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ECG Exercise 27 - The QRS Complex
ECG Exercise 27 - The QRS Complex

ECG Exercise 27 - The QRS Complex

Last updated 2/13/25

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Below is an ECG Exercise focused on the QRS complex (part of the Self-Study Curriculum) Consider reading the following ECG Topics before proceeding:

  • Basic Electrophysiology
  • Pericardial Effusion
  • Left Ventricular Hypertrophy
  • Right Ventricular Hypertrophy
  • Q waves
  • Transition Zone
  • QRS Notching and Osborn Waves

ECG 1

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What ECG findings define low voltage? Does this ECG qualify as low voltage?
  • All precordial QRS amplitudes ≤ 10 mm or all limb leads ≤ 5mm
  • Yes this qualifies in both precordial and limb leads
  • This patient had a pericardial effusion
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ECG 1497

ECG 2

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What is the 4th wide QRS complex in the rhythm lead?
  • A PVC
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Does ECG qualify as low voltage?
  • Yes - both precordial leads < 10mm and limb leads
  • The PVC looks smaller than the typical PVC
  • This patient had a high BMI and COPD which can put distance between the heart and ECG electrodes causing low qrs voltage.
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ECG 1498

ECG 3

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Does ECG qualify as low voltage?
  • Absolutely not, glad you’re paying attention. This is definitely high voltage.
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What is the cause of the abnormal voltage?
  • Left Bundle Branch Block
    • Wide QRS
    • rS in V1-V2 (dominant S waves)
    • Monophasic R wave in I and V6
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Is this diagnostic of acute OMI?
  • No, this does not meet Smith Modified Sgarbossa criteria for OMI.
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ECG 1499

LVH Diagnostic Criteria (Only need to fulfill one criteria)

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What is Seamens’ Sign?
  • Any touching or crossing of precordial QRS complexes
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What is Sokolow Lyon criteria?
  • S in V1 or V2 + R in V5/V6 ≥ 35mm
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What is Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
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What are R wave findings in the limb leads that may suggest LVH?
  • R in I ≥ 12 mm or
  • R in aVL ≥ 11 mm or
  • R in aVF ≥ 20 mm
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Click for basic LVH on ECG diagnostic algorithm
image

ECG 4

image
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Seamen’s Sign?
  • Yes, V2/V3 in one complex
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S in V1 or V2 + R in V5/V6 ≥35mm?
  • Yes using V2 + V5
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Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
  • No - using 28mm cutoff
‣
Meets R wave criteria in limb leads?
  • R in I ≥ 12 mm or (no)
  • R in aVL ≥ 11 mm or (no)
  • R in aVF ≥ 20 mm (no)
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ECG 1500

ECG 5

image
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Seamen’s Sign?
  • No
‣
S in V1 or V2 + R in V5/V6 ≥35mm?
  • Yes using V2 + V5
‣
Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
  • No - using 28mm cutoff
‣
Meets R wave criteria in limb leads?
  • R in I ≥ 12 mm or (no)
  • R in aVL ≥ 11 mm or (no)
  • R in aVF ≥ 20 mm (no)
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ECG 1501

ECG 6

image
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Seamen’s Sign?
  • Yes (V4 and V5)
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S in V1 or V2 + R in V5/V6 ≥35 mm?
  • Yes using V2 + V5
‣
Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
  • Yes - S V3 + S V4 ≥ 28mm
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Meets R wave criteria in limb leads?
  • R in I ≥ 12 mm or (no)
  • R in aVL ≥ 11 mm or (no)
  • R in aVF ≥ 20 mm (no)
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1502

ECG 7

image
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Seamen’s Sign?
  • No
‣
S in V1 or V2 + R in V5/V6? ≥ 35mm
  • No
‣
Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
  • No using 28mm
‣
Meets R wave criteria in limb leads?
  • R in I ≥ 12 mm or (Yes)
  • R in aVL ≥ 11 mm or (Yes)
  • R in aVF ≥ 20 mm (no)
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ECG 1503

ECG 8

image
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Seamen’s Sign?
  • Yes (V4-V6)
‣
S in V1 or V2 + R in V5/V6 ≥ 35mm?
  • Yes V1 + V5 or V6
‣
Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
  • Yes S V3 + S V4 ≥ 28mm
‣
Meets R wave criteria in limb leads?
  • R in I ≥ 12 mm or (Yes)
  • R in aVL ≥ 11 mm or (Yes)
  • R in aVF ≥ 20 mm (no)
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ECG-1504

ECG 9

image
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Seamen’s Sign?
  • Yes
‣
S in V1 or V2 + R in V5/V6 ≥ 35mm?
  • Yes V2 + V5
‣
Peguero Lo Presti?
  • Deepest S wave + S in V4 ≥ 23 mm (women) or 28 mm (men)
  • Yes S V2 + S V4 ≥ 28mm
‣
Meets R wave criteria in limb leads?
  • R in I ≥ 12 mm or (No)
  • R in aVL ≥ 11 mm or (Np)
  • R in aVF ≥ 20 mm (Yes)
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ECG 1505