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5. Cardiology > ECG Interpretation > Flashcards

ECG Interpretation Flashcards

1
Q

Describe the leads of a normal 12-lead ECG.

Which ones are unipolar, and which ones are bipolar?

A

UNIPOLAR:
Limb leads: aVR, aVL, aVF
Chest leads: V1-V6

BIPOLAR:
Lead I (right arm - left arm)
Lead II (right arm - left leg)
Lead III (left arm - left leg)
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2
Q

What are the 5 parts of a normal ECG wave?

What part of the electoral conduction system does each one indicate?

A

P wave - atrial depolarisation

PQ segment - AV junction/AVN conduction; conduction through bundle branches

QRS complex - ventricular depolarisation

ST segment - plateau phase of repolarisation

T wave - final rapid repolarisation

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3
Q

There are 4 different views of the heart measured by an ECG. Which leads indicate each view?

A

Inferior view: II, III, aVF
Lateral view: I, aVL, V5, V6
Anterior view: V3, V4
Septal view: V1, V2

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4
Q

How many electrodes are used in a 12-lead ECG?

Describe the proper placement of each ECG electrode.

A

10 electrodes

CHEST LEADS:
V1 - 4th intercostal space, right sternal edge
V2 - 4th intercostal, left sternal edge
V3 - halfway between V2 and V4
V4 - 5th intercostal space, midclavicular line
V5 - 5th intercostal space, left anterior axillary line
V6 - 5th intercostal space, mid-axillary line

LIMB LEADS:
aVR - right shoulder
aVL - left shoulder
aVF - left leg
Grounding electrode - right leg
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5
Q

List, step by step, how you would approach an ECG. (4)

What are the 5 things, in order, you would look at on an ECG?

A
  1. Clinical context
  2. Check patient details, including:
    a) Time/date of ECG
    b) Patient name
    c) Patient DOB
  3. Assess technical quality:
    a) Artefacts
    b) Paper speed
    c) Gain
  4. Look at ECG:
    a) Identify P/QRS/T waves
    b) Check HR
    c) Check ECG intervals
    d) Check QRS axis
    e) Check P/QRS/T morphology
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6
Q

When assessing technical quality of an ECG, what is normal for:

a) Paper speed?
b) Gain?

A

Paper speed: 25mm/s

Gain: 10mV/mm

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7
Q

List 3 methods by which you could determine heart rate from an ECG.

A
  1. Automatic reading at the top of the print out
  2. Number of QRS complexes across the whole ECG (10 seconds) x 6
  3. HR = 300 / (no. of large squares between each QRS complex)
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8
Q

When assessing ECG intervals, what is normal for:

a) PR interval?
b) QRS complex?
c) QT interval?

A

PR interval: <200ms (or <1 large square)

QRS complex: <120ms (or <3 small squares)

QT interval: <440ms (or <11 small squares)

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9
Q

When looking at the QRS axis on an ECG, what are the 4 possible axes?

A

Normal (-30° to +90°)

Left deviation (-30° to -90°)

Right deviation (+90° to +180°)

Extreme deviation (+180° to -90°)

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10
Q

When looking at P/QRS/T wave morphology on an ECG, what is normal? (3)

A

P wave is positive in inferior leads
ST segment is flat
T wave has same polarity as QRS

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11
Q

On an ECG, what are the features of:

a) Normal QRS axis?
b) Left QRS axis deviation?
c) Right QRS axis deviation?
d) Extreme QRS axis deviation?

HINT: normal and extreme are opposites, and right and left are opposites.

A

NORMAL:
Positive QRS in: I, II
Negative QRS in: aVR

LEFT DEVIATION:
Positive QRS in: I
Negative QRS in: II, aVF

RIGHT DEVIATION:
Positive QRS in: aVF
Negative QRS in: I

EXTREME DEVIATION:
Positive QRS in: aVR
Negative QRS in: I, II

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12
Q

What can cause left QRS axis deviation on an ECG? (1)

A

Conduction defects

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13
Q

What can cause right QRS axis deviation on an ECG? (2)

A

Right ventricular hypertrophy

Pulmonary conditions

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14
Q

What can cause extreme QRS axis deviation on an ECG? (1)

A

Ventricular tachycardia

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15
Q

What are the features of left bundle branch block on an ECG? (5)

A 
Long QRS
Dominant S wave in V1
Broad R wave in lateral leads
Absent Q wave in lateral leads
Notched R wave in V6
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16
Q

What are the features of right bundle branch block on an ECG? (5)

A 
Long QRS
Second R wave (M-shape) in V1
Wide, slurred S wave in V6
ST depression in V1-3
T wave inversion in V1-3
17
Q

Which 2 features allow you to differentiate between left and right bundle branch block?

A

LEFT BUNDLE BRANCH BLOCK:

  • Notched R wave in V6
  • Dominant S wave in V1

RIGHT BUNDLE BRANCH BLOCK:

  • Second R wave in V1
  • Wide, slurred S wave in V6
18
Q

List 8 examples of arrhythmias that can be seen on an ECG.

A 
Sinus bradycardia
Junctional bradycardia
Second degree AV block (Mobitz type 1)
Second degree AV block (Mobitz type 2)
Complete AV block
Atrial fibrillation
Supraventricular tachycardia
Ventricular tachycardia
19
Q

On an ECG, what is the difference between sinus bradycardia and junctional bradycardia? (1)

A

SINUS BRADYCARDIA:
-Normal wave form

JUNCTIONAL BRADYCARDIA:
-No P waves present

20
Q

Describe the features of second degree AV block on an ECG. Consider:

a) Mobitz type 1 (3)
b) Mobitz type 2 (3)

A

MOBITZ TYPE 1 AV BLOCK:
Irregular QRS complex (slowest rate: <60 bpm)
P:QRS complex is NOT 1:1
-Increasing PR interval
-Then a dropped beat (i.e. a P wave without a QRS complex)

MOBITZ TYPE 2 AV BLOCK
Irregular QRS complexes (slowest rate: <60 bpm)
P:QRS complex is NOT 1:1
-Constant PR interval
-Intermittent dropped beats
21
Q

What are the features of complete AV block on an ECG? (3)

A

Slow HR (<60 bpm)
Regular, broad QRS complexes
No relation between P waves and QRS complexes

22
Q

What are the features of atrial fibrillation on an ECG? (3)

A

Irregularly irregular, fast HR
Irregular, narrow QRS complexes
No P waves

23
Q

What is the difference between supraventricular tachycardia (2) and ventricular tachycardia (3)?

A

SUPRAVENTRICULAR TACHYCARDIA

  • High HR (150+ bpm)
  • P waves may not be present

VENTRICULAR TACHYCARDIA

  • High HR (120+ bpm)
  • Regular, broad QRS complexes
  • P waves are variable
24
Q

Describe the features of an acute STEMI on ECG. (4)

A

Regional ST elevation

  • Anterior: left anterior descending coronary artery (LAD)
  • Lateral: circumflex artery
  • Inferior: right coronary artery

Hyperacute T waves
Q waves
New left bundle branch block

25
Q

Describe the features of an acute NSTEMI on ECG. (3)

A

ST segment depression
T wave inversion
T wave flattening

26
Q

Describe the features of pericarditis on ECG. (5)

A 
Clinical features NOT consistent with MI
ST elevation in every lead
Concave ST elevation
No reciprocal ST depression
PR depression
27
Q

What is the main feature of hyperkalaemia on an ECG? (1)

A

Peaked, tented T waves

5. Cardiology (9 decks)

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