VII Glossary

12-lead electrocardiogram: A diagnostic test (referred to as an ECG or EKG) that uses leads attached to the client’s body to record the electrical activity of the heart on special graph paper.

Aorta: A large artery that carries oxygen-rich blood to the rest of the body.

Aortic valve: The valve that opens when blood flows out of the left ventricle to the aorta.

Arrhythmia: Also referred to as a dysrhythmia; a chronic deviation from the normal pattern of impulse conduction and contraction.

Arteries: Vessels that carry oxygen-rich blood from the heart to the body’s tissues.

Artifact: Interference with the tracing of the cardiac pattern on an ECG.

Asystole: No cardiac pattern on the ECG and the client does not have a pulse.

Atrial fibrillation (A-fib): An irregular heart rhythm originating in the heart’s upper chambers (atria) characterized by atrial quivering, lack of clear P waves, and a wavy baseline on the ECG tracing.

Atrial flutter: A condition where the heart’s upper chambers (atria) beat too quickly. This causes the heart to beat in a fast, but usually regular, rhythm and is characterized by a sawtooth pattern on the ECG tracing.

Atrial rhythms: Rhythms that originate in the atria rather than in the SA node.

Atrioventricular (AV) blocks: Conduction blocks that can occur anywhere between the SA node and Purkinje fibers.

Atrioventricular (AV) node: Node located in the lower part of the right atrium, which carries electrical signals from the SA node to the ventricles.

Atrioventricular (AV) valves: The valves located between the atria and ventricles within the heart.

Bigeminy: An abnormal heart rhythm where a premature ventricular contraction (PVC) occurs every other beat.

Biphasic: Two phases.

Bradycardia: Heart rate less than 60 beats per minute.

Bundle branch blocks: Conduction block of either left or right bundle branches and occur within the ventricles.

Bundle of His: A collection of cardiac cells found along the septum between the ventricles that sends electrical impulses from the AV node to the left and right bundle branches.

Capillaries: Small blood vessels where the body exchanges oxygen and carbon dioxide in the blood at the cellular level.

Cardioversion: The use of low-energy shocks to resume the heart’s normal electrical rhythm.

Coronary arteries: Blood vessels that run along the heart’s surface and carry oxygenated blood to heart tissue.

Couplets: Premature Ventricular Contractions (PVCs) occurring in pairs.

Decreased cardiac output: Lack of blood being pumped out of the heart by the ventricles causing signs and symptoms of decreased blood pressure, decreased pulses, increased capillary refill, dizziness, light-headedness, fainting, chest pain, or shortness of breath.

Defibrillation: The use of an electrical current administered immediately to a patient to help restore normal cardiac function.

Dysrhythmia: Also referred to as an arrhythmia; a chronic deviation from the normal pattern of impulse conduction and contraction.

Electrocardiograms (ECGs): Electrodes are attached to a client’s body to record the electrical activity of the heart on special graph paper or on a cardiac monitor.

Endocardium: The inner layer of the heart.

Epicardium: The protective outer layer of the heart.

First-degree AV block: There is a slowed impulse from the AV node to the ventricles.

Heart block: A conduction block that can occur due to any obstruction in the normal pathway of electrical conduction through the heart. The anatomical location of the block can be categorized as in the sinus node, atrioventricular node, or bundle branches.

Inferior vena cava: Carries deoxygenated blood from the lower body.

Isoelectric line: The baseline of the ECG tracing.

Left atrium: The upper left chamber of the heart receives the oxygenated blood and pumps it through the mitral valve into the left ventricle.

Left bundle branch: Offshoots from the bundle of His that send electrical impulses to the left ventricle.

Left ventricle: The lower left chamber of the heart.

Mitral valve: The valve between the left atrium and left ventricle.

Multifocal: Dysrhythmias cause the waveforms to look different because the impulse is originating from different areas of the heart

Myocardial infarction (MI): An emergency medical condition caused by a lack of blood flow to the heart muscle.

Myocardium: The muscular middle layer of the heart.

