threshold maybe on the rise

Hello - does any body know what your ventricular pacing threshold is? My daughter, 12 yrs, has a pm, and she is so unfortunate to have had problems before with her threshold rising until the point of no capture which means that she is now on her 3rd pm in three years. The one she has now is fine, however, we went in for the biannual check yesterday, and her threshold had risen from 0,8 in October 11 til 1,1 now. And I am starting to wonder if this thing may happen again to her - that the threshold will keep going up until there is no capture, and she has to have her leads replaced again. Should I be worried - or I am just too sensitive towards these numbers? The pm nurse was not worried, he noticed the slight rise, but all in all, it was just a small change, he said.
What do you think?

Er der nogen herinde, der er klar over, hvad jeres tærskel er ift pacing af ventriklen? Hermed mener jeg den mængde strøm, der skal bruges for at udløse et hjerteslag? Det er min datter, der har en pm (hun er 12 år), og hun har før døjet med, at hendes tærskel begynder at stige, indtil pm ikke har nok volt til at udløse et slag, hvorfor hun er blevet svimmel, og hun har 2 gange på 3 år fået skiftet pm. Pt har hun det godt, men i går til tjek på Skejby var hendes tærskel 1,1, hvor den i oktober var 0,75 - og jeg tænker selvfølgelig på, om det kan ske igen. Kan I huske, hvad jeres tærskler er - eller er jeg bare for nørdet? ;-)

2 Comments

disregard the last paragraph

by lok - 2012-04-26 08:04:42

Please disregard the last paragraph, it is my question in Danish - I cannot seem to delete it.

Loss of capture

by ElectricFrank - 2012-04-27 02:04:32

A few years ago I had a loss of capture problem. I'm much older than your daughter so you can't compare my actual readings to hers.

There are actually 2 threshold readings for each chamber. One is the actual threshold voltage for capture. The other is the set voltage which includes a safety factor. Typical safety factors run in the 2.5X to 3X. So it give some wiggle room.

My concern is why the threshold is changing. Is the lead impedance changing also. If so it could mean there is a change in the leads connection to her heart wall. It just struck me at her age and growth it may be a normal change. Anyway, at the very least I would consider having her checked fairly often until a pattern is found. I just noticed that you have had to change her leads once already. This would also indicate a need to keep an check on it.

Is it possible to be set up with a phone monitor to make it easier to check the readings?

frank

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