ECG Flashcards

1
Q

How do potentials arise at body surface

A

Currents flow when membrane potential changes in repolarisation & depolarisation

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2
Q

What happens when depolarisation moves towards a recording electrode

A

Upwards deflection on ECG

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3
Q

What happens when depolarisation moves away from recording electrode

A

Downwards deflection of ECG

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4
Q

What does no movement towards or away from recording electrode result in

A

NO deflection on ECG, Isopotential= every point has same potential (straight line)

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5
Q

What is the triangle that standard leads I, II & III create

A

Einthoven’s

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6
Q

What is RA, LA & LL

A

Right Arm
Left Arm
Left Leg
(right leg is neutral)

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7
Q

What is lead I connecting

A

RA -‘ve to LA +’ve
(LA is recording electrode)

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8
Q

What is lead II connecting

A

RA -‘ve to LL +’ve
(LL is recording electrode)

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9
Q

What is lead III connecting

A

LA -‘ve to LL +’ve
(LL is recording electrode)

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10
Q

What direction does lead II see the heart from

A

Inferior

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11
Q

What does P wave represent & what direction

A

Atrial depolarisation
towards recording electrode

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12
Q

What does QRS complex represent

A

Ventricular depolarisation

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13
Q

What does Q wave show & direction

A

Left to right depolarisation of interventricular septum moving AWAY from recording electrode

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14
Q

What does R wave show & direction

A

Main ventricular mass depolarisation TOWARDS recording electrode

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15
Q

What does S wave show & direction

A

Ventricles at base of heart depolarise moving AWAY from recording electrode

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16
Q

What is T wave & direction

A

Ventricular repolarisation
UPWARDS deflection as opposite direction to depolarisation

17
Q

What does PR interval in lead II tell us

A

Start of P to start of QRS
-Reflects time for SA node impulse to reach ventricles

18
Q

What is PR interval influenced strongly by

A

Delay in conduction through AV node

19
Q

What is the ST segment

A

From end of QRS complex to start of T wave
-Reflects isoelectric as when ventricles contract = systole

20
Q

What is QT interval

A

Start of QRS to end of T wave
-Reflects time of ventricular depolarisation & repolarisation

21
Q

What is TP segment

A

when ventricles relax= diastole

22
Q

What does standard 12 lead ECG compromise

A

3 standard limb leads (I, II & III)
3 augmented voltage (aV) leads
6 Chest leads

23
Q

What lead are bipolar and what are unipolar

A

bipolar = standard limb leads
unipolar= augmented voltage leads

24
Q

What are the 3 names of augmented voltage (aV) leads

A

aVR (for right arm)
aVL (for left arm)
aVF (for foot)

25
Q

What leads show vertical (frontal & coronal) direction & plane

A

Lead I, II, III, aVR, aVL & aVF

26
Q

which leads show horizontal (transverse) direction & plane of heart

A

Leads V1, V2, V3, V4, V5 & V6

27
Q

what 3 things does looking at all 12 leads help us do?

A
  • Determine axis of heart in thorax

-Look for ST or T changes in specific regions of heart = helpful in diagnosing ischaemic heart disease

-Look for voltage criteria changes = crucial to diagnose chamber hypertrophy

28
Q

what do unipolar leads mean

A

One +’ve electrode (recording) that linked to 2 other -‘ve

29
Q

What form aVR, aVL & aVF

A

aVR = RA (+) to LA & LF (-)
aVL = LA (+) to RA & LF (-)
aVF = LF (+) to RA & LA (-)

30
Q

What is a hexaxial reference system

A

total of 6 views from heart in frontal plane from standard & augmented limb leads

31
Q

where doe V1 lead go

A

4th intercostal space at right sternal edge

32
Q

where does V2 go

A

4th intercostal space at left sternal edge

33
Q

where does V4 go

A

5th intercostal space at left mid-clavicular line

34
Q

where does V3 go

A

between V2 & V4

35
Q

where does V5 go

A

Same horizontal level as V4 on left anterior axillary line

36
Q

where does V6 go

A

same horizontal level as V4 on mid-axillary line

37
Q
A