When doing a 12 Lead ECG, can the right leg lead be placed on the left leg to save time?
This discussion took place during the 2 day Rhythm/ECG course that I ran in Vernon BC. I was told that some of the ECG techs put the right leg electrode (which is just a ground lead and produces no picture on the 12 Lead ECG) on the left leg in order to save some time. I was asked if this practice is acceptable.
My response to the group was that, while the right leg lead is a ground lead and should not in any way impact on the ECG, I wasn’t 100% sure that was ok to do. I set out to find out if placing the right ground leg electrode on the left leg was acceptable practice.
While it is acknowledged that the right leg (RL) electrode acts as an electronic reference that serves to improve unwanted noise, there is no specific mention of where the RL electrode needs to be placed and further discussion on the limb leads only makes reference to the LA, LL, RA electrodes as part of Einthoven’s law (Kligfield et al, 2007).
In a separate article published by Philips which described the 12-Lead ECG Monitoring with the EASI System, they described the conventional 12 Lead ECG in the following manner: “…electrodes are placed on the right arm, left arm, and left leg to view leads I, II, and III. In addition, six electrodes are placed on the chest and a ground reference is placed on the right leg, although it could be anywhere”.
While this latter statement seemed to be the answer I would hoping to find, I am still not convinced that placing the right leg electrode can be placed anywhere. I need more proof. I spoke with an electrician who stated that one purpose of a ground lead is to close the loop or circuit. In the electrocardiography world, there is a ton of science that goes behind the rationale for where the limb leads are placed. My gut is telling me there’s more of a complicated answer to this question.
I am going to leave this question for the time being because time has run out to search out more definitive answers. I will keep looking into this really fascinating question and let you know when I find out anything new. In the meantime, I will be conducting a mini-study by performing ECGs on healthy subjects using the standard placement and compare these to ECGs using the modified approach of using the left leg to place both leg electrodes and see if there are any differences. If you are able to find out any information pertaining to this question, please email me.
The following articles were reviewed:
- Kligfield, P., Gettes, L., Bailey, J., et. al. (2007). Recommendations for the Standardization and Interpretation of the Electrocardiogram: Part I: The Electrocardiogram and Its Technology A Scientific Statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society endorsed by the International Society for Computerized Electrocardiology. Journal of the American College of Cardiology. Retrieved from http://content.onlinejacc.org/cgi/content/full/49/10/1109
- Phillips. (2002). 12-Lead ECG Monitoring with the EASI System
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Hi Jody, Thanks for asking this question. I actually have never heard this expression before but had an idea it would be referring to bundle branch blocks. I did a search online for “flipped bundle” and “flipped bundle on the ECG” and came across numerous references to bundle branch blocks. So, a “flipped bundle” is either a right or left bundle branch block. By stating the bundle is “flipped” indicates that the direction of the QRS complex has “flipped” from its normal position to the position that results from the bundle branch block.
One reference actually referred to the flipping up or down of the QRS complex as the Turn Signal Theory. In the Turn Signal Theory, when you look at V1 in a Right Bundle Branch Block, the wide QRS complex flips or turns to an upright position above the isoelectric line. When you look at V1 in a Left Bundle Branch Block, the wide QRS complex is in a negative position below the isoelectric line. The Turn Signal refers to when you are driving and approach a turn, you will indicate to other drivers which direction you are turning by putting your turn indicator either ‘up’ or ‘down’. When you want to turn LEFT, you turn your indicator “down”. Left = down (LBBB) in V1. When you want to turn RIGHT, you turn your indicator “up”. Right = up (RBBB) in V1.
The rationale for the QRS complex to flip to a certain direction in a RBBB or LBBB is related to the altered electrical force having to compensate for the blocked branch. This altered electrical force will assume a new pathway around the blocked branch and this extra force will start off in the non-affected branch and associated ventricle and travel to the affected branch and associated ventricle. A basic rule in ECG is that a QRS complex is upright if the energy is traveling towards the positive electrode and a QRS complex is negative if the energy is traveling away from the positive electrode. Therefore, in a RBBB, because the altered energy is traveling toward the right bundle and right ventricle, V1 (which is sitting pretty much right at the right ventricle) will be an upright QRS complex. In a LBBB, because the altered energy is now traveling from the right bundle and right ventricle toward the left bundle and left ventricle, and traveling away from V1, the QRS complex will now be negative. I hope this has helped clear things up. If not, let me know and I will look into it further. Darlene
Thanks to Dawn Altman for her fantastic website: ECG Guru.
Jason E. Roediger - Certified Cardiographic Technician (CCT) at http://ecgguru.com/content/bundle-branch-block.
A question was recently asked of Darlene at QRS Educational Services regarding the best placement for the limb leads when doing an ECG. Please read the proposed question and Darlene's response below for details as well as links to research and recommendations on this topic.
Question: "I wonder if you can help me answer a question that I can't seem to find a consistent answer to. What is the current recommendation for the limb lead placement when doing a 12 lead ECG? We have a varied practice and would like to be consistent. Is there a reference you can recommend?
FROM NELSON BC
Darlene's Response: Thank you for your email and request. I had to do some research before responding to you. There is a lot of practice variability in placing the limb leads and I have attached 2 articles on the topic that will help address your question.
Alternative Lead Apllications and Modified electrode placement must be recorded when performing 12-lead electrocardiograms
The recommendations are: arm leads are placed distal to the shoulder and legs leads distal to the hips. According to the recommendations, that means the arm leads can be placed anywhere as long as they are distal to the shoulders.
The second article is very interesting as it studied the application of the limb leads on the torso, which we do in our standard stress testing. However, their findings were that this is not a recommended placement for a standard 12 lead ECG. If the limb leads are placed on the torso (let's say it was done that way because the patient was very unstable, heavily clothed on the legs and the ECG needed to be as quickly as possible), there needs to be a notation on the ECG that this was done.
I hope this helps.
Dawn Altman from ECG Guru asks Darlene Hutton from QRS Educational Services the following "Ask the Expert" question...
As a fairly new educator in the telemetry/medical unit or Emergency Department, what steps would you suggest taking in helping new nurses to the unit understand ECG Interpretation?
To review Darlene's response check ECG GURU
