Electrocardiogram Flashcards
What does an ECG provide information about in regards to timing and direction of cardiac events
- atrial and ventricular depolarisation
- ventricular repolarisation
What does ECG tell you about rate/rhythm disturbances
- Tachy/bradycardia
- sinus rhythm
- arrhythmias
What doesn’t an ECG tell you about
mechanical force
When recording depolarisation and depolarisation using external electrodes, what does the potential difference reflect
The movement of current in relation to the positive electrode
What deflection is produced when a depolarisation is moving away from a positive electrode
Downward
What deflection is produced when a depolarisation is moving towards a positive electrode
Upward
What deflection is produced when a depolarisation is moving away from a negative electrode
Upward
What deflection is produced when a depolarisation is moving towards a negative electrode
Downward
If using bipolar electrodes, what would the final measurement be
Composite of what is seen at each electrode
What does depolarisation towards a positive electrode produce
Downward deflection
What does depolarisation away from a positive electrode give
Upward deflection
In a recording, what is the recorded potential difference a vectorial resultant (mean vector) of?
Several differently directed wavefronts
Stages of the cardiac cycle
Atrial depolarisation
Ventricular depolarisation
Ventricular depolarisation
In what direction does ventricular depolarisation travel
Opposite direction to depolarisation
Which cells are last to depolarise and the first to repolarise
-What does this mean their action potentials are like
Epicardial
-Shorter action potential
