Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Electrophysiology
basic electrophysiology
| Term | Definition |
|---|---|
| Absolute refractory period | corresponds with the onset of the QRS complex to approximately the peak of the T wave; cardiac cells cannot be stimulated to conduct an electrical impulse, no matter how strong the stimulus |
| Action potential | a five-phase cycle that reflects the difference in the concentration of charged particles across the cell membrane at any given time |
| Altered automaticity | a disorder of impulse formation in which cardiac cells fire and initiate impulses before a normal SA node impulse |
| Amplitude | height (voltage) of a waveform on the ECG |
| Arrhythmia | abnormal heart rhythm |
| Artifact | distortion of and ECG tracing by electrical activity that is non-cardiac in origin |
| Atrioventricular bundle | the bundle of His |
| Atrioventricular node | a group of cells that conduct and electrical impulse through the heart; located in the floor of the right atrium immediately behind the tricuspid valve and near the opening of the coronary sinus |
| Augmented limb lead | leads aVR, aVL, and aVF; these leads record the difference in electrical potential at one location relative to the electrical potential of another extremity |
| Automaticity | ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse without being stimulated from another source (such as a nerve) |
| AV bundle | the bundle of His |
| AV node | specialized cells located in the lower portion of the right atrium; delays the electrical impulse in order to allow the atria to contract and complete filling of the ventricles |
| Axis | imaginary line joining the positive and negative electrodes of a lead |
| Baseline | straight line recorded on ECG graph paper when no electrical activity is detected |
| Biphasic | waveform that is partly positive and partly negative |
| Bipolar limb lead | ECG lead consisting of a positive and negative electrode |
| Bundle of His | fibers located in the upper portion of the interventricular septum that receive and electrical impulse from the AV node and conduct the impulse to the right and left bundle branches |
| Complex | several waveforms |
| Conduction system | a system of pathways in the heart composed of specialized electrical (pacemaker) cells |
| Conductivity | ability of a cardiac cell to receive and electrical stimulus and conduct that impulse to an adjacent crdiac cell |
| Contractility | ability of cardiac cells to shorten, causing cardiac muscle contraction in response to and electrical stimulus |
| Depolarization | movement of ions across a cell membrane, causing the inside of the cell to become more positive, and electrical event expected to result in contraction |
| Dysrhythmia | abnormal heart rhythm |
| Ectopic | impulse originating from a source other than the SA node |
| Effective refractory period | period of the cardiac action potential that includes the absolute refractory period and the first half of eh relative refractory period |
| Electrode | and adhesive pad that contains a conductive gel and is applied at specific locations on the patient's chest wall and extremities and connected by cable to and ECG machine |
| Electrolytes | elements or compounds that break into charged particles (ions) when melted or dissolved in water or another solvent |
| Enhanced automaticity | abnormal condition in which cardiac cells not normally associated with the property of automaticity begin to depolarize spontaneously or when escape pacemaker sites increase their firing rate beyond that considered normal |
| Excitability | the ability of cardiac muscle cells to respond to an outside stimulus |
| Ground electrode | third ECG electrode (the first and second are the positive and negative electrodes), which minimizes electrical activity from other sources |
| His-Purkinje system | portion of the conduction system consisting of the bundle of His, bundle branches, and Purkinje fibers |
| Indicative changes | ECG changes observed in leads that look directly at the affected area of the heart; indicative changes are significant when they are seen in two anatomically contiguous leads |
| Inherent | natural, intrinsic |
| Interval | waveform and a segment; in pacing, the period, measured in milliseconds, between any two designated cardiac events |
| Intrinsic rate | rate at which a pacemaker of the heart normally generates impulses |
| Ion | electrically charged particle |
| Isoelectric line | absence of electrical activity; observed on the ECG as a straight line |
| J point | point where the QRS complex and ST segment meet |
| Lead | electrical connection attached to the body to record electrical activity |
| Membrane potential | difference in electrical charge cross the cell membrane |
| millivolt (mV) | difference in electrical charge between two points in a circuit |
| Myocardial cells | working cells of the myocardium that contain contractile filaments and form the muscular layer of the trial walls and the thicker muscular layer of the ventricular walls |
| Pacemaker cells | specialized cells of the heart's electrical conduction system, capable o spontaneously generating and conducting electrical impulsed |
| Permeability | ability of a membrane channel to allow passage of electrolytes once it is open |
| Polarized state | period after repolarization of a myocardial cell (also called the resting state) when the outside of the cell is positive and the interior of the cell is negative |
| PR interval | P wave plus the PR segment; reflects depolarization of the right and left atria (P wave) and the spread of the impulse through the AV node, AV bundle, right and left bundle branches, and the Purkinje fibers (PR segment) |
| Purkinje fibers | fibers found in both ventricles that conduct and electrical impulse through the heart |
| P wave | first wave in the cardiac cycle; represents atrial depolarization and the spread of to electrical impulse throughout the right and left atria |
| QRS complex | several waveforms that represent the spread of and electrical impulse though the ventricles (ventricle depolarization) |
| R wave | on an ECG, the first positive deflection in the QRS complex, representing ventricular depolarization; in pacing, R wave refers to the entire QRS complex, denoting and intrinsic ventricular event |
| Reciprocal change | ECG changes observed in leads in leads opposite the affected area of the heart; also called mirror image changes |
| Reentry | spread of and impulse through tissue already stimulated by that same impulse |
| Refractoriness | period of recovery that cells need after being discharged before they are able to respond to a stimulus |
| Relative refractory period | corresponds with the down slope of the T wave; cardiac cells can be stimulated to depolarize if the stimulus is strong enough |
| Repolarization | movement of ions across a cell membrane in which the inside of the cell is restored to its negative state |
| Segment | line between waveforms; named by the waveform that precedes and follows it |
| Sinoatrial node | normal pacemaker of the heart that normally discharges at a rhythmic rate of 60 to 100 bpm |
| ST segment | portion of the ECG representing the end of ventricular depolarization (end of the R wave) and the beginning of ventricular repolarization (T wave) |
| Supranormal period | period during the cardiac cycle when weaker than normal stimulus can cause cardiac cells to depolarize; extends from the end of phase 3 to the beginning of phase 4 of the cardiac action potential |
| T wave | waveform that follows the QRS complex and represents ventricular repolarization |
| TP segment | interval between two successive PQRST complexes during which electrical activity of the heart is absent; begins with the end of the T wave through the onset of the following P wave and represents the period from the end of ventricular repolarizton to the |
| Triggered activity | a disorder of impulse formation that occurs when escape pacemaker and myocardial working cells fire more than once after stimulation by a single impulse resulting in atria or ventricular beats that occur alone, in pairs, in runs, or as a sustained ectopic |
| Unipolar | lead that consists of a single positive electrode and a reference point |
| Voltage | difference in electrical charge between two points |
| Waveform | movement away from the baseline in either a positive or negative direction |
Created by:
pnkrangr87
Popular EEG sets