How to interpret an ECG rapidly? Part IV – The Axis

Rapid ECG Interpretation Part IV – How to identify the ‘Axis’ quickly  There are two easy ways to identify the axis of an ECG, the axis in both the ‘Horizontal’ & the ‘Frontal’ planes. Generally, Axis refers to the ‘Mean Frontal Plane QRS axis’ (or vector) during ventricular depolarization. As we recall when the ventricles depolarize (in a normal heart) the direction of current flows leftward and downward because most of the ventricular mass is in the left ventricle. We like to know the QRS axis because an abnormal axis can suggest disease such as pulmonary hypertension from a pulmonary embolism. Abnormalities of axis can hint at ventricular enlargement, conduction blocks (i.e. hemiblocks)                                                                                   Determining the Axis: The two most popular ways to determine axis are 1) The Equiphasic Approach & 2) The Quadrant Approach. The Equiphasic Approach: The popular way to determine axis by Prof. Leo Schamroth. Determine which lead contains the most equiphasic QRS complex.  The fact that the QRS complex in this lead is equally positive and negative indicates that the net electrical vector (i.e. ove...
Source: Doc2Doc BMJ Cardiology - Category: Cardiology Authors: Source Type: forums