BiV pacer question

[jo1828]

I work on a cardiac step-down unit, and was teaching as student the other day about pacer spikes. I told her that sometimes there are three pacer spikes--one before the P wave, and two close together right before the QRS complex. I had seen this occur just once or twice, and had been told it was from biventricular pacing.

My charge nurse corrected me and said this was just artifact. I assumed she was right, but when I researched it online, I found several sources that talked about 2 ventricular spikes showing up on the EKG.

Any thoughts would be appreciated!

[BelgianRN]

It is possible to have two ventricular spikes if your pacemaker activates the two ventricles separately and out of sync to some degree.

[ChaseZ]

Short answer: Yes, a BiV Pacemaker can have to ventricular pacer spikes. Long answer: A BiVentricular pacemaker, also know as a cardiac resynchronization device (CRT), has two pacing wires; one in the right ventricle and another resting in the coronary sinus which paces the ventricular septum (Next time take a look at your CHF patients Chest X-ray and see if you can identify the type of device : Dual chamber PM - AICD - CRT or CRT-D) Around here the CRT-D is becoming the most common. The purpose of this is to synchronize the contraction of the right and left ventricle therefore improving cardiac function. Ideally, both leads fire at the same time (or close enough that it is not noticeable on a surface EKG) resulting in what appears to be a single pacer spike (which in reality is two) kind of like how the QRS is actually each ventricle depolarizing separately but simultaneously. Just like with a bundle branch block when there is a conduction delay you start to see each independent depolarization (rabbit ears) there can be a delay between the two separate wires. This can happen for various reasons but I think the main reason is an alteration in cardiac structure like with a HCMO resulting in two separate spikes. If each ventricle depolarizes at a different speed then the pacer will pace each wire at different times to "synchronize" them. That is my understanding but I am in no way an expert so I may be wrong.

[martymoose, BSN, RN]

I've seen it once- ran it by the EP doc ,and he said yes , it was pacing both ventricles- for somereason we were able to see it.I guess they program it that way.