Arrythmia or Artifact?

Arrythmia or Artifact? 

4.22.2024

What are all these squiggly lines?

Dr. Jordan Singer

Case summary:

An ALS crew responded to 70s man who had fallen the previous day and was having back pain from the fall as well as a headache.  He denied being on blood thinners as well as denied nausea, vomiting, chest pain, dizziness, and shortness of breath.  The initial vitals were:

 

Vitals: BP 148/110,  HR 66,  RR 18,  Sat 95%

 

The crew threw the patient on the monitor.  They reported that the patient had a tremor and at one point became unresponsive for a few seconds and did not respond to a sternal rub.  They reported that it looked like a tachyarrhythmia on the monitor.  Right after placing the pads, the patient returned to normal and did not have any confusion.  The noticed that the patient was going in and out of wide complex rhythm with a pulse and they had the following rhythm strip at that time.

The crew decided that this was stable ventricular tachycardia (VT) since the patient was not confused or drowsy, not having any chest pain and had a reassuring blood pressure.  They treated this by starting 150mg of amiodarone over 10 minutes. 

 

The crew arrived at the receiving facility and the emergency department team took over and placed the patient on their monitor as well as looked at the rhythm strips that were obtained in the field.  The emergency department team felt that the rhythm was not ventricular tachycardia and was instead artifact.  The patient had a persistent tremor that was causing the irregularity seen on the rhythm strip.  They stopped the amiodarone and treated the patient for his back pain.

   

Highlights of the case:


What was the rhythm seen in the rhythm strip?

This patient had a tremor at baseline which can make determining the underlying cardiac rhythm very difficult since there is a large amount of artifact present from the tremor.  Whenever we are unsure if this is a ventricular arrythmia or artifact, the first thing we should do is look at the patient.  If the patient is awake, talking, with good skin color, and no complaints of chest pain or shortness of breath, then we can consider artifact as the potential cause (but it still could be VT).  If the patient looks, grey, is unconscious, showing signs of hypoperfusion, or complaining of crushing chest pain, we should assume that this is a ventricular arrythmia until proven otherwise.  This patient initially was unconscious, but then was completely well for the rest of the transport. 


Given he looked well during the time when the above rhythm strip was obtained, it gives use time to scrutinize is closer to look for signs of artifact.  In the case of this rhythm strip, there are clear signs that the rhythm seen is artifact and not a ventricular arrythmia.  The rhythm strip actually shows QRS complexes that march out regularly for a large portion of the strip that the crew brought to the hospital.  I placed red boxes around a couple of them on the strip below as well as underlined some throughout the rest of the strip.  If a patient is having a ventricular arrythmia, they would be able to also have regular QRS complexes at the same time.  It is possible to have in intermittent fusion beats and capture beats which both occur when the atria can send a signal to the ventricle while a ventricular arrythmia is occurring, however, they would not occur regularly as they are here. 


Fusion beats and capture beats can both be seen in VT.  In addition to the QRS complexes highlighted, this patient also has a regular pulse oximetry waveform that correlates with the QRS complexes.  These waveforms occur with each beat of the heart and it is why a pulse oximeter can give you a heart rate.  IF this patient was having a ventricular arrythmia, the waveform would either go away, or it would correlate with the ventricular contractions form the VT as opposed to the underlying normal QRS complexes we are seeing.  Both clues can help you confirm that the rhythm seen is artifact and not VT.  


Now, if the patient was in shock or unresponsive, we should assume a ventricular arrythmia and treat with electricity. These cases can be very difficult, and we should have a low threshold to involve online medical control in deciding the best treatment option.