Tag Archives: hexaxial reference system

QRS AXIS DETERMINATION

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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 the […]

Axis Determination – Part VI

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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 […]

Axis Determination – Part V

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In Part IV, 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 […]

Axis Determination – Part IV

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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 […]

Axis Determination – Part III

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In Part II, 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 […]

Axis Determination – Part II

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In Part I, 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 […]

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Comments
darren
79 year old female CC: Chest pain – Conclusion
What concerns me is the total waste of time doing Right sided precordial leads in this case: to what end is this relevant when we already have clear evidence of inferior-Lateral MI. Time wasted doing that I think.
2015-01-31 15:01:35
darren
79 year old female CC: Chest pain – Conclusion
Infero-lateral MI therefore circumflex and not RV wall. Possibly posterior involvement but irrelevant.
2015-01-31 14:58:21
Anne
Adenosine for sinus tachycardia: Try to avoid this!
If it were me, I would seek a second opinion; consult an electrophysiologist. Unlikely that you had sinus tachycardia at that rate.
2015-01-26 09:46:57
John
Adenosine given for a narrow-complex tachycardia over 150
If things such as Sepsis, Drug Use, Medication issues, Anxiety, Pain, etc.. have been ruled out, and the rate is still >160 (or whatever number you use). How else do you determine S-Tach Vs. SVT? Does a 12 Lead Help (QRS Complexes facing different directions due to different pathways etc..) or a simple 4 Lead?…
2015-01-19 19:44:32
Brandon O
Adenosine for sinus tachycardia: Try to avoid this!
She may not have had anxiety, but I bet she was a carrier...
2015-01-18 02:31:08

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