ECG Flashcards
A wave of approaching depolarisation approaching an electrode causes
an upward going blip
When using standard limb leads, what events are transmitted better, fast or slow?
Fast
On an ECG, what causes the P wave?
Atrial depolarisation
On an ECG, what causes the QRS complex?
Ventricular depolarisation
On an ECG, what causes the T wave?
Ventricular repolarisation
The PR interval is mainly due to transmission through what?
The atrioventricular node (AV node)
QRS is equal to
the time for the whole ventricle to depolarise
The QT interval is
the time spent while ventricles are depolarised
Atrial repolarisation coincides with
ventricular depolarisation
Do different parts of the ventricle depolarise at the same or different times?
Different
The inter ventricular septum depolarises in what direction?
From left to right
The bulk of the ventricle depolarises from
the endocardial to the epicardial surface
Why is the T wave positive-going?
Action potential is longer in endocardial cells than in epicardial cells, so wave of repolarisation runs in opposite direction to wave of depolarisation
What would happen if the heart developed hypertrophy on the left or atrophy on the right?
Axis deviation
What extra information do the precordial leads give you?
Information on the same events but in the transverse plane
Limb leads look at the spread of depolarisation and repolarisation from how many angles, in what plane?
6 angles in the frontal plane
A heart rate below 60 beats per minute is known as
Bradycardia
A heart rate above 100 beats per minute is known as
tachycardia
Give one thing that the rhythm strip can tell you
- heart rate
- if each QRS complex is preceded by a P-wave
- if PR interval is too short
- if QRS complex is too wide
- if QT interval is too long
What does STEMI stand for?
ST Elevated Myocardial Infarction
Is STEMI or NSTEMI clinically more severe?
STEMI
Give a method for measuring heart rate from the rhythm strip
- measure R-R interval and work out how many occur in 60 seconds
- count R waves in 30 large squares and multiply by 10
What is the normal QT interval?
About 0.42 seconds at 60 bpm
What is the normal duration of the QRS complex?
About 0.08 seconds
