note and it is not very clear, sorry.  My cardiologist thought it would be safe to let my heart rate get up to a maximum of 180 bpm.  I'm wondering if the clinician made a mistake by adjusting the tracking rate when she should have adjusted the sensor rate?

RvC

by IAN MC - 2017-01-10 14:12:49

I read somewhere that the Upper Sensing Rate should ideally be set slightly lower than the Upper Tracking Rate.   This safety margin makes sense because if the RR sensor drove your HR too high , in some situations the Upper Tracking Rate would keep your HR below the limit by skipping beats. Skipped beats would make you feel awful.

Cardiologist normally decide what is a safe Upper Tracking rate by taking into account your age and level of fitness. A formula for the maximum rate such as 220 minus your age is commonly used.

I would have thought that , in your case, your maximum Sensor Rate should be raised to around 175 bpm . I would be interested to know what they decide on the 16th

Best of luck

Ian

Chronotropically incompetent

by RvC - 2017-01-11 00:50:03

I may have jumped the gun on saying that I was chronotropically incompetent?  I have third degree heart block that is a result of my sinus node being accidentally cut during an aortic valve replacement surgery (tough mistake to avoid I'm told).  I'm paced 100% in the ventricular and 40%ish if I remember correctly in the atria.  Do you know if that makes me chronotropically incompetent?

What is chronotropic incompetence ?

by IAN MC - 2017-01-11 06:04:46

RVC  You are stretching my knowledge to its limits , but I will try !

 You did confuse me with your statement that you have 3rd degree block and are " therefore" chronotropically incompetent because the two do not necessarily go together; thanks for clarifying things.

You say that you have " major issues when exercising " . This is a classic symptom of C.I.

If you hunt around for definitions of C.I. you will find that the commonest one is : 

" The inability of the heart-rate to achieve at least 80% of the predicted value at PEAK exercise . The predicted value at peak exercise ( i.e. just before the exercise becomes anaerobic ) is calculated by the 220 minus your age formula but this figure is adjusted upwards of you are particularly fit.

I was not chronotropically incompetent for my first 2 yrs with a pacemaker but then it developed.  Lazy sinus nodes have the nasty habit of getting worse with time.

If you are  i) breathless when you exercise and   ii ) improve when Rate Response is switched on then you are chronotropically incompetent . Often it is diagnosed by trial-and-error with the RR function switched on and off .

I persuaded my cardiologist to wire me up while I was running on  a treadmill and this confirmed that my HR wasn't increasing with exercise the way it should so I WAS diagnosed as being chronotropically incompetent and did benefit from Rate Response.  I had already self-diagnosed it by wearing an HR monitor while running but the cardiologist needed evidence.

But if you are still suffering when you exercise , one possibility is that the various sensitivity settings of the Rate Response function need some adjustments.

Best of luck

Ian

Chronotropic Incompetence

by RvC - 2017-01-11 16:54:15

Ian, I VERY MUCH appreciate you letting me test your knowledge limits!!!  The issues I've been having have me standing at the edge of a cliff at the moment.  Don't worry, I won't jump, but I honestly don't know what to do anymore.  I read the book Pacemakers Made Easy after I declared myself CI, but after reading it, I'm not sure that I am.  That is one thing (of many) that I need to clarify on the 16th.  I'm afraid my "issues" are testing everyone's knowledge limits and therein lies the reason I'm on the edge of a cliff.  Here's to hoping we at least make progress on the 16th.  

Adjustment made

by RvC - 2017-01-17 01:07:45

Well, they adjusted the Rate Response Activity Threshold from medium-high to medium-low.  Despite asking a few times, I never got a clear response on whether I actually needed the rate response turned on.  I guess time will tell................

You are right, time will tell !

by IAN MC - 2017-01-18 07:07:18

I imagine you know already if the latest adjustment has been beneficial or not, I hope it has.

Interestingly I had my activity threshold moved the other way i.e. from medium-low to medium high and things aren't too bad but I had a check-up a couple of days ago and have persuaded them to get me on the treadmill AGAIN and do adjustments with some guru from Medtronic there.

I don't think you will be given  a clear answer on whether you need RR or not, only you can tell them !

I am genuinely interested in your final outcome so send me a private message if anything exciting  happens.

I see you are in Canada . I live in the UK but last year visited my sister in Winnipeg and I drove all the way through the Rockies down to Vancouver island ( Victoria is great , what better place to be chronotropically incompetent !! )

Best of luck

Ian