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m3 gah > ECG 101 > Flashcards

ECG 101 Flashcards

1
Q

5 surfaces of the heart

A

Anterior: RV, LV
Posterior: LA
Diaphragmatic: RV, LV
Right pulmonary: RA
Left pulmonary: LV

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2
Q

Right coronary artery supplies

A

RCA runs along right atrio-ventricular groove.

RCA supplies
- RA, RV
- SA, AV nodes
- posterior part of the IVS

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3
Q

Right marginal arteries supply

A

Right marginal arteries and posterior descending artery branches out from the RCA.

Marginal arteries supply:
- RV
- apex

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4
Q

Posterior descending artery supplies

A

Posterior descending artery and right marginal arteries branches out from the RCA.

PDA runs along posterior inter-ventricular groove.

Posterior descending artery supplies:
- RV, LV
- posterior 1/3 of IVS

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5
Q

Left coronary artery supplies

A

LA, LV
IVS
AV bundles

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6
Q

Left anterior descending supplies

A

LAD runs along anterior inter-ventricular groove.

LAD and left circumflex artery branches out from LCA.

LAD supplies
- LV, RV
- anterior 2/3 of IVS

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7
Q

Left circumflex artery supplies

A

Left circumflex artery runs along left atrio-ventricular groove.

LAD and left circumflex artery branches out from LCA.

Left circumflex artery supplies
- LA, LV

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7
Q

Left marginal arteries supplies

A

Left marginal arteries branch out of left circumflex artery.

Left marginal arteries supply:
- LV

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8
Q

Posterior descending artery runs with which vein?

A

Middle cardiac vein

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9
Q

Marginal arteries run with which veins?

A

Small cardiac veins

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10
Q

Anterior descending artery runs with which vein?

A

Great cardiac vein

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11
Q

The regions supplied by RCA and right marginal arteries are drained by which veins?

A

small cardiac veins
middle cardiac veins

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12
Q

The regions supplied by LCA, left anterior descending artery, left circumflex artery, left marginal arteries are drained by which veins?

Additionally, the region supplied by left marginal vein is drained by which other vein?

A

great cardiac vein

left marginal vein

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13
Q

Which vein drains the region supplied by posterior descending artery?

A

left posterior ventricular vein

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14
Q

What is the electrical wiring of the heart?

A

SA node -> atrial depolarisation -> AV node -> bundle of His -> right and left bundle branch (in inter-ventricular septum) -> purkinje fibres (in ventricular muscle mass)

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15
Q

What are the bipolar limb leads?

A

Lead I (R arm to L arm)
Lead II (R arm to L leg)
Lead III (L arm to L leg)

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16
Q

What are the augmented unipolar limb leads?

A

Lead aVR (right arm)
Lead aVL (left arm)
Lead aVF (left leg)

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17
Q

What are the unipolar chest leads?

A

V1-V6

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18
Q

What leads look at the anteroseptal region of the heart ie. right heart?

A

V1 and V2
V5 and V6 (image will be inverted)

*supplied by LAD

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19
Q

What leads look at the antero-apical region of the heart (LV and inter-ventricular septum)?

A

V3 and V4

*supplied by LAD

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20
Q

What leads look at the lateral side of the heart (LV)?

A

I, aVL, V5, V6

*supplied by left circumflex artery

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21
Q

What leads look at the inferior heart (LV/RV)?

A

II, III, aVF

*supplied by RCA

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22
Q

What leads look at posterior heart (LA)?

A

reciprocals of anterior leads (V1-V4)

*supplied by RCA
*uncommon to have isolated posterior infarcts

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23
Q

What is the significance of P wave?

A

atrial depolarisation by SA node -> atrial contraction

*normal P wave requires normal working of SA node

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24
Q

Features of normal P wave to be observed

A
  1. Location - should occur before QRS complex
  2. Shape - symmetrical, dome-shaped with single rounded apex
  3. Height - 2-3mm (2-3 small boxes)
25
Q

Possible abnormalities of P wave

A
  1. P pulmonale (peaked P wave)
    - seen in Lead II
    - Right Atrial Hypertrophy
    eg. pulmonary hypertension
  2. P mitrale (P wave looks like a flattened M)
    - seen in Lead II
    - Left Atrial Hypertrophy
    eg. mitral stenosis
  3. Biphasic (p wave + inverted p wave)
    - seen in V1
    - Left Atrial Hypertrophy
  4. Absent P wave
    - Atrial fibrillation
    - Junctional rhythms
    - Hyperkalaemia
  5. Inverted P wave
26
Q

P waves are best seen in which leads?

A

Leads II and V1

27
Q

How to differentiate P wave from T wave?

A

P wave:
- shorter (abnormal if same height as T wave)
- symmetrical
- occurs after T/U wave, before QRS complex

T wave:
- taller
- asymmetrical
- occurs after QRS complex

28
Q

What is the significance of QRS complex?

A

ventricular contraction

29
Q

What do the waves of QRS correspond to?

A

Q: septal depolarisation
- electrical stimulus pass through inter-ventricular septum -> left to right depolarisation at bundle of His -> separation into 2 bundle branches

R: early ventricular depolarisation
- electrical stimulus pass through main portion of ventricular walls from right to left
-

S: late ventricular depolarisation
- electrical stimulus pass through purkinje fibres at the terminal phase of depolarisation

30
Q

Which lead is ALWAYS negative on ECG?

