April 13th, 2023

Interpreting the ECG – Members’ Webinar Request

Conquering your fear of the ECG: a step by step guide

Kieran Borgeat BSc BVSc MVetMed CertVC FHEA MRCVS DipACVIM DipECVIM-CA presents this webinar promising to make ECG’s easy, and delivers on the promise incredibly well! ECG interpretation can be really tricky, especially in the emergency situations that it’s often necessary. The stress doesn’t make anything easier but Kieran pulls apart the squiggly lines on the paper into easily understandable parts and then quizzes us in the latter half of the webinar to show what we’ve learned.

The webinar starts off covering the conduction centres of the heart and what they look like when transcribed into electrical currents. The sinoatrial node, atrioventricular node, and fibrous atrioventricular plate as well as their accessory fibres – the purkinje fibres and bundle of his, are the stars of the first section of this webinar. Kieran continues to cover how these cells and their electrical conductivity, as well as the pathologies that can occur in hypoxia and damage. The concept of an ‘escape rate’ – that is ventricular or atrial escape rhythms, are explained and how they occur is described.

DogIt’s not just a calm dog

Slow heart rates can often seem reassuring – however slower heart rates (those under 100BPM) should still have phasic variation. In the case of lower heart rates, try to stimulate an excitement or stress response by opening a door, whistling, or meowing. This should result in a spontaneous temporary increased heart rate, if you don’t see it then it suggests a problem.

 What am I reading?

Understanding the ECG

The “lead 2” reading is the readout that you should be paying the majority of your attention to in first opinion practice, and Kieran breaks down each part of the P-QRS-T pattern and the changes that you can see – both normal and abnormal.

The next part of the webinar is the 4 questions that we need to ask ourselves when trying to interpret ECGs. These four parts are as follows:

What is the heart rate?

Is the rhythm regular or irregular?

P-QRS relationship
–  Is there a P for each QRS?
– Is there a QRS for every P?
– Are they reasonably and repeatably related?

Rhythm diagnosis (tachy/brady etc).

We also got a good trick for calculating heart rate using none other than the magic biro! Biro pens (roller ball pens) are about 15 centimetres long, so with a paper rate of 50mm/seconds, the amount of beats in the space of a pen is 3 seconds. Multiply by 20 and you have a heart rate! At 25mm/second, the amount of beats in the space of a pen is 6 seconds. Multiply this by 10, then you have your heart rate.

DogCase Studies

Putting the lessons to the test

The final part of the webinar has a set of case studies. I’ve said it before, but case studies are the keystone to efficient learning. Having an experienced member of the profession walk you through your interpretations leads to such strong lessons. The case studies had a poll when they were live, and although you couldn’t see the polls themselves in the recording, Kieran read out the options clearly and gave appropriate time to respond to them.


Another brilliant webinar by Kieran Borgeat and I’m thoroughly looking forward to future webinars. Previous webinars include “Heart murmurs: when should I investigate?”, “Treatment of feline cardiomyopathy: establishing the what, when and how?”, and “How to decide when a dog or cat ends treatment for heart disease”. You can find them here. You can find one of our popular blogs on cardiopulmonary resuscitation here!

Interpreting the ECG

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