So on my first day back I discussed with my budding paramedic partner (I promised not to mention Bobby’s name or anything… oops…) issues surrounding ACLS and what he is/was being taught about tachycardia. He was attempting to present the position that any rhythm with a rate above 160 in adults must therefore be supraventricular tachycardia and must absolutely be treated with anti-dysryhthmics or synchronized cardioversion.
It turns out the discussion arose during a call he made while I was off, with my other counterpart. It was a hot day, and a mailman had been walking his route and collapsed. When they arrived, they found the man with a heart rate in excess of 170. Classic heat stroke, but looking at the just the strip, my soon to be medic partner classified it as an SVT.
Technically, he is correct, but his mindset for treatment was very, very wrong. What I spent the next 10 minutes explaining was that even though the rate was super fast, it was still sinus tachycardia. He was debating that the rate made made it SVT. I explained that SVT is a blanket term that describes ALL tachycardiac rhythms that originate above the ventricles, atrial fibrillation with rapid response originates above the ventricles, therefore it is SVT, as does sinus tachycardia. The rhythm isn’t necessarily dependent on the rate, a healthy adult can run 3 miles and have a heart rate at the end of 170 or 180 and it still be sinus tachycardia, but Mrs. Smith with a history of AF and a heart rate of 180 raises that index of suspicion that it may not be due to exercise.
What I am getting at is that in your thought process you should consider the REASON for the tachycardia. The mailman, for example, was an easy case. Being outside on a hot day, lack of fluid intake or a cool place to sit made the treatment options very clear with increasing intravascular volume and cooling him down passively to avoid cooking his brain. I have posted other cases before regarding SVT, which was a true cardiac case. When a tachycardia starts suddenly, with no extra factors and considering patient history, you should be leaning more towards treating a cardiac problem.
So is it cardiac, or physiologic?