Cardiovascular: ECGs & Arrhythmia Flashcards
What are the 6 leads in the coronal plane?
The limb leads
* aVR
* aVL
* aVF
* I
* II
* III
What are the 6 leads in the transverse plane?
The chest leads
V1-V6
Describe the colour of the limb electrodes
Right shouder - Red
Left shoulder - Yellow
Left leg - Green
Right leg - Black
Hint: start with red for right then work through the traffic lights clockwise
Where do each of the coronal leads lie on the QRS axis?
- I: 0’
- II: +30’
- aVF: +90’
- III: +120’
- aVR: -150’
- aVL: -30’
What is the normal QRS axis range, and what defines a left axis deviation and a right axis deviation?
Normal: -30’ - +90’
RAD: +90’ - +180’
LAD: -30’ - -90’
This is because the wave of propagation normally goes from SA node through bundle of hiss and down in right-left downward direction.
How would you use a QRS deflection in leads I,II&III to calculation deviation?
Is there any axis deviation here?
No, I&II are positive deflection and III is negative, this is normal QRS axis
Is there any axis deviation here?
Yes, I is positive deflection and II&III are negative, this is therefore a left axis deviation
Is there any axis deviation here?
Yes, II&III are positive deflection and I is negative, this is therefore a right axis deviation
What does the P wave correspond to?
With regards to electrical conduction
Atrial depolarisation
What does the QRS complex correspond to?
With regards to electrical conduction
Ventricular depolarisation
What does the T wave correspond to?
With regards to electrical conduction
Ventricular repolarisation
What does the PR segment tell us about with regards to electrical conduction?
What does deviations in a PR segment therefore hint at?
If P is depolarisation of the atria and QRS is depolarisation of the ventricles then PR segment is the conduction through the AVN/ bundle of hiss.
A prolonged PR segment can indicate conductive tissue dissorder
A shortened PR can indicate that conduction is bypassing the AVN
What does the QRS complex tell us about with regards to electrical conduction?
What does deviations in QRS complex therefore hint at?
Time for ventricular depolarisation
Deviations can indicate conductive tissue dissorders in the ventricles such as right bundle branch block or left bundle branch block
What does the ST segment tell us about with regards to electrical conduction?
What does deviations in a ST segment therefore hint at?
ST segment – start of
ventricular repolarisation
(should be isoelectric aka flat)
ST elevation acute infarction
ST depression ischaemia
What does the T wave tell us about with regards to electrical conduction?
Ventricular repolarisation