- Are they TALL or are they small?
When looking at the QRS complex look to see if there is any evidence of hypertrophy. The Sokolow-Lyon method is the one I use. It allows rapid reading. I add the amplitudes of the S wave of V1 to the R wave or V5 or to V6.
Are the QRS complexes small? ie., is there something between them and the reading electrodes? This may be fluid or fat. Pericardial or pleural effusions are the ones to consider. Small complexes and tachycardia, should always make us think of a pericardial effusion.
- Are they Wide or narrow?
Here I am looking to see what the cause of a wide complex is. Sometimes we couple this question with fast or slow. For example, slow rates with a wide complex may be associated with a complex being initiated outside the atrioventricular node. If a complex passes through the AV node, it is narrow. Wide complex fast rhythms may be due to a number of causes including ventricular tachycardia, hyperkalaemia, Na channel blockade, ischaemia and more.
- Do they have abnormal morphology?
This is really referring to the delta wave of WPW
- Are they clumped?
This is a step I have included to ensure we don’t miss a Moritz block( which we would normally look for in the previous step). In mobitz blocks, we often (not always) see a clumping of the QRS waveforms. This reminds us to go back and look for a Moritz Block more closely.
This is a’The South African Flag Sign’. The patient had an obstructed diagonal artery.
Posterior leads are done here and the ECG is shown below. This is another STEMI Equivalent. This patient needs to go to the Cath lab.