Comments on: How much energy is applied by a pacemaker? http://virtuallyshocking.com/2009/04/02/how-much-energy-is-applied-by-a-pacemaker/ Not actually all that shocking. Tue, 07 Feb 2012 17:19:03 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Brock Tice http://virtuallyshocking.com/2009/04/02/how-much-energy-is-applied-by-a-pacemaker/comment-page-1/#comment-74439 Brock Tice Tue, 07 Apr 2009 21:15:17 +0000 http://virtuallyshocking.com/?p=1260#comment-74439 After doing the calculations, I get the following: Highest numbers: 31.25 µJ Lowest numbers: 2.6 µJ So that gives me a range. After figuring out the scaling factor for my mesh size vs the size of a human heart, I found that the stimulus I was working with is on the lower end of that range. Nice. Thanks again Dr Wes! After doing the calculations, I get the following:

Highest numbers: 31.25 µJ
Lowest numbers: 2.6 µJ

So that gives me a range. After figuring out the scaling factor for my mesh size vs the size of a human heart, I found that the stimulus I was working with is on the lower end of that range. Nice. Thanks again Dr Wes!

]]> By: Brock Tice http://virtuallyshocking.com/2009/04/02/how-much-energy-is-applied-by-a-pacemaker/comment-page-1/#comment-74435 Brock Tice Fri, 03 Apr 2009 13:53:58 +0000 http://virtuallyshocking.com/?p=1260#comment-74435 Dr Wes: Thanks! Those are the numbers I was having a hard time finding -- do you know of any published data on those numbers, or generally where to look? I suppose device documentation? Cardiology textbooks? Dr Wes: Thanks! Those are the numbers I was having a hard time finding — do you know of any published data on those numbers, or generally where to look? I suppose device documentation? Cardiology textbooks?

]]> By: Dr Wes http://virtuallyshocking.com/2009/04/02/how-much-energy-is-applied-by-a-pacemaker/comment-page-1/#comment-74433 Dr Wes Fri, 03 Apr 2009 03:31:56 +0000 http://virtuallyshocking.com/?p=1260#comment-74433 Energy = voltage x current x time Current = voltage / resistance (also called impedance) Substituting, one gets: Energy = [ (Voltage x Voltage) / impedance] x time Average pacing voltage 2.5-5.0 volts Average impedance 400-1200 ohms Average time energy is applied per pacing spike = 0.5 milliseconds or 0.0005 seconds So if you double the voltage for each pacing spike applied, you get four times the energy. Double the time for each pacing spike, you get twice the energy. Using these values, I'll let you do the math, but that should get you started. Regarding pain threshold, consider looking at the experience with automatic defibrillators, since in pacing voltages used commercially, even up to 7.5V at 1.5 msec (the largest pacing spikes) are generally not perceived by the patient. Cheers- Energy = voltage x current x time

Current = voltage / resistance (also called impedance)

Substituting, one gets:

Energy = [ (Voltage x Voltage) / impedance] x time

Average pacing voltage 2.5-5.0 volts
Average impedance 400-1200 ohms
Average time energy is applied per pacing spike = 0.5 milliseconds or 0.0005 seconds

So if you double the voltage for each pacing spike applied, you get four times the energy. Double the time for each pacing spike, you get twice the energy.

Using these values, I’ll let you do the math, but that should get you started.

Regarding pain threshold, consider looking at the experience with automatic defibrillators, since in pacing voltages used commercially, even up to 7.5V at 1.5 msec (the largest pacing spikes) are generally not perceived by the patient.

Cheers-

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