ECG

Question 1

Explain hexaxial leads

Answer 1

-Limb leads that look in frontal plane

Question 2

What leads are hexaxial view?

Answer 2

• Leads I, aVL (lateral)
• leads II, III, aVF (inferior)
• aVR: superiomedial

Question 3

What leads are bipolar?

Answer 3

Leads I, II, III

Question 4

What leads are unipolar?

Answer 4

• aVR (augmented voltage) right arm
• aVL (left arm)
• aVF (foot)

Question 5

Wha is the view of precordial leads?

Answer 5

• look in transverse plane

- v1 through v6

Question 6

__________ of __________ reflects how __________ or force is to axis.

Answer 6

Magnitude…..deflection……parallel

Question 7

_________ to axis results in _______ line.

Answer 7

Perpendicular…….flat

Question 8

What leads show inferior wall infarct?

Answer 8

II, III, aVF

Question 9

What leads show lateral wall infarct?

Answer 9

I, aVL, v5, v6

Question 10

What leads show anteroseptal wall infarct?

Answer 10

v1 through v4

Question 11

Define the mean QRS axis.

Answer 11

the average direction of ventricular depolarization in frontal plane based on leads I and II

Question 12

What is the normal QRS axis range?

Answer 12

+90 to -30

Question 13

How to determine QRS axis? (3 steps)

Answer 13

1. Look at hexaxial leads (I, II, III, aVR, aVL, aVF),Find most isoelectric
2. which lead is perpendicular to isoelectric lead?
3. Fine tune
   (down deflection moves left away hexaxial lead)
   (up deflection move right toward hexaxial lead)

Question 14

The more perpendicular the axis is to a lead, the more ________ the QRS complex will be.

Answer 14

isoelectric

Question 15

What determines a left axis deviation?

Answer 15

< -30 degrees

Question 16

What determines a right axis deviation?

Answer 16

> +90 degrees

Question 17

What can cause left axis deviation?

Answer 17

• inferior wall myocardial infarct
• left anterior fascicular block
• left ventricular hypertrophy (sometimes)

Question 18

What can cause right axis deviation?

Answer 18

• right ventricular hypertrophy
• acute right heart strain
• left posterior fascicular block

Question 19

What causes P wave abnormalities?

Answer 19

-atrial enlargement

Question 20

What leads are best to detect atrial enlargement in what planes?

Answer 20

II (frontal)

v1 (transverse)

Question 21

What ECG changes would you detect with RIGHT atrial enlargement?

Answer 21

Lead v1 would show upward deflection

Question 22

What ECG changes would you detect with LEFT atrial enlargement?

Answer 22

lead v1 would show downward deflection

Question 23

What leads best detect QRS abnormalities?

Answer 23

v1 and v6

Question 24

What causes QRS abnormalities?

Answer 24

ventricular hypertrophy

Question 25

What EKG changes detected with right ventricular hypertrophy?

Answer 25

• Wide R in v1
• Deep S in v6
• right axis deviation

Question 26

What EKG changes detected with left ventricular hypertrophy?

Answer 26

• Deep S in v1
• Tall R in v6
• left axis deviation

Question 27

BBB are best seen in which leads?

Answer 27

v1 and v6

Question 28

Ventricle must rely on what type of signaling?

Answer 28

cell to cell

Question 29

What prolongs depolarization and widens QRS?

Answer 29

Bundle branch block

Question 30

What EKG changes are present with RBBB?

Answer 30

• v1 shows RSR “rabbit ears”

- v6 prominent S

Question 31

What EKG changes are present with LBBB?

Answer 31

• v1 prominent S

- v6 notched R

Question 32

What is a fascicular block and what leads best detect on EKG?

Answer 32

• left ventricle (anterior and posterior branch one to each papillary muscle)
• aVL and aVF

Question 33

ST elevation vs. Non-ST elevation MI

Answer 33

• Ionic leak shifts EKG baseline
• shifts down if damage on surface (ST elevation)
• shifts up if damage at subendocardium (depressed ST)

Question 34

What causes pathological Q waves?

Answer 34

• Develop in leads overlying infarcted tissue

- no electrical activity, “window” for lead to see opposite side of heart depolarizing away from lead