Pacemaker Programming Calculator

This calculator works through the standard timing-cycle arithmetic of a dual-chamber pacemaker: pacing interval (ms between paced beats) is 60000 divided by the programmed lower rate limit, Total Atrial Refractory Period (TARP) is the programmed AV delay plus a fixed 250 ms PVARP, and the TARP-limited maximum tracking rate is 60000 divided by TARP. Lower rate limit alone determines the pacing interval; AV delay, pulse width, output voltage, and lead impedance have no effect on it. AV delay is the dominant driver of TARP and therefore of the maximum rate the device can track 1:1 -- lengthening AV delay directly lengthens TARP, which lowers the rate at which the ventricle can still track every atrial beat before AV-block-like behavior takes over; this calculator reports a single "rate where 1:1 tracking caps out," whichever is lower of the programmed upper rate limit or the TARP-limited rate, rather than modeling the full graded Wenckebach response some devices use across a range of rates before hitting hard 2:1 block.

The voltage safety margin compares the programmed output voltage to a single assumed typical chronic capture threshold of 0.75V, NOT to an actual measured threshold from this specific patient's lead -- in real practice, safety margin is calculated from a measured capture threshold obtained at the device check, and this calculator's status (inadequate/marginal/adequate/excessive) should be read only as an illustration of how the 2:1-or-greater margin convention works, not as a substitute for that measurement. The battery-life estimate combines the pacing-pulse current with a fixed ~9 uA baseline for the device's sensing, telemetry, and housekeeping circuitry, against a fixed 1.2 Ah capacity, assuming 100% pacing at these settings -- without that baseline term, low-output/low-rate settings would mathematically imply multi-decade battery life that no real device achieves, since pacing-pulse current alone can be a small fraction of a device's total continuous drain. Even with the baseline included, this remains a rough estimate: a real device's actual battery life depends on its specific circuitry, how much of the time it is actually pacing versus sensing intrinsic beats, and other factors this calculator does not model.