Gas station without pumps

2022 November 4

Holter monitor

Filed under: Uncategorized — gasstationwithoutpumps @ 11:38
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For the past 10 days, I’ve been wearing a Holter monitor made by Zio, in order to determine the real frequency of my premature ventricular complexes (PVCs).

I’ve checked the PVCs myself with my own home-made ECG starting about a year ago, but my ECG can only be used when I’m awake and generally sitting in one place, so it does not catch the full range of my heart activity. Because the amplifier board had to be connected to PteroDAQ running on a breadboard connected to a laptop, the ECG setup is not very portable, and I had to sit still to avoid disturbing the circuitry. I couldn’t even use the laptop to browse the web or read email while recording, since changing my contact with the laptop changed the bias voltage on my body, which the amplifier took a second or two to recover from.  So I only recorded about 5–10 minutes at a time.

Some of my recordings got a lot of PVCs, and some got almost none. I did notice that raising my heart rate through exercise seemed to abolish the PVCs. So I think that my PVCs are “slow-rate-dependent” PVCs—that is, that I only get the extra ventricular contractions when my sinoatrial node does not start frequent enough contractions.  Because my heart rate is most likely lowest when I’m sleeping, the ECGs that I did myself probably missed most of the PVCs.

I mentioned my curiosity about what my real PVC burden was at my annual checkup, so my doctor ordered a 14-day recording with a Holter monitor.

Holter monitors have gotten quite small. This Zio monitor has electrodes about 9cm apart and just sticks onto the chest.

Here is a closeup of the Zio Holter monitor.

The adhesive that holds the Zio on sticks well to dry skin (though it makes my skin itch a bit), but one day this week I got a bit sweaty cycling up to campus in my rain suit, and the monitor started to slide around. It seems to be firmly in place again after my skin dried, but I think it is slightly lower than its original placement.

I have to mail the Zio back to the manufacturer for them to unload the recorded data and send a report to the cardiology department.  I’m hoping that the cardiologist will provide me with the information I’m interested (things like what my minimum heart rate is when I’m sleeping, what the PVC burden is when I’m sleeping and overall, whether my PVCs are indeed slow-rate-dependent, whether there is a minimum heart rate for me above which very few PVCs are seen, … ).

Right now the PVCs are completely asymptomatic, which just means that I can’t tell when I have them without using an ECG. For asymptomatic PVCs, all the treatments are worse than the PVCs, so nothing needs to be done now, but if anything changes, I’ll want to know.  The treatments I’m aware of include ablation of the cells that trigger the premature complex, beta blockers to lower heart rate (not appropriate for slow-rate-dependent PVCs), and electrical pacemakers to start extra heartbeats at the sinoatrial node when the pacemaker cells fail to do so on their own.  I believe that my father had a pacemaker just for that purpose, and I suspect I may be getting one in a decade or so.

1 Comment »

  1. […] got back the results from wearing the Holter monitor for 14 days today, and they were not what I expected.  I was expecting to see frequent PVCs, […]

    Pingback by Holter monitor results | Gas station without pumps — 2022 November 17 @ 11:06 | Reply

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