How to manage ICDs and what it might mean when patients are repeatedly shocked (or: call the EP fellow)

I remember the first time I had a patient who had an implantable cardiac device (ICD) was on my emergency medicine rotation as an MS-IV. His device had shocked him several times in a row, and he came into the ED because he was worried about what it meant. I stared at his chest. I was worried, too.

ICDs sound overwhelming in theory (they keep people alive! There are so many different kinds! What do all the signals mean?) but for our purposes, there are really only a few things you need to understand:

  1. CRT/ICD=combined defibrillation and pacing.
  2. The device gets remotely monitored by whatever company made the device.
  3. The possibilities when your patient is being shocked multiple times include: arrhythmia like SVT, atrial fibrillation, or VT; ischemia (so monitor them for ST depressions or elevations); device malfunction–need to rule out a device infection.
  4. If there is a pacemaker as well, look at the underlying rhythm—slow down the pacing to like 40 bpm to see if any escape rhythms are revealed. Look at the P wave and the R-R interval. The most important thing to look for in a pacer is the trend of beats
  5. “Atrial capture threshold” tells you about battery life
  6. If someone has atrial fibrillation, they’ll require ventricular pacing because the atrium won’t be helpful anymore. You can tell what’s being paced by whether there’s a pacer mark at the P wave or the R wave.

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