ECG Flashcards
What direction does repolarisation of he Ventricular spread from?
The epicardium to the endocardium
Depolarisation occurs in the opposite direction.
What is an ECG?
The recording of potential changes detected by electrodes placed and positioned on the body surface.
Where do the potential changes arise from?
Arise from currents that flow when the membrane potential of the myocardial tissue is changing. The currents flow around the heart to complete the circuit.
What does the ECG provide information about?
Gives a 3D view of the heart.
Info on cardiac rate and rhythm, chamber size, electrical axis of the heart.
Main test for myocardial ischemia and infarction.
What are the electrodes on the skin coupled too?
The electrocardiograph
What is the electric dipole creates from the spearated charged?
A vector with magnitude and direction.
What direction does the electrical activity spread?
Inferiority and to the left.
What is the magnitude?
Determined by the mass of cardiac muscle involved in the generation of a signal (atria and ventricles dominate).
What is the direction?
Determined by the overall activity of the heart at any instant in time and varies during the cardiac cycle (allows estimation of electrical axis).
What is an ECG lead?
Imaginary line (lead axis) between 2 or more electrodes.
Within the ECG lead what is the role of the positive electrode?
It acts as the recording electrode (seeing electrode).
