L11 - ECG

Question 1

What is the function of the fibrous ring of the heart?

Answer 1

• Acts as an electrical insulator so that atria and ventricle contract separately
• anchors the myocardium and valves
• ensures only electrical connection is via bundle of his through it

Question 2

The rhythm set by the SA mode is called the ______ rhythm?

Answer 2

Sinus

Question 3

Depolarisation spreading away from a positive recording electrode will be recorded as an upward or downward deflection on the ECG?

Answer 3

Downward deflection

Question 4

What wave form would we see on an ECG if we had depolarisation spreading transversely to the electrodes?

Answer 4

No or biphasic complex

Question 5

The SA nodes electrical events are picked up by the ECG, true or false

Answer 5

False - the ecg picks up activity from areas with more myocytes

Question 6

Is the main electrode on the apex side of the heart negative or positive?

Answer 6

Positive

Question 7

What does the p wave represent?

Answer 7

Atrial depolarisation

Question 8

What does the Q wave correspond to? What direction does the depolarisation spread across the septum?

Answer 8

Depolarisation of the interventricular septum.

Spreads patients left to right across septum

Question 9

If the left ventricle of the heart were hypertrophied which wave would we see an increase in amplitude of?

Answer 9

R wave

Question 10

If an ECG is missing a QRS complex, what does this indicate?

Answer 10

A problem in the the AV node and bundle of his - AV heart block

Question 11

The 6 chest leads are labelled V1-V6. State where you put these on someone anatomically

Answer 11

V1 - 4th intercostal space, right of sternum
V2 - 4th intercostal space, left of sternum
v3 - midway between v2 and v4
V4 - 5th intercostal space, left mid- clavicular line
V5 - 5th intercostal space, left anterior axillary line
V6- 5th intercostal specie, left mid axillary line

Question 12

Which leads give views of the inferior surface of the ventricles (it’d be useful to draw out the lead planes for this - see lecture)

Answer 12

II, III and aVF

Question 13

Which leads give views of the right ventricle and septum?

Answer 13

V1 and v2

Question 14

This lecture you really need to look at the pics and be able to recognise the different planes

Answer 14

Yep

Question 15

At what rate does ECG paper move at per second?

Answer 15

25mm/second (25 small squares)

Question 16

How many large squares does ECG paper move by per second?

Answer 16

5 large squares

Question 17

How many large ECG boxes are there in one minute?

Answer 17

300

Question 18

It’s that the PR interval is actually the distance between the beginning of the p wave and the beginning of the QRS complex and QT interval is between Q wave and end of T wave. What is the normal range for the PR interval?

Answer 18

0.12-0.20 seconds (3-5 small boxes)

Question 19

What does a prolonged PR interval indicate?

Answer 19

Delayed conduction through AV mode and bundle of his

Question 20

What is the normal range for a QRS complex and what does a widened QRS complex indicate?

Answer 20

Less than 0.12 seconds. (Less than 3 small boxes)

Indicates a depolarisation starting in the ventricles and not going via the fast conducting bundle of his pathway

Question 21

Why does the QT interval need correcting?

Answer 21

Because patients have different heart rates and the interval decreases with an increase in heart rate, to look at solely this interval it needs correcting to the heart rate. It shows the time taken for the depolarisation and depolarisation of the ventricles

Question 22

What are the things needed to determine a sinus rhythm?

Answer 22

• regular rhythm
• HR 60-100
• p waves present
• normal PR interval (3-5 small boxes)
• normal QRS width (less than or equal to small boxes)
• every p wave followed by a QRS complex

Question 23

What are the colour of the electrodes:
Right arm 
Left arm
Right leg
Left leg

Answer 23

Red
Yellow
Black
Green

Question 24

What does a raised Or depressed ST segment indicate? (Should be isoelectric

Answer 24

Myocardial infarction or ischaemia