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1.2.1. Cardiovascular System > ECG Abnormalities > Flashcards

ECG Abnormalities Flashcards

1
Q

Where can electrical rhythms arise from?

A

SA node,
atrium,
AV node (= supraventricular rhythms),
ventricles (= ventricular rhythms)

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2
Q

When a normal QRS complex is present, what does this tell you?

A

Normal ventricular depolarisation

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3
Q

When electrical rhythm originates from the ventricles what change can be seen on an ECG?

A

Wide QRS complexes (>3 small boxes) –

rhythms from diff loci will have diff shapes

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4
Q

What is chaotic atrial depolarisation and how does it appear on an ECG?

A

due to multi atrial foci = no P waves = wavy baseline

impulses arrive at AV, only some conducted, ventricles depolarise/contract normally

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5
Q

What is ‘Heart Block’ and its common causes?

A

Delay/failure of conduction of impulses from atrium to ventricles via AV node and bundle of his

causes = acute MI, degenerative changes

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6
Q

What is first degree heart block?

A

Normal P wave, but slow conduction at AVN/bundle of His

= prolonged PR interval, QRS normal

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7
Q

What is second degree heart block type 1?

A

Mobitz type 1 = progressive lengthening of the PR interval, until 1 P wave is not conducted

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8
Q

What is second degree heart block type 2?

A

Mobitz type 2 = PR interval normal, but sudden non-conduction of QRS

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9
Q

What is third degree heart block?

A

SAN normal but impulses not conducted to ventricle = ventricular pacemaker takes over = ventricular escape rhythm = wide QRS, no relationship between P waves and QRS = random placement

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10
Q

What is a ventricular ectopic beat?

A

Ectopic foci in ventricles = abnormal conduction pathway = slower depolarisation = wider QRS

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11
Q

What is ventricular tachycardia and how does it appear on an ECG?

A

VT = 1 ectopic foci that has caused >3 consecutive ventricle depolarisations = risk of VF

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12
Q

What is ventricular fibrillation and how does it appear on an ECG?

A

VF = numerous ectopic foci = abnormal/chaotic/fast ventricular depolarisation = no co-ordinated contraction = no CO = cardiac arrest

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13
Q

What is the diff between ventricular tachycardia and fibrillation?

A

T = 1 ectopic foci, still have CO. F = numerous ectopic sites, no CO

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14
Q

What tissue is most at risk due to reduced myocardial perfusion from coronary atherosclerosis?

A

Sub endocardial muscle – due to being the furthest away from the blood supply on the epicardial surface

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15
Q

What is STEMI and when is it seen?

A

ST segment elevation myocardial infarction = complete occlusion = muscle injury extends full thickness from endocardium to epicardium = abnormal current during depolarisation

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16
Q

How does acute STEMI present on an ECG?

A

ST elevation in leads facing MI, which merges with tall broad T waves

17
Q

What are the persistent changes that can be seen on an ECG due to MI?

A

Q waves develop = muscle necrosis = window is now open for the electrode to measure the Q wave produced from the septal L to R depolarisation, ST elevation still present

18
Q

What does hyperkalaemia do to the RMP?

A

RMP less –ve (more depolarised)

19
Q

What does hypokalaemia do to the RMP?

A

RMP more –ve (hyper polarised)

20
Q

How does hyperkalaemia present on an ECG?

A

RMP less –ve = inactivates some Na+ channels = heart becomes less excitable = conduction problems.

High T wave –> prolonged PR interval, depressed ST –> atrial standstill, intraventricular block, abesent p wave –> VF

21
Q

How does hypokalaemia present on an ECG?

A

Low T wave, high U wave, low ST segment = each new feature added with lowering potassium

22
Q

What is the cardiac axis?

A

Average direction of spread of the ventricular depolarisation = usually downward and to the left: -30 to +90 degrees

23
Q

What is left axis deviation?

A

Overall direction of ventricular depolarisation = upward and to the left: associated with = conduction block of anterior branch of left bundle, inferior MI, LV hypertrophy

24
Q

What is right axis deviation?

A

Overall direction of ventricular depolarisation = downwards and to the right: associated with RV hypertrophy

25
Q

How should you report an ECG?

A 
Rhythm
Rate
PR interval
QRS interval
QT interval
P wave (LA or RA enlargement)
Description of QRS complex
ST segment
T wave
Axis
26
Q

How does atrial fibrillation present on ECG?

A

no p waves

wavy baseline with QRS

27
Q

How does VF appear on ECG?

A

no QRS

completely wavy recording

1.2.1. Cardiovascular System (18 decks)

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