ECG - Introduction Flashcards
What does the P wave represent?
Atrial Depolarization
What does the QRS complex represent?
Ventricular depolarization
What does the T wave represent?
Ventricular RE-polarization
What is is the Isoelectric line?
Beneath the line = negative impulses
Above the line = positive impulses
Isolelectric line = Baseline; no electrical activity
What is the J point?
The end of the QRS complex
What does the PR interval tell us, and how is it measured?
measured from START of P wave to START of the QRS complex.
Tells us the time from Atrial depolarization –> to ventricular depolarization
What is a normal PR interval
0.12 - 0.20ms (3-5 small squares)
What is a normal QRS complex duration?
0.12ms (3 small squares)
What does the QT interval tell us, and how is it measured?
Tells us the time it takes for ventricular depolarization and depolarization to both occur.
take Measured from START of QRS complex to end of the T wave.
What is a normal QT interval?
Males = 440ms
Females = 460ms
What does the ST segment tell us, and how is it measured?
represents the period between ventricular depolarization (the QRS complex) and the beginning of ventricular repolarization (the T wave)
It is measured from the end of the QRS complex and the beginning of the P wave.
What is a normal ST segment time?
0.08 - 0.12 seconds or 80 - 120ms
how long is 1 small box on an EC?
0.04 seconds or 40ms
5 small boxes = 1 big box, how long does 1 big box represent?
0.2 seconds or 200ms
how long does 5 big boxes boxes represent?
1 second or 1000ms.
Vertical Axis?
represents amplitude
How to measure heart rate on an ECG?
if it is a six second lead strip ( 30 big boxes) = times the heart rate by 10
1500 method: count the small boxes in between two QRS complexes and divide that by 1500 <– only works accurate for regular rhythm
