ECG Flashcards
What do the P wave, QRS complex and T wave show
P wave: atrial depolarisation
QRS complex: ventricular depolarisation
T wave: ventricular repolarisation
why is arial repolarisation not shown?
It occurs at the same time as ventricular depolarisation
what to the different leads show?
The standard limb leads and the augmented limb leads show the frontal view electrical activity of the heart
The precordial limb leads show the transverse activity of the heart
Standard limb leads
SLL1- left arm wrt to right arm
SLL2- left leg wrt to right arm
SLL3- left leg wrt to left arm
SLL2- R wave most in line with line of depolarisation
Explain the QRS complex in SLL2
Q wave: electrical activity spreading from the left to right side of heart so -ve
R wave: down inter ventricular septum- +ve
S wave: up towards top of septum -ve
Augmented limb leads
2 limb leads tied together wrt to 1 limb lead
AVF- most +ve
AVR - most -ve
AVL- mismatch
Precordial limb leads
v4/v5/v6 positive
V1/V2/V3 negative
between v3/v4 there is a swap over called progression
how long should each section be?
PR- between start of P and end of Q- 0.12- 0.2 MS
QT- 0.42-0.6
QRS- 0.08
Rhythm strip:
- what does it show
- what can it be used to calculate?
Should run at 25mm/sec calibrating pulse should be 0.2 sec = 1 large square can be used to calculate HR: -number of R waves in 30 large squares -multiply by 10 or if QRS complexes are regular: -count number of large squares between them -divide by 300
ARI BAR
Any electrical activity Rate Irregular or regular Broad or narrow Atrial activity? Relationship between atria and ventricles
Broad/narrow QRS complexes
- should usually be less than 3 small squares
- usually lasts 0.12 s
- if more than this then indicates that depolarisation has started in the ventricles
Atrial activity in relation to QRS complex
PR interval should be <0.2s so 1 large square - 3-5 small squares
