Impedance Shock

   Hello,
I recently had a Medtronic EnPulse implanted in July.  It is my seventh pacemaker (first was 1975) and I have 26 year old unipolar leads (Medtronic 6957 and 6957J).  Recently I have been able to feel the impedance check every three hours in the form of a shock that makes my arm and chest wall jump.  My appointment with my EP is not until Oct 16th.  Everything else seems to be OK.  Ventricular function seems fine (no dizziness) and phone monitoring revealed nothing out of order.  Just quite a jolt every three hours without fail.  
Is this something I should deal with immediately or can it wait until my appt?
Thank you.
Gellia

[Michael J. McWilliams, M.D.]

That is interesting, you taught me something.  I called Medtronic's technical support line.  The EnPulse has a new feature that tests lead impedance as you describe every three hours at 5 Volts and 1 millisecond, far more than your normal pacing threshold.  Because your lead is unipolar and the pacemaker can is an active part of the circuit, you can have pacemaker pocket stimulation.

The autoimpedence check is not a vital part of the system and can be turned off.  There is not danger to waiting, but if it is keeping you awake at night or there is significant discomfort it can be turned off.  If you need it done now, you will have to get a hold of your doctor.  My local Medtronic representative was telling me last week that he reprogrammed a device in a local diner last week because that is where the patient was and he didn't want them to go the ER on the weekend.

The short answer is that it can wait if you can.

I hope this helps and thanks for posting.

[Gellia]

Thank you so much for your reply. You have relieved my mind tremendously.  I really want to wait for my appointment with my EP so I'll just hang in there.  It doesn't keep me awake, but I wouldn't want to be holding a cup of coffee when it goes off.  LOL
Thank you again and have a wonderful weekend.