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CR2 > ECG Review and Analysis > Flashcards

ECG Review and Analysis Flashcards

1
Q

Draw cardiac cycle on ECG xx

What is PR interval showing? [1]

QT: interval shows? [1]

A

What is PR interval showing? [1]
time for SAN–> AVN, mostly represented by physiological delay in AVN

QT: interval shows? [1]
**ventricular depol. & repolarisation

AVN –> Bundle of His –> Bundle branches –**

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2
Q

What is the difference between ST segment and ST interval?

A

Note that the ‘ST segment’ is from end of S wave to START of T wave.

‘ST interval’ is from end of S wave to END of T wave.

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3
Q

How can you calculate HR? [3]

When can’t you use 300 rule? [1]

A

1. 300 / big boxes of R-R if have regular rhythm

2. 6 x no. HB if have irregular rhythm.

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4
Q

What is a sinus / non sinus rhythm? [2]

How can you distinguish between the two?

A

-Sinus rhythm means pacemaker signal originates in sinoatrial node.

sinus:

  • If RR interval is constant
  • there is normal shaped P wave before every QRS complex
  • Heart rate is between 60-100 bpm, then normal sinus rhythm, or NSR, is present.

Not sinus:

  • R-R intervals not constant
  • *- P wave** not followed by QRS
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5
Q

What is normal PR interval? [1]

What is indicated if PR is prolonged? [1]

A

What is normal PR interval? [1]
120-200 ms

Indicates problem with conducting system & heart block if prolonged (over 220 ms)

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6
Q

What should QRS interval be? [1]

What does overlong QRS duration indicate? [1]

Under normal circumstances, where are Q waves not seen? [1]

A

What should QRS interval be? [1]
less that 120

An overlong QRS duration indicates that ventricular depolarization is slow or desynchronised, or that part of ventricular muscle is not contracting normally.

Under normal circumstances, where are Q waves not seen? [1]
V1-V3

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7
Q

What does Q wave represent? [1]

Which leads do you not normally see Q waves? [1]

A

Depolarisation of interventricular septum

V1-V3

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8
Q

T wave

A
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9
Q

When might you see larger T waves that expected? [2]

A

Hyperkalemia
Myocardial infarction within first 30-60 mins

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10
Q

Describe the features of sinus bradycardia

Which populations do you see them in? (If benign / not healthy?)

A

If HR below 60 bpm

benign in:

  • healthy young people
  • beta blockers

warning in:

  • fibrosis in cardiac conduction system
  • MI with SA or AVN
  • hypoglycaemia
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11
Q

What is junctional rhythm a result of? [1]

What are the features of junctional rhythm? [3]

A

In junctional rhythm there is damage: to sinoatrial node or a block in conduction pathway in atria.

When this happens, atrioventricular node takes over as pacemaker.

  • bradycardia: 40-60 bpm
  • a normal QRS complex
  • the P wave will either be absent or inverted in lead II.
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12
Q

What is an ectopic focus?

A

Ectopic focus. An ectopic focus of conduction in the heart is an area that begins to release electrical stimuli outside the normal conduction pathways. A stimulus released from an ectopic focus can disturb the normal conduction and , in some cases, take over the pacemaker role of the SA node.

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13
Q

Describe the features of atrial fibrillation and why they occur xx

What are R-R intervals like?

A
  • Atrial contraction lost: atria just “quiver”: NO P WAVES – just :wavy baseline (SAN not working)
  • ventricles depolarized normally – so normal QRS

IRREGULARLY IRREGULAR R-R intervals

Impulses reach AV node at rapid irregular rate, but not all are conducted

•Afib can be

–SLOW – ventricular response < 60 bpm

–FAST – ventricular response >100

–Normal rate – 60-100 bpm

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14
Q

Why are patients with atrial fibrillation at risk of ischaemic stroke?

A

Loss of atrial contraction leads to increased blood stasis c/w normally contracting atria, most often in left atrium

Small clots can occur in LA, which goes into cerebral arteries

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15
Q

What are supraventricular tachycardias? [1]

What are the 3 main types of Supraventricular Tachycardias? [3]

A

Supraventricular tachycardia (SVT) is an abnormally fast heart rate arising from abnormal electrical activity in the atria or atrioventricular node..

  • *atrial flutter**
  • *AV nodal** reentrant tachycardia
  • *Wolff–Parkinson–White syndrome**.
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16
Q

Describe the features of atrial flutter

A

Electrical impulses in atria cause a high frequency bombardment of AV node (~300 bpm) leading to a high but regular heart rhythm. Only one excitatory focus (unlike AF)

P wave replaced with multiple F (fluter waves)

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17
Q

Describe the features of AV nodal reentrant tachycardia

A

AVNRT occurs when a ‘re-entry’ circuit forms within or just next to the atrioventricular node - atrial impulses instead of dying away after activating the AV node go around ‘in a circle.’

