Normal ECG: Rate and Rhythm

Read chapters 4 and 22

ECG Interpretation*Standardization

Rate

1. RR interval

2. Heart rate

Rhythm

3. PP interval

4. P wave

width, height, shape, etc.

5. PR interval

6. QRS

width (and height)

axis

R wave progression

abnormal Q waves

ST segment

T waves

QT interval

U waves*See Chapter 22

ECG Interpretation

Univ. of Wisconsin Medical School

• http://www.fammed.wisc.edu/pcc/ecg/

The Normal ECG

Normal = normal sinus rhythm

Rate

1.R-R interval

Is it regular?

2.What is the heart rate?

300, 150, 100, 75, 60, 50

300 / (# of large boxes)

1500 / (# of small boxes)

Count the number of cardiac cycles in 10 seconds and multiple by 6.

Rate

Bradycardia

less than 60 bpm

Tachycardia

greater than 100 bpm

Rate

3.P-P interval

Rhythm

4.P wave

5.PR interval

6.QRS

4. P Wave

Lead II and aVR

Positive in II

Negative in aVR

< 2.5 mm in amplitude

< 0.12 sec. in width

Normal P Wave

aVR?

II?

Figures 4-2 and 4-3

Normal direction of atrial depolarization

Abnormal P Wave

aVR?

II?

Direction of atrial depolarization with junction rhythm

This is an example of a retrograde conduction

P wave

The same direction as QRS

Only one P wave in front of QRS

Do all the P waves look alike?

5. PR interval

0.12 - 0.20 seconds

6. QRS Complex

What is the width? (less than 0.10 seconds)

Do all the QRS waves in the same lead look alike?

R wave progressionAxisAbnormal Q waves (infarction)

QRS Complex

Q waves

Normal QRS

Two phases

brief phase; depolarization of ventricular septum

longer phase; depolarization of both ventricles but the left is larger

First Phase

Depolarization of ventricular septum

Second Phase

Depolarization of both ventricles but the left is larger

Precordial Leads

V1

V6

Normal QRS

V1? V1?

V6?V6?

Fig. 4-6

Normal QRS

V1 V6

Normal QRS

• Septal r wave

• Septal q wave

6. QRS Complex

R wave progression

Normal R Wave Progression

Transition Zone?

R Wave Progression

Transition Zone?

Transition Zone

Figure 4-7

Early & Delayed Transition

• Figure 4-7

V1 V2 V3 V4 V5 V6

6. QRS Complex

What is the electrical axis?

normal

left axis deviation

right axis deviation

extreme axis deviation

7. St Segment

ST segment elevation or depression

(see chapters 8 & 9)

8. T Wave

Normally positive where QRS wave is positive

V3- V6 and II, but negative in aVR

Abnormally tall T waves

Practice

ECG Library

http://www.ecglibrary.com/ecghome.html

ECG: The Art of Interpretation

http://www.12leadecg.com/full/

Normal

Not normal PR interval - Mobitz Type II block

Not normalLAD, R wave progression

RBB w/inferior MI

Not normal -First degree block, left atrial enlargement, left

bundle branch block, & inferior MI

Not normalAtrial fibrillation

Normal

Not normalJunctional rhythm

Not normalLAD, late R wave progression

Acute MI

Not normalPremature ventricular contractions

Not normal

Ventricular tachycardia: note fast rate and wide bizarre QRS.

Normal

Not normal

Second degree AV block - type II

Not normalRAD, R wave progression

Not normal

Third degree AV block

Not normal

Right bundle branch block. Note the wide QRS waves

Normal

Not normal

Left bundle branch block. Note the wide QRS waves

a. yesb. verticalc. V3d. yese. yesf. yes

2. No. Although there are P waves, they are negative. negative P waves indicate a retrograde conduction likely coming from the AV junction.