We responded to a call for a 65 year old female with a rapid heart rate. When we arrived this woman was sitting in a chair telling us that she has a history of SVT and has tried valsalva maneuvers, a cold shower, relaxation and nothing has brought her heart rate down and now she is getting really tired. Her heart was racing at about 220 beats per minute. She said this had been going on for about three hours now. Yeah, no wonder she was tired. That's like running a marathon. She immediately asked if we carried Adenosine (the ant- arrhythmic drug we use to combat SVT) on the truck, so she knew her stuff and knew what was going to happen next. She wasn't happy about it though.
We laid her down on the floor and established an IV so we could administer the Adenosine. Adenosine causes a transient (brief) heart block in the AV node (pacemaker) of the heart causing a cessation of the irritability and allows the heart to essentially reset itself. In layman's terms: we stop their heart and hope it fixes itself.
We generally don't explain it to people that way of course because that is just a little bit alarming. We also don't tell them how horrible it feels when it is administered. Imagine going from 220 bpm to 0 in a couple seconds. It's like your heart hit a brick wall in a Ferrari. We usually say, "This may be uncomfortable for a minute". This lady knew what was coming and asked me to hold her hand when we did it. Fortunately I have a two medic crew and was able to do my part and hold her hand at the same time. Adenosine is so fast acting and has such a short half life that it has to be pushed rapidly as close to the IV site as possible and immediately followed with a saline push from the next available port in the IV line. So, two syringes pushed one after the other into the IV line. My firefighter pushed the drug and I pushed the saline as this woman tried to break my fingers with her kung fu grip. I watched the monitor as the time ticked by, ten seconds, no change, fifteen seconds, no change. Damn. I guess we will have to go to a second dose. But just then her grip tightened, which I didn't think was possible and she let out a painful moan. I watched the heart monitor drop from 220 down to about sixty and back to 120 and finally level off at about 94 bpm.
She said she could feel the slam of the Adenosine all the way through her body. It felt like hell, but it worked. The ambulance arrived just as we were finishing pushing the meds. We had the IV done, drugs administered, and rhythm converted for them which just left them transport to the hospital where our patient would be monitored for a few hours to make sure her heart remains stable. Sorry guys.
