# Normal ECG: Rate and Rhythm

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Normal ECG: Rate and Rhythm

ECG Interpretation* *See Chapter 22 Standardization Rate RR interval
Heart rate Rhythm PP interval P wave width, height, shape, etc. PR interval 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

The Normal ECG Normal = normal sinus rhythm

Rate R-R interval Is it regular? 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 P-P interval

Rhythm P wave PR interval 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 aVR? II? Figures 4-2 and 4-3

Abnormal P Wave Direction of atrial depolarization with junction rhythm aVR? II? 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 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 progression Axis Abnormal 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

Normal QRS V6? V6? V1? V1? 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
V V V V V V6 Figure 4-7

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

Normal

Not normal PR interval -
Mobitz Type II block

Not normal LAD, R wave progression RBB w/inferior MI

Not normal - First degree block, left atrial enlargement, left bundle branch block, & inferior MI

Not normal Atrial fibrillation

Normal

Not normal Junctional rhythm

Not normal LAD, late R wave progression Acute MI

Premature ventricular contractions
Not normal Premature ventricular contractions

Ventricular tachycardia: note fast rate and wide bizarre QRS.
Not normal Ventricular tachycardia: note fast rate and wide bizarre QRS.

Normal

Second degree AV block - type II
Not normal Second degree AV block - type II

Not normal RAD, R wave progression

Not normal Third degree AV block

Right bundle branch block. Note the wide QRS waves
Not normal Right bundle branch block. Note the wide QRS waves

Normal

Left bundle branch block. Note the wide QRS waves
Not normal Left bundle branch block. Note the wide QRS waves

a. yes b. vertical c. V3 d. yes e. yes f. yes

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