Question of the Month: December 11 2015
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