Search AV Hysteresis

Question 1

What is Search AV Hysteresis?

Answer 1

An algorithm functional in dual chamber mode that proactively searches for intrinsic conduction.

Question 2

How does Search AV Hysteresis work?

Answer 2

AV sequences are monitored in a rolling 16 beat window and are classified as EARLY, ON TIME or LATE. If 8 Vs fall in the EARLY category, the AV delay is shortened by 8 ms; ON TIME stays the same, and LATE extends the AV delay 62 ms.

Question 3

How far will the AV delay extend during Search AV?

Answer 3

If the Vs continues to fall into the LATE zone, the AV delay will continue to extend until the Vs falls in the ON TIME zone or until the maximum offset is reached.

Question 4

What happens when the Search AV MAX OFFSET is reached and there are still late Vs?

Answer 4

If 8 out of 16 beats are classified as LATE and the max offset has been reached, the search will be postponed and AV delays will return to programmed settings for 15 minutes. After 15 minutes, the device will look at the next fifteen beats, if 8/16 continue to be late, the search will postpone again and repeat at 30 min, 1 hr, 2 hr, etc., up to 16 hours.

Question 5

What happens if Search AV is postponed up to the 16 hour mark?

Answer 5

After 10 failures at the 16 hour mark (this takes about one week), Search AV will be disabled until the next interrogation.