Ineffective or inappropriate ICD shocks – Part II

Discussion

Inappropriate ICD shocks are not benign events. They can have profound psychological consequences for the patient, they can trigger ventricular dysrhythmias, and perhaps most importantly, they deplete the battery life of the device.

Often, paramedics (and Medical Control Physicians) are reluctant to disable ICDs. That’s because we’re generally not experts when it comes to implantable medical devices. However, we are (or should be) experts in Advanced Cardiac Life Support.

Adding to the dilemma is the fact that supraventricular tachycardias (SVTs) good enough to fool the ICD’s detection enhancement algorithms are difficult to dismiss as benign.

Note: that’s assuming the ICD has detection enhancement algorithms, and that the detection enhancement algorithms are active! Sometimes, they are not activated until the patient has documented episodes of inappropriate ICD shocks!

Atrial fibrillation and atrial flutter are not uncommon dysrhythmias in heart failure patients. Nor are conduction abnormalities like right and left bundle branch block.

If it’s wide and fast, it’s VT until proven otherwise.

But wait… what are we told from the first day of cardiology?

Treat the patient, not the monitor.

We need to ask ourselves a couple of questions to simplify matters here.

Left to our own devices (no pun intended) would we shock a hemodynamically stable patient over and over again?

I certainly hope not.

Albert Einstein once said that the definition of insanity was doing the same thing over and over again and expecting a different result.

If a particular heart rhythm has been shocked by an ICD 8, 10, or 12 times, can we reasonably expect that something different will result from shock numbers 13? 14? 15?

Maybe the patient is hypokalemic with a prolonged QT interval and experiencing recurrent runs of Torsades de Pointes. You can shock the Torsades all you want. It’s probably going to come back until the underlying problem is corrected.

In this case, the ICD is shocking a relatively slow wide complex tachycarida that is otherwise well tolerated by the patient.

Would you shock it? If not, then you probably shouldn’t let the ICD shock it either.

Consider this algorithm cropped from:

Emergency management of arrhythmias and/or shocks in patients with implantable cardioverter defibrillators (ICDs) – A statement on behalf of the Resuscitation Council (UK), Heart Rhythm UK (formerly The British Pacing and Electrophysiology Group, BPEG), The Joint Royal Colleges Ambulance Liaison Committee (JRCALC) and the Ambulance Services Association (ASA). Resuscitation, Volume 71, Issue 3, Pages 278-282

Here’s another helpful algorithm from:

Clinical Assessment and Management of Patients With Implanted Cardioverter-Defibrillators Presenting to Nonelectrophysiologists. Circulation. 2004;110:3866-3869.

Consider this thought:

The patient has an ICD because a paramedic can’t be there 24 hours a day, 7 days a week.

If the ICD is effectively terminating episodes of VF or pulseless VT, that’s one thing. Clearly, the patient needs special treatment at the hospital and the antitachydysrhythmia functions of the device should not be disabled.

However, if the device is shocking a conscious, hemodynamically stable patient, and the rhythm is not changing after the ICD shocks, a ring magnet should be applied, and the antitachydysrhythmia functions of the device should be disabled.

If you do not disable the antitachydysrhythmia functions of the device, you could at least consider sedating your patient!

Conclusion

If you get called to a patient with an ICD that has fired, place the patient on the monitor immediately. Capture a 12 lead ECG. Hit the ‘print’ button (or assign someone to sit there with his or her finger on the print button) so you capture the pre and post-shock rhythm.

If you determine that the shock(s) are inappropriate or ineffective, and if your protocols allow it, apply a ring magnet (these can be obtained from the manufacturer) and treat the underlying cause of the dysrhythmia.

After all, you’re a paramedic! Remember?

If you need to shock the patient, remove the ring magnet. The antitachydysrhythmia functions should resume automatically.* If they don’t, tape the magnet back in place and treat according to ACLS guidelines with one modification.

If the powerplant (can) is in the upper-right chest, don’t place your pads in the standard position. Electrical current follows the path of least resistance (in this case, the leads between the tip and can, which can damage the ICD). Consider anterior-posterior pad placement instead.

Image credit: Physio-Control

Note: the device will usually be implanted in the patient’s upper-left chest, so you can use standard anterior-lateral pad placement.

In any case, follow your protocols.

* There is a caveat for devices from Boston Scientific. I will address specific procedures for ring magnet application in my next (and final) article in this series.

See also:

Inappropriate or ineffective ICD shocks – Part I

Inappropriate or ineffective ICD shocks – Part II

Inappropriate or ineffective ICD shocks – Part III