ECG Flashcards
In ECG:
What is the duration of a small square?
0.04 seconds.
In ECG how tall (the amplitude) of a small square?
1 mm.
In ECG describe one big squares dimensions
One big square is made of 5 small squares and is 0.20 seconds long.
In ECG
What does the P wave represent and what is the duration of it?
- It represents atrial depolarisation.
- < 0.12s or < 3 small squares.
What is the morphology of P waves?
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
In ECG
Describe right atrial enlargement in lead II.
Lead II:
• P wave amplitude > 2.5mm (width < 0.12s).
Describe the normal P wave morphology in lead II
• Duration < 0.12 sec
• Amplitude < 2.5mm
Describe left atrial enlargement in lead II
• Duration > 0.12s
• Amplitude < 2.5 mm
• (Not always) Abnormal notch separating the right P wave and the left P wave P mitrale.
Lead V1: describe the normal P wave morphology.
- It is biphasic (with similar sizes of the positive and negative deflections).
- Amplitude < 1.5mm (in all precordial leads)
Lead V1: describe right atrial enlargement
- > 1.5mm amplitude of the initial positive deflection of the wave.
Lead V1: describe left atrial enlargement
On the terminal negative portion of the biphasic P wave
1. There’s widening of > 0.04 sec in duration
2. Deepening > 1mm deep
In ECG: what is P mitrale?
- Notched / bifid P waves in Lead II.
- It’s a sign of left atrial enlargement.
- Caused by mitral stenosis.
In ECG: what is P pulmonale?
- Peaked P waves in Lead II.
- Sign of right atrial enlargement.
- Caused by pulmonary hypertension, cor pulmonale.
In ECG: describe the Q wave.
- 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.
In ECG: when are Q waves considered pathological?
- Seen in V1-3
- > 0.04s in duration
- > 2mm in depth
- > 25% depth of QRS complex
In ECG: what are the causes of pathological Q waves?
- Current or prior MI.
In ECG: what does the loss of Q waves in V5-6 mean?
Absent Q waves in V5-6 is caused by LBBB.
In ECG: describe the normal R wave
- It is the first positive deflection after the P wave.
- It is caused by early ventricular depolarisation
What are the abnormalities of the R wave?
- Dominant R wave in V1
- Dominant R wave in aVR
- Poor R wave progression
Describe what is the T wave.
- It represents ventricular repolarisation.
- It’s a positive deflection after the QRS.
What are the normal T waves characteristics?
- Upright in all leads except aVR and V1;
- Amplitude < 5 mm in limb leads;
- Amplitude < 10 mm in precordial leads
Abnormal T waves characteristics?
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.
Hyperkalaemia: ECG changes
- Tall tented T waves
- Loss of P waves
- Widening of QRS complex
Hypokalaemia: ECG changes
- Flat T waves
- ST depression
- Prominent U waves
Hypocalcaemia: ECG changes
Prolonged QT interval.
Hypecalcaemia: ECG changes
Shortened QT interval.
ECG features of AF
- Narrow QRS
- Irregular RR intervals
- No P waves
ECG features of SVT
- Narrow QRS
- Regular RR interval
- No P waves
ECG features of ventricular tachychardia
- Broad QRS
- Regular RR interval
- No P waves
ECG features of ventricular fibrillation
- Broad QRS
- Irregular
- Varying amplitude
ECG features of:
Wolff-Parkinson-White syndrome
- Short PR interval (<0.12s or 3 small squares)
- Broad QRS
- Delta wave (upstroke of the QRS)
Define what is the PR interval
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).
What is the normal range for PR interval
- 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).
What is the normal range for the QRS complex
- 0.07 - 0.1 sec
Describe how to determine axis deviation.
➜ 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.
How to do a quick ECG reading?
- Rate
- Rhythm
- Axis
- Waves
- 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
What is the management for palpitations?
24h ECG / Holter.
What is the normal QT interval?
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
How to determine hyperthrophy on the ECG?
◉ 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
