Micra AV

Question 1

What does the atrial sensing setup feature do?

Answer 1

It measures the A3 and A4 signals detected by the three vectors in the accelerometer
Programs the parameters related to atrial contraction detection with patient specific values: chosen vector, initial values for auto A4 threshold, A3 threshold, A3 window end, min/max A3 window end.

Question 2

How to run auto atrial sensing setup?

Answer 2

It runs automatically after implant when the telemetry header has been removed for at least 3 mins.
Ensure the device is programmed VDD and Auto Setup is programmed ON

Question 3

What functionalities does Micra AV provide?

Answer 3

Micra AV provides AV synchrony at rest to patients with normal sinus rhythm and VVIR pacing during periods of high activity.

Question 4

When is a Micra AV device contraindicated?

Answer 4

1) In patients with SND
2) High sinus rates requiring atrial tracking (young patients that require AV synchrony at higher rates)
3) weak atrial contraction (as the device won´t work properly) -?how to assess this prior to implant
4) patients symptomatic to loss of AV synchrony (pacemaker syndrome)
5) frequent PVCs or APBs requiring AV syncrhony after the premature beats

Question 5

Describe the accelerometer vectors that Micra AV detects

Answer 5

A1 - occurs during ventricular systole and coincides with the the R wave on ECG
A2 - end of ventricular systole, end of T wave on the ECG
A3 - occurs in diastole when the blood flows passively into the ventricles. Corresponds to the E wave on doppler echo. We want to avoid detecting A3 signal as the atrial contraction
A4 - represents the atrial contraction, after the P wave on the ECG.

Question 6

What does Auto A3 window end represent?

Answer 6

This feature detects the A3 signal end and keeps it seprated from A4 signal over time

Question 7

What does Auto A4 threshold feature do?

Answer 7

It automatically adjusts the A4 threshold ito be below the A4 signal in order to prevent undersening of the A4 (atrial contraction signal)

Question 8

What does Auto A3 threshold feature do?

Answer 8

Automatically adjusts the A3 threshold to be above the A3 signal to prevent oversensing of the A3 signal (passive diastolic filling)