ECG Terminology — Medical Vocabulary for Telemetry Technicians

Essential ECG and cardiac vocabulary. Master 115 clinical terms.

  • Atrium (plural: Atria) — One of two upper chambers of the heart. The right atrium receives blood from the body; the left atri
  • Ventricle — One of two lower chambers of the heart. The ventricles pump blood out of the heart to the lungs (rig
  • Right Atrium — The right upper chamber of the heart. Receives deoxygenated blood from the body through the vena cav
  • Right Ventricle — The lower right chamber of the heart that receives deoxygenated blood from the right atrium and pump
  • Septum (plural: Septa) — Partition or wall dividing a cavity; such as the interatrial septum (between atria) and interventric
  • Aorta — Largest artery in the body. Carries oxygenated blood from the left ventricle to the rest of the body
  • Aortic Valve — Opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's larg
  • Mitral Valve — Valve between the left atrium and the left ventricle; also called the bicuspid valve.
  • Tricuspid Valve — Located between the right atrium and the right ventricle; it has three (tri-) leaflets, or cusps.
  • Pulmonary Valve — Valve positioned between the right ventricle and the pulmonary artery.
  • Valve — Structure in veins or in the heart that temporarily closes an opening so that blood flows in only on
  • Coronary Arteries — Blood vessels that branch from the aorta and carry oxygen-rich blood to the heart muscle.
  • Pulmonary Artery — Artery carrying oxygen-poor blood from the heart to the lungs.
  • Pulmonary Vein — One of two pairs of vessels carrying oxygenated blood from the lungs to the left atrium of the heart
  • Vena Cava (plural: Venae Cavae) — Largest vein in the body. The superior and inferior venae cavae return blood to the right atrium of
  • Superior Vena Cava — A large vein that receives blood from the head, neck, upper extremities, and thorax and delivers it
  • Myocardium — Muscular, middle layer of the heart.
  • Endocardium — Inner lining of the heart.
  • Pericardium — Double-layered membrane surrounding the heart.
  • Artery — Largest type of blood vessel; carries blood away from the heart to all parts of the body.
  • Arteriole — Small artery.
  • Capillary — Smallest blood vessel. Materials pass to and from the bloodstream through the thin capillary walls.
  • Vein — Thin-walled vessel that carries blood from body tissues and lungs back to the heart. Veins contain v
  • Venule — Small vein.
  • Inferior Vena Cava (IVC) — Large vein that carries deoxygenated blood from the lower body to the right atrium.
  • Left Atrium — The upper left chamber that receives oxygenated blood from the pulmonary veins.
  • Left Ventricle — The lower left chamber that pumps oxygenated blood to the body via the aorta. It has the thickest my
  • Semilunar Valves — The valves (aortic and pulmonary) that prevent backflow from the arteries into the ventricles.
  • Atrioventricular (AV) Valves — The valves (tricuspid and mitral) that separate the atria from the ventricles.
  • Sinoatrial Node (SA Node) — The natural pacemaker of the heart, located in the right atrium. It generates electrical impulses th
  • Atrioventricular Node (AV Node) — Specialized tissue between the atria and ventricles that delays electrical impulses slightly, allowi
  • Bundle of His — Specialized muscle fibers that carry electrical impulses from the AV node down through the septum to
  • Purkinje Fibers — The final pathway of the cardiac conduction system. These fibers spread electrical impulses througho
  • Depolarization — The electrical activation of heart cells that triggers contraction. Depolarization is the electrical
  • Repolarization — The electrical recovery or "reset" of heart cells after contraction, allowing them to relax and refi
  • Conduction System — The specialized electrical pathway that transmits impulses through the heart in an organized sequenc
  • Pacemaker (SA Node) — Specialized nervous tissue in the right atrium that begins the heartbeat. An artificial pacemaker is
  • Artificial Pacemaker — A device that uses electrical impulses to regulate the heart rhythm or to reproduce that rhythm. An
  • Contraction — The tightening and shortening of a muscle.
  • Systole — Contraction phase of the heartbeat. From the Greek systole, meaning a contracting.
  • Diastole — Relaxation phase of the heartbeat. From the Greek diastole, meaning dilation.
  • Action Potential — The change in electrical potential associated with the passage of an impulse along the membrane of a
  • Automaticity — The ability of cardiac cells to spontaneously generate an electrical impulse.
  • Bundle Branches — The left and right branches of the Bundle of His that conduct impulses down the interventricular sep
  • Modes of Cardiac Pacing — Pacing modes described by a 3–5 letter code (e.g., VVI, DDD, AAI). The first letter indicates chambe
  • Unipolar vs Bipolar Pacing — Unipolar vs Bipolar Pacing is an advanced electrophysiology or pacing-related pattern. For monitor-t
  • Arrhythmia — Any abnormal heart rhythm. The heart may beat too fast (tachycardia), too slow (bradycardia), or irr
  • Heart Rhythm Disorders — Abnormal rhythm of the heartbeat due to irregularities in transmission of electrical signals. Also k
  • Tachycardia — A rapid heart rate, usually defined as greater than 100 beats per minute. Types include sinus tachyc
  • Bradycardia — A slow heart rate, usually defined as less than 60 beats per minute.
  • Fibrillation — Incoordinate twitching of the heart muscle fibers.
  • Acute Coronary Syndromes (ACSs) — Unstable angina and myocardial infarction (heart attack), which are consequences of plaque rupture i
  • Angina (Pectoris) — Chest pain resulting from myocardial ischemia. Stable angina occurs predictably with exertion; unsta
  • Cardiac Arrest — Sudden, unexpected stoppage of heart action; sudden cardiac death.
