Axis and Hypertrophy

Question 1

If all the small vectors are added up in ventricular depolarization the sum is…

Answer 1

Mean QRS vector

Question 2

‘Mean QRS Vector’ represents…

Answer 2

the general direction of ventricular depolarization

Question 3

A normal q wave represents…

Answer 3

septal depolarization

Question 4

Normal ventricular depolarization recorded by aVL is…

Answer 4

negative first then positive

Question 5

Normal ventricular depolarization recorded by aVF is…

Answer 5

positive first then negative

Question 6

A normal Mean QRS axis is typically at…

Answer 6

45 degrees

Question 7

The frontal plane is numbered with 0 degrees being at ?? and 180 degrees being at ??.

Answer 7

• left hand
• right hand

Question 8

The degrees are positive on the ?? of the frontal plane.

Answer 8

bottom half

Question 9

The degrees are negative on the ?? of the frontal plane.

Answer 9

top half

Question 10

What are used to determine the position of the “Axis” of the Mean QRS vector?

Answer 10

the limb leads

Question 11

Quadrant I is angles ??-?? in the clockwise direction of the frontal plane?

Answer 11

-90 - 0 degrees

Question 12

Quadrant II is angles ??-?? in clockwise direction of the frontal plane?

Answer 12

0 - 90 degrees

Question 13

Quadrant III is angles ??-?? in a clockwise direction on the frontal plane?

Answer 13

90 - +/-180 degrees

Question 14

Quadrant IV is angles ??-?? in a clockwise direction on the frontal plane?

Answer 14

+/-180 - -90 degrees

Question 15

If the QRS is positive in Lead 1 this means the vector is pointing…

Answer 15

somewhere to the patients left half

Question 16

If the QRS is positive in Lead aVF this means the vector is pointing…

Answer 16

somewhere downward to the patients left

Question 17

A normal QRS axis is confirmed with…

Answer 17

1. a positive QRS in Lead 1
2. a positive QRS in Lead aVF

Question 18

A left axis deviation is confirmed with…

Answer 18

1. a positive QRS in Lead 1
2. a negative QRS in Lead aVF

Question 19

A right axis deviation is confirmed with…

Answer 19

1. a negative QRS in lead 1
2. a positive QRS in lead aVF

Question 20

An extreme right axis deviation is confirmed with…

Answer 20

1. a negative QRS in lead 1
2. a negative QRS in lead aVF

Question 21

A normal QRS axis is typically in the degree range of…

Answer 21

-30 - 90 degrees

Question 22

T/F: A normal axis can be in quadrant 1 (0 - -90 degrees).

Answer 22

TRUE – but only to -30 degrees

Question 23

How do you differentiate a normal axis from a LAD?

Answer 23

1. Lead 1 = positive QRS
2. lead aVF = negative QRS
3. Lead 2 = positive QRS

- if lead 2 is positive = normal axis
- if lead 2 is negative = LAD

Question 24

What are the 2 causes of LAD?

Answer 24

1. LVH
2. previous right ventricular myocardial infarction

Question 25

What are the 3 causes of RAD?

Answer 25

1. RVH
2. previous left ventricular infarctions
3. right heart strain due to pulmonary embolism

Question 26

T/F: The precordial reference plane is used in determining the QRS axis.

Answer 26

FALSE – used in plotting the heart’s electrical activity in horizontal plane

Question 27

What are the 3 causes of LVH?

Answer 27

1. hypertension
2. aortic valve stenosis
3. cardiomyopathy

Question 28

Where can a LVH be seen on an ECG?

Answer 28

V1 and V5
- large S/R in these leads

Question 29

What is added to determine LVH presence?

Answer 29

S in V1 + R in V5

Question 30

How many mm (boxes) determine LVH?

Answer 30

35 mm or 7 big boxes

Question 31

What is a strain pattern?

Answer 31

an ST depression in V5 - T wave inversion characteristic of longstanding LVH

Question 32

ECG criteria for LVH

Answer 32

1. Sum of S and R waves
   - V1 + V5 is greater than 35 mm
2. R wave or S wave only
   - R wave in V5 is greater than 30 mm
   - S wave in V1 is greater than 20 mm
3. R wave only
   - lead 1 is greater than 20 mm
   - aVL is greater than 11 mm