Friday, May 09, 2008

MacGyver Moments in Medicine

I love MacGyver moments in medicine. You know, those time when you're stuck in a predicament with a sick patient and have to come up with a creative way to get out of a jam. I had mine this week.

It was an elderly patient, but not too old, with recurrent incessant ventricular tachycardia and a very weak heart muscle. The rhythms were repetitive, and it was clear there was more than one morphology of the ventricular tachycardia was noted on EKG's obtained. Amiodarone, lidocaine, procainamide, beta blockers and even general anesthesia were all ineffective at stopping the rhythm, but helped slow the rhythm. She was taken for a catheter ablation, but this too was unsuccessful at finding the dominant VT - even after working on it for over eight hours, for this was not just ANY ventricular tachycardia - this was a ventricular tachycardia that was not reentrant, but triggered. And despite our best efforts, we could not figure out what the heck it took to trigger it so we could map and ablate it.

It was an ugly situation. Simply ugly.

So what better time to turn to MacGyver, that cool, calm secret agent who made his contraptions on the fly to get him out of the most difficult of circumstances. After all, if MacGyver can use two candlestick holders, a floor mat, and an electrical power cord as a makeshift defibrillator to revive a fallen comrade, he can do just about anything.

My problem was this: I had a lady with recurrent ventricular tachycardia in whom medications and ablation didn't work and in whom a defibrillator would be contraindicated if it meant she'd receive recurrent ICD firings. It was impossible to provoke her arrhythmia to see if we could even pace-terminate it. So what to do?

Well, first, I elected to leave a temporary pacing wire in her heart. Maybe, just maybe, we could overdrive pace the rhythm with an external pacer, rather than leaving her in minutes of VT or having to shock her while we treated her heart failure.

It was worth a try.

But it soon became apparent that the rapid ventricular tachycardia rate did not lend itself to an adequate comfort zone for the ICU staff to attempt pace-termination. Somehow turning on ventricular pacing at 180 b/min for a few seconds was just too nerve-wracking for the nurses and housestaff to perform reliably, and was not always effective - possibly because of the hesitancy to pace the ventricle that fast.

Implantable cardiac defibrillators have different ways to pace-terminate a rhythm - they can "burst pace" a rhythm at a certain percentage of the tachycardia cycle length for, say, eight beats at a set rate, or they can "ramp-pace" - that is, pace the rhythm with eight successively shorter beats. These pacing algorithms also respond very quickly to the arrhythmia - in seconds.

"If I could just use the algorithms in an ICD to pace her heart," I thought.

And then I had an idea. Could I connect the temporary pacing wire to an ICD? I had an old explanted one in our lab. Maybe I could use it? But the small ports where the leads plug in are difficult to access. The connections are housed inside the header of the device, shown below:

And somehow I had to attach the ICD to a pacing cable that would connect to the temporary wire, seen here:

So I took an old lead adapter that split from the "IS-1" pin connector used inside the defibrillator to two terminals and shoved some old defibrillator patch wires inside and tightened the little securing hex nuts and suturing the cable to the adapter with a little silk suture, shown here:

Then, it was just a matter of a bit of splicing and taping:

Then it just got all connected together to make a antitachycardia pacing device that could be connected to the patient's temporary pacing wire:

And the cool thing is...

... it worked like a charm: 100% pace-termination with ramp pacing at 84% of the VT cycle length within seconds.

Anyone else have such a moment?



rlbates said...


Hope you'll submitt this to SurgeXperiences. Sterile Eye is doing this one on tools of the trade.

Anonymous said...

why didn't you just implant the defibrillator once you saw pace termination worked?

regardless, cool!

DrWes said...

anony 1:12 PM -

why didn't you just implant the defibrillator once you saw pace termination worked?

Well, I guess there's a reason we're seeing the wires used now, eh? Nothing like a little biV pacing and ATP to cure what ails ya! ;)

Jay said...


In an effort to minimize the liklihood of temporary pacer lead dislodgments, we, for years, have been using "permanent" pacer leads as our temporaries.

We implant whatever active fix lead is available cheaply through a peel away introducer through the IJ and sew the suture sleeve to the neck. In most cases, we'll then attach the lead to an old pacer generator and tape it to the neck. We then allow even pacer dependent patients to be fully ambulatory on a telemetry unit. I figure that if we prevent even one off-hours dislodgement, we'll pay off a whole bunch of leads.

This would be an alternative way to do what you've described.

Way back in my days at University of Pittsburgh (~1995), I recall using this setup with an old Intermedics Intertach antitachycardia pacer and pacer terminating just like you've described.

Hope your patient settles down, and your lead stays put!!


DanDan said...

I guess you didn't have time to go with the IV-pump+wall-mounted-O2+resident's-iPhone, +nurses's-hair-pin/arc-welder route...


Dragonfly said...