12 Lead Interpretation a review of the Basics

Introduction

12-Lead Interpretation is easier to read than normal ECG Interpretation

Techniques used are performed in steps

You can interpret a 12- lead ECG in 60 sec or less.

Reading a 12-Lead

There are 12 Pictures taken of the heart every time a 12-Lead is taken.

When looking at the ECG we pick out only 1 complex in every picture that represents that picture of the heart.

Leads used

Limb Leads I, II, IIl Augmented Limb Leads:

AVR, AVL, AVF, V-Leads or Precordial Leads

If you don’t label the leads, you If you don’t label the leads, you don’t know Jack!!!!!!!don’t know Jack!!!!!!!

Enthovens triangle

Triangular representation of Leads I,II,II

Augmented Voltage leads

AVR AVL AVF Uses a center ground computer

assisted

Precordial Leads

V1-V6

Additional Leads

V4R

V4R

5th intercostal space mid clavicular line

V4R

V4R

Significance of V4R in relation to RCA occulsions vs. LCA circumflex branch occulsions

Things the 12 Lead “sees”

Basics of 12 Lead ECG's: Vector

Basics of 12 Lead ECG's:Vector

Basics of 12 Lead ECG'sVector

By understanding this concept of vector and knowing the "normal" vector of each of the 12 leads of the 12 lead ECG it becomes quite easy to identify problems in the direction of depolarization. It is also from this knowledge that one identifies the Mean QRS Axis. Using the six limb leads we identify the axis in relation to what is known as the frontal plane. Two major factors help to determine this mean QRS Axis, they are:

 

1. The anatomical position of the heart

2. The direction of ventricular depolarization.

Basics of 12 Lead ECG's Determining AXIS

1. Leads 1 and AVF dividethe thorax into quadrants, (Left, Normal, Right, No Man's) 2. If leads 1 and AVF are both

upright then the Axis is normal.  3. If lead 1 is upright and lead

AVF is downward the Axis is Left.

Basics of 12 Lead ECG's Determining AXIS

4. If lead AVF is upright and lead 1 is downward then the Axis is Right

5. If both leads are downward then the Axis is extreme Right Shoulder and most often is Vent. Tachy

LEAD 1 LEAD 2 LEAD 3

Normal UPRIGHT UPRIGHT UPRIGHT

Physiological Left Axis

UPRIGHTUPRIGHT / BIPHASIC

NEGATIVE

Pathological Left Axis

UPRIGHT NEGATIVE NEGATIVE

Right Axis NEGATIVEUPRIGHT

BIPHASIC

NEGATIVEUPRIGHT

Extreme Right Axis

NEGATIVE NEGATIVE NEGATIVE

Evolution of an AMI

Footprints of Posterior MI

Never runs alone (always with another MI; Inferior, Lateral, and/or RVI)

Most of the Posterior Wall supplied by RCA or LCX

Look for Tall R wave in V1,V2,V3 with ST segment depression

Run Posterior Leads V7,V8,V9

““You see what you You see what you look for and only look for and only

recognize what you recognize what you KNOW”KNOW”

Example 1

Example 2

Example 3

Example 4

Example 5