AV delay

AV-delay

by golden_snitch - 2013-02-28 04:02:32

Hi MT!

I read this definition of what the AV-node does somewhere, and it helps to explain the AV-delay:

"The AV node serves as an electrical relay station, slowing the electrical current sent by the sinoatrial (SA) node before the signal is permitted to pass down through to the ventricles. This delay ensures that the atria have an opportunity to fully contract before the ventricles are stimulated."

The delay mentioned in the definition is the so-called AV-delay or AV-interval. In most pacers you need to program the AV-delay at rest and during exercise. There are also pacemakers that automatically search for the best AV-delay, and there are some which automatically shorten this delay during exercise (so you don't need to program that).

Usually, the AV-delay at rest is somewhere around 150ms, the delay when exercising is shorter, for instance 60 or 80 ms. BUT there is really no standard setting, the AV-delay differs in every patient. Sometimes the setting is optimized by doing an echo.

60 ms at rest sounds a bit too short to me, maybe it's the exercise setting. As you probably understood from the definition, the delay is important because it gives the atria time to fully contract. If it's programmed too short, they won't pump all the blood into the ventricles before the ventricles contract (when the ventricles contract, the valves between atria and ventricles are closed).

Hope this helps.

Inga

Add

by golden_snitch - 2013-02-28 04:02:32

My AV-delay at rest is 140ms and exercise is 65ms, and this is what was programmed one month after AV-node ablation.

Inga

My AV delay

by Janey L - 2013-02-28 11:02:01

Hi Mtulau
Good to hear your AV node ablation went well.

As you know, I had my AV delay "optimised" a few weeks ago, by echo as Inga described.

At rest they found my optimum AV delay is 140. On exertion the shortest they could go to was 100. Any shorter than that & they saw on the echo that my atria & ventricles were not filling properly.

So I'm now set at 140 at rest. They turned on a function on my PM so that the AV delay shortens on exertion but to a max of 100.

Inga- your description/explanation of the AV node & AV delay is excellent. I found it very interesting to read. Thank you.

Best wishes
Janey

My AV Delay Setting

by Keithwhelpley - 2019-12-30 16:42:18

I read with interest this exchange because I only now am tryig to read my summary sheets I get after my device interrogations. I understand AV delays and the settings now that you all have explained them. But on my sheet the Paced and Sensed AV delay on my Dual Chamber is set for 300ms. Now, based on what actural delays should be, -- either natural or paced -- I can only assume that the 300ms I'm set at is only to keep it far from having to do anthing, since I don't have an incompetence in that area. 

Is that correct?

Yes that is correct.

by PacedNRunning - 2020-01-02 05:57:41

300 ms is a long AV delay and gives your heart plenty of time to work. This is set this way if you have normal AV conduction.