Volts Standards for PM wire in Atrium and Ventricular

Beyond my payscale

by piglet22 - 2024-08-02 10:09:37

Q1

Go with what your pacing specialist says and don't rely too much on Dr Google.

Changes in lead voltages might indicate a change in the lead impedance. If I wanted to maintain a fixed current through a resistance and the resistance increased, I would have to raise the voltage to drive it.

Muscle would only come into it if your device was in unipolar mode where the flow and return paths for current is part wire lead and part muscle and tissue. Most leads are bipolar where the flow and return is in the two wires of the lead.

Q2

Even trickier to answer.

I would expect to see some feedback going on to change settings on the fly, but if you read the clinician manual for any pacemaker, you will see there are myriads of potential settings.

2-months is still in settling down time.

Once implanted and operating, there is nothing apart from damage to leads or pacemaker that can be adjusted through surgery.

All readings, memory, settings are read through non-contact methods, sometimes Near Field Communication (NFC) on older devices, Bluetooth on newer devices.

Hope that helps.

There is no 'standard' for pacing lead outputs...

by crustyg - 2024-08-02 11:04:44

...however, in general one wants the lowest possible output voltage AND the shortest possible pulse-width to generate reliable activation as this uses the least current from the battery.

Ideally, each lead should be able to produce reliable activation around 0.5-0.7V at 0.4ms pulse width at all pacing rates (with bipolar leads).  In the real world this is often not possible, and a higher output voltage is required.  Remember that EP-teams will usually leave the device at 2*minimum capture to provide a safety margin (in case lead=>heart muscle connection changes), *especially* if auto-adjust capture is turned off.

Many (perhaps most?) PMs are set to automatically adjust pacing output but many contributors here find that unpleasant, and some vendors have their device do this check at the same time every night which is unwelcome.

Changing output pulse-width can also affect capture voltage.  Increasing pulse-width may permit a reduction in pacing voltage (this doesn't always reduce battery consumption), and capture settings may need to be increased for reliable capture at high heart rates.

Unless you have a good reason to focus on pacing output voltage this is something *usually* best left to the EP-techs.  I specifically got my RV output reduced as the sensation of RV pacing was quite unpleasant.  The cost was doubling pulse-width, so it will reduce device life.  Auto-adjustment is off on my device (and is inhibited for some modes).