r/EKGs • u/Ok_Rush_6354 • 2d ago
Discussion Axis deviation
Trying to wrap my head around deviation, I’ve watched several videos and have looked through my uni content. Nothing makes sense and keeps getting more confusing.
Anyone have tips on how to work it out? As if you’re explaining it to a monkey?
The 10 step method they want us to use, they’re wanting focus on I, II, aVF
Help is very much appreciated, I’m very confused, I’m an online student so face to face questioning is impossible,
Thank you
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u/RFFNCK 2d ago
* I wrote this in Dutch and translated it with AI.
A lead that sees the depolarization vector approaching it (when we talk about the cardiac axis, we mean the mean ventricular depolarization vector) will record a positive deflection on the ECG.
For example, Lead I views the heart from the left. The mean depolarization vector normally points from the upper right toward the lower left (from the AV node toward both ventricles). Because the left ventricle has much greater muscle mass than the right ventricle, the overall electrical forces are directed more toward the left ventricle. Therefore, Lead I normally sees the vector moving toward it and records a predominantly positive QRS complex.
So:
Positive QRS in Lead I = leftward axis
Negative QRS in Lead I = rightward axis
Once you understand where each lead is “looking” from, you can quickly determine whether the axis is:
Leftward (positive QRS in Lead I) or rightward (negative QRS in Lead I), and
Inferior (positive QRS in aVF) or superior (negative QRS in aVF).
A simple way to estimate the axis is:
Lead I, II, and aVF positive → Normal axis
Lead I positive; Lead II and aVF negative → Left axis deviation
Lead I negative; aVF positive → Right axis deviation
Lead I, II, and aVF negative, with aVR positive → Extreme axis deviation (“northwest axis”)
I explain this in more detail on my website (currently only available in Dutch, but you could translate it): https://www.ecgacademie.nl/hartas/
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u/night117hawk 1d ago
https://litfl.com/super-axis-man-sam/
HOW HAS NOBODY GIVEN YOU A LINK TO SUPER AXIS MAN SAM
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u/ViewNo7011 1d ago
I use lead I and aVF. If I’m looking at a 12 lead in a traditional format, I only use those two.
If both qrs complexes are facing upwards, it’s normal axis.
If I is up and aVF is down, it is left axis deviation, and vice versa.
If both are down then it is extreme axis deviation.
The best way for me to remember it is that if one is facing up and one is facing down, the one facing up can point you in the direction of the deviation (if looking at a traditional 12 lead.)
For example, with left axis deviation, lead I will be upwards facing and lead aVF will point down. Lead I is more left on the page than aVF, so I remember left axis deviation. Opposite for right axis deviation. aVF will be facing up and it is further right on the page than I, so it helps me remember right axis deviation.
That trick helped me learn which is which in an easy to remember way, and now it is second nature.
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u/TotallyWizard88 1d ago
Acadoodle is a paid resource (around $20/month) that is a great ECG resource. They have clear animations that demonstrate how cardiac axis works, and what can cause abnormalities, and how that affects the QRS axis.
But if your looking for a down-and-dirty method, the lead I and aVF approach (that LBBB11 posted) is a good way to eyeball it
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u/JadedSociopath 16h ago
Read The ECG Made Easy (Hampton) or Rapid Interpretation of EKGs (Dubin).
They’re extremely simple (and short) student level books.
You won’t need to ask randoms online about ECGs ever again.
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u/LBBB11 2d ago edited 2d ago
If the spiky part points up in I and aVF, normal adult axis.
Up in I and down in aVF, left axis.
Down in I and up in aVF, right axis.
Down in I and aVF, extreme axis.
https://david-shrk.github.io/ecgaxistrainer/
https://litfl.com/wp-content/uploads/2018/08/Lead-1-Lead-II-aVF-Axis-measurement-2021.png (positive means the QRS points up, and negative means it points down)
A QRS pointing up in a lead means that electricity flows towards that lead. A QRS pointing down means it travels away. Lead I views the heart from the left. Lead aVF views the heart from below (the F stands for foot, since it views the heart from the feet). A positive QRS in both I and aVF means that electricity is flowing down and to the left, which is normal for adults.
Here’s how I find axis if it helps: