Introduction of ECG a Basic Idea about ECG with general description of 12 Leads

Connect leads:

• . RA (Red) to right arm
• • RL (Black) to right leg
• · LA (Yellow) to left arm
• · LL (Green) to left leg

Connect the precordial leads Vi – V 6 as follows:

• · Vi to the right of sternum in the 4^th intercostal space
• · V₂ to the left of the sternum in the 4^th intercostal space
• · V₃ midway between V₂ and V₄
• · V₄ midclavicular line left fifth intercostal space
• · V_s and V₆ in the same line as V₄ in anterior and mid axillary lines respectively.

The 12 leads are:

• – 3 standard limb leads L I, L II, L III
• – 3 augmented leads AVR, AVL, AVF
• – 6 precordial leads V1 to V6

Normal ECG consists of 12 leads recorded serially or simultaneously or in groups. In the above picture, 3 leads have been recorded at a time

• Look at the waves and intervals in the ECG.

• The first wave is the P wave.
• The next tall and narrow wave and often consistin RS wave followin which is the T
• From the beginning of P wave to beginning of QRS is the PR interval.
• · From the beginning of Q to the end of T is the QT interval.
• · From beginning of QRS to the end of QRS is the QRS interval.
• · From the end of R to the beginning of T is the ST segment.

• 1 mm = 0.04 see
• 5 mm = 0.2 see
• 1 mm = 0.1 mv

On the ECG paper, time is represented in seconds horizontally and voltage is represented in millivolts vertically.

• · 1 small square is 0.04 s horizontally and 0.1 mv vertically, if the paper speed is 25 mm/s.
• · This means that 10 mm = 1 mv.
• · 5 small squares = 5 x 0.04 = 0.2 s.
• · 1 big square = 0.2 s, 5 big squares = 0.2 x 5 = 1 sec.

• This is a Basic idea about ECG, with a introduction to measuring ECG .