ECG Flashcards
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What is the function of an Electrocardiogram?
Measures and records the electrical activity of the heart via electrodes placed on the skin in specific locations.
What are the waves recorded on?
International standard ECG paper
Name the 5 waves produced from the ECG
P, Q, R, S, T waves
What accounts for the P wave?
Atrial depolarization
What initiates atrial depolarization?
SA node
Why is the impulse delayed at the AV node after atrial depolarisation
Delay is caused by the slim AV node fibres which restricts the impulse from passing through freely
What component of the ECG is produced from this impulse delay
Isoelectric PR segment
Explain the QRS complex
Ventricular depolarization begins at the septum- left to right (Q), spreads to the apex (R), and the post part pf ventricular muscle (S).
What does the Isoelectric ST line indicate?
Ventricular depolarization is complete
Ventricular repolarization begins at the apex and results in which wave forming
T wave
Where is atrial repolarization
Wave is hidden as it takes place at the same time as ventricular depolarization which overshadows it.
What is the range of the duration and amplitude of a normal P wave?
Amplitude: 0.05mV-0.25mV
Duration: 0.06s-0.10s
What is the range for duration of the PR interval
0.12s - 0.20 s
What is the range of the duration and amplitude of a normal QRS complex?
Amplitude: 0.5- 3.0mV
Duration: 0.06-0.10s
What is the J point?
Start of the ST segment
What does the QT interval measure?
Measures time of ventricular depolarization and repolarization
What is the duration of the QT interval
0.36-0.44s
Which wave often goes unnoticed and what does it signify
U wave
Signifies the repolarization of papillary muscles/purkinje fibers