Vectors

Question 1

mean electrical vector

Answer 1

the average current flow of all the action potentials at a given point in time

Question 2

when does a positive deflection occur?

Answer 2

when the vector of depolarization travels towards the positive electrode

Question 3

when does a negative deflection occur?

Answer 3

when the vector of depolarization travels away from the positive electrode

Question 4

when does a biphasic deflection occur?

Answer 4

when the vector of depolarization travels perpendicular to the positive electrode

Question 5

the heart depolarizes from the __ to __

Answer 5

base to the apex and the endocardium to the epicardium

Question 6

what is the polarity during depolarization?

Answer 6

the myocytes go from internally negative to internally positive
This produces a positive electrical current

Question 7

Vector of Repolarization =

Answer 7

the T wave

Question 8

Vector of Depolarization =

Answer 8

the QRS complex

Question 9

the heart repolarizes from the ___ to __

Answer 9

the apex to the base and the epicardium to the endocardium

Question 10

what is the polarity during repolarization?

Answer 10

the myocytes go from internally positive to internally negative
This produces a negative current

Question 11

Bipolar leads =

Answer 11

I, II, and III

Question 12

Limb leads =

Answer 12

aVR, aVL, and aVF

Question 13

Precordial leads =

Answer 13

V1-6

Question 14

Lead I monitors which region of the heart?

Answer 14

Lateral
Circumflex artery

Question 15

Lead II monitors which region of the heart?

Answer 15

Inferior
Right Coronary Artery

Question 16

Lead III monitors which region of the heart?

Answer 16

Inferior
Right Coronary Artery

Question 17

aVL lead monitors which region of the heart?

Answer 17

Lateral
Circumflex

Question 18

aVF lead monitors which region of the heart?

Answer 18

Inferior
Right Coronary Artery

Question 19

V1 lead monitors which region of the heart?

Answer 19

Septum
Left Anterior Descending Artery

Question 20

V2 lead monitors which region of the heart?

Answer 20

Septum
LAD artery

Question 21

V3 lead monitors which region of the heart?

Answer 21

Anterior
LAD

Question 22

V4 lead monitors which region of the heart?

Answer 22

Anterior
LAD

Question 23

V5 lead monitors which region of the heart?

Answer 23

Lateral
Circumflex artery

Question 24

V6 lead monitors which region of the heart?

Answer 24

Lateral
Circumflex artery

Question 25

The axis represents __

Answer 25

the direction of the mean electrical vector in the frontal plane

Question 26

If lead I and aVF point up, _____

Answer 26

then the axis is normal (two thumbs up)

Question 27

If the leads are reaching towards each other, ____

Answer 27

then we have right axis deviation (I points down and aVF points up)

Question 28

If the leads are leaving each other, ____

Answer 28

then we have left axis deviation (I points up and aVF points down)

Question 29

If both leads point down, ___

Answer 29

then we have extreme right axis deviation (two thumbs down)

Question 30

What is normal axis deviation?

Answer 30

-30 and +90 degrees

Question 31

What is left axis deviation?

Answer 31

more than -30 degrees

Question 32

What is right axis deviation?

Answer 32

more than positive 90 degrees

Question 33

The axis can shift as a consequence of _____

Answer 33

hypertrophy, conduction block, or a physical change in the position of the heart

Question 34

The mean electrical vector tends to point towards ___

Answer 34

areas of hypertrophy (there is more tissue undergoing depolarization)

Question 35

The mean electrical vector tends to point away from ____

Answer 35

areas of myocardial infarction (the vector has to move around these areas)

Question 36

Causes of right axis deviation

Answer 36

COPD Acute bronchospasm Cor pulmonale pulmonary hypertension pulmonary embolus

Question 37

Causes of left axis deviation

Answer 37

Chronic hypertension LBBB Aortic stenosis Aortic insufficiency Mitral regurgitation