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 Have you been shocked for a-fib by your ICD? 
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Joined: August 15th, 2007, 4:39 pm
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Post Have you been shocked for a-fib by your ICD?
Prior to having vfib and subsequent scd, I had problems with a-fib off and on since 1998. When I do go into a-fib, I'm always at a fast rate (often over 200 bpm). Thankfully, I tolerate the a-fib well even at such a fast rate and I usually self convert in less than an hour, though a few times I've had to go to the ER for meds (cardizem, ibutilide).

I'm fairly certain I will go into a-fib again as this is fairly commom for me. My question is, now that I have an ICD, how likely will it be that I get shocked for the a-fib? My ICD is set to go off at a HR > 200. Can the ICD tell it is a-fib and not shock or will it just shock any rate > 200 regardless of the rhythm?

TIA for any info.

Paula

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Sudden Cardiac Death 07-29-07 at 42 years of age. Cause of SCD unknown, no heart defects found. Medtronic Virtuoso ICD implanted 08-01-2007.


Last edited by Paula on August 25th, 2007, 8:38 am, edited 1 time in total.



August 24th, 2007, 11:09 pm
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I don't about yours but mine does, and its not surpose to. Last week I got shocked at a 220 Heart rate. We have adjusted my device many times "St Jude Device with a single lead". And Lord knows we have changed my meds alot. I've never been shocked for v tach or v fib. I'm sure others have had the same thing happen to them. Ny Doc said he is going to replace it with a dual lead device when the bat gets lower. But he is also talking about the ablation now. Different devices may be better about reading a fib. I don't know.


August 24th, 2007, 11:15 pm
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Paula,

Like Sean, I have never been shocked for vt of v-fib, but have been shocked three times for A-Fib. Fortunately enough I have meds that work for the most part (sotalol) and if the situation gets worse I have also been talked to about ablation. I have a Medtronic Intrinsic dual lead. I also have a high heart rate when I go into a-fib but I don't convert back so easily, so actually it works like a cardioversion- not exactly what I want to happen but it does. :/

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"The mind is like a parachute, it only only works when it is open"- Frank Zappa

Round One: ICD implanted Feb. 2006: Medtronic Intrinsic, 2 leads- St.Jude 1388tc (Atrial), 6947 Medtronic Sprint Quattro Secure (RV/SVC).....
Round Two: July 17 2011, meet Medtronic Virtuoso 2 DR- same leads, cleaner scar.
5 shocks whoooo hoooo!

Image Run Matilda, Run!


August 25th, 2007, 8:18 am
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Thanks for your responses guys. I have a dual lead too, so maybe that will help. I am aslo on sotalol Mark, beta blockers had not worked in the past for my a-fib, but so far so good on the sotalol. I was taking flecainide for the a-fib before which is what I think actually caused the scd. Dang meds, darned if you take em' darned if you don't.

Paula

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Sudden Cardiac Death 07-29-07 at 42 years of age. Cause of SCD unknown, no heart defects found. Medtronic Virtuoso ICD implanted 08-01-2007.


August 25th, 2007, 8:37 am
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Paula -- I've been shocked 7 times for a-fib. The ICD just detects that the heart rate is too fast, and bam. Have you asked about an ablation? I had one in 2003, and haven't gone into a-fib since (staying below 130 or 140). You may want to ask your doc about it. It's a same-day procedure; pretty much painless (except for the fact that they had to external paddle me when they triggered the wrong rhythm, so I had chest burns for a week.)

Jana


August 25th, 2007, 7:41 pm
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Hi Jana,

They tried to ablate the a-fib in 2003 but were unable to elicit the rhythm. They did find an svt pathway that they were able to ablate (never had problems with svt). Of course 2 days after being in the hospital for the ablation I went into a-fib on my own.

Paula

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Sudden Cardiac Death 07-29-07 at 42 years of age. Cause of SCD unknown, no heart defects found. Medtronic Virtuoso ICD implanted 08-01-2007.


