VF TRIGGER RATE

My husband's icd is programmed with vf trigger rate of 220 what exactly does this mean?he previously had 15 vt episodes before his icd gave him a shock and his hr had reached 170.how does cardiologist determine what to set trigger rate at?tks

4 Comments

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by boxxed - 2014-01-22 08:01:02

ICD Therapy can be very programmable, and every EP/Cardio has their own favorite batch of settings that they tweak from patient to patient. Their "typical" settings can be wildly different from doctor to doctor.

This is going to be long-winded, so sorry in advance. And please bear in mind that this is only based on my own personal experience. Everyone's device is programmed different over time.

ICD Therapy have Zones in which they do certain things. These zones are rate dependent.

So for example there may be a zone where it's from 150-170bpm, and all that zone is meant to do is monitor. It won't treat, it won't shock, it'll just keep an eye on it and record for the doctor.

Then there's a VT Zone. This is the "middle" zone. And the rate criteria is dependent on physician presence. This zone will typically try to "pace" you out of a "circuit" based rhythm like VT a few times before it relies on a shock. This zone sometimes have "discriminators", which is a a set of rules and conditions and algorithms. "If X, do Y. But if X and Z, do A & B." This is a set of rules that is programmable that helps the ICD figure out what is a "real" fast rhythm that is dangerous and a "fake" fast rhythm that isn't dangerous. Think VT vs. fast heart rates from exercise. Both can be 180. But discriminators allow the device to figure out what's normal and what's not. We don't want ICD's shocking for exercise.

The last zone is a VF zone. This is the "upper" zone. This zone can be pretty aggressive with shocks, and will throw out most of the discriminators out and just decide if it will shock or not purely on rate. This is typically why VF zones are pretty high (like 220 like your mentioned). Since the VF Zone doesn't try to see the difference between normal and not normal, we don't want it to be close to a HR that could be normal. And most dangerous rhythms can greatly exceed 220bpm.

It sounds like (and I'm guessing on very limited information) that your husband has a VT Zone that treated him @ 170. The 220 zone is the fail-safe zone above that rate. If he ever fell into a far more dangerous rhythm, or his VT degenerated into something more sinister, it would probably speed up into the VF zone and the device would treat aggressively.

Cardiologists have their stock settings, but they will adjust up and down if there are inappropriate shocks, if there is a history of documented VT or other types of rhythms @ certain rates, and other factors. Might not be a bad idea to ask him.

Well said

by Marie12 - 2014-01-22 09:01:11

Boxxed is right on and explained it very well. My EP explained it exactly in the same manner. ICD starts watching me at 150 provides therapy as the rate moves up but does do the big shock until around the 220 range.

Well said ditto

by Cheryl B - 2014-01-22 10:01:37

Thanks, Boxxed. You really have explained it well. I have gotten more info from this site than talking to a $400 an hour doctor. I know I am not supposed to feel intimidated, but sometimes I do, so I don't ask what I feel aren't important questions of my EP. Don't get me wrong, though. If there is something I definitely want to know, I will ask him.
I think he's warming up to me, though. I actually got him to laugh. I told him how I get a sluggish feeling after about 20 minutes in a Home Depot store, and is this normal. He just looked at my husband and said, "She's just trying to get out of going shopping at Home Depot." And he actually laughed. I go to Home Depot now and feel fine. I think he was right. LOL.
Thanks again, Cheryl B.

Trigger rate

by Sylvia1 - 2014-01-23 02:01:43

Tks for a detailed explanation re settings on icd,so well explained.as not long had icd and never get opportunity to ask cardiologist.sylvia 1

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