ECG Case 018

75-year old patient presents with palpitations

ECG Case 018a Top 100

Describe and interpret this ECG



  • 150


  • Regular without p waves


  • LAD (-39 deg)


  • PR – No visible p waves
  • QRS – Normal (100-120ms)
  • QT – 280ms (QTc Bazett 440ms)


  • Possible ST depression V3-6


  • Flutter waves visible in V1
  • T Wave Inversion V1-2, aVL
  • LVH (aVL>11mm)


Atrial Flutter 2:1 Block

  • Narrow Complex Tachycardia
  • Ventricular rate 150bpm

Other differentials include AVNRT / AVRT however the rate is usually higher in these.

‘Mapping’ of flutter waves may be helpful, this may be easier if paper speed is altered e.g. 50mm/sec

Trial of vagal maneuvers of adenosine may help differentiate Atrial Flutter

This patient received adenosine, rhythm strip below, revealing obvious flutter waves. In comparison to ECG Quiz 017, this patient does not cardiovert to sinus rhythm following an adenosine bolus. Instead, the degree of AV block is transiently increased, revealed underlying flutter waves and confirming the diagnosis of atrial flutter with a 2:1 block.

Would the Lewis Lead have helped?

The Lewis lead configuration can help to detect atrial activity and its relationship to ventricular activity. 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


TOP 100 ECG Series

Emergency Medicine Specialist MBChB FRCEM FACEM. Medical Education, Cardiology and Web Based Resources | @jjlarkin78 | LinkedIn |


  1. I think this only appears to be 6:1 or 7:1 because of the adenosine bolus leads to a transient increase in the AV block. In the original ECG V1 has a 2:1 atrial flutter pattern.

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