Lewis Leads & Invisible P’s

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    Lewis Leads & Invisible P’s

    You ever have a tough time visualizing P waves on EKGs? Have no fear, a Lewis Lead EKG might just be the thing you need!

    The Lewis Lead (aka S5) is a modified EKG obtained in a manner that basically triangulates atrial activity to help make the p-waves of your EKG more prominent. Lead placement includes the RA lead placed on the manubrium, the LA lead placed at the 5th intercostal space at the R sternal border, a LL lead placed at the right lower costal margin, and +/- the RL lead placed that the right leg.

     

    In this configuration, lead I will travel directly over the atria, maximizing the size of the P wave

    Lewis Lead (diagram 2)

     

    Why or when would you ever want to do this?

    • EKGs with questionable P waves — those such as atrial fibrillation/flutter, wide complex tachycardia

    What does this even look like?

    regular EKG

    Regular 12-Lead; Leads I & II

    Lewis Lead I

    Lewis Lead I

    Lewis Lead II

    Lewis Lead II

    And there you have it folks! Feel free to throw that one at your next VT vs AFib RVR with aberrency!

     

    Resources:

    The Lewis Lead

    EMCrit Wee: The Lewis Lead and a course in ECGs with Christopher Watford

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