AV synchrony in lead-less Micra AV pacemaker: How does it sense Atria ?

The Medtronic leadless Micra TPS pacemaker
In 2016, EP world saw a major breakthrough when Medtronic introduced leadless Micra TPS pacemaker. This device that looked like a small bullet, was implanted in the RV apex without the need for lead insertion and surgical pocket. It was real innovation but was not able to take off even after 4 years of marketing. The reason was simple. Though it was a smart device, it was a journey backward in time, as Micra TPS provided only non-physiological VVI pacing. (In the current era of multi-site and His bundle pacing)
Physiological pacing requires two are more leads.(Except single lead VDD, now obsolete AAI ) . Atria must be sensed for AV synchrony to happen. Atrial sensing is accomplished by

A dedicated atrial lead as in AAI or DDD
A floating atrial lead as in VDD mode

How does the leadless pacemaker attached to RV apex bring in AV synchrony without any add on leads ?
Medtronic, has come out with new add on to TPS ie “Micra AV” .The same gadget has been upgraded with a software to do atrial sensing. The accelerometer in the pacemaker senses the motion of the blood in early diastole followed by atrial contraction mediated S4 . This is sensed, and ventricular lead is set to fire after a programmed Interval.

The initial experience appears promising. The results of the MARVEL study is published (Ref 1) However, there are important limitations. The atrial sensing function is not fully tested in real-life exertion. Further, ItR...

Source: Dr.S.Venkatesan MD - April 3, 2020 Category: Cardiology Authors: dr s venkatesan Tags: Uncategorized atrial sensing lead in micra medtroinc dual chamber vs micra medtroinc how does micra av sense atria is micra a physiological pacing medtronic micra pacing medtronic micra tps vs av Source Type: blogs