alternating current (AC) interference
electrical interference that appears as small, uniform spikes on ECG tracing.
device on the electrocardiograph that magnifies or enlarges the heart's electrical impulses so they can be recorded.
unwanted changes in an ECG tracing caused by movement, machine malfunction, or other factors.
atrioventricular (AV) node
knot of specialized cells in the lower portion of the right atrium that produces the heart's electrical impulses.
leads that measure cardiac activity from one electrode on the body at a time; recordings are augmented (made larger) so they can be read.
line that separates the various cardiac waves; representative of the space between heartbeats while the heart is "resting"; also called isoelectric line.
bundle of branches
branches of cardiac fibers that receive electrical impulses from the bundle of His.
bundle of His
small band of atypical cardiac muscle fibers that receive electrical impulses from the AV node.
device that detects and converts the amplified electrical signal into a tracing on the ECG machine.
(MI) heart attack; death of heart tissue caused by blockage of the heart's blood vessels.
normal sinus rhythm (NSR)
rhythm measurement that start at the SA node, occurs within an established time frame, and follows an expected, established pattern.
paroxysmal atrial tachycardia (PAT)
sudden onset and ending of atrial tachycardia, 150 to 250 beats per minute.
premature atrial contraction (PAC)
condition in which an electrical impulse in the atria starts before the next expected heartbeat.
premature ventricular contraction (PVC)
condition in which the ventricles receive an impulse prematurely and contract early.
cardiac fibers that receive impulses from the bundle branches and take them throughout the heart muscle.
ECG pattern that shows when the impulse moves through the ventricles and reaches the Purkinje fibers, depicting contraction of both ventricles.
process of ensuring that an ECG taken on one machine will compare to a tracing taken on another machine.
normal, small upward curve that occasionally follows a complete ECG cycle after the PQRST; has unknown indication.
ventricular fibrillation (V fib)
life-threatening condition of ventricular twitching that causes ineffective pumping action, stopping blood circulation.