August 25th, 2007, 9:17 pm
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Paula

The manufacturers have been working diligently for years to enable the ICD to detect different rhythms, such as Afib, SVT and VT. To date they have had only moderate success. So the simple answer is that if your ventricular rate exceeds your set point you will probably receive therapy.

To clarify for you, SVT is caused by Afib. SVT simply means Supra Ventricular Tachycardia, i.e. a fast heart rate that originates above the ventricles. There's two ways this can happen. The AV node buffers the impulses traveling from the atrium to the ventricles. If the atrial contractions get too fast for the AV node to buffer them then you have the ventricles going into tachycardia. The other way for SVT to originate is if there's an accessory pathway from the atrium to the ventricles that bypasses the AV node. That's what they ablated for you previously and that's a good thing. That lessens the chances of your receiving therapy from Afib but doesn't eliminate it completely.

Keep in mind that an atrial ablation is not a 'one chance' thing. You can have it done again. I've known folks who have had as many as five atrial ablations. My suggestion is that if you want to try it again you research who's the best in the field. If you can find a doctor who specialises in the procedure and has a good track record your chances of success are greatly increased. I wouldn't let my friendly neighborhood EP attempt this procedure. But that's just me. Also keep in mind that procedures for ablation are constantly being improved. Simply put, they are better at it than they were a few years ago.

A last option that may or may not become appropriate for you is to ablate the AV node. If that was done you would become pacemaker dependent. It has been done, both on purpose and by accident during an atrial ablation. I wouldn't think it is a good option unless you are constantly receiving therapy and all other methods have failed.

I have had great success with sotalol for controlling Afib. I hope you have the same success. As an aside, don't be conned into buying Betapace AF. It's the exact same medicine (sotalol) as in generic sotalol. The only differences between Betapace and Betapace AF are the wording of the package inserts and the price LOL. I take generic sotalol and it works just as well as the high dollar stuff.

Good luck.

don


August 26th, 2007, 9:10 am
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Hi Don,

Thanks for your input. I do understand the differences in a-fib, a-tach, a-flutter, wandering atrial pacemaker and svt (which is the basket of atrial fruit) - I have a Master's Degree in cardiac rehab. My EP did talk about ablating the AV node (if I was going to refuse to take sotatlol) and we may re-visit ablation again for a-fib down the road if I continue to have problems. Like you said, they are getting much better at being able to ablate the a-fib, it is so difficult because of the many pathways causing the a-fib. I might just wait until they perfect the techniques a bit more. I actually work with a cardiac surgeon that does a great MAZE procedure for a-fib with good results, but I'm not ready to have my chest opened up just for that.

I take the generic sotalol too. Thanks for the heads up though.

Paula

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Sudden Cardiac Death 07-29-07 at 42 years of age. Cause of SCD unknown, no heart defects found. Medtronic Virtuoso ICD implanted 08-01-2007.


August 26th, 2007, 3:06 pm
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Hi Paula

The MAZE procedure is still a last attempt at attempting the results. It is very serious surgery. For someone who has never even been given therapy for AT/AF/VF it would seem to me to be killing the fly with a machine gun. It's a last ditch attempt when everything else has failed. The MAZE has mostly been abandoned in the last few years as much more effective and les invasive procedures have been initiated.

Good luck..You don't need to be concerned with all the treatment options as you haven't even been shocked yet. When you have received therapy and when you weigh the therapy against the treatment options you may have a different opinion. I've been shocked over two dozen times but it isn't so horrible as to make me look to more drastic treatments. Your experience may differ.

don


August 26th, 2007, 9:00 pm
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I agree 100% Don. Not ready for the Maze yet and by the time I need to really do something (I hope) there will be much easier and more successful ways of treating a-fib. I know my EPs nurse was discussing new techniques that are just on the horizon. Thanks for your support and info - it really helps.

Paula

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Sudden Cardiac Death 07-29-07 at 42 years of age. Cause of SCD unknown, no heart defects found. Medtronic Virtuoso ICD implanted 08-01-2007.


August 26th, 2007, 9:59 pm
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Quote:
…how likely will it be that I get shocked for the a-fib? My ICD is set to go off at a HR > 200. Can the ICD tell it is a-fib and not shock or will it just shock any rate > 200 regardless of the rhythm?


