I can’t find this information anywhere — how much energy is applied per pulse by a typical pacemaker? I’m sure it depends on lead implantation and so on, but there must be some reasonable range used for the design of the devices.

A related question I’m also having trouble answering is “what is the typical pain threshold for cardiac stimulation?”. Any pointers to answers are welcome. The fact that most of the (potentially) relevant papers are locked up and not indexed by Google is not helping.

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-

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?

After doing the calculations, I get the following:

Highest numbers: 31.25 ÂµJ

Lowest numbers: 2.6 ÂµJ

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!