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PLAB 1 August 2024 > ECG > Flashcards

ECG Flashcards

1
Q

In ECG:

What is the duration of a small square?

A

0.04 seconds.

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2
Q

In ECG how tall (the amplitude) of a small square?

A

1 mm.

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3
Q

In ECG describe one big squares dimensions

A

One big square is made of 5 small squares and is 0.20 seconds long.

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4
Q

In ECG
What does the P wave represent and what is the duration of it?

A
  1. It represents atrial depolarisation.
  2. < 0.12s or < 3 small squares.
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5
Q

What is the morphology of P waves?

A

They are:
• Monophasic in lead II
• Biphasic in V1
• Upright in leads I and II
• Inverted in aVR
• < 2.5mm tall (amplitude) in the limb leads
• < 1.5mm of amplitude in precordial leads

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6
Q

In ECG
Describe right atrial enlargement in lead II.

A

Lead II:
• P wave amplitude > 2.5mm (width < 0.12s).

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7
Q

Describe the normal P wave morphology in lead II

A

• Duration < 0.12 sec
• Amplitude < 2.5mm

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8
Q

Describe left atrial enlargement in lead II

A

• Duration > 0.12s
• Amplitude < 2.5 mm
• (Not always) Abnormal notch separating the right P wave and the left P wave P mitrale.

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9
Q

Lead V1: describe the normal P wave morphology.

A
  • It is biphasic (with similar sizes of the positive and negative deflections).
  • Amplitude < 1.5mm (in all precordial leads)
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10
Q

Lead V1: describe right atrial enlargement

A
  • > 1.5mm amplitude of the initial positive deflection of the wave.
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11
Q

Lead V1: describe left atrial enlargement

A

On the terminal negative portion of the biphasic P wave
1. There’s widening of > 0.04 sec in duration
2. Deepening > 1mm deep

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12
Q

In ECG: what is P mitrale?

A
  • Notched / bifid P waves in Lead II.
  • It’s a sign of left atrial enlargement.
  • Caused by mitral stenosis.
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13
Q

In ECG: what is P pulmonale?

A
  • Peaked P waves in Lead II.
  • Sign of right atrial enlargement.
  • Caused by pulmonary hypertension, cor pulmonale.
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14
Q

In ECG: describe the Q wave.

A
  • It is any negative deflection that precedes the R wave.
  • It is caused by the depolarisation of the interventricular septum.
  • Are seen in small size in leads I, aVL, V5 and V6.
  • Do not appear in V1-3.
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15
Q

In ECG: when are Q waves considered pathological?

A
  • Seen in V1-3
  • > 0.04s in duration
  • > 2mm in depth
  • > 25% depth of QRS complex
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16
Q

In ECG: what are the causes of pathological Q waves?

A
  • Current or prior MI.
17
Q

In ECG: what does the loss of Q waves in V5-6 mean?

A

Absent Q waves in V5-6 is caused by LBBB.

18
Q

In ECG: describe the normal R wave

A
  • It is the first positive deflection after the P wave.
  • It is caused by early ventricular depolarisation
19
Q

What are the abnormalities of the R wave?

A
  • Dominant R wave in V1
  • Dominant R wave in aVR
  • Poor R wave progression
20
Q

Describe what is the T wave.

A
  • It represents ventricular repolarisation.
  • It’s a positive deflection after the QRS.
21
Q

What are the normal T waves characteristics?

A
  • Upright in all leads except aVR and V1;
  • Amplitude < 5 mm in limb leads;
  • Amplitude < 10 mm in precordial leads
22
Q

Abnormal T waves characteristics?

A

Peaked T waves
- Seen in hyperkalaemia (tall, narrow and symmetric).

Hyperacute T waves
- Broad/wide, asymmetrically peaked
- Early stages of STEMI (often preceding the appearance of ST elevation or Q waves).

