CVS 7.1 - ECG Flashcards Preview

ESA 2 > CVS 7.1 - ECG > Flashcards

Flashcards in CVS 7.1 - ECG Deck (19):
1

What does the P wave on an ECG show?

Atrial depolarisation

2

What does the Q wave on an ECG show?

Septal depolarisation (not always seen)

3

What does the R wave on an ECG show?

Main ventricular depolarisation (spreads along the axis to the left of the septum)

4

What does the S wave on an ECG show?

End ventricular depolarisation (up to the base of the ventricles)

5

What does the T wave on an ECG show?

Ventricular repolarisation

6

What is the purpose of an ECG?

- Measure the electrical activity of the heart

- Shows if it's working correctly

7

How is the ECG measured?

- Signals are recorded during systole

- Measured extracellularly with electrodes

8

How does the ECG change when there is a depolarisation towards the electrodes?

There is a positive deflection from the baseline

9

How does the ECG change when there is a depolarisation away from the electrodes?

There is a negative deflection from the baseline

10

How does the ECG change when there is a repolarisation towards the electrodes?

There is a negative deflection from the baseline

11

How does the ECG change when there is a repolarisation away from the electrodes?

There is a positive deflection away from the baseline

12

What is temporal dispersion?

Repolarisation that doesn't happen in a uniform manner

13

Describe the pattern of spread of excitation over the heart

1) SAN

2) Internodal tracts

3) Spreads to AVN and is delayed for ~120ms

4) Bundle of His

5) Right/left bundle branch

6) Purkinje fibres

7) Over myocardium from inside to outside

14

When do the cardiac myocytes begin to repolarise?

After about 280ms

15

In what direction does repolarisation spread?

- Opposite direction to depolarisation

- Outside to inside/ epicardial to endocardial surface

16

What do the limb leads show?

A vertical view of the heart

17

What do the chest leads show?

A horizontal view of the heart

18

What is the organisation of the limb leads?

- Red - Right, upper limb

- Yellow - Left, upper limb

- Green - Left, lower limb

- Black - Right, lower limb

19

How can heart rate be calculated from a rhythm strip?

- 300/ number of squares in the R-R interval

- If irregular, use a larger interval than one R-R interval e.g. number of beats in 10 seconds x 6

Decks in ESA 2 Class (63):