EXAM #1: BASIC ECG

Question 1

Where does the Bundle of His lie?

Answer 1

Left side of the IV septum

Question 2

What is the first part of ventricular depolarization?

Answer 2

High left ventricular septum

Question 3

Is the sinus node depolarization contained in the PR interval?

Answer 3

No

Question 4

Why is the T-wave upright?

Answer 4

Myocardium repolarizes in the opposite direction of depolarization

Question 5

What is the clinical importance of the relative refractory period and the supranormal period?

Answer 5

Arrhythmiogenesis

Question 6

Draw and label the hexaxial diagram.

Answer 6

p. 21

Question 7

What does a small square on the ECG correspond to? What is one big square on the ECG?

Answer 7

0. 04 sec

0. 20 sec

Question 8

List the numbers that correspond to each large square in interpreting heart rate.

Answer 8

300 
150 
100 
75 
60 
50 
43 
37 
35 
30

Question 9

Vertically, what does one small square correspond to?

Answer 9

0.1 mV

Question 10

Vertically, what does 1 mV equal?

Answer 10

2x large boxes

Question 11

How do you check the regularity of the heart rhythm?

Answer 11

Check the R-R interval

Question 12

What does the p-wave correspond to?

Answer 12

Atrial depolarization

Question 13

Where should you look at the p-wave?

Answer 13

II and V1

Question 14

In what leads are p-wave upright?

Answer 14

Inferior (II, III, and aVF)

Lateral (I and aVL)

Question 15

Where will the p-wave normally be negative?

Answer 15

aVR

Question 16

What is the normal p-wave duration?

Answer 16

Less than 0.12 sec or 120 msec

Question 17

What is the normal p-wave amplitude?

Answer 17

Less than 0.25 mV or 2.5mm (small boxes)

Question 18

What are the indications of a RAA? Where do you look?

Answer 18

II and V1= Tall/ narrow (greater than 2.5mm)

Question 19

What are the indications of a LAA? Where do you look?

Answer 19

II= notched and greater than 0.12 sec 
V1= wide and biphasic

Question 20

What does the PR interval correspond to?

Answer 20

Depolarization in:

• AVN
• His Bundle
• Bundle branches
• Purkinje fibers

Question 21

What is the normal PR interval?

Answer 21

0.12-0.20 sec

Question 22

What is the definition of a 1st degree AV block?

Answer 22

PR interval greater than 0.20sec

*Note that there are NO pathologic implications regarding a 1st degree AV block

Question 23

What is a short PR interval?

Answer 23

PR interval less than 0.12

Question 24

What does a short PR interval correspond to?

Answer 24

Pre-excitation

Question 25

What is the normal QRS interval?

Answer 25

0.07 sec to 0.11sec

Question 26

What does a wide ORS interval correspond to?

Answer 26

Bundle branch block

Question 27

What is "low voltage?"

Answer 27

QRS complex is less than 5mm in amplitude in I, II, and III

Question 28

What does low voltage indicate?

Answer 28

Current is not getting to the surface ECG - Obesity - Pericardal effusion

Question 29

Where are Q-waves normal?

Answer 29

``` aVR II III aVF aVL V4-V6 ```

Question 30

What is the normal duration of a Q-wave?

Answer 30

Less than 0.03 sec (less than 1 small box)

Question 31

What is the criteria for a pathologic Q-wave?

Answer 31

- More than 25% of the r-wave amplitude | - Wider than 0.03 sec

Question 32

Where is the R-wave coming from?

Answer 32

Upper left IV septum

Question 33

What is the normal R-wave progression?

Answer 33

Small r-wave in V1 and then getting bigger laterally

Question 34

What is the normal S-wave progression?

Answer 34

Big s-wave in V1 and then getting smaller laterally

Question 35

Where is the normal R/S transition?

Answer 35

V3 or V4 *Transition between S-predomination to R-predomination*

Question 36

What does the ST segment correspond to?

Answer 36

Phase 2 or plateau phase

Question 37

What is the normal amplitude of T-waves?

Answer 37

``` Limb= less than 5mm Chest= less then 10mm ```

Question 38

What is concordance of the T-wave?

Answer 38

T-wave should have same deflection as QRS i.e. - QRS +, T-wave + - QRS -, T-wave -

Question 39

What are very tall peaked t-waves an indication of?

Answer 39

1) Very early signs of MI | 2) Hyperkalemia?

Question 40

What is a U-wave?

Answer 40

Small rounded wave after the T-wave

Question 41

What causes U-waves?

Answer 41

1) Hypokalemia | 2) Quinidine

Question 42

What is the QT interval?

Answer 42

Measurement of the duration of the entire cardiac cycle i.e. depolarization to repolarization *Remember that you measure from the beginning of the Q-wave to the end of the T-wave*

Question 43

How does the QT interval change with increased HR?

Answer 43

QT Interval gets SHORTER

Question 44

What is associated with prolonged QT interval?

Answer 44

Sudden cardiac death

Question 45

What is the normal QRS axis in the frontal plane?

Answer 45

- 15 to 100+ | * Typically ~60+

Question 46

How can you calculate the specific QRS axis in the frontal plane?

Answer 46

1) Find equipotential QRS complex | 2) Go 90 degrees to that (positive)