Normal sinus rhythm (NSR): Originates from the sinus node and describes the characteristic rhythm of the healthy human heart.

Paced rhythms: A client who has a pacemaker with a set heart rate.

P-P interval: The interval that represents the duration between atrial heartbeats.

Pericardium: The protective sac that covers the entire heart.

Premature atrial contractions (PAC): An ectopic beat that originates in the atria.

Premature ventricular contractions (PVCs): A random ventricular contraction stimulated by an area of the heart other than the SA node and characterized by a wide, bizarre QRS complex.

Pulmonary arteries: Arteries that carry deoxygenated blood to the lungs.

Pulmonary valve: The valve that opens when blood flows from the right ventricle into the pulmonary arteries (then to the lungs).

Pulmonary veins: Arteries that carry oxygenated blood back to the left atrium.

Pulseless electrical activity (PEA): There is electrical activity in the heart, but it is not strong enough to cause a contraction or a pulse.

Purkinje fibers: A network of thin filaments that carry electrical impulses that cause the ventricles to contract and pump blood out of the heart.

R-R interval: The interval that represents the duration between the ventricular heartbeats.

R on T phenomenon: When a PVC occurs on the T wave.

Respiratory sinus arrhythmia: Rhythm correlates to the respiratory cycle; the rate increases when the client breathes in and slows when they breathe out.

Right atrium: Two large veins called the superior vena cava and the inferior vena cava deliver oxygen-poor blood to the upper right chamber of the heart.

Right bundle branch: Offshoots from the bundle of His that send electrical impulses to the right ventricle.

Right ventricle: This lower right chamber of the heart pumps the oxygen-poor blood through the pulmonary valves and then through the pulmonary arteries to the lungs.

Second-degree Type 1 AV block: The impulse from the AV node to the ventricles gets slower and slower with each beat until there is a dropped beat. The pattern then repeats itself.

Second-degree Type 2 AV block: The impulse from the AV node to the ventricles is variable. Some beats will be normal, and other beats will be dropped.

Semilunar (SL) valves: Values that open when blood flows out of the ventricles.

Sinoatrial blocks: Failed conduction of the impulses beyond the SA node, resulting in prolonger PR intervals or dropped P waves on the ECG

Sinoatrial (SA) node: Node located in the upper part of the right atrium and a major element of the conduction system.

Sinus bradycardia: A sinus rhythm that is a slower rate than normal (i.e., less than 60 beats per minute in an adult).

ST elevation: An elevation of the ST segment on an ECG that can indicate myocardial infarction.

Superior vena cava: Carries deoxygenated blood from the upper body.

Supraventricular tachycardia (SVT): An irregularly fast but regular heart rhythm that affects the heart’s upper chambers. SVT is also called paroxysmal supraventricular tachycardia.

Tachycardia: Heart rate greater than 100 bpm.

Telemetry: A portable device used to continuously monitor clients’ heart rhythms.

Third-degree AV block: The impulse from the AV node to the ventricles is blocked. The atriums and ventricles beat independently of each other.

Torsades de pointes: A life-threatening ventricular tachycardia that can be caused from long QT intervals or magnesium deficiency.

Tricuspid valve: The valve between the right atrium and right ventricle.

Trigeminy: An abnormal  heart rhythm where a premature ventricular contraction (PVC) occurs every third beat.

Unifocal: Dysrhythmias causes the waveforms to look the same because the signal is originating from the same area in the heart

Veins: Carry oxygen-poor blood back to the heart.

Ventricular fibrillation: An abnormal heart rhythm with disorganized electrical conduction signals causing the lower chambers of the heart (ventricles) to twitch (quiver) uselessly and not pump blood to the rest of the body.

Ventricular rhythms: Rhythms that originate in the ventricles (rather than the SA node) and cause the heart to beat faster.

Ventricular tachycardia: An abnormal heart rhythm originating in the lower chambers of the heart (ventricles) characterized by regular, wide QRS complexes, no P waves, and a rate of 150-300 per minute with or without a pulse.