What happened here

[MendedHeart]

Cardiac surgery pt, POD#1 transfer to tele floor, AAI pacing d/t acc. Junt beats vs. Wandering pacemaker. On arrival, pt A paced sensing, capturing and firing approximately. After pt settled, about 30minutes later, pacing spike firing closer and closer to the qrs with each beat until it fires on the qrs. It was firing all over the place. I checked the connections, they were secure. The weird part was that both A wires were the same color and both V wires were same colir and lengths too. I tried to turn the sensitivity up, the MA up, nothing worked. Ended up getting order to pause it, check underlying and turn of if ok rhythm. I cant figure out what happened, also the pt had ST elevations in V2 on tele since a little bit after surgery

[MunoRN, RN]

"Firing all over the place" usually indicates undersensing, which means the sensing threshold needs to be turned down to increase the sensitivity. AAI is an odd pacer setting for epicardial wires in my experience and I would think it would be problematic since epicardial wires typically have trouble sensing in the atria. With both atrial and ventricular wires, DDD is usually preferable.

As for what happened and why the sensing seemed to change, if the patient's intrinsic rate was at first less than the rate set on the pacer the patient will be pacer dependent which limits the opportunity for issues related to competition between the patient's intrinsic rhythm and the pacer settings, once the patient's intrinsic rate exceeds that of the pacing rate you're more likely to see sensing faults.

[MendedHeart]

Yea, our pts usually are on VVI..

It was odd to have AAI.

The sensitivity was already at 0.5, the MD decided to just turn off, the pt did fine.and stayed in nsr. It was weird though.

[Esme12, ASN, BSN, RN]

Just the atrial wires were hooked up right?

AAI pacing offers better hemodynamic characteristics than dual-chamber pacing and is the optimal mode for patients with sick sinus syndrome without AV conduction disorders. Most heart patients are sensitive to atrial kick

If the atrial spikes were not sensing it is possible the the atrial of the heart had decided to take over....the chest leads were having difficulty sensing the return of the underlying return of Sinus rhythm. The best response is to shut off the pacer.

AAI: atrial paced, atrial sensed, inhibited by atrium

A great simple resource....http://www.cardiacengineering.com/pacemakers-wallace.pdf

[MendedHeart]

I understand what it means, I assumed it was hooked up correctly because the patient was pacing appropriately and then it just went wacky after about 20 minutes post transfer. The wires were not handled until I unwrapped them to check for secured connection. The only thing I could think was that the tip may have dislodged a bit from the atrium like the above post suggested. I am trained on epicardial pacers, but this was my first one, and, alas, Of course I would have an issue with it...cant kick this new nurse black cloud...lol

[Esme12, ASN, BSN, RN]

No need to kick yourself.....we have all been there.....it the atrium is firing the pacer should sense it. I think it was competing....in other words....the patients own rhythm (intrinsic rhythm) was overriding......atrial wires aren't always the MOST reliable.

The only thing I could think was that the tip may have dislodged a bit from the atrium

There is not a real...."tip".... they are "sutured" right onto/into the epicardium......the outer layer of heart muscle—during cardiac surgery.

Typically, the surgeon places four wires, attaching one positive and one negative electrode to both the right atrium and the right ventricle before the chest is closed. The physician loosely sutures the leads onto the epicardium and threads the wires through to the outside of the chest via small, stab-like incisions.

The wires attached to the atrium exit the chest on the right side of the sternum; those attached to the ventricle exit the chest on the left......pacing wires can easily become dislodged.

[MendedHeart]

Thank you^^^^

[Esme12, ASN, BSN, RN]

any time.....cardiac is my first love.