ECG

Question 0

What direction is limb lead 2?

Answer 0

RA - LL

Question 1

What direction is limb lead 1?

Answer 1

RA - LA.

Question 2

What direction is limb lead 3?

Answer 2

LA - LL

Question 3

What are the colours of the four limb leads?

Answer 3

RA - White
LA - black
RL - green
LL - red

Question 4

What limb lead is earthed?

Answer 4

Right leg.

Question 5

What causes the PR interval?

Answer 5

Largely ventricular node delay.

Question 6

What is the ST segment?

Answer 6

Ventricular systole.

Question 7

What is the TP interval?

Answer 7

Diastole.

Question 8

What is an ECG actually recording?

Answer 8

Potential electrical differences between different sites.

Question 9

What creates an electrical dipole in the heart?

Answer 9

Different parts being depolarised or polarised at the same time.

Question 10

What does the dipole in the heart create that can be measured by ECG leads?

Answer 10

An electrical field called lines of isopotential.

Question 11

When is the measured potential difference the greatest in relation to the lead axis?

Answer 11

When the lead axis is parallel to the direction of the dipole.

Question 12

When is the measured potential difference 0?

Answer 12

When the lead axis is perpendicular to the direction of the dipole.

Question 13

What does the dipole represent and what are the characteristics of this?

Answer 13

A vector, it has magnitude and direction.

Question 14

What determines the magnitude of the ECG vector?

Answer 14

The mass of cardiac muscle involved in the generation of the signal.

Question 15

What determines the direction of the ECG vector?

Answer 15

Overall activity of the heart at any given instant.

Question 16

What does a positive deflection on an ECG mean?

Answer 16

Depolarisation towards the electrode.

Question 17

What does a negative deflection on an ECG mean?

Answer 17

Depolarisation away from the electrode.

Question 18

What does each large square on an ECG correlate to?

Answer 18

5mm amplitude and 0.2 seconds.

Question 19

What does each small square on an ECG correlate to?

Answer 19

0.04 seconds and 1mm of amplitude.

Question 20

How do we calculate heart rate from an ECG?

Answer 20

300/ the number of large squares between the RR interval.

Question 21

How long should the p wave last?

Answer 21

0.08 - 0.10 seconds.

Question 22

How long should the QRS complex last?

Answer 22

Less than 0.10 seconds.

Question 23

How long should the pr interval last?

Answer 23

0.12 - 0.20 seconds.

Question 24

What is the ST segment?

Answer 24

Maintained ventricular depolarisation e.g. Systole.

Question 25

At what points is an ECG isoelectric?

Answer 25

During the PR segment, the ST segment and the TP interval.

Question 26

What is the PR segment? How does this differ from the PR interval?

Answer 26

Atria are completely depolarised. This is different from the PR interval as it includes the act of atrial depolarisation.

Question 27

What formation do augmented leads have? What do they do?

Answer 27

They have a different view from standard limb leads. | They use the einthovens triangle formation, which is the imaginary triangle made of the two shoulders and the pubis.

Question 28

Where do we place 12 lead ECG chest leads?

Answer 28

V1 - right sternal edge, 4th intercostal. V2 - left sternal edge 4th intercostal V3 - halfway between V2 and V4 V4 - apex beat (may vary with patients). V5 - horizontal from v4 anterior axillary V6 - horizontal from v4 mid axillary

Question 29

How do we calculate the HR from an ECG if it is irregular?

Answer 29

Count the number of QRS complexes in 30 large squares and then divide it by 10.

Question 30

What are the 11 steps in reading an ECG?

Answer 30

1. Very name and DOB 2. Check date and time taken 3. Check calibration 4. Look at rhythm strip. 5. Electrical activity present? 6. Regular or irregular? 7. What is the HR? 8. Is there p waves present? 9. What is the PR interval? 10. Each p wave followed by a QRS? 11. Is the QRS duration normal Then we look at individual leads for changes.

Question 31

What kind of ECG should we do if we suspect intermittent rhythm disturbance?

Answer 31

Do an ambulatory recording for 24hrs or 7 days.

Question 32

What type of ECG should we do for suspected stable angina?

Answer 32

Exercise ECG. Look for ST changes during or after exercise.

Question 33

What leads are anterolateral? What do these represent?

Answer 33

Circumflex and LAD. V4-V6 1 and AVL.

Question 34

What leads are inferior? What arteries/structures do these represent?

Answer 34

II, III and AVF. Right coronary artery.

Question 35

What leads are anteroseptal? What arteries/structures do these represent?

Answer 35

V1 - V3 LAD/bundle branches.

Question 36

What leads are anterior? What arteries/structures do these represent?

Answer 36

V2 -V5 Usually left coronary artery.

Question 37

What leads are posterior?

Answer 37

V1 and V2

Question 38

If lead one has a mainly positive deflection and leads II and III are negative mainly what does this mean?

Answer 38

Left axis deviation.

Question 39

If lead one has a mainly negative deflection and leads II and III are mainly positive what does this mean?

Answer 39

Right axis deviation.

Question 40

What deflection should leads I,II and III normally have?

Answer 40

All positive.