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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
If the transition zone (i.e. isoelectric points) shift from V3/4 to V5/6 what does this suggest
Heart rotated towards persons left i.e. LV hypertrophy
26
What may shift the QRS transition zone to the right?
MI of the left side of the heart or right sided cardiac hypertrophy (vice versa for left)
27
Right atrial enlargement shows up in an ECG as? What are the causes of right atrial enlargement?
Large P wave in V1 and 2. Also large P wave in leads 2, 3 and aVF. Causes include stenotic tricuspid valve
28
Left atrial enlargement shows up in an ECG as? What are the causes of leftt atrial enlargement?
2 p waves in Lead 2 Biphasic (peak and trough) p wave in lead v1 Caused by stenotic mitral valve
29
What are the ECG signs of RV hypertrophy?
Dominant R wave in lead V1 Dominant S wave in lead v5 Often accompanied by some right axis deviation
30
Give a cause of RV hypertrophy
Pulmonary hypertension
31
LV hypertrophy has almost the opposite features of RV hypertrophy. So what are the ECG features
Dominant S wave in v1 (and ST elevation) Dominant R wave in v5 (and ST depression + t wave inversion)
32
What are the causes of LV hypertrophy
Systemic hypertension
33
What are the 2 types of ischaemia/infarction of the heart?
Transmural (entire thickness of myocardium) or subendocardial (innermost layer of myocardium)
34
What is a giveaway sign of subendocardial ischaemia?
ST depression (can be upward/downward sloping or horizontal) Leads 1, 2, v4, v5 and v6 affected
35
What does a CURVED ST depression indicate?
Digitalis effect - i.e. patient takes digoxin
36
Transmural ischaemia arises from atherosclerotic plaques that rupture. When may transmural ischaemia show up?
Unstable angina or NSTEMI NSTEMI leaks out troponin and CK-MB
37
What are the ECG signs of transmural ischaemia
ST depression and T wave inversion in contiguous chest leads (v2-6)
38
What are the ECG signs of subendocardial infarction
ST depression and T wave inversion Troponins and CK-MB increased
39
Transmural infarction occurs when coronary artery is completely blocked for e.g. 20 mins. What are the ECG signs
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
Name 3 causes of ST elevation that are not MI
Coronary artery vasospasm LV hypertrophy Pericarditis
41
Septal wall infarctions show pathologic Q waves in which leads?
V1 and V2
42
Anterior wall infarction shows pathologic Q wave in which leads
V3 and V4
43
Anterolateral wall infarction shows pathologic Q wave in which leads?
V3-6, leads 1 and aVL
44
Subendocardial infarction DOES NOT show pathologic Q waves. Also which lead is not reliable for showing pathologic Q waves?
aVR
45
Pathologic Q waves can be caused by what other than transmural infarction? Remember they linger longer than ST elevation or T wave inversion
Left BBB, Wolff Parkinson White syndrome

Year 3 - Cardiology cases (22 decks)

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