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Med 155 Key Terms
Chapter 37
Amplified: Made larger or enlarged. The amplifier of the electrocardiograph enlarges the electrical
impulse activity and the recording can be read more easily.
Amplitude: Amount, extent, size, abundance, or fullness.
Angina Pectoris: Severe constricting chest pain, often radiating from the precordium to the left shoulder
and down the arm, due to insufficient blood supply to the heart that is usually caused by coronary
disease. Also called stenocardia.
Angiogram: Series of X-rays of a blood vessel(s) after injection of a radiopaque substance.
Arrhythmia: Anything other than normal sinus rhythm.
Artifact: Anything artificially produced.
Augment: To add or increase.
Baseline: Flat, horizontal line that separates the various waves of the ECG cycle.
Bipolar: having two poles or processes.
Bradycardia, sinus: A heart rate less than 60 beats per min.
Calibration: Determination of the accuracy of an instrument by comparing the information provided
with an accepted standard known to be accurate.
Cardiac Catheterization: Passage of a catheter into the heart through an arm or leg vein and blood
vessels leading into the heart. The purpose is to obtain cardiac blood samples, detect abnormalities, and
determine intracardiac pressure. Contrast medium can be injected and a coronary artery angiogram can
be performed.
Cardiac Cycle: Period from the beginning of one heartbeat to the beginning of the next succeeding beat,
including systole and diastole. One complete heartbeat.
Cardioversion: Conversion of a pathological cardiac rhythm (arrhythmia), such as ventricular
fibrillation, to normal sinus rhythm.
Countershock: Application of an electric current to the heart directly or indirectly to alter a disturbance
in cardiac rhythm.
Defibrillation: Stopping fibrillation of the heart by use of drugs or by physical means.
Defibrillator: A machine that delivers an electric current to alter a disturbance in cardiac rhythm.
Deoxygenated: Blood that is high in carbon dioxide, low in oxygen, and pumped through the heart to
the lungs where the carbon dioxide is exchanged for oxygen.
Med 155 Key Terms
Chapter 37
Depolarization: Process of reducing to a nonpolarized condition. Generation of an electrical current is
enhanced. Electrical activity generated when the atria or ventricles contract.
Diastole: One component of blood pressure measurement representing the lowest amount of blood
pressure exerted during the cardiac cycle; the force exerted on the atrial walls during cardiac relaxation.
Electrocardiogram: Record of the electrical activity of the heart; showing P, QRS, and T waves.
Electrocardiograph: Instrument for recording the electrical activity of the heart.
Electrocardiography: Process of recording the electrical activity originating in the heart.
Electrode: Also known as a sensor. Used to conduct electricity from the body to the electrocardiograph.
Electrolyte: Substances that conduct electricity whose components are important in maintaining fluid
and acid-base balance.
Galvanometer: Mechanism in the electrocardiograph that changes the voltage into a mechanical motion
for recording purposes.
Holter Monitor: A portable continuous recording of cardiac activity for a 24-hour period.
Implantable Cardioverter-Defibrillator (ICD): An implantable device used for life-threatening
arrhythmias. Its purpose is to shock the heart out of the arrhythmia and into a more normal sinus rhythm.
Ischemia: Local and temporary lack of blood to an organ or part caused by obstruction of circulation.
Isoelectric: Having equal electrical potentials. It is represented on the ECG as the flat horizontal line,
the baseline.
Lead Wire: A conductor attached to an electrocardiograph. Consists of limb leads and chest leads.
Mounting: Process of applying in sequence a portion of each of the 12 leads of the ECG recording onto
a commercially prepared mounting form or plain sheet of paper as part of the patient’s permanent
record.
Myocardial Infarction: A heart attack; usually caused by a blockage of one or more of the coronary
arteries.
Noninvasive: A procedure that does require penetrating the skin or a body opening.
Normal Sinus Rhythm: Term used to describe the heart’s rhythm when it is within the normal range.
Oscilloscope: An electronic device used for recording electrical activity of the heart, brain, and
muscular tissues.
Med 155 Key Terms
Chapter 37
Percutaneous Transluminal Coronary Angioplasty (PTCA): A procedure that widens a narrowed or
blocked coronary artery.
Precordial: Pertaining to the area on the anterior surface of the body overlying the heart.
Repolarization: Reestablishment of a polarized state in a muscle after contraction.
Rhythm Strip: ECG recording of a single lead, usually lead II, that is used to determine the rhythm of
the heartbeat. An arrhythmia can more easily be seen in a rhythm strip because it is run longer per
provider’s request.
Sensor: Term used to describe a metallic-coated paper tab that is applied to the patient’s body in
preparation for an ECG (also known as electrode). Sensors are placed on specific locations on the skin,
then attached to the ECG with wires. The sensors conduct electricity from the patient to the ECG
machine.
Sonographer: Professionally trained individual capable of performing the ultrasound examination.
Stylus: Heated slender wire of the electrocardiograph that melts the wax off of the ECG paper during
the recording.
Syncope: Fainting.
Systole: One component of blood pressure measurement representing the highest amount of pressure
exerted during the cardiac cycle; the force exerted on the arterial walls during cardiac contraction.
Tachycardia, sinus: Abnormally rapid heartbeat greater than 100 beats per minute.
Test Cable: Accessory device that attaches between the Holter monitor and the electrocardiograph to
check for correct waveform and lack of artifact.
Thallium stress testing: Chemical element given intravenously and used in cardiac stress tests. The
radioisotope localizes in the myocardium, and a scanning device picks up the distribution of the thallium
and can identify blockages in the coronary arteries. An accurate test for coronary artery disease.
Tracing: Graphic record usually of an event that changes with time, as with the electrical activity of the
heart.
Transducer: Device that converts one form of energy to another. During an ultrasound procedure, the
transducer picks up echoes and converts them to electrical energy. The energy is transformed into
digitalized images that can be viewed and printed.
Ultrasonography: A process of placing a handheld transducer against a body area to be tested. The
transducer sends sound waves through the skin and the various internal organs. When echoes are
formed and sent back the transducer converts them into electrical energy. This energy is transformed
Med 155 Key Terms
Chapter 37
into a picture on a monitor or printed on paper. Photographs of the images can be taken and become
part of the patient’s permanent record.
Unipolar: Having or pertaining to one pole process.