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Year 3 - Cardiology cases > ECG > Flashcards

ECG Flashcards

1
Q

Leads 2, 3 and aVF are what type of leads?

A

Inferior leads - they’re near the inferior wall of the heart

This part receives blood from the Right coronary artery

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2
Q

Leads 1, aVL, V5 and V6 are what type of leads?

A

Lateral leads - the lateral part of the heart receives blood from the left circumflex artery

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3
Q

V1 and V2 are what type of leads?

A

Septal leads

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4
Q

V3 and V4 are what type of leads?

A

Anterior leads

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5
Q

The septal and anterior parts of the heart are supplied by which artery?

A

LAD

Left anterior descending

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6
Q

When calculating rate, 1 big box apart equates to what rate?

A

300bpm

so R waves 2 big boxes apart = 150bpm, etc

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7
Q

What causes atrial flutter?

A

When ectopic focus (i.e. an irritated atrial myocyte) contracts at about 250-300bpm - this is atrial rate

Ie SAN isn’t really regulating the contraction

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8
Q

What causes atrial fibrillation

A

Multiple ectopic foci in atria all firing at once

Atrial rate is 350-450 bpm

If atrial fibrillation no reliable way of estimating HR because heart is just quivering

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9
Q

Bundle branch block results in what?

A

Wide QRS complexes

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10
Q

How might we tell a 3rd degree heart block

A

P wave with no following QRS complex

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11
Q

How long is a PR interval?

A

PR interval = from START of P wave to START of QRS complex

Usually 0.12-0.2 seconds (3-5 little boxes)

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12
Q

What may cause longer/shorter PR intervals?

A
  1. Irritable atrial cell (length of PR interval depends on how far it is from AVN)
  2. First degree heart block - where the conduction travels slower through AVN
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13
Q

How long is a QRS complex

A

Usually less than 0.1s (2.5 little boxes)

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14
Q

What may cause changes in QRS complex duration

A

Ventricular ectopic focus (e.g. irritated ventricular cell)

If ventricular cell contracts the contractions go through slow muscle cells rather than electrical conduction system = QRS wider

Intermediate = 0.1-0.12s
Prolonged >0.12s

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15
Q

The QT interval represents ventricular systole (i.e. depolarisation to repolarisation). How long should it be?

A

Roughly half a cardiac cycle or less

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16
Q

What are some causes of a prolonged QT interval

A

Medications (Eg amiodarone) or inherited mutations (Eg LQT1/LQT2/LQT3)

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17
Q

How can a QRS vector become larger?

A

If there is a larger myocardium layer - e.g. hypertrophic cardiomyopathy

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18
Q

How can a QRS vector become smaller?

A

If the myocardium gets damaged - e.g. heart attack

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19
Q

Aside from hypertrophic cardiomyopathy or heart attack, what else may influence the average QRS vector?

A

Obesity (vectors more left)

Thin (vectors more right)

20
Q

What is a normal axis for the heart?

A
  • 30 to +90 degrees

i. e. QRS should be positive in lead 1 and aVF OR positive lead 1 and slightly negative in QRS

21
Q

What is left axis deviation and what are its causes?

A

When the ECG axis is between -30 to -90

Can be caused if LV hypertrophies or RV damaged

22
Q

What is right axis deviation and what are its causes

A

ECG axis between +90 to + 180

When the RV hypertrophies or when LV damaged

23
Q

What is extreme right axis deviation

A

When ECG axis is from +180 to -90 degrees

Can occur when there is an ectopic focus which causes depolarisation to start from LV

24
Q

If the “transition zone” (i.e. isoelectric points) shift from V3/V4 to V1/2 then what does this suggest?

A

Suggests that heart is rotated towards persons right - e.g. due to RV hypertrophy

25
Q

If the transition zone (i.e. isoelectric points) shift from V3/4 to V5/6 what does this suggest

A

Heart rotated towards persons left i.e. LV hypertrophy

26
Q

What may shift the QRS transition zone to the right?

A

MI of the left side of the heart
or right sided cardiac hypertrophy

(vice versa for left)

27
Q

Right atrial enlargement shows up in an ECG as?

What are the causes of right atrial enlargement?

A

Large P wave in V1 and 2. Also large P wave in leads 2, 3 and aVF.

Causes include stenotic tricuspid valve

28
Q

Left atrial enlargement shows up in an ECG as?

What are the causes of leftt atrial enlargement?

A

2 p waves in Lead 2

Biphasic (peak and trough) p wave in lead v1

Caused by stenotic mitral valve

29
Q

What are the ECG signs of RV hypertrophy?

A

Dominant R wave in lead V1

Dominant S wave in lead v5

Often accompanied by some right axis deviation

30
Q

Give a cause of RV hypertrophy

A

Pulmonary hypertension

31
Q

LV hypertrophy has almost the opposite features of RV hypertrophy. So what are the ECG features

A

Dominant S wave in v1 (and ST elevation)

Dominant R wave in v5 (and ST depression + t wave inversion)

32
Q

What are the causes of LV hypertrophy

A

Systemic hypertension

33
Q

What are the 2 types of ischaemia/infarction of the heart?

A

Transmural (entire thickness of myocardium) or subendocardial (innermost layer of myocardium)

34
Q

What is a giveaway sign of subendocardial ischaemia?

A

ST depression (can be upward/downward sloping or horizontal)

Leads 1, 2, v4, v5 and v6 affected

35
Q

What does a CURVED ST depression indicate?

A

Digitalis effect - i.e. patient takes digoxin

36
Q

Transmural ischaemia arises from atherosclerotic plaques that rupture. When may transmural ischaemia show up?

A

Unstable angina or NSTEMI

NSTEMI leaks out troponin and CK-MB

37
Q

What are the ECG signs of transmural ischaemia

A

ST depression and T wave inversion in contiguous chest leads (v2-6)

38
Q

What are the ECG signs of subendocardial infarction

A

ST depression and T wave inversion

Troponins and CK-MB increased

39
Q

Transmural infarction occurs when coronary artery is completely blocked for e.g. 20 mins. What are the ECG signs

A

T wave inversion OR hyper acute T waves in 2 contiguous leads and ST elevation. May also get a pathologic Q wave

Transmural infarction suggests STEMI

40
Q

Name 3 causes of ST elevation that are not MI

A

Coronary artery vasospasm
LV hypertrophy
Pericarditis

41
Q

Septal wall infarctions show pathologic Q waves in which leads?

A

V1 and V2

42
Q

Anterior wall infarction shows pathologic Q wave in which leads

A

V3 and V4

43
Q

Anterolateral wall infarction shows pathologic Q wave in which leads?

A

V3-6, leads 1 and aVL

44
Q

Subendocardial infarction DOES NOT show pathologic Q waves. Also which lead is not reliable for showing pathologic Q waves?

A

aVR

45
Q

Pathologic Q waves can be caused by what other than transmural infarction?

Remember they linger longer than ST elevation or T wave inversion

A

Left BBB, Wolff Parkinson White syndrome

Year 3 - Cardiology cases (22 decks)

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