An ALS crew responded to 70s man in a car.  He appeared grey and diaphoretic and had vomit on his shirt.  The patient reported he was having chest pain and general malaise.  The crew obtained vitals and the following rhythm strip.

Vitals: BP 60/48,  HR 112,  RR 30,  Sat 97% on RA

The crew felt this was unstable ventricular tachycardia (VT) given the wide complex rhythm and his overall clinical picture given ashen appearance and hypotension.  The crew placed pads on the patient and promptly synchronized cardioverted him at 100J and 150J, but both times the rhythm failed to convert.  The patient remained hypotensive, so the crew started giving 150 mg of amiodarone over 10 minutes and attempted a third cardioversion at 200J right after starting the amiodarone.  The patient immediately started to become more bradycardic and goes into asystole.  The crew started CPR and transported to the nearby hospital with the patient still being in cardiac arrest at the time of transfer of care to the receiving facility. 

The crew felt this was unstable ventricular tachycardia (VT) given the wide complex rhythm and his overall clinical picture given ashen appearance and hypotension.  The crew placed pads on the patient and promptly synchronized cardioverted him at 100J and 150J, but both times the rhythm failed to convert.  The patient remained hypotensive, so the crew started giving 150 mg of amiodarone over 10 minutes and attempted a third cardioversion at 200J right after starting the amiodarone. The patient immediately started to become more bradycardic and goes into asystole.  The crew started CPR and transported to the nearby hospital with the patient still being in cardiac arrest at the time of transfer of care to the receiving facility. 

Highlights of the case:

Slow ventricular tachycardia is a trap.

VT is defined as a wide complex tachycardia that is originating from the ventricles.  There are several different forms of VT, but they all require a tachycardic rate.  Some sources define the minimum rate for VT is 120 with others defining it is 130.  Most of the time, VT will have rates much higher than 130.  The reason that this defining characteristic is so important is that wide complex rhythms under 120-130 are caused by things that are worsened by antiarrhythmics.  Hyperkalemia and sodium channel toxicity (such as with a tricyclic antidepressant overdose) will cause widening of the QRS, and if the rates are fast enough, it can look very similar to VT making distinguishing between them difficult.  However, hyperkalemia and sodium channel poisonings can have rates that are below 120-130.  Hyperkalemia and sodium channel toxicity will cause a sine wave appearance if severe enough.  A fast sine wave can look very similar to VT.  Amiodarone treats ventricular tachycardia by blocking sodium channels in the heart.  Therefore, if you give amiodarone to a patient with sodium channel toxicity, it will make things worse and lead to asystole.  Amiodarone has a similar effect on patients with hyperkalemia.  The patient in this case had a wide complex rhythm with a rate under 120, which effectively rules out VT because it is too slow.  This makes hyperkalemia or a sodium channel poison the most likely cause, and likely explains why the patient went into asystole after getting amiodarone.  The treatment for hyperkalemia is calcium and the treatment for sodium channel poisons is sodium bicarb.  The good news is that if you cardiovert a patient with hyperkalemia or sodium channel poisoning, it will not make them worse, but it will also not make them better.  So when in doubt, you can always try cardioverting.  In addition, if you give someone with VT calcium or sodium bicarb, it will not harm them or help them.  This means that if you are not sure if this is VT or hyperkalemia or sodium channel toxicity, treating them with cardioversion, calcium and bicarb is a good way to start.  The order you move through these should be based on what you think is the most likely.  This was a very difficult situation, and the crew did a great job pulling the trigger on cardioversion right away for a patient they believed had unstable VT.  Distinguishing between VT, hyperkalemia, and sodium channel toxicity can be tough.  While this patient did not have the best outcome, we can still learn from this case.  The key is that if the rate is <120, it is NOT VT, and if it is <130 it is very unlikely to be VT.  In these situations, we should be very cautious around using amiodarone and other antiarrhythmics.  We should consider discussing the case with online medical control before using these meds since it can be very nuanced.  If you ever catching yourself saying that the patient has “slow VT,” that should give you a ton of pause and it is likely the patient does not have VT at all.