Autocapture

11/10/2010 I received a St Jude pacemaker
For the next 7 weeks I sufferred from jolting and kicking
1/28/2011 they removed the Autocapture
and the jolting stopped completely
How good may the pacemaker be without the Autopilot

2 Comments

Autocapture

by shockbox340 - 2011-01-31 10:01:53

You felt the jolts because Autocapture in a St. Jude device requires unipolar pacing. Unipolar can stimulate your pectoral muscle. They turned Autocapture off, switched you to bipolar pacing and gave you what is called a 2:1 safety margin. I'll explain that later.

Don't worry about not having your 'autopilot'. Autocapture is an algorithm to confirm that a pace actually makes your heart beat, and allows the PM to be programmed at a lower output to try to preserve battery life. PM's didn't have this feature for decades, so going without them just means doing it the old fashioned way.

For example, let's assume your threshold is 1.0 Volts. That means if they pace you at 1.0 Volts your heart beats every time, but if they turn it down to 0.9 Volts, sometimes it beats and sometimes it doesn't. 1.0 Volts is your lowest reliable pacing output as of that day. With a threshold of 1.0 Volts, the 'old fashioned' way is to program your device to at least 2.0 Volts, giving you what is called a 2:1 safety margin.

With Autocapture and our theoretical 1.0 Volt threshold, you might be pacing at 1.2 or 1.3 Volts. You are using less energy to pace, and the device confirms capture after every pace. All sounds great, right?

Well, the 'old fashioned' way works just as well. There is no confirmation of capture, but that is enough safety margin to all but ensure capture unless a lead comes loose or a wire breaks, etc. As far as the battery savings, it is actually quite minimal (say, a few months over the life of the device). That is because all that confirmation of capture and daily threshold testing burns up most of the savings by having the outputs turned down.

If this is too much information, I apologize. I thought you might want to understand why you were feeling the jolting and did not want you worried about having that feature turned off.

Good luck!

Interesting

by ElectricFrank - 2011-02-01 01:02:33

I wonder why the the St Jude requires unipolar pacing for auto capture. My Medtronic Kappa 701 (first pacer) and the Adapta that replaced it both perform auto capture calibration in bipolar mode.

frank

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