Aveir VR LP — Can nocturnal non‑capture be stopped without raising voltage?

Question

Is it possible to stop the issue of nocturnal non‑capture in an Aveir VR leadless pacemaker (LP) without modifying the output voltage?

Short answer

Sometimes, yes. Night‑time non‑capture can often be reduced (or eliminated) without increasing the voltage amplitude by addressing physiologic drivers of threshold rise and by using programming changes that don’t touch amplitude.

What to adjust that isn’t voltage

Increase pulse width. Lengthening the pulse width lowers the effective capture threshold at the same voltage (chronaxie/rheobase relationship). This is the standard first move when thresholds drift with circadian/autonomic changes.
Raise the nighttime lower rate (or disable sleep‑rate lowering). Capture can be rate‑dependent—very slow rates may unmask non‑capture. A modest increase in the lower rate during sleep (and avoiding aggressive hysteresis) may close a low‑rate “non‑capture window.”
Review Aveir VR safety margins & timing features. In the Merlin programmer, confirm an adequate safety margin around the highest measured threshold, and ensure mode/rate features and refractory timing aren’t promoting prolonged pauses overnight.
Correct reversible physiologic causes that worsen at night. Electrolyte shifts (K⁺/Mg²⁺), acid–base changes, hypoxemia/sleep apnea, and medication effects (e.g., class I/III antiarrhythmics) can transiently raise thresholds. Addressing these often restores capture at existing settings.
Consider early post‑implant threshold drift. If you are in the early post‑implant period, thresholds may be temporarily higher; re‑measure and stabilize before altering amplitude.

Practical programming sequence (no amplitude change)

Recheck a nighttime threshold (or simulate with slow rates during testing) and lengthen the pulse width.
Raise the lower rate during sleeping hours and disable aggressive hysteresis/sleep functions.
Review medications, check K⁺/Mg²⁺, and screen for sleep apnea / nocturnal hypoxemia.
Program a conservative safety margin based on the highest observed threshold, not just daytime values.

Want a tailored example? Share the latest interrogation values (threshold, pulse width, mode/rates) and the time window of missed captures, and we’ll draft exact pulse‑width and rate settings appropriate for your Aveir VR.