Drop in Heart Rate and Blood Pressure During Exercise

Hey all,

I wanted to tap into the collective wisdom of the board since my doctors haven't been able to diagnose the issue.

This past spring I developed an issue while exercising (speed walking - 2.8 to 3.0 mph).  After going 2.3-3.0 mi, my HR will suddenly drop (less than 30s) to my resting HR (I have a Galaxy Watch, Wahoo arm band, and Polar H10 chest strap).  I then become dizzy and feel fatigued; furthermore, I am unable to raise my HR more than 10-20 bpm and am just dragging along trying to get home.  This happens almost all the time I go out to exercise, but is now varying in distance/time of my walk.  I measured my BP with a reliable wrist cuff and my systolic falls to <110 and diastolic to 60-45.

I am 67, fairly active, and do a fair amount of hiking.  I am T!D for over 54 years, with no CAD, , and have had 3 stents placed in my RCA in the previous 6 years.  In December I had a Medtronic single lead Azure PM replaced with a Boston Scientific Accolade PM, again with single lead.  The initial diag. was SSS, chronotropic incompetence.  My lower rate is set to 60, and upper to 150 but reduced recently to 140.  The cool down period is set to 8 min. Within the past month I had a stress test on a treadmill, and a nuclear medicine stress test.  Both showed no problems either with the PM or vascularization of the heart.  My ejection fraction is 61%.   My last echo cardiogram showed no enlargements of chambers or other problems.  I wore a Holter monitor in April, but it did not show any problems.

I do have high blood pressure that is hard to control.  I was on 20 mg Lisinopril and 25 mg of HCTZ.  However, I was having orthostatic hypotension in late afternoon an during the evening, whcih was resolved when the HCTZ was stopped.  Beta blockers had a small effect on BP and caused fluid retention. 

The HR drop has yet to occur when I am using my elliptical, which is indoors; but I assume that it is not as rigorous or as long as my walks.  And during the cold months after PM replacement used my elliptical or went for shorter and less strenuous speed walking.

The EP doc says there is nothing wrong with the PM, and the cardiovascular doc says there is nothing wrong with my heart.  Has anyone experienced such symptoms, or know what could be causing this?

Thanks for taking the time to read this post, and any ideas of what is causing this.



Rate dropping

by AgentX86 - 2020-07-06 13:37:20

Hi Mike,

Welcome to one of the least popular clubs around. First, none of those heart rate measurement gizmos are reliable if you're in any sort of arrhythmia. Always feel and count your pulse manually. If you find anything unusual with the pulse in your wrist, take it from your carotid artery.

I find an elliptical to be more strenuous than walking. I walk a lot (10mi every day that it's not raining, from 6:00 to 9:00AM). Before  Covid I walked ~20mi throughout the day (half on a treadmill at the gym). I just can't seem to handle even a short workout on an elliptical. My legs won't do it.

When your heart rate drops to its "resting rate", do you mean the pacemaker"s bottom rate (60bpm)? If this is the case, I'd guess that your pacemaker"s rate response has been turned off and your SI node is giving up the ghost. If you have a log from one of your monitors, I'd show it to your EP and demand answers. I'd (and I am NOT a doctor) say that it's time for a Holter monitor. If you can't get any joy from your EP, find another.


Sounds like a PM issue to me

by crustyg - 2020-07-06 16:08:59

I too have an Accolade for SA-node failure and CI.  Dual lead but V-lead disabled, so I'm AAIR.  Keen road cyclist, making heavy use of Minute Volume: is yours enabled?  Key piece of information!  It seems a reasonable guess that it is.

Two mechanisms seem likely: you're dropping into an atrial tachy and triggering the protection mechanism of your PM - although I'm not sure that this would take you down to LRL.  It's quite common for athletes with SA-damage and CI to be prone to atrial tachy, and it can come and go.  None of your devices will reliably spot an atrial tachy, although you can purchase and carry a single-lead ECG gadget for $70 or so which would reliably record such an episode.  One month of a Holter wouldn't necessarily pick this up, but it depends on what you felt.

Second idea: the MV in BostonSci PMs is *very* sensitive to external magnetic fields - the magnetic brake of a bike turbo-trainer will easily disrupt this, and reduce the signal => reduced feed into RR.  I know, I've experienced this several times and confirmed it with some careful testing.  But normally this would drop you to something modest (perhaps 110bpm), not LRL.

Years ago I was offered a Reveal implant to try and work out why I was having the same symptoms as you (pre-PM) but didn't properly understand what I was being offered.  You'd be a good candidate for this, in order to get to the bottom of what you're experiencing and get you to a diagnosis.  PM's are not that good at detecting and recording tachy episodes, and I can tell you from extensive checking with BostonSci/my EP team that your Accolade will NOTdetect and record a ventricular tachy episode with your set up (or mine, as it happens).  It's not that uncommon to have a Reveal implant *and* a PM!

Best wishes.

Low HR andBP

by Mike417 - 2020-07-07 01:33:06


Thanks for the suggestions.  I have a single lead ECG, and it has not shown any tachy.  And the MV is on; this was a major reason for getting the Accolade.  I needed to have the PM increase my HR when hiking with a pack and ascending a trail.  I only have had a-tach when they riase my HR up to 160, and then I get a 2:1 drop out. 

My EP reached out to me (he is tops in the area) and wants to get me in within 24 hrs of the next episode.  They said there are other settings to tweak.  Hopefully I will get this fixed and be able to exercise more


Not sure I understand!

by crustyg - 2020-07-07 12:38:08

Hi Mike: Perhaps I'm missing something obvious here but you seem to have just described the mechanism causing your issue - 2:1 HB at a decent HR.  That would cause a *big* reduction in cardiac output just when your body was demanding the most.

We're of a similar age (okay, you're a little more senior): I would have expected you to be able to sustain 160bpm for long periods without chest pain or developing heart failure, as it gives time for cardiac blood flow which you say is known to be good.  200bpm would be tiger country.  But suddenly having your vent-rate drop to 80bpm from 160bpm due to 2:1 block would make you feel terrible.  I know if I've been working hard cycling up a mountain, rest on a downhill section (where I can easily drop to <70bpm - decay time only 2min) and then try to stand on the pedals for a short, sharp climb, I feel terrible until my PM gets me back up to 110bpm or more.

Sounds as though your EP doc is doing the right things.

Best wishes.


Solution (?)

by Mike417 - 2020-07-10 15:47:37

My EP doc asked me to come in with 24 hr after I had another episode, which turned out to be this past Tuesday afternoon.  The PM did not reveal any Tachy/abnormal beats, etc.  The Boston Scientific rep, Clarence, was there also.  The PM doc is extremely good, and one of the best in the area.  Clarence has been working hard on the issue and was in contact with the company techs.  There was one thing they had not tried, and that was calibrating the PM.

That took 5 min.  And that may have been the trick.  Wed.s and today I did a little over 5 mi.,and it went very well.  No drop in HR, no fatigue, or aches and pains.

Clarence was excellent.  He stayed late to make sure he could see me that day.



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