Think Before You Freak Out!

The other night I was getting report from the say nurse on a post-pacemaker placement patient (try saying that 5 times fast!) who was all in a tizzy.  Scattered and doing things that really didn’t make a whole lot of sense.  It had been a busy day, but it seemed like she was making more work for herself than she needed.  Almost like running in circles.  Not productive at all.

When the excreted fecal matter hits the proverbial air oscillator, I make sure I take a moment to assess the situation.  Following the Fat Man, I check my pulse and then begin to gather the situational information.  It seems that the ability to do this was lost upon my colleague and she went from zero to “Holy Shit!” in about 30 milliseconds.  Over what?  A simple 5 beat run of V-Tach.

Yes, V-Tach is bad.  We all know V-Tach is bad.  5 beats though?  Self-limiting in a patient who just come back from getting a pacemaker?  With a slightly low potassium?  Not all that surprising.  But no, flew off the handle she did. Called for labs, called the doc and worked herself into the fore-mentioned tizzy,  Through this the patient is fine.  Happily chatting with his wife about this or that.  He’s on the monitor, already has a K-rider infusing and is about as content as one can be in the hospital.  Why the drama?

Because all to often people don’t think before they act.  Had the nurse been thinking things through and not reacting several things should have gone through her mind.  First, the ventricular ectopy in the form of multiple PVCs and a single run of VT was caused by two different things, the hypokalemia – the patient was 3.6 on the AM labs and the fact that the cardiologist has just been poking and prodding and electrified piece of wire inside this dude’s right ventricle.  Or in other words they had been pissing it off.  Second, she already was correcting the hypokalemia with the running rider and if she really wanted a magnesium level, a quick add to blood still in lab would have sufficed.  Third, she needed to look at the patient.  Vitals OK?  Feeling OK?  No chest pain or discomfort?  Yes, yes and no were the answers.  Simple isn’t it?

I think why this got under my skin so badly was that the nurses isn’t exactly new.  She’s been a nurse far longer than I and has been in cardiology for nearly the entire time:  she should know better.  But it seems that my day shift has been functioning in the fight or flight mode for so long that any little issue, real or imagined, gets turned into a full-scale shit storm.  It’s like when the LOLs with delirium are extra hyper-alert that the slightest thing sets them off.  So it is with the day shift.  They forget to think.  Unfortunately many nurses are in the same boat, we’re running scared and rile ourselves up faster to make sure Bad Things© don’t happen.  So stop, think, then act.

As for the pacer dude, well, things worked out just fine.  All that drama for nothing.

hmmm…drama for nothing and chest pain free… h/t Dire Straits

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Biventricular Pacemakers

One of our EP docs has been doing a roaring business in bivent pacers lately.  Between upgrades to existing pacemakers and new bivents we’ve been seeing these frequently.  On top of that, when we moved, our telemetry provider upgraded our system and software so we could actually see bivent pacing.  I figured that a quick primer on bivents was in order.

What is a biventricular pacemaker anyway?  It is what it says.  There is a lead in each ventricle, pacing each ventricle.  Historically, pacemakers have been one sided only, usually the right ventricle (RV) and/or right atrium (RA) due to ease of access.  You pop into the venous system, float a wire into the right side and you’re good to go.  The difficulty ramped up in reaching the left ventricle (LV) generally, the veins of the coronary sinus are harder to access and of a smaller caliber.  Thanks to advances in catheter size and mobility, this has gotten easier.

But why do this?  In heart failure, espcially dilated cardiomypoathy, the dilation of the heart makes the ventricles, well, floppy.  They get big and stretched out and consequently the condution system gets stretched out as well.  What begins to happen is that the RV and LV start beating out of time (or asynchronously), which in the end makes the heart work harder to achieve the output needed.  The harder workig heart stretches more, which make it work harder to maintain output and on and on down the spiral.  Cardiac resynchronization therapy (CRT) with the use of bivent pacing enables the heart to start beating in time once gain.

I know that I’ve way oversimplified this, but I’m going for core concepts here.  But talking about CRT allows me to post up some great strips that I’ve picked up to demonstrate visually what is happening.

click for largerLooking closely, you notice a couple of things.  This is both a bivent and a dual chamber pacer.  Notice the spikes before the P wave and then the double spikes leading into the QRS complex.  We’re able to see both the RV and LV leads firing.  So instead of having only 1 lead firing in the RV and having the conduction impulse cross via cell-to-cell contact, each side of the heart is being paced, thereby getting better contractility and a better ejection fraction (EF).

Here’s the same patient:

click for largerI changed the tracing speed to 50mm/s to better illustrate the 2 separate ventricular spikes.

In many cases, this is coupled with a defibrillator (CRT-D) for the prevention of sudden cardiac death due to ventricular arrhythmias that folks with severe heart failure can be prone to.  And it is proven to work.  In the MADIT-CRT trials, there was a “29% reduction in death or heart failure interventions when comapred to traditional implated cardioverter defibrillators.”  (h/t Dr. Wes)

Yes, there are risks, there are patients this doesn’t work for and the cost is pretty steep (I’ve heard in the range of $45,000 for the device alone…) but it appears to do what it is intended to do.

Here’s a couple of resources for some in-depth information:

Cleveland Clinc: Biventricular Pacemaker

About.com: Cardiac Resynchronization Therapy

WebMD: Cardiac Resynchronization Therapy

EKG of the Week #1

click for larger view

Pretty classic example of failure to sense and failure to capture.

As you can see, the pacer is firing but there is no response from the heart.  No P-waves, no QRS complexes, just lone pacer spikes hanging out.  This is classic failure to capture.  Possible causes of this can be a fractured or dislodged lead, battery failure or electrolyte abnormalities among others.  Luckily in this case the patient has an intrinsic rhythm that is probably perfusing them.

The second item shown is failure to sense.  Notable for this is the pacer spikes in the ST-segments.  Failure to sense is exactly what is says, the pacer is failing to sense the cardiac cycle and inappropriately pacing.  Again, luckily in this case the pacer is not capturing so the inappropriate pacing is not causing issues.  The biggest problem with this failure is inappropriate firing when the heart is not quite yet refractory possibly initiating ventricular arrhythmias.  Causes of failure to sense include lead issues (dislodgement, fracture or poor positioning) or sensitivity issues requires a change to sensitivity.

In this particular case, it appears the patient is in atrial fibrillation, which may be causing issues with both capture and sensitivity.  The erratic electrical signals emanating from the atria may be throwing off the pacer, but many times they are programmed with this in mind.  For nurses the important things to remember is to check on the patient when the pacer is acting up and ensure they are stable.  Past that, with permanent pacemakers, we need to get the cardiolosit involved.  If it the nurse who is running a temporary pacer at the bedside, adjustments to both output and sensitivity may be required to ensure adequate sensitivity and capture (but that’s a whole other ball-game!).

Here’s what a pacer strip should look like:

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Each spike has a corresponding activity, just like it should.