A first look at the ECG Flashcards
What is Einthovens triangle?
Einthoven’s triangle is an imaginary formation of three limb leads in a triangle used in electrocardiography, formed by the two shoulders and the pubis/left ankle The shape forms an inverted equilateral triangle with the heart at the center that produces zero potential when the voltages are summed.
Where is SLL I found?
right arm to left arm
Where is SLL II found?
Right arm - left leg
Where is SLL III found?
Left arm to left leg
What does the PR interval represent?
Time from atrial depolarisation to ventricular depolarisation
How long is the PR interval normally?
0.1 - 0.2 seconds
What does the QRS interval represent?
Time for the whole of the ventricle to depolarise
How long is the QRS complex normally?
0.08 seconds
What does the QT interval represent?
Time spent while ventricles are depolarised and repolarised
How long is the QT interval normally?
0.42 sec (at 60bpm)
What does the ST segment represent?
Time spent where ventricles are depolarised (before they repolarise)
How long are ST segments normally?
0.12 sec
What is progression in terms of ECG leads?
When using the precordial chest leads, V1 will produce a negative blip, while V6 produces a positive blip, with the direction switching around V3/V4
What heart rate describes bradycardia?
<60bpm
What heart rate describes tachycardia?
> 100bpm
