Cardiac Axis Trainer

Learning cardiac axis interpretation can be tedious.

I have created an open source webapp hosted on CardiacAxis.com. Here you will be able to analyse in English and German the ECG variations with axis deviation.

The Axis trainer online is interactive and the arrow can be moved to demonstrate each of the specific QRS complex changes. Bookmark to your phone homepage and try it out for yourself. Below is a quick demonstration through 360 degrees…


I try to emphasise the importance of visualizing and understanding the basics instead of simply memorising rules both when I teach as well as when when I study myself.

I initially designed the Cardiac Axis Trainer in German. Converting this to an international version was more complicated than translating text. The system of determining axis types is unnecessarily extensive in Germany. If you want to see how many axis types students have to deal with here, switch to the German version

Remember that understanding ECG vectors is not only useful for cardiac axis interpretation but also provides a basis for more ECG-skills such as PVC-origin localization, SVT/VT differentiation or understanding the morphology of bundle branch blocks.


I added the feature of biphasic QRS complexes instead of flatlines. It makes it a bit harder to read in some cases but it adds some realism. Thank you very much again for the feedback.

Additional resources


Cardiology and invasive electrophysiology fellow from Germany pursuing an M.Sc. degree in medical computer science. Passionate about ECGs, #FOAMed and coffee (in no particular order) Twitter | cardiotools.net

BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.