There is indeed some logic in the ICD to try to tell the difference between AT/AF and VT/VF. It often works, but it is not infallible. Unfortunately an AF episode can last a long time and the logic can be working correctly for hours, days, weeks at a time - and then the ventricular rate speeds up or the pattern changes for just a few beats and you get a shock.

Technically, if there are more “p-waves” (atrial beats) than “r-waves” (ventricular beats), AND the ventricular rhythm is irregular, AND the average ventricular rate isn’t “too fast”, OR there is a consistent relationship between the p-waves and r-waves, then the ICD recognizes AF and will not shock, even if you are above the rate that you are set for (200 bpm in your case).

What makes the problem really hard for the ICD is that it has to allow for the possibility that a person has both AF and VT/VF at the same time. This is more common than you might imagine. So to be on the safe side, anytime the ventricular rate gets “really fast” or “really regular”, then the ICD will shock regardless of the fact that the AF pattern is being met. It will classify the rhythm as a double tachycardia: SVT+VT or SVT+VF.

I’m afraid that 200 bpm is most likely considered “really fast”.

Is 200 the limit of the VT or the VF zone? The ICD is more likely to not shock in the VT zone. And there is a parameter called SVT Limit that defines the fastest rate for which the ICD will even try to discriminate. It is not typical programming, but they could get real aggressive on these limits to try to discriminate even more than normal.

Like the others have said, there is a fair chance that you’ll get shocked for AF with V rate>200.

Mark, have you had AF episodes where you didn’t get shocked? Anyone else? Believe me these discriminators do work for some of these rhythms.


August 27th, 2007, 12:17 pm
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flyingcamel wrote:
Mark, have you had AF episodes where you didn’t get shocked? Anyone else? Believe me these discriminators do work for some of these rhythms.


I have mode switches where I didn't get shocked, nor paced out of it. Does that count?

_________________
~Mark
"The mind is like a parachute, it only only works when it is open"- Frank Zappa

Round One: ICD implanted Feb. 2006: Medtronic Intrinsic, 2 leads- St.Jude 1388tc (Atrial), 6947 Medtronic Sprint Quattro Secure (RV/SVC).....
Round Two: July 17 2011, meet Medtronic Virtuoso 2 DR- same leads, cleaner scar.
5 shocks whoooo hoooo!

Image Run Matilda, Run!


August 27th, 2007, 12:46 pm
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flyingcamel wrote:
Quote:
I’m afraid that 200 bpm is most likely considered “really fast”.

Is 200 the limit of the VT or the VF zone?
Like the others have said, there is a fair chance that you’ll get shocked for AF with V rate>200.


I have no idea if 200 is the limit for the VT or VF zone, I was just given the number of > 200 for defib. Might be a good thing to ask.

I was afraid that I would get shocked with a-fib >200 - hopefully the sotalol that I am on now will keep me out of a-fib or keep my usual high a-fib rate down for me.

Paula

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Sudden Cardiac Death 07-29-07 at 42 years of age. Cause of SCD unknown, no heart defects found. Medtronic Virtuoso ICD implanted 08-01-2007.


August 27th, 2007, 1:07 pm
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Paula wrote:
flyingcamel wrote:
Quote:
I’m afraid that 200 bpm is most likely considered “really fast”.

Is 200 the limit of the VT or the VF zone?
Like the others have said, there is a fair chance that you’ll get shocked for AF with V rate>200.


I have no idea if 200 is the limit for the VT or VF zone, I was just given the number of > 200 for defib. Might be a good thing to ask.

I was afraid that I would get shocked with a-fib >200 - hopefully the sotalol that I am on now will keep me out of a-fib or keep my usual high a-fib rate down for me.

Paula


No, 200bpm is not the upper rate. Mine is set faster than that at my insistence. I don't know what the upper limit is but you must weigh things such as how fast can you remain conscious an how fast can you still maintain a blood supply to your brain. A lot will depend on other heart conditions. If you aren't getting shocked then 200 is probably fine for you.

don


August 28th, 2007, 6:07 pm
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