EKG

Front

Electrocardiography Noun

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[uh-lek-troh-kar-dee-og-ruh-fee]

Back

Electrocardiography

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The process of producing a recording of the heart's electrical activity, used to diagnose various cardiac conditions.

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Example: This diagram shows where to place sensors, called electrodes, on the chest to record the heart's electrical activity during an electrocardiography (EKG) test.

Front

Electrocardiogram (EKG/ECG) Noun

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[uh-lek-troh-kar-dee-uh-gram]

Back

Electrocardiogram (EKG/ECG)

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The graphical representation or tracing that shows the heart's electrical activity, recorded by an electrocardiography machine.

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Example: An electrocardiogram (EKG) shows the heart's electrical activity as a waveform with distinct parts like the P wave, QRS complex, and T wave.

Front

Amplitude Noun

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[am-pli-tood]

Back

Amplitude

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The measure of voltage on an EKG, representing the strength of the heart's electrical signal, measured vertically on the grid.

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Example: This diagram shows a wave, similar to an EKG trace. Amplitude is the height of the wave from the center line to its highest point (peak).

Front

Calibration Noun

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[kal-uh-brey-shuhn]

Back

Calibration

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The process of setting standard measurements for an EKG machine, such as speed and gain, to ensure accurate readings.

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Example: This image shows a serial dilution, a lab technique to create solutions of known concentrations. This is a form of calibration in chemistry, not for an EKG machine.

Front

Gain Noun

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[geyn]

Back

Gain

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A setting on an EKG machine that controls the amplitude or height of the waveforms displayed on the tracing.

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Example: This image shows an EKG calibration pulse, where a 1 millivolt (mV) signal creates a 10 millimeter (mm) high box, demonstrating the machine's 'gain' or sensitivity.

Front

Deflection Noun

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[dih-flek-shuhn]

Back

Deflection

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The movement of the EKG stylus either up or down from the baseline, creating the waves and complexes of the tracing.

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Example: This diagram shows that when a wave of electrical charge moves toward a positive sensor (lead), it causes an upward spike, or positive deflection, on an EKG.

Front

Sinoatrial Node Noun

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[sahy-noh-ey-tree-uhl nohd]

Back

Sinoatrial Node

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A small mass of specialized tissue in the heart's right atrium that acts as the natural pacemaker, initiating heartbeats.

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Example: This diagram shows the sinoatrial (SA) node at the top of the heart, where the electrical signal for a heartbeat begins and travels downwards.

Front

Depolarization Noun

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[dee-poh-ler-uh-zey-shuhn]

Back

Depolarization

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The electrical activation of heart muscle cells that causes them to contract and pump blood throughout the body.

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Example: This diagram shows depolarization as sodium ions (Na+) rush into a cell through an open channel, making the inside of the cell more positive.

Front

Repolarization Noun

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[ree-poh-ler-uh-zey-shuhn]

Back

Repolarization

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The electrical recovery of heart muscle cells as they return to their resting state after a contraction or depolarization.

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Example: This graph shows that after a heart cell's electrical charge peaks (action potential), repolarization is the phase where the charge returns to its negative resting state.

Front

P Wave Noun

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[pee weyv]

Back

P Wave

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The first upward deflection on an EKG tracing, representing the electrical impulse spreading through and depolarizing the atria.

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Example: This EKG diagram shows the P wave, the first small bump, which represents the electrical signal causing the heart's upper chambers (atria) to contract.