Proficiency vs Deficiency… The Art Of Electrocardiography Analysis

Understanding the different types of assessments, assessment tools, and findings acquired from these assessments, are all part of proper patient care in both acute and chronic emergency medicine management, in every realm of the term “PATIENT CARE”. One of the most important tools, in both the prehospital setting and long term care, is the 12 lead ECG, which just like any other tool, requires attention to detail, probably even more so than other tools. We have to know when to use it, why to use it, and be able to recognize the information given to use through its use.


It’s an art which requires never-ending practice and will never reach a limit.  We will never know it all, and we will never be able to say, “I have seen it all”. Over the years we have seen providers and clinicians, in every setting and level of care, both being proficient and completely lacking ECG interpretation skill. Often, many clinicians, from Paramedics to Physicians, rely on the computerized ECG interpretation for proper patient care and management.

But how do we truly define “PROPER“?

Let’s discuss some scenarios…

This 93 year old male has been brought to the Emergency Department by a family member after complaining of sudden spells. He is overall healthy considering the age, with minimal pertinent history and just takes daily vitamins, at least per the family. The following 12 lead ECG was obtainedScan_20150522There appears to be sinus bradycardia with variant AVB (Atrioventricular Block), IVCD (both RBBB and LBBB morphologies) with Leftward frontal axis (Left Anterior Fascicular Block) at approximately -70 degrees (aVR is the most isoelectric lead perpendicular to aVL), aberrantly conducted impulses during the 2nd and 7th beats, with a QTc (using Bazett’s formula) of approximately 400 ms, not taking into consideration the slight afterdepolarizations which cause a false QT prolongation)

Because of the initial computerized ECG interpretation of “EXTREME TACHYCARDIA WITH WIDE COMPLEX”, lack of awareness (for professionalism’s sake) by the receiving physician, and chief complaint of dizziness, the patient was initially on the verge of receiving a full Amiodarone drip of 150 mg over 10 min, but thank goodness for compensatory hypertension. In this case, there were multiple things wrong with the computerized interpretation, and treatment to be followed.

  • There Heart Rate is not 283 beats/min, but in the 30’s
  • The QTc is not 1121 ms
  • There is AV dissociation, with variant blocks throughout ED visit, from 1st degree to 3rd degree AVB
  • Amiodarone is definitely not indicated in bradycardias or high degree AVBs

Click on the highlighted title for an Amiodarone breakdown, UNDERSTANDING AMIODARONE   One tool I use in these cases of bradycardia, is SPo2 monitoring. Remember, with every systole achieving arterial pressures, the Pulse Oximeter will provide a value and waveform. We are not focusing on oxygenation values right now, just the presence of an SPo2 pleth coinciding with each QRS on the cardiac monitor.

Conclusion to 1st case:

This patient was admitted to the cardiovascular unit,  awaiting pacemaker placement.


Another example of why we should not solely rely on the computerized ECG interpretation:

wrong interpt.There is a sinus rhythm with LVH, physiologic Leftward axis (aVF is the isoelectric lead perpendicular to Lead I) at approximately -10 degrees. No primary (ischemic) ST-T changes with normal R wave progression and QT prolongation.

The computerized ECG interpretation is  SINUS TACHYCARDIA WITH 2nd DEGREE AV BLOCK 2:1 AV CONDUCTION”

 Does this mean that we will give Atropine or stand by pacing for the 2nd degree AVB? If you answer is NO, then you’re on the right track…


Now, in most instances, the computerized interpretation is accurate and useful:


 While other times, it may not be as specific, depending on variations, most commonly movement and poor lead placement leading to Artifact:

77yof-unresponsive-12L    Artifact is one of the most common causes of inaccurate Atrial Fibrillation and Atrial Flutter computerized interpretation

Other causes of inaccurate computerized interpretation include:

  • QRS width
  • Intrinsic rate and irregularity
  • ST segment and T wave morphology

This is taking into consideration that each system has an analysis algorithm, like the Physio-Control’s Lifepak 15, one of the most common cardiac monitors used prehospitally, which uses the Glasgow Analysis Algorithm, which gives us the computerized interpretations based on calculations and measurements of the recorded waves from parameters set by the creators. 12-Lead ECG Analysis Algorithms_2_450

 Image obtained from Physio-Control




1.We should not base our ECG interpretation and our patient’s care and treatments solely on the computerized interpretation provided.

2. The computerized interpretation gives us a second opinion on cardiac electrical system analysis, and is not a confirmed statement.



  • Mike says:

    Common sense is 99% of what we do. Use it and you will have a long and gratifying career.

  • Ray says:

    My read on the top strip is:
    1. Normal sinus rhythm (notice that the atrial rate is around 90 bpm and is not disturbed). The term “normal” and “sinus” actually applies to the atrial rate, not the ventricular response. (reference Marriott’s Practical Electrocardiography)
    2. The ventricular response is principally 3rd degree AVB. The PR interval is completely variable. I agree that there is a slight slowing in the rate of beats 3 and 4, which I can’t explain except that the ventricular pacing site slowed a bit.
    3. I think that beats 2 and 7 are likely conducted. If you plot out the P waves (again, the atrial rate doesn’t change from about a rate of 90), they fall such that the PR interval is able to actually allow conduction of beats 2 and 7.
    4. You are exactly right about the bizarre interpretation of this strip by the machine. That is why we should ALWAYS make our OWN interpretation first and THEN read the strip.
    5. Finally, from an emergency perspective, you have to quickly say “sick or not sick”. The overall rate of about 30 is scary, and the (almost) completely variable PR interval is equally scary. It’s great that the patient’s BP hung in there, but I would put pacing pads on this guy quickly.
    6. Thank goodness that they didn’t give this guy an anti-arrhythmic, or his next adventure could have been asystole.

    Good case! Let me know if you would like some others!

  • Ray says:

    If you’ll forgive comments on the strip with the artifact:
    1. Lead three is most helpful. Take calipers and look at the beats that go downward (below the baseline). These are suspicious for being the underlying rhythm. If you then use this caliper width across the strip, it allows you to identify all of the patient’s intrinsic beats.
    2. Now, is it atrial flutter with about a 4:1 block? The trick is that now that we know the underlying ventricular response (through the calipers) we can see (though with some effort in the V leads) that the ventricular response isn’t disturbed. And, the baseline in between with ALL of those spikes is bizarre. Knowing the ventricular beats in aVR and aVL, we can see the enormous amplitude of those “other spikes”, especially aVR. Are these “interpolated PVC’s”? A salvo of VTach in between beats? Honestly, without a disturbance of the underlying ventricular response, it would be exceptionally unlikely.
    3. By the way, my best read on this LAD with likely a RBBB, given what I THINK is an RsR’ pattern in V1 and V2 with an S wave in V6.
    4. It’s so interesting in medicine how we so often reach for a medication to give a patient – especially when we are scared for the patient and feel like we should do SOMETHING – when what we REALLY should reach for is a blanket!

    • Jon Kavanagh says:

      Ray makes a good point–the use of calipers.

      Perhaps if we want to stop being technicians, we need to start using tools to figure things out. How often do we miss improper lead placement? How often we do scratch our head on a rhythm because we don’t use the rules? How often can we not figure something out because we don’t know what normal looks like other than Lead II?

      Yes, a pointy caliper in the back of a moving ambulance could pose problematic, but I’d wager that the artifact would have been present while everyone was safe and sound at the side of the couch when you first saw the patient…

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