ECG Interpretation

Question 1

If the magnitude of the upward and downward deflections are equal, this is known as isoelectric and indicates that the depolarization wave is moving

Answer 1

Perpendicular to the lead

Question 2

The 6 limb leads (Inferior: II, III, and aVF, left lateral I and aVL, and right lateral aVR) tell us about the

Answer 2

Frontal plane of the heart

Question 3

What does the PR segment show?

Answer 3

Atrial depolarization and AV node delay

Question 4

How do we determine electrical axis of the heart?

Answer 4

Determine QRS voltages from leads I, II, and aVF

Question 5

The average cardiac electrical axis approximates 50-60 degrees and falls somewhere between 0 and 90 degrees. Both leads I and aVF are predominantly

Answer 5

Positive

Question 6

Leads I and II are positive and lead aVF is negative for a

Answer 6

Normal variant of 0-30 degrees

Question 7

If

1. ) Lead I is negative
2. ) Lead II is isoelectric
3. ) Lead aVF is positive

We have an axis of

Answer 7

Greater than 100 degrees and RIGHT axis deviation (RAD)

Question 8

If

1. ) Lead I is positive
2. ) Lead II is negative
3. ) Lead aVF is negative

We have an axis between

Answer 8

-30 and -90 degrees and a LEFT axis deviation (LAD)

Question 9

On an ECG, one LARGE horizontal box equals

Answer 9

0.20 seconds

Question 10

In an ECG, each SMALL horizontal box equals

Answer 10

0.04 seconds

Question 11

How do we calculate beats per minute?

Answer 11

Look from R to R and do 300/number of large boxes

Question 12

To calculate BPM from small boxes, do

Answer 12

Number of small boxes x 0.04

THEN

60 seconds / answer

Question 13

Sinus brachycardia is a rate

Answer 13

Below 60 BPM

Question 14

Sinus Tachycardia is a rate

Answer 14

Above 100 BPM

Question 15

Refers to the time between R-R intervals

Answer 15

Rythym

Question 16

During sinus rhythm, the time between R-R intervals is consistent during a given

Answer 16

Rate

Question 17

Means that R-R intervals are not consistent

Answer 17

Irregular rhythm

Question 18

How do we determine the rate for a slow irregular rythm?

Answer 18

Count the number of R peaks within 30 large boxes and multiply by 10

Question 19

A normal PR interval is between

Answer 19

0.12 - 0.20 seconds

Question 20

How do we determine PR interval?

Answer 20

For the LONGEST PR seen, count number of little boxes between beginninng of P wave and first deflection of QRS

Question 21

Normal QRS intervals are

Answer 21

Less than 0.12 seconds

Question 22

Increased QRS intervals are

Answer 22

Greater than or equal to 0.12 seconds

Question 23

How do we calculate corrected QT interval?

Answer 23

QT interval / square root of preceding R-R interval

Question 24

What is a normal corrected QT interval?

Answer 24

0.35-0.43 seconds

Question 25

Normally isoelectric with the other segments. Elevation or depression an indicate a pathological process such as myocardial injury or ischemia

Answer 25

ST segment

Question 26

The time when the myocardium is electrically silent

-isoelectric line of ECG

Answer 26

TP interval

Question 27

Leads I and aVF are equally positive than

Answer 27

Axis is midway between 0 and 90 degrees (normal)

Question 28

If ledds I and aVF are both positive but Lead I is MORE positive than aVF than

Answer 28

Axis is oriented more towards 0 (20 degrees to 40 degrees)

-The normal variant

Question 29

If lead I is positive and lead aVF is almost isoelectric than

Answer 29

The axis is approaching 0

-still normal

Question 30

When lead I is positive and lead aVF is negative than

Answer 30

The axis is oreiented negatively past 0

-Left axis deviation (-30)

Question 31

If lead I is negative and lead aVF is positive than

Answer 31

Right axis deviation

Question 32

If both leads I and aVF are negative than we have an

Answer 32

Intermediate axis (-135)

Question 33

If the QRS axis in leads I and II are positive than we have a

Answer 33

Normal axis

Question 34

When interpreting P waves use leads

Answer 34

II and V1

Question 35

If one half of the P wave is larger than the other, than we see

Answer 35

Atrial enlargement

Question 36

Most common cause for left atrial enlargement?

Answer 36

Chronic hypertension or aortic stenosis

Question 37

What is the criteria for classifying SINUS rythm

Answer 37

P precedes QRS and ratio is 1:1

Question 38

What are some other things to look at on ECG?

Answer 38

1. ) P wave for atrial enlargement (II and V1)
2. ) ST elevation or depression
3. ) Be able to localize an MI
4. ) Inverted T waves in leads I, II, III

Question 39

For rythm, don’t forget to check the

Answer 39

Rythm strip

Question 40

In a normal heart, P and T waves should be positive in leads

Answer 40

I and II

Question 41

Biphasic P waves are normal in the

Answer 41

Precordial leads

Question 42

Atrial enlargement is best seen in Leads

Answer 42

II and V1

Question 43

What is the criteria for A-fib?

Answer 43

1. ) Irregularly irregular rythm

2. ) Absence of discernible P waves

Question 44

Prolonged PR signifies

Answer 44

Primary Heart Block

Question 45

Multiple P waves suggests

Answer 45

Secondary Heart Block

Question 46

In order, what 5 things do you calculate on ECG?

Answer 46

1. ) Rate and rythm
2. ) PR interval
3. ) QRS interval
4. ) QT interval (and QTc for brachycardia and tachycardia)
5. ) QRS axis