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T2: Theme 3: CVS > Lecture 7: ECG > Flashcards

Lecture 7: ECG Flashcards

1
Q

What is a syncytium?

A

One large cell having many nuclei that are not separated by cell membrane

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2
Q

What is a functional syncytium?

A

Many cells functioning as one

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3
Q

What are the 3 types of cardiac myocyte cell?

A

Pacemaker cells
Conducting cells
Contractile cells

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4
Q

How quickly do contractile cells propagate the signal?

A

0.3-0.5m/s

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5
Q

How quickly do conducting cells (purkinje fibres) propagate the signal?

A

Up to 5m/s

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6
Q

How quickly does the AV node propagate the signal?

A

0.05m/s

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7
Q

How quickly do internal bundles propagate the signal?

A

1m/s

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8
Q

What are the 4 internal bundles?

A

Anterior (to AVN)
Middle (to AVN)
Posterior (to AVN)
Bachmanns (to LA)

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9
Q

How long is the delay of excitation from atria to ventricles by AV node?

A

0.1-0.2s

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10
Q

What is a lead on an ECG?

A

A configuration of electrodes

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11
Q

Describe lead 2.

A

Positive electrode on left leg, negative electrode on right arm and ground electrode on right leg

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12
Q

What are the 12 standard leads?

A

3 Bipolar
3 Augmented
6 Precordial

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13
Q

What is shown by the QRS complex?

A

Transmission of depolarisation through the ventricular myocardium

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14
Q

What is shown by P-wave?

A

Depolarisation of the atria

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15
Q

What is shown by PR segment?

A

Delay of AV node to allow filling of ventricles

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16
Q

What is shown by T wave?

A

Ventricular repolarisation

17
Q

What is shown by ST segment?

A

Beginning of ventricle repolarisation - should be flat

18
Q

What is sinus tachycardia?

A

Tachycardia driven by the SA node beating too quickly - normal PR intervals and each P is matched with a QRS

19
Q

What is the normal duration of PR interval?

A

3-5 boxes

120-200ms

20
Q

What is the normal duration of QRS complex?

A

2-3 boxes

80-120ms

21
Q

What is the normal duration of QT interval?

A

9-11.5 boxes

360-460ms

22
Q

How many ms is one little box?

A

40ms

23
Q

How many ms is one big box?

A

200ms

24
Q

How do you calculate beats per minute?

A

Rate = 300/big boxes

1 big box = 300bpm
2 = 150
3 = 100
4 = 75
5 = 60 
6 = 50
10 = 30
25
Q

What is atropine?

A

Muscarinic antagonist

reduces parasympathetic activity

26
Q

What are the causes of heart block?

A

Ischaemia of AVN
Compression of AVN
Inflammation of AVN

27
Q

What are the symptoms of heart block?

A 
Can be asymptomatic 
Palpitation 
Dizziness
Malaise
Syncope
Risk of sudden death
28
Q

What is first degree heart block?

A

When PR interval is greater than 5 little boxes (200ms)

But all Ps followed by QRS

Young people, rarely treated

29
Q

What is Mobitz type 1 second degree heart block?

A

Wenchebach

PR interval gets longer until QRS wave fails to follow P wave

Likely cause is AV node damage

No treatment given

30
Q

What is Mobitz type 2 second degree heart block?

A

Hay

Some P waves are blocked and are not followed by QRS, PR interval remains the same

Likely problem is bundle of his

High risk

31
Q

What is third degree heart block?

A

Atrial signals consistently fail to arrive at ventricles, ventricular rate is consistent (30-40 bpm)

Time between atrial beats is variable

PR interval varies radically

32
Q

What is an escape beat?

A

When the atrial signal is very delayed or prevented - triggered by the natural rhythmicity of non-atrial tissue

33
Q

What is a premature beat?

A

Triggered by irritable tissue

34
Q

What do premature ventricular contractions look like on ECG?

A

Unusually wide ventricular activity

No S wave, instead a wide negative dip where the T wave should be

35
Q

What does AF look like on ECG?

A

No P wave, instead flat line or wiggly line

36
Q

What is respiratory sinus arrhythmia?

A

Heart beat slightly faster during inspiration and slightly slower during expiration

37
Q

What is the iso-electric baseline?

A

From the end of T to the next P

T2: Theme 3: CVS (18 decks)

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