Exam 2

Question 1

What is the function of the AV node?

Answer 1

Pace setter. Relays and intensifies impulse generated by SA node. It can fire an impulse if the SA node fails.

Question 2

What is the function of the SA node?

Answer 2

Pacemaker.

Question 3

What is the normal rate of the SA node?

Answer 3

50-100 per min

Question 4

What is the normal rate of the AV node?

Answer 4

40-60 per min

Question 5

How many second’s is each small box on an EKG strip? How about the big box?

Answer 5

0. 04 sec per small box

0. 2 per large box

Question 6

What is the amplitude of each small box on a EKG?

And a big box?

Answer 6

1 mm or 0.1 mV

5 mm or 0.5 mV

Question 7

What is the P wave? and what is it’s normal duration?

Answer 7

Atrial depolarization (SA node firing.)
Does not exceed 3mm in amplitude.

Question 8

What does a change in the P wave mean?

Answer 8

The cardiac impulse originated from somewhere other than the SA node.

Question 9

What is the PR interval measure?

Answer 9

Time it takes for impulse to depolarize the atria, travel to AV node and dwell there before entering the bundle of His.

Question 10

How long is a normal PR interval? What does it mean is it is too fast/too slow?

Answer 10

A. 0.12-0.20 seconds. (3-5 small boxes wide)

B. Conduction is either delayed in the AV node, or abnormally fast.

Question 11

What is QRS complex?

Answer 11

Ventricular depolarization.

Question 12

How do you determine a a pathological Q wave? and what does it mean?

Answer 12

Has a width of 0.04 seconds and depth greater than one fourth of R wave amplitude.
Indicates myocardial infarctions.

Question 13

What is the T wave?
What is it’s shape?
What is it’s normal height?

Answer 13

A. Ventricular repolarization
B. Asymmetrical (bigger than P wave)
C. No higher than 5mm or 5 small boxes

Question 14

At what time do you measure ST segment changes? And what do you uses as a reference point?

Answer 14

0.04 secs after J point.

The isoelectric PR segment.

Question 15

What does a wider QRS complex signify?

Answer 15

Greater than 0.10 seconds means delayed conduction.

Caused by either MI, atherosclerosis, or cardiomyopathy.

Question 16

What does a change in direction or amplitude in T wave mean?

Answer 16

Electrical disturbances from electrolyte imbalances, myocardial ischemia, or injury.

Example: hyperkalemia- tall peaked T waves. And ischemia causes inverted T wave.

Question 17

What does a large U wave mean?

Answer 17

Hypokalemia, cardiomyopathy, and digoxin toxicity.

Question 18

What does QT interval measure?

Answer 18

The total time for ventricular depolarization and repolarization.

Question 19

What causes depolarization? (4)

Answer 19

1. SA node creates electrical current.
2. This current changes the cell permeability.
3. K- rushes out of the cell and Na+ rushes in causing a contraction
4. Ca slowly diffuses into the cell to maintain a longer contraction

Question 20

What is the U wave?

What is its height?

Answer 20

Repolarization of small segments of the ventricles.

Less than 2mm in height.

Question 21

What does a large U wave mean?

Answer 21

Hypokalemia, cardiomyopathy, and digoxin toxicity.

Question 22

How do you determine heart rate using the small box method?

Answer 22

Count the number of small boxes between QRS wave forms and divide that number into 1500.

Question 23

When can’t you use the large and small box method?

Answer 23

When the rate is irregular.

Question 24

How do you determine heart rate using the six-second method?

Answer 24

Count the number of QRS wave forms and multiply by 10 to get bpm.

Question 25

How do you determine heart rate using the large box method?

Answer 25

Count the number of large boxes between QRS wave forms and divide that number into 300.

Question 26

What is a first degree heart block?

Answer 26

Delayed AV node conduction represented by a prolonged PR interval (greater than 5 boxes or 0.20 secs)

Question 27

What causes a third degree hear block?

Answer 27

A blockage from the atria to the ventricles occurring in either the AV node, bundle of His, or bundle branches.

Question 28

What is the rate and rhythm of a third degree blockage?

Answer 28

20-40 bpm.
Atrial rate is greater than ventricular.
P-P and R-R are at regular intervals but have no association,

Question 29

What are the causes and main treatment for a third degree block?

Answer 29

Causes:
A. Ischemic heart disease
B. Acute MI
C. Conduction system disease
Treatment:
PPM

Question 30

How does breathing effect sinus arrhythmias?

Answer 30

Inspire = increase rate
Expire = decrease rate

Question 31

How to identify atrial fibrillation on a rhythm strip? (4)

Answer 31

1. No P wave
2. Atrial rate 350-700 bpm
3. QRS less than 0.12 secs.
4. Irregular rhythm

Question 32

What causes A-fib? (3)

Answer 32

Ischemic heart disease, lung disease, and valvular disease.

Question 33

How to identify atrial flutter on a rhythm strip?

Answer 33

1. No P wave
2. Narrow QRS (less than 0.12)
3. Regular HR
4. Regularity sawtooth shaped flutters

Question 34

What are the conduction rates of the AV node and the SA node?

Answer 34

SA: 60-100 bpm
AV: 40-60 bpm

Question 35

How do you identify 3rd degree heart block on EKG?

Answer 35

1. P waves have no association to QRS complex.
2. Wide QRS interval
3. Ventricular rate 20-40 bpm / Atrial rate 60-100