ECG 1 (Primciples)

Question 1

Which way do the ventricles depolarise? endo cardium to epicardium or vice versa?

Answer 1

Endocardium to epicardium

Question 2

Describe the course of the conducting system as it passes down the heart

Answer 2

SA Node
AV node (Delay)
Budle of His
Left and right fasicle bundles
Purkinje fibres

Question 3

Describe what each stage represents on the normal ecg

Answer 3

before P- Sa node depolarises (Undetectable)
P- Atrial depolarisation
P to Q- Delay at the AV node
Q- Depolarisation of the interventricular septum (left to right)
R- Depolarisation of the apex
S- Travelling up the ventricular walls
T- Ventricular repolarisation

Question 4

Why is there a delay at the Av node

Answer 4

Allow the ventricles time to refill

Question 5

What dies the bundle of His (and only the bundle of His cross)

Answer 5

The fibrous ring separating the atrium and ventricle

Question 6

What direction does the septum depolarise?

Answer 6

Left to right

Question 7

What changes on the ECG if the ventricular wall hypertrophies

Answer 7

R wave taller

Question 8

How many electrode are there and how many are placed on the chest and the limbs?

Answer 8

6-chest

4-limb

Question 9

How many views do the limb leads provide?

Answer 9

6

Question 10

How many views do the chest leads provide?

Answer 10

6

Question 11

How many small and large squares on a ecg equals 1 second?

Answer 11

5 large

25 small

Question 12

1 large square equals?

Answer 12

o.2 secs

Question 13

how many large squares in 1 min?

Answer 13

300

Question 14

How to work out heart rate?

Answer 14

Count no of boxes between R to R

300 divided by this

Question 15

How to calculate heart rate if irregular?

Answer 15

Count thee number of QRS complexes in 6 seconds (30 squares)

times 10

Question 16

Time span for a normal PR interval?

Answer 16

0.12 secs to 0.2 secs (If larger than 1 large box, prolonged)

Question 17

Time span for a normal QRS interval?

Answer 17

less than 0.12 secs

Question 18

Which leads view the heart laterally?

Answer 18

1, AvL, V5, V6

Question 19

Which leads view the heart inferiorly?

Answer 19

2,3,AvF

Question 20

Which leads view the septum?

Answer 20

V1 and V2

Question 21

which leads view the heart Anteriorly?

Answer 21

V2,3,4