A

Lead aVR

31
Q

What to look out for from the R waves of Leads V1-V6?

A

Normal R wave progression
- increasing R wave from leads V1 to V6

&

S wave depression

32
Q

Possible abnormalities of R wave?

A
  1. Poor R wave progression
    In contiguous leads:
    - nil/small R waves
    - deep Q waves
    => evolved/old STEMI
    a. anteroseptal
    b. anteroapical
    c. anterolateral
    d. inferior

In entire ECG:
- nil/small R waves
- small QRS complexes
=> pericardial effusion

  1. Exaggerated R wave progression
    => Left ventricle hypertrophy
  2. Reversed R wave progression
    => Right ventricle hypertrophy
33
Q

What is the normal duration of QRS complex?

A

0.085s-0.12s (2-3 small squares)

34
Q

Possible abnormalities of QRS complex

A
  1. Wide complex (>3 squares)
    - ventricular ectopic beats
    - BBB
    - SVT with concomitant aberrant ventricular conduction eg RBBB
  2. Tall R in V1
  3. Deep S in V1
35
Q

What is the significance of T wave?

A

repolarisation of muscle (muscle returns to resting electrical state)

36
Q

Features of normal T wave to be observed

A
  1. Shape - asymmetrical with slightly rounded apex
  2. Height - < 10mm in precordial leads (10 small squares, 2 big squares)
  3. Deflection
    - Upright: lead I, II
    - Inverted: lead aVR, V1
37
Q

Possible abnormalities of T wave

A
  1. Disappear/flattened
  2. Inverted
    - Ischaemia/strain pattern
    - Normal variant in:
    a. children </= 14yo (leads V1-V4)
    b. males (leads V1-2), females (lead V1)
  3. Peaked (>10mm)
    - Early AMI
    - Hyperkalaemia
    - Normal variant: Grusin type II
38
Q

What is the significance of U wave?

A

possible repolarisation of Purkinje fibres or papillary muscles
*abnormal wave form

39
Q

Features of normal U wave to be observed

A
  • occurs after T wave, before P wave
  • smaller than P wave
40
Q

What conditions can U wave be seen in?

A

hypokalaemia, CAD

41
Q

What is the significance of PR interval (start of P wave to start of QRS complex)?

A

time taken for impulse to travel from the SA node to Purkinje fibres, right before ventricular depolarisation
- reflects AV nodal delay

42
Q

What is the normal duration of PR interval?

A

0.12-0.2s (3-5 small squares)

43
Q

Possible abnormalities of PR interval

A
  1. PR prolonged
    - 1st degree heart block
    - hyperkalaemia
  2. PR shortened
  3. Depressed
44
Q

What is the significance of QT interval (start of QRS complex to end of T wave)?

A

time taken for ventricular depolarization and repolarization

45
Q

What is the normal duration of QT interval?

A

0.42-0.48s (10-12 small squares)

46
Q

How can corrected QT interval (QTc) be calculated?

A

Bazett formula: QTc = QT / (square root of RR)
Framingham formula: QTc = QT + 0.154(1 - RR)
Hodges formula: QTc = QT + 1.75(HR - 60)

47
Q

Possible abnormalities of QT interval

A
  1. QT prolonged
    - Hypokalaemia
    - Hypocalcaemia
    - Hypomagnesemia
    - Drug toxicity
  2. QT shortened
    - Hyperkalaemia
    - Hypercalcaemia
48
Q

Long QT interval predisposes to

A

Torsades de pointes

*def: ventricular tachycardia that happens in the setting of Long QT interval
*can lead to ventricular fibrillation

49
Q

Potential abnormalities of ST interval**

A
  1. ST raised
  2. ST depressed
50
Q

ECG usually calibrated at a speed of

A

25mm/s

51
Q

1 small square corresponds to how long?

A

0.04s

52
Q

1 big square (5 small squares) corresponds to how long?

A

0.2s

53
Q

How to calculate regular heart rate?

a. using R-R interval
b. using number of R waves

A

a. HR = 300/number of big squares between 1 R-R interval
b. count the number of QRS complexes in the long lead
HR = number of QRS complexes x 6
*limitation: (b) can only be used when ECG is calibrated at 25mm/s (if not, slower ecg = falsely low HR; faster ecg = falsely fast HR)

54
Q

How to calculate irregular heart rate?

A

Using R-R interval:
1. Calculate HR using longest R-R interval
2. Calculate HR using shortest R-R interval
!!!Give a range from slowest to fastest HR

*Do not estimate or give an average

55
Q

What is the normal HR according to age?

A

Newborn : 110-150bpm
2YO : 85-125bpm
4YO : 75-115bpm
6YO and above : 60-100bpm

*HR is faster in paeds patients

56
Q

In right bundle branch block, what is seen in V1V2 leads? *impt

A

rSR

57
Q

In right bundle branch block, what is seen in V5V6 leads?

A

broad and slurred S (mirror image of V1V2)

58
Q

In left bundle branch block, what is seen in V1V2 leads?

A

deep and broad S waves

59
Q

In left bundle branch block, what is seen in V5V6 leads? *impt

A

broad and clumsy R waves

60
Q

Features of normal sinus rhythm

A
  1. P wave must be correctly oriented
  2. PR interval must be normal
  3. Every P wave must be accompanied by QRS and T
  4. Every QRS and T must be preceded by a P wave

m3 gah (3 decks)

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