What is definition of ECG?

An electrocardiogram (ECG) is a graphical representation of the heart's electrical activity. It is one of the simplest, most effective, and widely used tests for assessing cardiac function and detecting heart abnormalities. The ECG was developed by the Dutch physician and physiologist Willem Einthoven, who created the first practical electrocardiograph between 1895 and 1903.

What is leads and electrode?
What are the ECG Electrodes? [1]

Electrodes are small adhesive sensors, that are attached to specific areas of the body to detect the heart's electrical activity. 

• 6 Precordial electrode

  1. V1:4^th Intercostal space, right margin of the sternum
  2. V2:4^th Intercostal space,  the left margin of the sternum
  3. V4:5^th Intercostal space, mid-clavicular line
  4. V3:midway between V2 and V4
  5. V5:5^th Intercostal space, anterior axillary line
  6. V6: 5^th Intercostal space, mid-axillary line

• 4 Limb electrodes

  1. RA: Right arm
  2. LA: Left arm
  3. LL: Left leg
  4. RL: Right leg

 

What are the ECG Leads?

An ECG lead is a graphical view of the heart's electrical activity recorded from a specific angle. There are 12 ECG lead. 6 of them are precodial leads and rest of them are limb leads.

• Precordial leads

  1. 6 Precodial leads(same as 6 precordial electrodes)
     • V1-V6

• Limb Leads

  • 3 Bipolar limb leads
    1. Lead I
    2. Lead II
    3. Lead III
  • 3 Unipolar limb leads (augmented lead)
    1. aVR: Augmented vector right
    2. aVL: Augmented vector left
    3. aVF: Augmented vector foot

What is Einthoven's Triangle? [2]

Introduction

• Einthoven's Triangle is used to record 3 bipolar limb leads.
• Please remind following easy to remember notes
  1. Right arm electrode(RA) is always negative
  2. Left leg electrode(LL) is always positive
  3. Left leg electrode(LL) is always positive to right Arm(RA), but negative to left leg(LL)
• Einthoven's Triangle created 3 bipolar leads with following calculation
  1. Lead I = LL-RA
  2. Lead II = LA-RA
  3. Lead III = LL-LA

What is Goldberger ECG Leads? [3]

 

 

Introduction

• Goldberger's leads are the three augmented unipolar limb leads of a standard 12-lead ECG:
  • Augmented vector right(aVR)
  • Augmented vector left(aVL)
  • Augmented vector foot(aVL)

• What Do Goldberger's leads They View?

  Lead	View of the Heart	Normal QRS
  aVR	Right upper side (right shoulder)	Mostly negative
  aVL	High lateral wall of the left ventricle	Small positive
  aVF	Inferior wall	Positive