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Flashcards in Basic ECG (Reading) Deck (57)
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1
Q

Why is it necessary to do multiple ECGs?

A

Takes only one picture in time

Need to do multiple to compare

2
Q

What other lead ECGs can be done?

A

3 and 5

3
Q

What is the baseline?

A

Isoelectric line

4
Q

What is the ECG paper speed?

A

25 mm/sec

5
Q

What is the paper square size?

A

Small square = 0.04 sec
Large square = 0.2 sec
Small square = 0.1 mV
2 large squares = 1 mV

6
Q

What is happening in the heart if the line is flat at any time in the ECG?

A

No electrical activity at that particular moment

7
Q

What does the direction in which the waves point indicate?

A

Whether electricity is moving towards or away from a particular lead

8
Q

What are the six chest leads and where are they attached?

A

V1, V2, V3, V4, V5, V6

Attached across patients chest

9
Q

What are the three limb leads and where are they attached?

A
aVR = right arm
aVL = left arm
aVF = left leg
10
Q

What is the lead that is attached to the right leg?

A

Earth, not active lead

11
Q

What are the three bipolar leads?

A

Lead I, lead II, lead III

12
Q

What is Einthoven’s Triangle?

A

Triangle, or line of sight created by the three limb leads
These form leads I, II, and III
Leads run negative to positive

13
Q

What forms lead I?

A

aVR (-) to aVL (+)

14
Q

What forms lead II?

A

aVR (-) to aVF (+)

15
Q

What forms lead III?

A

aVL (-) to aVF (+)

16
Q

What is the universal monitoring lead?

A

Lead II

17
Q

How do you measure the rate with a regular rhythm?

A

Number of large squares between 2 R waves/300

18
Q

How do you measure the rate with an irregular rhythm?

A

Number of QRS complexes in 6 second strip x10 OR

Number of QRS complexes on an ECG page x6

19
Q

What does the P wave represent?

A

Atrial depolarisation

SA node firing

20
Q

What is the intrinsic rate of the SA node?

A

60-100 bpm

21
Q

What should the P wave be?

A

Rounded and upright in all leads, except aVR
Less than 0.12 sec (3 small squares)
1:1 with QRS complex

22
Q

What does a peaked P wave mean?

A

Right atrial enlargement

23
Q

What does a bifid or prolonged P wave mean?

A

Left atrial enlargement

24
Q

What does the PR interval represent?

A

SA node to AV node

25
Q

What should the PR interval be?

A

0.12-0.20 sec (3-5 small squares)

26
Q

What is the intrinsic rate of the AV node?

A

40-60 bpm

27
Q

What does a shortened PR interval mean?

A

Pre-excitation or alternate accessory pathway exists

28
Q

What does a prolonged PR interval mean?

A

AV block

29
Q

What does the Q wave represent?

A

First negative deflection

Depolarisation of bundle of His (septum)

30
Q

When is the Q wave abnormal and pathological?

A

If >2 mm in depth or >1/3 of R wave height

31
Q

What does an abnormal Q wave indicate?

A

Previous myocardial infarct

32
Q

What does the QRS complex represent?

A

Ventricular depolarisation

33
Q

What should the duration of the QRS complex be?

A

Less than <0.12 sec (3 small squares)

34
Q

What does a prolonged QRS complex mean?

A

Conduction delay or if impulse generated in ventricles

35
Q

What can vary the QT interval?

A

Gender
Time of day
Heart rate

36
Q

What is the normal QT interval?

A

Less than 0.44 sec (11 small squares)

Less than half of RR interval

37
Q

What does a prolonged QT interval indicate?

A

Delayed repolarisation due to many causes:

  • Congenital
  • Low electrolyte levels
  • Drugs; eg: tricyclic antidepressants
38
Q

How does the R wave change from V1 to V6?

A

Becomes more upright

V3 often biphasic

39
Q

What should the ST segment be?

A

Isoelectric

40
Q

What change in the ST segment is indicative of a myocardial infarction?

A

ST elevation >2 mm in chest leads or >1 mm in limb leads

41
Q

What can an ST depression indicate?

A

Ischaemia

Reciprocal changes

42
Q

What does the T wave represent?

A

Depolarisation of ventricles

43
Q

What should the T wave look like?

A

Upright
Rounded
Larger than P wave

44
Q

What can a T wave inversion indicate?

A

Myocardial ischaemia

45
Q

What does a peaked T wave indicate?

A

Hyperkalaemia

46
Q

When is the U wave most obvious?

A

Hypokalaemia

47
Q

Which leads represent the lateral surface of the heart?

A

Low lateral = V5, V6

High lateral = I, aVL

48
Q

Which leads represent the anterior surface of the heart?

A

V3, V4

49
Q

Which leads represent the septal surface of the heart?

A

V1, V2

50
Q

Which leads represent the inferior surface of the heart?

A

II, III, aVF

51
Q

What does the S wave represent?

A

Second negative deflection

Depolarisation of Purkinje fibres

52
Q

How do you determine the rhythm?

A

Is there a P wave?
Where is the rhythm being generated?
Map out R - R regularity

53
Q

What indicates left atrial enlargement?

A

Bifid P wave

Terminal negative P wave deflection >1 mm deep and 0.04 (1 small square) long in V1

54
Q

What indicates right atrial enlargement?

A

Peaked P waves in V1 and V2 >1.5 mm tall

55
Q

What indicates left ventricular hypertrophy?

A

Add largest R wave of V5 or V6 to largest S wave of V1 or V2
Total >35 mm (7 large boxes)
R wave in aVL >9mm in females or >11 mm in males

56
Q

What indicates right ventricular hypertrophy?

A

R wave in V1 >7 mm

S wave in V5 or V6 >7 mm

57
Q

What indicates ischaemia or infarction?

A

In contiguous leads

  • ST segment changes
  • T wave inversion
  • Pathological Q waves