Recurrent SVT

Recurrant SVT


A pest that keeps coming back

Dr. Jordan Singer

An ALS crew was dispatched to an elderly man who called for general illness.  They arrived to find the patient in bed and family reported he had a cold for the past few days but also has a cardiac history but were unable to elaborate.  Patient did not seem to be in any distress and had the following vitals:


Vitals: P 120/78,  HR 80,  RR 18,  Sat 98%


The crew extricated the patient to the rig, placed an IV and then proceeded to transport the patient to the hospital on the cardiac monitor.  While in route, the patient suddenly went into a narrow complex, regular tachycardia with a rate of 180 that was consistent with a supraventricular tachycardia (SVT).  The patient denied any chest pain or shortness of breath and looked well so they treated with 6mg of adenosine which failed to convert the rhythm.  The patients BP recycled and was 74/47.  They placed pads on the patient and performed synchronized cardioversion at 100J which converted the rhythm but it rapidly changed back to SVT.  The shocked at 150J which again led to a temporary conversion but then he went back into SVT.  They cardioverted at 200J and the same result happened.  The crew arrived in the ED less than a minute after the 3rd shock and handed off care to the emergency department team.


In the emergency department, the patient was cardioverted 3 more times with the same result and subsequently loaded with 150 mg of amiodarone over 10 minutes before a 4 shock was delivered which successfully converted the patient into a sinus rhythm where he remained during his time in the emergency department. 


Highlights of the case:

Electrical cardioversion is the treatment for unstable SVT

This patient is developed recurrent SVT that was causing shock.  If a patient has a stable SVT, then it is reasonable to treat with vagal maneuvers and/or adenosine.  The good news is that the majority of patients with SVT are likely going to be stable.  However, if the patient is unstable, such as having crushing chest pain, pulmonary edema, or hypotension, the treatment is electrical cardioversion.  The older patients get and the faster the rate of the SVT, the higher the likelihood that the patient will be unstable if they go into this rhythm.  Most times, once the patient converts, they stay in sinus rhythm.  However, if they are recurrently going into this tachyarrythmia we will need to treat them with subsequent doses of adenosine (if stable) or electricity (if unstable).  This crew quickly determined that the patient went into SVT and once they realized it was unstable, they used synchronized cardioversion which was perfect.  While not something that is in our protocol, this patient ended up needing an antiarrhythmic to get his heart to respond to the electricity we were delivering.  If you have a long transport time and a patient is not responding to appropriate cardioversion treatments, consider calling med control to discuss use of an antiarrhythmic before the next attempt at cardioversion.