Transcript
Page 1: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

EKG Overview

Page 2: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Heart Walls• Inferior Wall• Septal Wall• Anterior Wall• Lateral Wall• Posterior Wall

Page 3: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Inferior Wall• II, III, aVF

• View from Left Leg • inferior wall of left ventricle

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Page 4: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Septal Wall

• V1, V2• Along sternal borders• Look through right ventricle &

see septal wall

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Page 5: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Anterior Wall• V3, V4

• Left anterior chest• electrode on anterior chest

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

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Lateral Wall

• V5 and V6• View from Left Arm • lateral wall of left ventricle

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Page 7: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Lateral Wall

• I and aVL• View from Left Arm • lateral wall of left ventricle

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Page 8: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Key Principles of Electrocardiography

There are 12 leads. The six that reflect electrical activity in the fontal plane are I, II, III, AVL, AVR and AVF. The six reflecting the horizontal plane are V1 through V6.

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Summary of EKG LeadsIn summary, the 12 standard leads are:

Limb leadsI, from the right arm (-) toward the left arm (+)

II, from the right arm toward the left leg     III, from the left arm toward the left leg   

  Augmented LeadsaVR, augmented lead toward the right (arm) aVL, augmented lead toward the left (arm) aVF, augmented lead toward the foot

Page 10: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Summary of EKG Leads

In summary, the 12 standard leads are:Chest Leads

• V1 through V6, starting over the right atrium with V1, and placed in a semi-circle of positions leftwards, to the left side of the left ventricle.

• V1 and V2, on the right and left sides respectively, are placed just off the sternum at the 4th intercostal spaces (the space between the 4th and 5th ribs, which can be felt through the skin) and the others travel around to V6 under the armpit, as shown in the diagram.

Page 11: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Summary of EKG Leads

Page 12: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

12 Lead Paper and Measurements

• At one end of each ECG strip there is usually a step-like structure called a calibration box. The standard box is 10 mm high and 0.20 seconds wide. The calibration box is there to confirm that the ECG conforms to the standard format.

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12 Lead Paper and Measurements• The easiest way to calculate the rate is to use the

method of separated boxes. Find a QRS complex that starts on a thick line. The best is to use the tip of the tallest wave on the QRS complex- R wave. This will be a starting point. As a second step, find the next QRS complex or any other spot- your end point. Then just count the thick lines in between the two spots, and calculate the rate from memorized numbers 300, 150, 100, 75, 60, 50, where each number represents one of the previous rates.

Page 14: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

12 Lead Paper and Measurements

Page 15: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

12 Lead Paper and Measurements

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EKG Complex: PQRSTU

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12 Lead EKG Workshop

One of the most important reasons for obtaining an ECG is to help evaluate the patient who presents with new-onset chest pain.  By doing so we hope to determine:

• If any acute changes are present.

• If there is evidence of prior infarction.

Page 18: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

12 Lead EKG Workshop

Specifically, we want to determine if the patient being evaluated is acutely infarcting or ischemic. If so, what area of the heart is involved, how extensive is the involvement, are other abnormalities present (i.e., AV block, conduction defects, arrhythmias) and most importantly, is the patient a candidate for acute intervention (i.e., with thrombolytic therapy or angioplasty)?

Page 19: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Acute Infarction: What are the Changes?

• There are 4 principal ECG indicators of acute infarction:

• ST segment elevation

• T wave inversion

• Development of Q waves

• Reciprocal ST segment depression.

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Acute Infarction: What are the Changes?

• A and B show a normal QRS complex before any changes develop.   

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Acute Infarction: What are the Changes?

• Picture C shows the "hyperacute" stage, which is the earliest change of Acute MI, in which the T wave becomes broader and peaks (almost as if "trying" to lift the ST segment).  This change may be subtle (and easy to miss!); it usually is short-lived.    

Page 22: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Acute Infarction: What are the Changes?

• Picture Dshows conventional ST elevation follows (with ST coving/"frowny" shape) and developing Q waves.

Page 23: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Acute Infarction: What are the Changes? • Picture E and F

show Q waves becoming bigger, ST elevation is maximal, and T wave inversion begins. T waves evolve as ST segments return to baseline (in F).

Page 24: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

Acute Infarction: What are the Changes? • Picture G

shows ST-T wave abnormalities resolving (or nearly resolving) but there is persistence of Q waves.

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KEY Points regarding the ECG with Acute MI: • Not all patients with Acute MI develop ECG

changes.  As many as 1/3 do not develop changes, especially if MI occurs in electrically silent areas of the heart.

• The A thru F sequence in the figure above represents the "typical" evolution of Acute MI. Variations on this theme are common (i.e., ST depression or T wave inversion may be the only change, Q waves don't always develop, Q waves sometimes resolve with time, etc.).

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Rhythm Identification: P Waves

• Are there visible P waves?• Does a QRS follow EVERY P wave?

• If not, how many P waves are before each QRS?

• Is it a consistant number of P waves before each QRS?

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Rhythm Identification: PR Interval

• Time interval from start of P wave to start of QRS

• 0.12 - 0.20 sec. In length

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Rhythm Identification: QRS (reg or irreg)

• Next, look at the QRS. • Is it narrow or wide? • Ask yourself again, do they occur at regular or

irregular intervals? • If irregular, is the rhythm regularly irregular or

irregularly irregular?

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Blocks

“R-S-R1” wave

• The leads to look in first for right bundle branch block (RBBB for short) are leads V1 & V2. • In RBBB, the QRS complex has two R-waves which give the QRS a double-peaked appearance. This is called the “R-S-R1” wave.

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Blocks

• The leads to look in first for left bundle branch block (LBBB) are leads V5, V6, and I.• If the QRS is wide, mostly upright, and the T waves are inverted, then you are most likely looking at LBBB.

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MI IdentificationInferior MI:

The leads to look in are leads II, III, & AVF.

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MI IdentificationSeptal MI:

Look at leads V1-V2 for MI’s.

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MI IdentificationAnterior MI:

Look at leads V3-V4 for MI’s.

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MI IdentificationLateral MI:

The leads to look in for lateral MI are leads I, AVL, V5, & V6.

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MI Identification Posterior MI: This one is tricky, and the EKG is not the definitive diagnostic tool for

this type of MI. Look for tall R waves and ST depression as sign to suspect Posterior MI in V1 & V2.

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MI IdentificationPosterior MI:

If you suspect Posterial MI then need to perform a “right sided EKG”

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Obtaining the 18-Lead ECG

A) Right Ventricular Leads

Move V1 to V3R Move V2 to V4R Move V3 to V5R

Move V4 to V7 Move V5 to V8 Move V6 to V9

B) Posterior Leads

Page 37: EKG Overview. Heart Walls Inferior Wall Septal Wall Anterior Wall Lateral Wall Posterior Wall

MI IdentificationPosterior MI:

Label the new leads that you changed to either V7, V8, V9 or V4R, V5R, V6R.

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Heart Walls and Lead Correlation

38Lateral Wall

Inferior Wall

Septal Wall

Anterior Wall


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