During ECG interpretation, cardiac axis, or direction of electrical impulses, may be normal (physiologic) or abnormal (pathologic), suggesting abnormal cardiac conductivity. Although every deflection obtained on the ECG will have an axis, we will focus on the ventricular axis. When we think of our cardiac monitoring lead placement, we have to understand cardiac Vectors, which is […]

This is the conclusion to 90 year old female CC: Seizure. Be sure to start there first! When we left off, we had completed our initial assessment of a 90 year old patient who, based on bystander accounts, had a seizure. She is pale, cold to the touch, and feels lethargic. During our assessment she […]

This is the discussion to 64 year old male CC: Indigestion. If you recall, we had a stubborn gentleman complaining of indigestion with a significant cardiac history. Considering the symptoms kept our patient awake, are highly suggestive of a coronary event, and we have uncompensated hypotension, we should have a keen interest on any ECG […]

So you’ve read our blog, followed us on Facebook, submitted your own case studies, but you’re looking for more. You’re looking for the next big thing in EMS 12-Lead education. As a test run I’ve put together a video, shot Kahn Academy style using a pen and tablet, covering rapid axis determination. When I learned 12-Lead interpretation in […]

By now you can predict the QRS axis in the frontal plane within 15 degrees as long as you have an equiphasic (or isoelectric) lead in the frontal plane. So what constitutes a normal QRS axis? What is a left axis deviation? A right axis deviation? If you don’t have a copy of the hexaxial […]

In Part 4 I promised that I’d show you a fascinating relationship between the standard 12-lead ECG and the hexaxial reference system. You will recall that to use the hexaxial reference system, you find the most equiphasic (or isoelectric) lead in the frontal plane (first 6 leads of the 12-lead ECG) and look for the […]

By now you should have a fairly good grasp of how the hexaxial reference system is derived from the first 6 leads of the 12 lead ECG. Before we break down the finished diagram, let’s look at the hexaxial reference system laying on top of the patient’s anterior chest, with the arrows and leads in […]

In Part 2 we discussed the heart’s mean electrical vector and how Einthoven’s Triangle (leads I, II, and III) can be redrawn to form the first 3 spokes of the hexaxial reference system. Essentially, we ended up with a shape like the one on the right. When leads I, II, and III are drawn this […]

In Part 1, we looked at Einthoven’s Equilateral Triangle and Einthoven’s Law, and I told you that it was the key to understanding the formation of the hexaxial reference system. But before we delve further into the hexaxial reference system (the instrument we’ll be using to calculate the heart’s QRS axis) we need to address […]

Few subjects related to 12 lead ECG interpretation provoke more controversy (or anxiety) than axis determination. It is controversial in that not everyone agrees it is a necessary skill for prehospital providers to learn. It is anxiety provoking in that it can be difficult to understand, especially when taught poorly. I am of the opinion […]