EKG fundamentals Flashcards
How long should the PR interval take?
0.12-0.2 sec or 3-5 small squares (this represents the time that the conduction is ‘stuck’ at the AV node to allow ventricular filling to complete)
too long= 1st degree heart block
How long should the QRS complex take?
less than 0.12 sec or 3 small squares
How long should the QT interval (beginning of Q to end of T wave) take?
varies inversely with heart rate (faster HR = shorter QT)
at 60 bpm, the QT should be between 0.35-0.46 seconds (9-12 squares)
What lead is being read on a rhythm strip?
lead II
How to read a rhythm strip.
1) divide 300 by the number of large squares between 2 adjacent R waves
2) or if the rhythm appears irregular, look at the number of R waves that occur within 30 large squares and multiply by 10
What could cause a prolonged QRS complex?
- impulse blocked after AV node
- pulse originates in the ventricles (ventricular tachycardia)
How would atrial fibrillation look on an ECG?
- no P wave
- irregular QRS
AV node is overwhelmed and only some impulse gets through
What would super ventricular tachycardia look like on an ECG?
- absence of P wave
- Very close QRS complexes
What would an atrial flutter look like?
-sawtooth shape of P wave
the SA is firing way too fast (300 bpm) and the AV only lets through half (150bpm), a third (100bpm), or 1/4th (75bpm)
What are the two types of 2nd degree heart block?
Mobitz 1
What does Moritz 1 look like on an ECG?
continually increasing PR interval before dropping a PR interval completely and resetting
What does Moritz 2 look like on an ECG?
dropped QRS with an otherwise regular PR interval- can be random or patterned
What does a 3rd degree bock look like?
- very serious
- AV node is defective and eventually the ventricles will begin to fire on their own as a safety net
What is the cardiac axis?
average direction of flow of electricity in the heart
What is the normal cardiac axis?
+90 to -30
