Lewis lead


The Lewis lead configuration can help to detect atrial activity and its relationship to ventricular activity. Named after Welsh cardiologist Sir Thomas Lewis (1881-1945) developed and described (1913) his lead configuration to magnify atrial oscillations present during atrial fibrillation.

Useful in:

  • Observing flutter waves in atrial flutter
  • Detecting P waves in wide complex tachyarrhythmia to identify atrioventricular dissociation

Lewis lead placement
  • Right Arm (RA)electrode on manubrium
  • Left Arm (LA) electrode over 5th ICS, right sternal border.
  • Left Leg (LL) electrode over right lower costal margin.
  • Monitor Lead I
Lewis Lead ECG placement AV dissociation
Lewis lead (S5-lead) placement

Associated Persons

Alternative names
  • S5-lead placement

Further reading (Dr Smith’s ECG blog)

eponymictionary CTA


the names behind the name

Emergency physician MA (Oxon) MBChB (Edin) FACEM FFSEM with a passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

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