Topic 16 - Evaluate the given ECG curve! Flashcards
Which parameters is important to think of when interprenting an ECG?
- Details
- Axis
- Rate
- Rhythm
- Morphology
Name the waves of an ECG:
- P-wave
- QRS-complex
- T-wave
(4. U-wave)
Name the intervals of an ECG:
- PR-interval
- ST-segment
(3. J-point) - QT-interval
What is the P-wave?
Atrial depolarization
What is the QRS-complex?
Ventricular depolarization
What is the T-wave?
Ventricular repolarization
What is the U-wave?
Occasionally follow the T-wave
What is the PR-interval?
The time between atrial depolarization and ventricular depolarization
What is the ST-segment?
The time between ventricular depolarization and repolarization
What is the J-point?
It is where the S-wave ends and the ST-interval begins
What is the QT-interval?
The time between ventricular depolarization and the end on repolarization
When you look at an ECG, what will indicate a normal P-wave?
- Positive on lead II
- Each p-wave should be follows by QRS-complex
What will an abnormal P-wave indicate?
Dilated right or left atrium
What will an absent P-wave indicate?
Atrial fibrillation
What will a prolonged PR-interval indicate?
It shows a slower conduction between atria and ventricles, which indicates and 1st degree AV block
What will a variable PR-interval indicate?
2nd AV block
How do we describe a QRS-complex?
- normal
- narrow (abnormal)
- widened (abnormal)
What will a narrow QRS-complex indicate?
Suggests that the problem is supraventricular (=above the ventricles)
What will a widened QRS-complex indicate?
Suggests that the problem is of ventricular origin or there is a block in the conduction system carrying the electrical signal to one of the ventricles
High amplitude of QRS-complex indicates?
Amplitude = avstanden fra en bølges største utslag (toppunkt eller bunnpunkt) til likevektstilstanden (midten)
Ventricular hypertrophy
Variable amplitude of QRS-complex indicates?
Pericardial effusion
What can an elevation of the ST-interval indicate?
Pericarditis
What can an depression of the ST-interval indicate?
Ischaemia
Elevated J-point:
Can cause the appearance of the ST-elevation
What is another name for ST-elevation?
Benign early repolarization
How can we describe the T-wave?
Tall
Flat
Inverted
Normal T-wave:
Positive and after with the QRS-complex
What is a negative T-wave called?
Inverted T-wave
When is an inverted T-wave normal?
In V, aVR and lead III
When does an inverted T-wave become abnormal?
In the absence of ST-changes it might indicate ischaemic event
What can a tall T-wave indicate?
Hyperkalaemia
What can a biphasic T-wall indicate?
= Both negative and positive
Hypokalaemia
Ischaemia
QT-interval
It varies with the heart rate
Faster heart rate = short QT-interval
Slower heart rate = longer QT-interval
What can happen if the QT-interval is prolonged?
It may trigger a lethal ventricular arrythmia
What is the U-wave?
It is associated with imbalances and hypothermia
How can we examine the axis of an ECG?
We look at the different leads
Why do we check the axis of an ECG?
We check for deviation.
It is not specific, byt can signal further abnormalities
What does a normal axis look like?
Both lead 1 and aVF are positive
What is shown if there is a right axis deviation?
Lead 1 is negative, but aVF is positive
What happens if both lead 1 and aVF is negative on the axis?
there is an extreme axis deviation
What happens if lead 1 is positive and aVF is negative on the axis?
There is a upper quadrant deviation
How do we calculate the heart rate?
We count the squares of the ECG
How long is a tiny square and a big square on the ECG, if the calibration is 25 mm/s?
Show how we can calculate the heartrate if it is IRREGULAR:
We count the number of QRS-complexes over 10 seconds and multiply with 6 to get BPM
what is it called when the heart rate is low?
Bradycardia
what is it called when the heart rate is high?
Tachycardia
How we find the rhythm of the heart rate?
We look at the gap between the QRS-complexes, and if it is an irregular gap = irregular rhythm
What is the gap between the QRS-complexes called?
RR-interval
Different irregular rhythms, what are they called?
- Irregularly irregular
- Regular irregular
What is an irregularly irregular rhythm, and what can it indicate?
No clear pattern
Indicates: Atrial fibrillation
What is an regular irregular rhythm, and what can it indicate?
Clear pattern
Indicates: 2nd degree AV block
Additional considerations with ECG:
- ECG is a snapshot of the electrical activity
- The ECG needs to correlate with the presentation - Why the pasient needed an ECG to begin with
- Need to consider changes that happens over time
What does a positive wave look like?
Upwards is positive
If a QRS-complex points upward = positive
What does a positive wave look like?
downwards is negative
If a QRS-complex points downward = negative
why do we get positive and negative waves?
There is a positive deflection when the activity goes toward the electrode and negative when it goes away from it.