Flattened T waves
- Hypokalaemia
- Ischaemia (in contiguous leads)

Inverted T waves
- Normal finding in children
- Persistent juvenile T wave pattern
- Myocardial ischaemia and infarction
- BBB
- Ventricular hypertrophy
- Pulmonary embolism
- Raised ICP

Biphasic T waves
(the 2 waves go in opposite directions)
- Ischaemia: T wave goes Up and then down (positive and negative).
- Hypokalaemia: goes down and up

Camel hump T wave

  • Hypokalaemia: U wave fused at the end iof T wave.
  • Heart block or sinus tachycardia: P wave in T waves.
23
Q

Hyperkalaemia: ECG changes

A
  • Tall tented T waves
  • Loss of P waves
  • Widening of QRS complex
24
Q

Hypokalaemia: ECG changes

A
  • Flat T waves
  • ST depression
  • Prominent U waves
25
Q

Hypocalcaemia: ECG changes

A

Prolonged QT interval.

26
Q

Hypecalcaemia: ECG changes

A

Shortened QT interval.

27
Q

ECG features of AF

A
  • Narrow QRS
  • Irregular RR intervals
  • No P waves
28
Q

ECG features of SVT

A
  • Narrow QRS
  • Regular RR interval
  • No P waves
29
Q

ECG features of ventricular tachychardia

A
  • Broad QRS
  • Regular RR interval
  • No P waves
30
Q

ECG features of ventricular fibrillation

A
  • Broad QRS
  • Irregular
  • Varying amplitude
31
Q

ECG features of:
Wolff-Parkinson-White syndrome

A
  • Short PR interval (<0.12s or 3 small squares)
  • Broad QRS
  • Delta wave (upstroke of the QRS)
32
Q

Define what is the PR interval

A

It’s the time from the onset of the P wave to the start of the QRS complex.

It reflects the conduction through the AV node.

0.12 - 0.20s (3 - 5 small squares).

33
Q

What is the normal range for PR interval

A
  • 0.12 sec - 0.20 sec (3 - 5 small squares).
  • > 0.20 sec: 1st degree heart block
  • < 0.12 sec: pre-excitaction (accessory pathway between atria and ventricles).
34
Q

What is the normal range for the QRS complex

A
  • 0.07 - 0.1 sec
35
Q

Describe how to determine axis deviation.

A

➜ Lead I: left thumb
➜ Lead II: right thumb

  • Lead I positive + Lead II positive (both thumbs up) = normal axis.
  • Lead I positive + Lead II negative = left axis deviation.
  • Lead I negative + Lead II positive = right axis deviation.
36
Q

How to do a quick ECG reading?

A
  1. Rate
  2. Rhythm
  3. Axis
  4. Waves
  5. Intervals

◉ Rate
* Calculate HR;
* Is it bradycardia (< 60) or tachycardia (> 100)?

◉ Rhythm
* Sinus rhythm?
* Arrhythmias?

◉ Axis
* Rule of thumbs

◉ Waves
➜ P wave:
* Present: what is the morphology
* Absent: sinus arrest or AF.
➜ QRS:
* Narrow or broad?
* Regular or irregular?
* Look for Q waves on all leads.
➜ T waves
* Look on all leads
➜ U wave
* Present or not.
➜ Relationship between P wave and QRS:
* AV association (P waves followed by QRS);
* AV dissociation (no association between P waves and QRS).

◉ Intervals
➜ * PR interval:*
* > 0.2 sec: 1st degree heart block
* < 0.12 sec: acessory pathway
➜ ST segment
* Elevated: infarction
* Depressed: ischaemia / hypokalaemia
➜ QT interval

37
Q

What is the management for palpitations?

A

24h ECG / Holter.

38
Q

What is the normal QT interval?

A

From the beginning of the QRS complex to the end of the T wave.

► Normal 9 - 11 small boxes

➜ Long QT in Men: QTc > 440 ms
➜ Long QT in Women: QTc > 460 ms

39
Q

How to determine hyperthrophy on the ECG?

A

◉ V1 + V5/V6:
* Add the S wave in V1 with the R wave on V5/V6
* If the sum is > than 7 big boxes (35mm) than there is hyperthrophy.

Aortic stenosis can cause hyperthrophy

PLAB 1 August 2024 (32 decks)

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