ECG Flashcards
what does one large square on an ECG represent
5mm = 0.2s
what does the p wave represent
atrial depolarisation
what does the QRS complex represent
ventricular depolarisation
how long is a QRS complex normally
< 0.1s
what does a T wave represent
ventricular repolarisation
how long is a normal T wave
0.12-0.2s
what does PR interval represent
AV nodal delay
how long is a normal PR interval
0.12 - 0.2s
what does the ST segment represent
ventricular contraction (systole)
what does the TP interval represent
ventricular relaxation (diastole)
how do you work out HR
300/no. of large squares between QRS (regular)
or number of QRS in 30 squares x 10
or number of QRS in 10 squares x 3 x 10
what plane are the limb leads
frontal / vertical
what plane are the chest leads
horizontal
if there is ST elevation in the following leads where is the MI and what artery is blocked
leads II, III and aVF (foot of the ECG)
inferior - foot is inferior
shaped like a foot
right coronary artery
if there is ST elevation in the following leads where is the MI and what artery is blocked
V1-V4
anterior
LAD
if there is ST elevation in the following leads where is the MI and what artery is blocked
lead I, V5 and V6, aVL
lateral
circumflex artery
if there is ST elevation in the following leads where is the MI
V1 - V3
anteroseptal
what is cardiac axis
the overall direction of electrical spread within the heart
what should the cardiac axis be in a healthy person
11 o’clock to 5 o’clock
what leads do you look at to determine cardiac axis
lead I II and III
what should you always remember when reading an ECG
check patient details
check date and time
check calibration
what should you look for in the rhythm strip (II)
regular / irregular HR P waves what is the PR interval is each p wave followed by a QRS is each ORS preceded by a p wave is QRS normal
what ECG changes would be seen in STEMI
ST elevation
new onset BBB
T wave inversion
what ECG changes would be seen in NSTEMI
no ST elevation
may be ST segment depression or T wave inversion
what does ST depression show
ischaemia
what ECG changes would be seen in Torsades de Pointes
long QT interval
wide and continually changing QRS
what is the treatment for TdP
Iv magnesium sulfate
what is the pathology: tall tented T waves wide/bizarre QRS complexes long PR interval severe bradycardia sine wave pattern
hyperkalaemia
what is the pathology:
prolonged PR interval
small inverted T waves - go down then up
ST segment depression
hypokalaemia
what is the pathology:
sinus tachycardia
RH strain
T wave inversion in anterior leads
PE
what is the pathology:
Broad QRS with slurred upstroke on R wave (delta wave)
Wolff-parkinson white syndrome
what is the ECG for SVT
narrow QRS
regular rhythm of 150bpm
what is the ECG for VT
wide QRS - broad complex tachycardia
if someone had wide QRS and a history or coronary artery disease/heart failure what would you suspect
VT
what is the pathology:
saw tooth baseline
regular rhythm
150bpm
atrial flutter
what is the pathology:
absence of P waves
irregularly irregular rhythm
irregular baseline
Atrial fibrillation
what is the ECG change for BBB
wide QRS
what is the pathology:
fixed PR intervals > 0.2s
1st degree heart block
what is seen on a ECG for 3rd degree heart block
very broad QRS
no association between p waves and QRS
what is seen on an ECG for Mobitz I
progressive lengthening of PR interval eventually resulting in dropped beat
usually 3:1
what is seen on an ECG for mobitz II
intermittent dropped beats without lengthening
- P wave often not followed by QRS
usually 2:1
what is the pathology:
saddle shaped ST elevation
PR depression
acute pericarditis
what is seen in the digoxin effect on an ECG
depressed ST segments in V5 and V6
what is seen in cardiac tamponade
electrical alternans
what is one of the first ECG changes seen in an MI
tall peaked T waves
