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CVS > 6/7-ECGs > Flashcards

6/7-ECGs Flashcards

1
Q

What is the normal conduction pattern in the heart?

A
  • electrical activity starts at Sino Atrial Node
  • impulse spreads across atria
  • impulse delayed at atrio ventricular node to allow complete atrial contraction
  • conduction spreads to bundle of His-right/left bundle branch-purkinje fibres to stimulate myocardial contraction
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2
Q

Name the colours and locations of the limb leads

A

Right upper limb lead - red - right shoulder
Left upper limb lead - yellow - left shoulder
Right lower limb lead - black - right ankle
Left lower limb lead - green - left ankle

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3
Q

Name the colours and locations of the chest leads

A

V1 - red - 4th right intercostal space
V2 - yellow - 4th left intercostal space
V3 - green - 5th left intercostal space (closest to sternum)
V4 - blue - 5th left intercostal space
V5 - orange - 5th left intercostal space
V6 - purple - 5th left intercostal space (closest to mid clavicular line)

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4
Q

Where can the QRS complex normally be seen?

A

aVL, I, II, aVF

Which is between -30 and +90 degrees

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5
Q

What is left axis deviation?

A

Where the QRS complex is present at less than -30 degrees

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6
Q

What causes left axis deviation?

A

Inferior wall MI
LV hypertrophy
Left anterior bundle block

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7
Q

What is right axis deviation?

A

Where the QRS complex is found above 90 degrees

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8
Q

What causes right axis deviation?

A

RV hypertrophy
Acute right heart strain (e.g. Pulmonary embolism)
Left posterior bundle block

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9
Q

What is the standard recording speed of ECGs?

A

25mm per second

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10
Q

How many seconds are equivalent to big and small squares?

A

Big square = 0.2 seconds

Small square = 0.04 seconds

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11
Q

Where is the P-R interval measured from and what is the normal range?

A

Measured from start of p to start of q

Normally 3-5 small squares

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12
Q

What does a long P-R interval indicate?

A

Indicates a slow atria ventricular conduction, 1st degree heart block

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13
Q

Where is QRS width measured from and what is the normal range?

A

Measured from start of q to end of s

Normally 2-3 small squares

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14
Q

What does a wide QRS complex indicate?

A

Indicates abnormal conduction for ventricular depolarisation

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15
Q

Where is Q-T interval measured from and what is the normal range?

A

Measured from start of q to end of t

Normally 0.35-0.43 seconds

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16
Q

What does a prolonged Q-T interval indicate?

A

Indicates prolonged repolarisation of ventricles leading to arrhythmias e.g. prolonged QT syndrome

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17
Q

Where is S-T segment measured from?

A

End of s to start of t

18
Q

What does a raised or depressed S-T segment indicate?

A

Should be equal to baseline (isoelectric), raised/depressed indicates ischaemia/MI

19
Q

What is the equation to calculate a regular heart rate?

A

No of small squares per minute / no of small squares between peeks
=1500/x

20
Q

What is needed to be classed as sinus rhythm?

A

Identical round P waves
Followed by QRS complex every time
Regular rhythm

21
Q

Why are the depolarisation/repolarisation waves orientated in the same direction?

A

Repolarisation occurs in opposite direction so usually inverted deflections orientated in same direction

22
Q

What differences are there between the depolarisation and repolarisation waves?

A

Repolarisation waves are more prolonged and lower amplitude

23
Q

What are the features of atrial fibrillation?

A

Wavy baseline
No p waves
Irregularly irregular rhythm

24
Q

What causes atrial fibrillation?

A 
Hypoxia 
Hypertension
Sepsis 
Alcohol 
Ischaemic heart disease
25
Q

What are the consequences of untreated atrial fibrillation?

A

Clot leading to stroke

Rapid ventricular rate leading to hypertension/angina/ heart failure

26
Q

How is atrial fibrillation treated?

A

Rate control - digoxin/ beta blockers
Anti-arrhythmics- amiodrone
Anti-thrombotics - warfarin/ dabigatron

27
Q

What causes ventricular fibrillation?

A

Ischaemic heart disease
Hypoxia
Post MI
Prolonged QT arrhythmia

28
Q

How is ventricular fibrillation treated?

A

Implanted cardiac defibrillator

Anti-arrhythmics - amiodorone

29
Q

Describe the features of first degree heart block

A

Prolonged P-R interval greater than 0.2 seconds

Sinus rhythm

30
Q

Describe the features of 2nd degree heart block, mobitz type 1

A

Progressive p-r elongation until QRS is not conducted

31
Q

Describe the features of 2nd degree heart block, mobitz type 2

A

Fixed PR interval until sudden dropped QRS complex

32
Q

Which mobitz type has a high risk of developing into third degree heart block?

A

Mobitz type 2

33
Q

Describe the features of 3rd degree heart block

A

No relationship between atrial and ventricular activity
Wide QRS complex (from escape rhythm)
Bradycardic 30-40 bpm

34
Q

How is heart block treated?

A

Anticholinergics - atropine
Beta agonist - isoprenaline
Pacemaker if severe

35
Q

What causes heart block?

A 
MI
Rheumatic fever
Calcium channel blockers 
Beta blockers 
Sarcoid
36
Q

Describe the features of ventricular ectopic beats

A

Wide, abnormally shaped QRS complexes as impulse is spread slower by abnormal conduction system to ventricles

37
Q

Describe the stages of a STEMI on an ECG over several weeks

A

Acute - ST elevation in leads facing injured area
Hours later - ST elevation, depressed R wave, Q wave begins
1/2 days later - t wave inversion p, Q wave deepens
Days later - ST normalises, T wave still inverted
Weeks later - T wave normalises, Q wave persists

38
Q

What effect does hyperkalaemia have on ECGs?

A

RMP less negative, so voltage gated Na channels inactivated making heart less excitable, causing conduction issues leading to ventricular fibrillation

39
Q

What effect does hypokalaemia have on ECGs?

A

RMP more negative, leading to
Low t waves
High u wave (after t wave)
Low ST segment

40
Q

What are the differences between atrial and ventricular fibrillation?

A

Atrial has coordinated ventricular contraction, ventricular doesn’t
Atrial has cardiac output, ventricular doesn’t
Atrial has a pulse, ventricular doesn’t
Atrial has an irregularly irregular heart rate, ventricular has no heart beat

CVS (10 decks)

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