No P waves
140-220 beats
Regular rhythm and QRS

Causes heart palpitations

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18
Q

Describe the features of Wolff-Parkinson-White Syndrome

A

Electrical circuit bypasses AVN and goes to ventricles: decreased PR interval. May not cause problems itself, but can lead to afib or paroxysms of AV nodal reentrant tachycardia

Characterised by a Delta wave in the QRS

19
Q

What are (Premature) Ventricular ectopic beats (contractions) - PVCs?

What happens when have run of >3 consecutive PVCs?

A

Ectopic focus in ventricle muscles

Impulse does not spread via fast His-Purkinje system: Therefore, much slower depolarization ventricular muscle

Therefore, Wide QRS

Run of ≥ 3 Consecutive PVCs: Ventricular tachycardia, which can lead to ventricular fibrillation

20
Q

Describe the features of ventricular fibrillation

A

Rhythm - Irregular

Rate - 300+, disorganised

QRS Duration - Not recognisable

P Wave - Not seen

LETHAL due to no CO

21
Q

What is heart block?

What are the 3 types of conduction blocks?

A

Heart Block: •Delay/failure of conduction of impulses from atria to ventricles via AV node (more than physiological) and Bundle of His

•First degree heart block:

Every single atrial impulse eventually makes it to the ventricles.

The high yield concept here is that the only abnormality is a prolonged PR interval, and it’s usually asymptomatic, so it does not require treatment.

PR> 220ms. longer for AVN to trigger AP in Bundle of His

•Second degree heart block

Mobitz type 1 second degree heart block:

In Mobitz 1, each atrial impulse encounters a longer and longer delay until one of them does not make it through to the ventricles.
PR interval progressively large until PR is blocked (dropped beat) & then starts again

•Mobitz type 2 second degree heart black:
There is no progressive prolongation of the PR interval in Mobitz 2. On the ECG, Mobitz 2 shows a couple of normal PR intervals followed by a dropped beat.
PR intervals are consistent but P-waves dont conduct. Due to failure of conduction of His-Purkinje system

•Third degree heart block: complete heart block

The ventricles recognize that they’re not getting any impulses, and respond by generating their own electrical rhythm called a ventricular escape rhythm

Complete AV dissociation: P waves present but unsynchronised with QRS complex (contract independently)

with no supraventricular impulses conducted to the ventricles., marked brachycardia

22
Q

What indicates bundle branch block? [1]

What is difference in ECGs in Right BBB v Left BBB? [2]

A

ECG normal
QRS duration prolonged (>120ms)

RBBB:

  • QRS > 120 ms (3 small squares)
  • RSR’ pattern in V1-V3
  • Wide, slurred S wave in lateral leads – I, aVL, V5-V6

LBBB:

  • QRS duration > 120ms (3 small squares)
  • Dominant S wave in V1
  • Broad, monophasic R wave in lateral leads – I, aVL, V5-V6
  • Absence of Q waves in lateral leads
  • Prolonged R wave > 60ms in leads V5-V6
23
Q

How should ST segment appear in a healthy person?

What does it represent?

A

Flat xx

ST segment represents the period in which the myocardium maintains contraction to expel blood from the ventricles.

24
Q

What does STEMI stand for? [1]

What does it arise from? [1]

How do you recognise on an ECG? [1]

A

ST Segment Elevation Myocardial Infarction (STEMI)

Due to complete occlusion of coronary artery

ECG: ST elevation in multiple ECG leads (e.g. Leads II / III)

25
Q

Non STEMI arises from? [2]

Non STEMI characterised by on an ECG? [1]

A

Non STEMI:

From:

  • Subendocardial infarction
  • Ischaemia

ECG:

  • ST depression
  • T wave inversion
26
Q

Which leads are typically T waves not upright / inverted in? [2]

A

Leads not upright: aVR & V1

If arisen in other leads usually from:

  • inferior wall ischaemia
  • myocardial ischaemia
  • myocarditis
27
Q

What are physiological reasons for Q waves?

What are pathological reasons for Q waves?

A

Physiological: shows L to R depolarisation of interventricular septum. Not normally seen in V1-V3

Pathological: Persist after MI forever, if seen in V1-3 indicates previous MI

28
Q

What does this ECG indicate?

Atrial fibrillation
Ventricular fibrillation
Atrial flutter
AVN reentrant tachycardia
Junctional Rhythm

A

What does this ECG indicate?

Atrial fibrillation
Ventricular fibrillation
Atrial flutter
AVN reentrant tachycardia
Junctional Rhythm

29
Q

What does this ECG indicate?

Atrial fibrillation
Ventricular fibrillation
Atrial flutter
AVN reentrant tachycardia
Junctional Rhythm

A

What does this ECG indicate?

