Sunday, March 7, 2021

Adenosine or CCBs for SVT

First10EM EM - By Justin Morgenstern - September 5, 2017
... Bottom line: The studies aren’t huge, but calcium channel blockers seem to be a better choice than adenosine as a first line agent in the management of SVT...
A couple practical points
  • Hypotension seems to be more common with verapamil than with diltiazem (although I have not seen a head to head comparison). I tend to stick with diltiazem. 
  • Go low and go slow. Although the diltiazem dose used in the Lim study was 2.5 mg/min to a maximum of 50 mg, 75% of patients had converted by 18mg. I tend to give 15 mg of diltiazem over 10 minutes. It almost always works, but when it doesn’t I just repeat the dose. 
  • Always be prepared. Although SVT patients almost never crash, you should always be prepared to cardiovert any emergency department patient with an arrhythmia. At the doses I use, calcium channel blocker induced hypotension is almost never a problem. However, I am always prepared for clinically significant hypotension. My first step here would be to simply cardiovert the patient out of SVT. If that was not enough, I would start a fluid bolus with or without a dose of IV calcium, or in the worst case scenario, start a vasopressor. (This is not like the dreaded calcium channel blocker overdose.)