| A | B |
| artifact | abnormal marking on ECG tracing due to muscle tremor and slight patient movement |
| bradycardia | heart rate below 60 bpm |
| tachycardia | heart rate above 100 bpm |
| hertz | unit of frequency that indicates cycles or events per second |
| gain | a control in the ECG machine that increases or decreased the size of the deflections on the ECG tracing |
| millivolt | a unit of measurement to indicate voltage on the ECG tracing. Voltage is measured on the vertical axis |
| millimeter | a unit of measurement to indicate time on the ECG tracing. Time is measured on the horizontal axis |
| Einthovan triangle | a triangle formed by three of the limb electrodes |
| limb lead | lead that attaches to the arms or legs |
| somatic tremor | voluntary or involuntary muscle movement; body tremor |
| wandering baseline | artifact in which the tracing drifts away from the center of the graph paper |
| AC interference | unwanted markings on the ECG caused by other electrical current sources |
| dextrocardia | when the heart is on the opposite or right side of the chest |
| suprasternal notch | the dip at the base of the neck just above where the clavicle attaches to the sternum |
| manubrium | the top of the sternum |
| clavicle | extends from the sternum to the scapula |
| seizure | an interruption of the electrical activity of the brain that causes involuntary muscle movement and sometimes unconsciousness |
| stat | immediately |
| midscapular line | imaginary line on the back that runs vertically through the center of the scapula |
| midclavicular line | an imaginary line on the chest that runs vertically through the center of the clavicle |
| anterior axillary line | an imaginary vertical line starting at the front axilla that extends down the left side of the chest |
| midaxillary line | an imaginary vertical line that starts at the middle of the axilla and extends down the side of the of the chest |
| bipolar lead | a type of ECG lead that measures the flow of electrical current in both directions |
| augmented lead | normally small ECG lead tracings that are increased in size by the ECG machine in order to be interpreted |
| right arm | white lead |
| left arm | black lead |
| right leg | ground |
| left leg | red lead |
| chest leads | precordial leads |
| standard lead | limb leads |
| bipolar leads | standard leads |
| precordial leads | a type of lead placed ion the chest in front of the heart known as a V lead |
| electrodes | sensors placed on body to pick up electrical activity |