View Full Version : Can anyone explain these numbers from my NIPS and EP Study?

05-17-2005, 04:32 PM
I recently received my records from my EP Study and NIPS study and I don't quite understand the results. Can anyone explain any of this?

EP Study Findings:
At baseline corrected sinus node recovery time was 230 msec, antegrade Wenckebach was 240 msec, antegrade ERP of AV node at 600 msec drive train 220 msec, A-H interval 98 msec, H-V interval 50 msec. No evidence of dual A-V nodal physiology. No evidence of antegrade or retrograde conduction using an accessory pathway.

Programmed stimulation performed in the right ventricle at the apex and outflow tract using drive trains at 600 and 400 msec showed no inducible VT with up to 3 extrastimuli at the shortest coupling interval of 190 msec. Burst pacing at both sites failed to induce any ventricular tachycardia. Two micrograms of isoropterenol per minute was given and programmed stimulation again repeated without any inducible VT

No inducible VT. No SVT. No abnormal conduction. The patient had syncope with HCM and rapid heart rate.

NIPS Study Findings:
The patient was given conscious sedation with Versed and also given etomidate up to 10 mg intravenously. He underwent induction of VT of T-wave shock which failed at 12 joules, failed again at 22 joules. He had to be externally cardioverted. There was no evidence of T-wave oversensing at this point with sensitivity set at .45 mV in the ventricular chamber.

The patient then had a re-induction of ventricular fibrillation and was converted at 20 joules without any drop-out of signal between termination of tachycardia

Did I "jump the gun" in allowing my cardiologist to implant an ICD?... I will present these questions to my EP when I see him but that is not scheduled for a couple of months...any information0n in the mean-time would be helpful.

05-17-2005, 10:01 PM
Hi Matt,

EP studies are not really meaningful with regard to those with HCM. In order to decide if you should have an ICD, there are 5 or so risk factors which should be evaluated in deciding whether or not to get one. These are:

Family history of sudden death under age 50
History of fainting
Septum thicker than 3 cm
multiple repetitive V tach on holter monitor
Abnormal blood pressure response on exercise test

If you have a positive EP study, you could still be at risk of having a sudden death episode, so even if yours was negative, it doesn't mean that you made a mistake in getting your device.

BTW, I don't know what those numbers and stuff mean. No idea.

05-18-2005, 01:12 AM
i never saw my EP study report, so thanks for posting yours. very interesting. as for the numbers, they are (as you can imagine) extremely technical and describe the time it took for your heart beat to happen.

the first paragraph basically says that the heart beat didn't find travel the wrong route through the heart.

the second paragraph says they couldn't get vtach to happen.

but it goes on to say that you had vt and vfib. i don't understand the vtach part, but "a re-induction of vfib" is pretty clear. "converted at 20 joules means that that was the amount of current it took to get you back to normal. lucky you. they can go as high as 300.

cynaburst is right on about the ICD placement though. that is what you have to go by. and the fact that they did get vfib to happen.

take care,


Lisa Salberg
05-18-2005, 08:04 AM
Implantable devices have the ability to shock at no more then 33 joules(only one device goes this high the rest are at 30), external defibrillators can go much higher - in the 300 range.

In short your heart went out of rythm and it was not easy for them to shock you back, thus they used the external defib. I am not sure what your other risk factors are but it sounds like a good idea for an ICD for you.

Be well,

05-18-2005, 10:36 AM
sorry. i was posting late and night and didn't distinguish between external and internal defibrillating.

when the shock comes from inside (the catheter or internal paddles in an open heart procedure) it is as Lisa said, 30 joules.

when the shock is from external paddles (which they have on hand when doing a catheter procedure), they can go as high as 300 b/c your body is absorbing most of the juice.

Pam Alexson
05-18-2005, 03:39 PM
In regards to the NIPS findings , this does sometimes happen that the AICD does not convert back to NSR after the induction of VT. I had this happen several times in the earlier days of AICD. They had to do the external with paddles and use 200 joules . After my EP got more aquainted with me and my particular pattern , she realized that there was a sensitive spot at which time if she induced the VT too soon and at that particular moment she would have to convert me externally and not be successfull with my devise getting me back into NSR. They no longer have to do the externals and I also had a habit of going into A-Fib in the earlier days requiring external conversion. Things change with our hearts and the people who have knowlege of their workings and the technicalities do also change as time goes on. They even successfully used my devise to convert me out of some persistent A-Fib one time 3 years after implant, this was never the case in those earlier days.

I believe the second part or paragraph , states clearly that THEY re -induced VT and your devise cardioverted you at 20 joules. This is necessary in order to ensure that your devise would be successfull at converting you back if it were called upon to do so.

I hope our combined efforts have helped , bottom line ... Your devise is working efficiently.. YEAH!!!!


05-18-2005, 05:09 PM
Thanks for all your responses. It helped to make things a little clearer. I guess my next question is, since I had to be "induced" into V-Tach does that mean I'm susceptible to that or can anyone, with enough manipulation, be "induced into V-Tach. Also, why were they able to induce V-tach in the NIPS Study but not the EP Study?

05-18-2005, 05:34 PM
From what my EP has told me, with a NIPS test, the manner in which they induce V-tach would induce V-tach in anyone.

When they are doing an EP study, they are doing it in a more scientific way to see if it is likely that you would go into V-tach on your own or not. They are not trying to make sure that you go over the edge, so to speak. They are seeing if you are susceptible to being pushed. In contrast, with the NIPS test, they are pushing you with all of their might.

05-18-2005, 05:52 PM
Thanks cynaburst, that's is what I thought but was not certain!