The cardiac axis is just one way of summarising the overall direction of ventricular depolarisation.
You might have heard of other types of axis like the X and Y axis (in maths) or the Earth's axis (in geography). In electrocardiography, the axis is just another imaginary line.
We can calculate the direction of an axis by using several limb leads from the 12-lead ECG (I, II, III, aVR, aVL, aVF). We can also calculate different axes for the atria or the ventricles of the heart. There are a range of directions that can be normal for each axis.
- Hampton, J and Hampton, J (2019) - The ECG Made Easy, 9th edn, Elsevier
- Rowlands, A and Sargent, A (2019) - The ECG Workbook, 4th edn, M&K Publishing
- Thaler, MS (2018) - The Only EKG Book You'll Ever Need, 9th edn, Lippincott Williams and Wilkins
- Houghton, AR and Gray, D (2014) - Making Sense of the ECG: A Hands-on Guide, 4th edn, Taylor and Francis
- Wagner, GS and Strauss, DG (2013) - Marriott's Practical Electrocardiography, 12th edn, LWW
- Goldberger, A (2006) - Clinical Electrocardiography: A Simplified Approach, 9th edn, Elsevier
- Alila Medical Media (2016) - Cardiac Axis Interpretation, Animation., (Accessed: 30/06/2019)
- Anna Pickens (2015) - EKG interpretation, (Accessed: 11/08/2019)
- Anna Pickens (2015) - EKG interpretation axis, (Accessed: 11/08/2019)
- Osmosis (2019) - ECG Axis | Osmosis, (Accessed: 07/09/2019)
- Strong Medicine (2012) - Intro to EKG Interpretation - Rate and Axis, (Accessed: 02/09/2019)