17& 18 EKG

Question 1

Which EKG leads provide information in the frontal plane of the body?

Answer 1

Bipolar limb leads - I, II, and III

Augmented unipolar limb leads- aVR, aVL, and aVF

Question 2

Which EKG leads provide information in the transverse plane of the body?

Answer 2

Precordial leads V1-V6

Question 3

What information can be obtained from an EKG?

Answer 3

1) Pattern and frequency of events
2) Conduction time
3) Direction of depolarization and repolarization
3) size of chamber

Question 4

What are the things an EKG cannot tell you?

Answer 4

1) Not a lot about mechanical activity (contraction and relaxation) except during ventricular fibrillation
2) It does not make an diagnosis

Question 5

What does the P wave correspond to?

Answer 5

Atrial depolarization

Question 6

What does the PR segment correspond to?

Answer 6

AV nodal delay

Question 7

What does the QRS complex correspond to?

Answer 7

Ventricular depolarization

Question 8

What does the ST segment correspond to?

Answer 8

The time during which the ventricles are contracting and emptying ( completion of ventricular depolarization and beginning of ventricular repolarization)
-Also corresponds to the plateau of the ventricular action potential

Question 9

What dos the T wave correspond to?

Answer 9

Ventricular repolarization

Question 10

What does the TP interval correspond to?

Answer 10

Time during which the ventricles are relaxing and filling

Question 11

Where does the PR segment start and stop?

Answer 11

Starts at the end of the P wave and stops at the beginning of the Q wave

Question 12

Where does the PR interval begin and end?

Answer 12

Begins at the start of the P wave and ends at the start of the Q wave

Question 13

What is the difference between a segment and interval?

Answer 13

A segment is a period of time BETWEEN waveforms that is normally isoelectric. And interval is a period of time that INCLUDES wave

Question 14

Are the Q, R, and S waves present in all QRS complexes?

Answer 14

They do not have to be

Question 15

What can T wave inversion indication?

Answer 15

Coronary ischemia or left ventricular hypertrophy

Question 16

What can tall and narrow T waves indicate?

Answer 16

Hyperkalemia

Question 17

What can flat T waves represent?

Answer 17

Coronary ischemia or hypokalemia

Question 18

Why is the T wave an upper deflection?

Answer 18

Repolarization of the membrane. Repolarization of the ventricle happens in the opposite direction of depolarization and is a negative current. This double negative of direction and charge is why the T wave is positive.
The cell becomes more negatively charged, but the net effect is positive, so the EKG reports it as positive

Question 19

Where is the wave for atrial repolarization?

Answer 19

Masked behind the QRS segment

Question 20

Where is the depolarization of the SA and AV node seen on an EKG? Why?

Answer 20

They are not reflected by a wave in the EKG because the mass of the tissue is too small

Question 21

What is used as a baseline to evaluate for ST segment displacement?

Answer 21

The PR segment

Question 22

What does the PR interval represent?

Answer 22

Time for atrial depolarization and the delay through the AV node

Question 23

What is the normal value for a PR interval?

Answer 23

0.12-0.20 seconds- ONE LARGE BOX

Question 24

What is the QT interval?

Answer 24

Measured from the onset of the QRS complex to the end of the T wave

Question 25

What does the QT interval correspond to?

Answer 25

The time for ventricular depolarization and repolarization (time for ventricular action potential) -Very dependent on heart rate

Question 26

What is the P-P interval?

Answer 26

The time between consecutive atrial depolarizations, measured from beginning of one P to the beginning of the next P

Question 27

What can the P-P interval be used to determine?

Answer 27

Atrial rate

Question 28

What is the R-R interval?

Answer 28

Time between consecutive ventricular depolarizations, measured between beginning of one QRS to the beginning of the next QRS

Question 29

What can the R-R interval be used to determine?

Answer 29

Ventricular rate This will not always be identical to the P-P interval

Question 30

HR is typically determined using what?

Answer 30

The R-R interval

Question 31

How much time is one large box on EKG?

Answer 31

0.20 seconds

Question 32

How much time is one small box on EKG?

Answer 32

0.04 seconds

Question 33

What is the calculation to get heart rate from an EKG?

Answer 33

HR= 300/ #large squares per cycle

Question 34

What is LAD?

Answer 34

When the mean QRS axis is more negative than 0 degrees

Question 35

What is RAD?

Answer 35

When the mean QRS axis is more positive than 90 degrees

Question 36

What are common causes for LAD?

Answer 36

LV hypertrophy, obesity, and pregnancy

Question 37

What are the common causes for RAD?

Answer 37

RV hypertrophy, LV infarct, and a tall, thin body type

Question 38

What is a prolonged PR interval?

Answer 38

A PR interval greater than 200 ms

Question 39

What is a 1st degree AV block?

Answer 39

Prolonged P-R interval greater than 200ms due to slowed conduction through the AV node or bundle of his. -There is a P wave for every QRS complex

Question 40

What is a second degree AV block?

Answer 40

- Partial dissociation of atria and ventricles | - Not every P wave is followed by a QRS complex

Question 41

What is a 3rd degree AV block?

Answer 41

- Complete heart block - No conduction though the AV node - Complete dissociation of atria and ventricles - P and QRS are completely independent of one another