A
Height (voltage) of a waveform on the ECG
What is Amplitude?
The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.
What is Action Potential?
The period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied.
What is Absolute Refractory Period?
Together with lead I, II, III, augmented limb leads record the difference in electrical potential.
What is Augmented Limb Lead?
Ectopic automatic firing of myocardial cells.
What is Altered Automaticity?
ECG lead consisting of a positive and negative electrode which are lead I, II, III
What is Bipolar Limb Lead?
Ability of a cardiac cell to receive an electrical stimulus and conduct that impulse to an adjacent cardiac cell.
What is Conductivity?
Straight line recorded on ECG graph paper when no electrical activity is detected.
What is Baseline?
Period of the cardiac action potential that includes the absolute refractory period and the first half of the relative refractory period.
What is Effective Refractory Period?
Loss of polarization, especially the loss of difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell.
What is Depolarization?
The state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.
What is Permeability?
Third ECG electrode which minimizes electrical activity from other sources.
What is Ground Electrodes?
Refers to the accelerated generation of an action potential by either normal pacemaker tissue or by abnormal tissue within the myocardium.
What is Enhanced Automaticity?
A period measured in milliseconds that extends from the beginning of the P wave until the beginning of the QRS complex.
What is PR Interval?
Associated with right and left atrial depolarization.
What is P Wave?
Portion of the ECG representing the end of ventricular polarization and the beginning of ventricular repolarization.
What is ST Segment?
Movements of ions across a cell membrane in which the inside of the cell is restored to its negative charge.
What is Repolarization?
Corresponds to the depolarization of the right and left ventricle of the human heart.
What is QRS Complex?
The first positive upward deflection in the QRS complex, representing ventricular depolarization.
What is R Wave?
Line between waveforms; named by the waveform that precedes and follows it.
What is Segment?
A lead of an ECG in which one electrode is placed on the chest in the vicinity of the heart or on one of the limbs, while the other is placed at an area of zero potential.
What is Unipolar Lead?
Represents the time when the heart muscle cells are electrically silent. It is the region between the end of the T wave (ventricular repolarization or electrical inactivation) and the next P wave (atrial depolarization or electrical activation).
What is TP Segment?
Waveform that follows the QRS complex and represents ventricular polarization.
What is T Wave?
A curve showing a shape of a wave at a given time.
What is Waveform?
Distortion of an ECG tracing by electrical activity that is non-cardiac in origin.
What is Artifact?