Atrial fibrillation
Ventricular fibrillation
Atrial flutter
AVN reentrant tachycardia
Junctional Rhythm: starts at AVN not SAN: no P wave & bradycardia

30
Q

What does this ECG indicate?

STEMI
Non STEMI
Atrial Flutter
Atrial Fibrillation
AVN Reentrant Tachycardia

A

What does this ECG indicate?

STEMI
Non STEMI
Atrial Flutter
Atrial Fibrillation
AVN Reentrant Tachycardia

31
Q

What does this ECG indicate?

STEMI
Non STEMI
Atrial Flutter
Atrial Fibrillation
AVN Reentrant Tachycardia

A

What does this ECG indicate?

STEMI
Non STEMI
Atrial Flutter
Atrial Fibrillation: lack of P wave
AVN Reentrant Tachycardia

32
Q

What does this ECG indicate?

STEMI
Non STEMI
Atrial Flutter
Atrial Fibrillation
AVN Reentrant Tachycardia

A

What does this ECG indicate?

STEMI
Non STEMI
Atrial Flutter
Atrial Fibrillation
AVN Reentrant Tachycardia

33
Q

What does this ECG indicate?

Type 1 Heart Block
Type 3 Heart Block
Wolf-Parkinson-White Syndrome
AVN Reentrant Tachycardia
Atrial Flutter

A

What does this ECG indicate?

Type 1 Heart Block
Type 3 Heart Block
Wolf-Parkinson-White Syndrome
AVN Reentrant Tachycardia
Atrial Flutter

34
Q

What does this ECG indicate?

Type 1 Heart Block
Type 3 Heart Block
Wolf-Parkinson-White Syndrome
AVN Reentrant Tachycardia
Atrial Flutter

A

What does this ECG indicate?

Type 1 Heart Block
Type 3 Heart Block
Wolf-Parkinson-White Syndrome
AVN Reentrant Tachycardia
Atrial Flutter: saw toothed !!

35
Q

What does this ECG indicate?

Type 1 Heart Block
Type 3 Heart Block
Wolf-Parkinson-White Syndrome
AVN Reentrant Tachycardia
Atrial Flutter

A

What does this ECG indicate?

Type 1 Heart Block
Type 3 Heart Block
Wolf-Parkinson-White Syndrome
AVN Reentrant Tachycardia
Atrial Flutter

36
Q

Which does the following describe best?

Each atrial impulse encounters a longer and longer delay until one of them does not make it through to the ventricles.

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

A

Which does the following describe best?

Each atrial impulse encounters a longer and longer delay until one of them does not make it through to the ventricles.

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

This is reflected as the PR interval getting progressively longer and longer until all of a sudden, the heart drops a beat.

37
Q

Which does the following describe best?

Every single atrial impulse eventually makes it to the ventricles, prolonged PR interval

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

A

Which does the following describe best?

Every single atrial impulse eventually makes it to the ventricles, prolonged PR interval

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

38
Q

Which of the following does this ECG best represent?

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

A

Which of the following does this ECG best represent?

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

none of the electrical impulses are conducted through the AV node, and that’s why it’s also called complete heart block.

So in 3rd degree AV block, the ventricles recognize that they’re not getting any impulses, and respond by generating their own electrical rhythm called a ventricular escape rhythm, just to hang on to dear life.

Because the atria and the ventricles each have their own pacemakers, they now contract independent of one another, which is called AV dissociation. This desynchronization of the heart chambers can reduce cardiac output dramatically, leading to syncope or even sudden cardiac death.

On the ECG, the P-waves and QRS complexes have nothing to do with each other, each appearing at their own rates.

39
Q

Which of the following does this ECG best represent?

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

A

Which does the following describe best?

Couple of normal PR intervals followed by a dropped beat.

First degree heart block
Second degree, Mobitz 1 heart block
Second degree, Mobitz 2 heart block
Third degree heart block

40
Q

What does this ECG indicate?

A

Right bundle branch block

41
Q

What does this ECG indicate?

A

Left branch bundle block

42
Q

Name the causes of A and B [2]

A 
A = Afib
B = Atrial flutter (saw toothed)
43
Q

What ventricular rate would you expect in atrial flutter?

  • 300 bpm
  • 200 bpm
  • 150 bpm
  • 75 bpm
  • 100 bpm
A

What ventricular rate would you expect in atrial flutter?

  • 300 bpm
  • 200 bpm
  • 150 bpm
  • 75 bpm
  • 100 bpm

Atrial flutter consists of a 2:1 block. This means it takes 2 atrial beats for each ventricular beat.

During atrial flutter there will be a atrial rate of 300 and a ventricular rate of 150 bpm.

CR2 (59 decks)

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