ECG Flashcards
What is Ohm’s law?
V= IR
What is P wave?
Atrial depolarization
What is a QRS complex?
Ventricular depolarization
What is a T wave?
Ventricular repolarisation
What are normal values of a PR interval?
120 – 200 ms
(3 to 5 small squares)
What are normal values of a QRS complex width?
Less than 120 ms
(3 small squares)
What is a QT interval?
Measure of time to ventricular repolarization
Time from onset of QRS to end of T
What are normal values of a QT interval?
Men 350-440 ms
Women 350-460 ms
What is a ECG electrode?
Physical connection to patient in order to measure potential at that point
10 electrodes to record a 12 lead ECG
What is a ECG lead?
Graphical representation of electrical activity in a particular ‘vector’
Calculated by the machine from electrode signals
12 leads for a 12 lead ECG (I-III, aVL, aVF, aVR, V1-6)
What is a bipolar lead?
Measures the potential difference (voltage) between two electrodes
One electrode designated positive, the other negative
What is a unipolar lead?
Measures the potential difference (voltage) between an electrode (positive) and a combined reference electrode (negative)
Sometimes known as augmented leads
What is a neutral electrode?
- Reduces artefact
- not directly involved in ECG measurement
What is a unipolar limb lead?
Measure potential from a single electrode (designated as positive) using a combined reference electrode as negative
Use same electrodes as the bipolar limb leads
What happens if there is Prolonged QRS?
QRS >120 ms
Bundle branch block
