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PMACI > ECGs 2 > Flashcards

ECGs 2 Flashcards

1
Q

Which ECG leads look at the inferior side of the heart?

A

Lead II
Lead III
aVF

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2
Q

Which ECG leads look at the lateral side of the heart?

A

Lead I
aVL
V5
V6

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3
Q

Which ECG leads look at the anterior side of the heart?

A

V1-V4

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4
Q

Which ECG leads look at the right side of the heart?

A

V1
V2 (partly)

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5
Q

What is the first rule of ECGs?

A

The PR interval is between 0.12 & 0.2 sec (3 -5 small squares)

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6
Q

How long should the PR interval be?

A

Between 0.12 & 0.2 sec (3 -5 small squares)

-Rule 1

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7
Q

What is a long PR interval suggestive of?

A

First degree heart block

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8
Q

What is a short PR interval a sign of?

A

Pre-excitation (Accessory pathway)
OR
AV nodal (Junctional) rythm

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9
Q

What is the second rule of ECGs?

A

The QRS duration is <0.12 sec (<3 small squares)

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10
Q

How wide should the QRS complex be?

A

<0.12 sec (<3 small squares)

-Rule 2

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11
Q

What can cause a wide QRS?

A

Broad complexes may be ventricular in origin or due to aberrant conduction secondary to:

Bundle branch block (RBBB or LBBB)
Hyperkalaemia
Poisoning with sodium-channel blocking agents (e.g. tricyclic antidepressants)
Pre-excitation (i.e. Wolff-Parkinson-White syndrome)
Ventricular pacing
Hypothermia
Intermittent aberrancy (e.g. rate-related aberrancy)

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12
Q

What are the complex morphologies of LBBB shown in V1 and V6?

A

V1can be:
-‘W’ shaped
-Small r wave with deep S
-Absent R wave and deep Q wave

V6 can be:
-‘M’ shaped
-Notched
-Broad and monophasic
-RS pattern

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13
Q

What axis deviation is seen with LBBB?

A

Left

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14
Q
A
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15
Q

What causes narrow QRS complexes?

A

Narrow (supraventricular) complexes arise from three main places:

-Sino-atrial node (= normal P wave)

-Atria (= abnormal P wave / flutter wave / fibrillatory wave)

-AV node / junction (= either no P wave or an abnormal P wave with a PR interval < 120 ms)

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16
Q

If a narrow complex rythm is present with a normal P wave where is it most likely to originate from?

A

The SA node

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17
Q

If a narrow complex rythm is present with abnormal P waves where is it most likely to originate from?

A

Abnormal OR fluttering OR fibrillating P wave:
Atria

Abnormal P wave with a short PR (<120ms):
AV node / junction

18
Q

If a narrow complex rythm is present with absent P waves where is it most likely to originate from?

A

AV node/junction

19
Q

What is the third rule of ECGs?

A

The QRS complex should be predominantly upright in leads I & II

20
Q

In which leads should the QRS complex be predominantly upright?

A

Leads I & II

-Rule 3

21
Q

When are Q waves considered pathological?

A

If they are:

> 40 ms (1 mm) wide
2 mm deep
25% of depth of QRS complex
Seen in leads V1-3

22
Q

What are pathological P waves usually a sign of?

A

Pathological Q waves usually indicate current or prior myocardial infarction, especially when present with ST elevation and/or T wave inversion.

Differential diagnoses include:
- Myocardial infarction
-Cardiomyopathies (Hypertrophic (HCM), infiltrative myocardial disease)
-Rotation of the heart (Extreme clockwise or counter-clockwise rotation)

23
Q

In which leads can Q waves be normal?

A

Small Q waves are normal in most leads

Deeper Q waves (>2 mm) may be seen in leads III and aVR as a normal variant

24
Q

Where are Q waves not normally present (in the absence of pathologies)?

A

V1-V3

25
Q

What can predominantly negative QRS complexes in some chest leads be caused by?

A

Axis deviation - caused by a number of pathologies, can be normal variants.

26
Q

What is the fourth rule of ECGs?

A

QRS & T waves tend to have the same general direction in the limb leads

27
Q

In which leads should the QRS and T waves have the same general direction?

A

The limb leads

-Rule 4

28
Q

What are the characteristics of normal T waves?

A

Upright in all leads except aVR and V1
Amplitude < 5mm in limb leads, < 10mm in precordial leads (10mm males, 8mm females)
Duration relates to QT interval

29
Q

What amplitude is considered abnormal for T waves?

A

More than 10mm in males and 8mm in females

30
Q

What is the fifth rule of ECGs?

A

Confirm that aVR is negative (if not check limb lead placement)

31
Q

What is the sixth rule of ECGs?

A

The R wave in the precordial leads must grow from V1 to at least V4

32
Q

How is R wave progression assessed on ECGs?

A

The R wave should grow from V1 to at least V4

-Rule 6

33
Q

What can cause poor R wave progression?

A

Prior anteroseptal MI
Left Ventricular Hypertrophy (LVH)
Right Ventricular Hypertrophy (RVH)
Dilated cardiomyopathy
May be a normal variant

“Crap R, crap heart”

34
Q

What is the seventh rule of ECGs?

A

The ST segment should start isoelectric except in V1 & V2 where it may be slightly elevated

35
Q

In which leads may there be some slight normal ST elevation?

A

V1 & V2

-Rule 7

36
Q

What is the ST elevation criterea for MIs?

A

New ST segment elevation at the J point in at least two contiguous leads of ≥ 2 mm in men or ≥1.5 mm in women in leads V2-V3 and/or of ≥ 1 mm in other contiguous chest leads or the limb leads.

37
Q

How much ST elevation are you looking for in leads V2-V3?

A

≥ 2 mm in men or ≥1.5 mm

38
Q

How much ST elevation are you looking for in contiguous chest leads other than V2-V3 or the limb leads?

A

≥ 1 mm in men and women

39
Q

What reciprical changes might you expect to have in an anterior STEMI?

A

ST depression in inferior leads (mainly III and aVF)

40
Q

In which MIs might you not see reciprical changes?

A

Anterior STEMIs that do not involve high lateral leads.

41
Q

What is the eighth rule of ECGs?

A

The P waves should be upright in I, II & V2 to V6

42
Q

In which leads are atrial abnormalities most easily seen, why?

A

Atrial abnormalities are most easily seen in the inferior leads (II, III and aVF) and lead V1, as the P waves are most prominent in these leads.

PMACI (14 decks)

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