ECG Flashcards
What does the SAN contain + do?
- spontaneously active cells
* conducts current down atria + internodal pathways
What does the SAN produce on the ECG?
P-wave of ECG
What does the AVN do?
- acts like a gate-keeper
- slows down current
- allows atrial muscle to contract to supply blood to ventricles
Where does the current travel to after the AVN?
- current travels through septum + down the bundle of His + up through Purkinje fibres
- allows for ventricular contraction
What does the His-Purkinje system produce on the ECG?
QRS complex
What represents the T-wave of the ECG?
cardiac muscle (ventricles) relaxes + membrane potential recovers / repolarises
What represents the QRS complex of the ECG?
His-Purkinje system
What represents the P-wave of the ECG?
SAN node conduction
What is Lead II?
- reads for electrical currents the move from right shoulder to left lung
- has the biggest QRS complex as it goes from negative to positive current
What is RAD or LAD?
right / left axis deviation
What causes axis deviation?
• change in heart position
• change in position of electrical conduction
(current no longer runs parallel to the lead, vice versa)
How can axis deviation be identified?
Lead II - QRS complex is smaller but then has a bigger deflection
How does trial fibrillation present on an ECG?
loss of P-wave
How does atrial flutter present on an ECG?
saw-tooth pattern of the P-wave
