ECG Flashcards
how do ECGs work?
as cells depolarise they become positively charged and the leads detect this positive charge moving in their direction
how many electrodes are there in a standard ECG?
10;
4 limb
6 precordial (chest leads)
which electrodes line up in the transverse plane of the heart?
V1-V6
what electrodes line up in the coronal plane of the heart and what leads do these produce?
RA, LA, RL, LL
aVR
aVL
aVF
which leads are bipolar?
lead I, II and III
what makes up limb I?
right arm (-ve) left arm (+ve)
what makes up limb lead II?
right arm (-ve) left leg (+ve)
what makes up limb lead III?
left arm (-ve) left leg (+ve)
in what chest leads will the depolarisation wave be mostly negative?
V1 and V2
in what chest leads will the depolarisation wave be isoelectric?
V3
in what chest leads will the depolarisation wave be mostly positive?
V4, V5, V6
what are the inferior leads
what is the blood supply of this area?
lead 2 ,3 avF
right coronary artery
what are the lateral leads
what is the blood supply of this area?
leads 1, avL, v5, v6
left circumflex artery
what are the septal leads?
v1, v2
what are the anterior leads
v3, v4
what artery supplies the septal and anterior region?
left anterior descending
how much time does one small square represent on ECG?
0.04secs
what is the p wave representing?
atrial depolarisation
what does the QRS complex represent/
ventricular depolarisation
what does the T wave represent?
ventricular repolarisation
how big should the p wave be?
3 small boxes wide and high
how big should the pr interval be?
<5 small boxes
how big should the QRS complex be?
<3 small boxes
where should ST segment be?
has to lie on the isoelectric point
how big should the T wave be?
<2 big boxes high
how can you work out the heart rate on an ECG?
an ECG strip shows 10 seconds so count the number of R waves on the ECG and times by 6
what is atrial flutter and what would it look like on an ECG?
an ectopic focus in the atria
supraventricular tachycardia
on ECG there are numerous p waves per QRS complex therefore there is a fast atrial rate
what is atrial fibrillation?
multiple ectopic foci
fast atrial rate.
few if any p waves
irregularly irregular
