Week 1 - ECG Flashcards
What is the P wave?
atrial depolarisation
what is the QRS complex?
ventricular depolarisation
What is the T wave?
ventricular repolarisation
What does the ECG give us info about?
hearts rhythm and conducting system of the heart
What are standard limb leads and what do they tell us?
tell us info about events of heart - direction and prescence of depolarisation/repolarisation
What are the 3 limb leads?
(I) is left arm relative to right arm
(II) is left leg relative to right arm
(III) is left leg relative to left arm
How many leads are there on an ECG and what are they?
3 limb leads (I, II and III), 3 augmented limb leads (aVR, aVL and aVF) and 6 chest leads (V1-V6)
What are waves of depolarisation shown as on an ECG?
depolarisation towards the electrode sticker causes an up-going blip on ECG.
depolarisation away from a sticker causes a down-going blip
repolarisation is the opposite - away is up-going blip and towards is down-going blip
What is the PR interval?
start of P to start of QRS. 0.12-0.2s
What is the QRS complex and its duration?
time taken for entire ventricle to depolarise. 0.08s
What is the QT interval?
start os QRS to end of T. changes depending on BPM. its 0.42s at 60BPM.
What is the significance of standard limb lead II?
its axis is most similar to that of the direction of depolarisation in the heart, so it has the largest R wave. this is also the rhythm strip
Why is the p wave upward going?
depolarisation is towards leg
Why is the q wave downward going in II?
depolarisation is from middle to outside of heart - opposite direction to leg
Why is the R wave upward going in II?
bundle of his moved depolarisation down the heart, in direction of leg