Skip to content

Axis

SHARE VIA:

Calculated using the hexaxial reference system that shows the frontal view of the electrical activity of the heart via six limb leads (aVR, aVL, aVF, 1, 2, 3).

Easily remembered when represented as:

(The horizontal reference system uses the six precordial leads V1‐V6 (+/‐ V4R) to show the horizontal view of the electrical activity of the heart)

hexaxial reference

In lead 1, the R wave represents the leftward force, the S wave the rightward force.

In aVF, the R wave represents the downward force, the S wave the upward force.

A suggested method of axis calculation: the successive approximation method.

axis calculation

Use leads 1 and aVF to locate a quadrant 

e.g. from panel 1 – the net QRS deflection seen from lead 1 is positive i.e. left ward, the net deflection of aVF is also positive i.e. downward, therefore the QRS axis is 0 ‐+90 degrees.

Find a lead with an equiphasic QRS complex (height of R equals depth of S). The QRS axis will be perpendicular to this in the previously determined quadrant.

Normal QRS axis varies with age 

1 week – 1 month: + 110 (range +30 ‐ +180)

1 month – 3 months: + 70 (range +10‐ +125)

3 months – 3 years: + 60 (range +10 ‐ +110)

3 years +: + 60 (range +20 ‐ +120)

Adult: + 50 (range ‐30 ‐ +105)

Author

KEEP READING

Playing-in-harmony-HEADER

Getting everyone to sing in harmony

Choosing-wisely-AXR-HEADER

Choosing Wisely – Radiographs in children with suspected constipation

, ,
Antibiotics-in-the-EDHEADER

Antibiotics in the paediatric emergency department

, ,
Copy of Trial (1)

Bubble Wrap PLUS – September ’23

CT-seizures

Choosing Wisely – Investigations for seizures that have returned to baseline

, ,
Threadworm-HEADER

Threadworms

ikigai HEADER

Ikigai – A reflection on DFTB23

Medical clearance

Choosing Wisely – Investigations for Paediatric Patients presenting with Psychiatric Symptoms

, ,
Life-in-Art-HEADER

Life in Art

CW - CXRs

Choosing Wisely – Radiographs in children with respiratory symptoms

, ,
Breaking barriers HEADER

Breaking down barriers

Mediastinal massesHEADER

The emergency management of mediastinal masses

, ,
Pause HEADER

The Pause- a recognition of a life

,
DCM HEADER

Dilated Cardiomyopathy in Children

,
Bedbugs-HEADER

Itching in the streets, Bed bugs in the sheets

DFTB WORLD

EXPLORE BY TOPIC