ECG

Electrocardiogram (ECG)

A graphic representation of cardiac electrical activity.

Electrodes

Conductive pads placed on the body surface to transmit cardiac electrical currents to an ECG machine.

Lead Axis

An imaginary line joining the positive and negative poles of the lead system in an ECG.

Isoelectric Line

The baseline on the ECG that occurs when there is no current flow in the heart.

Positive Deflection

Occurs on the ECG when electrical current flows toward the positive pole.

Negative Deflection

Occurs on the ECG when electrical current flows away from the positive pole toward the negative pole.

Bipolar Limb Leads

Three leads (I, II, III) that measure electrical activity between two points on the body in an ECG.

Unipolar Leads

Leads that consist of a single positive electrode without a corresponding negative electrode.

Telemetry System

A battery-operated transmitter that sends ECG data to a remote monitor for ambulatory patients.

Full-Disclosure Monitors

Monitors that continuously store ECG rhythms in memory for access and documentation.

ECG Strip

A graphical recording of the heart's electrical activity printed on standardized graph paper.

P Wave

The wave representing atrial depolarization in a normal ECG.

QRS Complex

The complex representing ventricular depolarization in a normal ECG.

T Wave

The wave representing ventricular repolarization in a normal ECG.

PR Segment

The segment between the end of the P wave and the start of the QRS complex.

QT Interval

The interval that measures the time from the start of the Q wave to the end of the T wave.