Heart rate

Hi. I have 3rd degree total heartblock I was told. That is why my rate suddenly plunged to low 40s high 30s. Now with pace maker I often get into the 70s. The rate response thing is turned off so I was told anything over 60 is my heart doing the work. But if I have complete heart block and prior to pacemaker I was in the low 40s, how is it now my heart can be beating 70 on it's own?

3 Comments

2 Chamber PM

by BillH - 2016-03-06 05:03:40

With a heart block you most likely have a 2 chamber PM that is setup with one lead in the atria to monitor the naturally functioning sinus node.

And the 2nd lead in the ventricle. It monitors the ventricle to see if the ventricle naturally fires after the atria fires. If not it fires the ventricle on a one for one basis.

So a long as the atria (sinus node) is functioning normally and increases as needed during "load" rate response is not needed.

When you feel the pulse it is from the ventricle firing. So if you have a heart rate of 30-40 you probably had an atria beat in the 60-70's or higher.

In your case the PM is basically just a "conductor" that bypasses the defective circuit that is between the atria and ventricle.


BillH

by glennagain99 - 2016-03-06 06:03:30

Thank you for that response. It makes perfect sense now.

Doesn't make sense to me.

by donr - 2016-03-07 04:03:37

It all depends on what your cardio means by your heart doing all the work at 70 BPM.

If RR is turned off & your HR is 70, it means that the Sinus Node is setting the pace for you. That's all it means.

W/ a complete block, the AV node is a washed out bridge on the road between the SA & AV Nodes & the PM is pacing the ventricles completely, BUT the PM is following the rate set by the SA Node, your natural pacemaker.

The PM senses the SA node's P wave, starts counting milliseconds, looking for a QRS Complex, telling it that the Ventricles at contracting. When the count reaches a set value w/o the natural QRS being sensed, The PM sends the pacing spike to the ventricles. Doesn't matter what the HR is.Regular as clockwork - but that's what it is!

Back when you were experiencing HR's in the 30's & 40's, that was probably your AV Node running at its escape rate because it was NOT receiving any signals from the SA Node. The AV has that capability, just in case a block occurs.

Whoever designed the heart's control system should have worked for NASA designing control systems - pretty bright guy, to say the least.

Donr

You know you're wired when...

Lifetime warranty no longer gives peace of mind.

Member Quotes

Think positive and go out and take on the world.