  • Heart Failure — Inability of the heart to pump blood with normal efficiency. The heart is unable to provide adequate
  • Infarction — Area of dead tissue.
  • Occlusion — Closure of a blood vessel due to blockage.
  • Embolus (plural: Emboli) — Clot or other substance that travels to a distant location and suddenly blocks a blood vessel.
  • Palpitations — Uncomfortable sensations in the chest related to cardiac arrhythmias, such as premature ventricular
  • Pericardial Friction Rub — Scraping or grating noise heard on auscultation of the heart; suggestive of pericarditis.
  • Agonal Rhythm — A slow, irregular idioventricular rhythm, usually < 20 bpm, signifying a dying heart.
  • Bigeminy — A rhythm pattern where every other beat is an ectopic beat (e.g., Ventricular Bigeminy: Normal-PVC-N
  • Trigeminy — A rhythm pattern where every third beat is an ectopic beat (e.g., Normal-Normal-PVC).
  • Quadrigeminy — A rhythm pattern where every fourth beat is an ectopic beat.
  • Bundle Branch Block (BBB) — A block in the conduction of electrical impulses down either the right or left bundle branch, causin
  • Couplet — Two consecutive premature complexes (e.g., two PVCs in a row).
  • Ectopic Beat — A heartbeat that originates from a site other than the sinoatrial node (the normal pacemaker).
  • Escape Beat — A beat that arises from a subsidiary pacemaker (AV node or ventricle) after a pause when the SA node
  • Hyperkalemia — Elevated serum potassium levels, often causing tall "peaked" T waves and widened QRS complexes on EC
  • Hypokalemia — Hypokalemia is an ECG-associated pattern often discussed in relation to metabolic, medication, or re
  • Ischemia — Inadequate blood supply to a part of the body, notably the heart muscle, often causing ST segment de
  • Myocardial Infarction (MI) — Tissue death (necrosis) of the heart muscle caused by lack of blood flow; a heart attack. ST-Elevati
  • Premature Atrial Contraction (PAC) — An early beat originating from an irritable focus in the atria. P wave morphology differs from sinus
  • Premature Ventricular Contraction (PVC) — An early, wide, and bizarre QRS complex originating from the ventricles. Usually has no preceding P
  • R-on-T Phenomenon — When a PVC occurs on the T wave of the preceding beat (the vulnerable period), potentially triggerin
  • Sick Sinus Syndrome — A group of heart rhythm problems due to malfunction of the sinus node, often manifesting as alternat
  • Left Bundle Branch Block (LBBB) — A conduction delay or block in the left bundle branch causing the left ventricle to depolarize late.
  • Right Bundle Branch Block (RBBB) — A conduction delay or block in the right bundle branch causing late right ventricular depolarization
  • AV Nodal Reentrant Tachycardia (AVNRT) — The most common form of SVT, caused by a reentrant circuit within or near the AV node using dual pat
  • AV Reentrant Tachycardia (AVRT) — A reentrant tachycardia using an accessory pathway (e.g., Bundle of Kent in WPW) to form a circuit b
  • Ventricular Flutter — A very rapid ventricular tachyarrhythmia (~300 bpm) producing a sinusoidal waveform on ECG where dis
  • Wide Complex Tachycardia (WCT) — Any tachycardia (>100 bpm) with a QRS duration ≥120 ms. Differential includes ventricular tachycardi
  • Digoxin Toxicity — Digoxin Toxicity is an ECG-associated pattern often discussed in relation to metabolic, medication,
  • Long QT Syndrome (LQTS) — Long QT Syndrome (LQTS) is an ECG-associated pattern often discussed in relation to metabolic, medic
  • Left Ventricular Hypertrophy (LVH) — Left Ventricular Hypertrophy (LVH) describes a conduction or chamber-pattern finding that is most re
  • Right Ventricular Hypertrophy (RVH) — Right Ventricular Hypertrophy (RVH) describes a conduction or chamber-pattern finding that is most r
  • Pacemaker-Mediated Tachycardia (PMT) — Pacemaker-Mediated Tachycardia (PMT) is an advanced electrophysiology or pacing-related pattern. For
  • Electrocardiogram (ECG/EKG) — A recording of the electrical activity of the heart using electrodes placed on the skin. It shows th
  • QRS Complex — The deflections in the ECG tracing, comprising the Q, R, and S waves, that represent the ventricular
  • Heart Rate — The number of heartbeats per unit time, usually per minute, based on ventricular contractions. May b
  • Pulse — Beat of the heart as felt through the walls of the arteries.
  • Blood Pressure — The pressure of the blood within the arteries, produced primarily by the contraction of the heart mu
  • Defibrillator — A device used to correct a dangerously abnormal heart rhythm, usually ventricular fibrillation, by d
  • Cardiology — The study and treatment of heart disorders.
  • Cardiovascular — The circulatory system comprising the heart and blood vessels which carries nutrients and oxygen to
  • Circulatory System — The system that moves blood throughout the body, composed of the heart, arteries, capillaries, and v
  • Pulmonary Circulation — Flow of blood from the heart to the lungs and back to the heart.
  • Systemic Circulation — Flow of blood from body tissue to the heart and then from the heart back to body tissues.
  • Oxygen — Gas that enters the blood through the lungs and travels to the heart to be pumped via arteries to al
  • Carbon Dioxide (CO2) — Gas (waste) released by body cells, transported via veins to the heart, and then to the lungs for ex
  • Deoxygenated Blood — Blood that is oxygen-poor.
  • Endothelium — Innermost lining of blood vessels.
  • Artifact — Any electrical signal on the monitor that does NOT come from the heart—it's noise that can mimic or
  • Isoelectric Line — The flat baseline of the ECG, representing periods of no electrical activity.
  • J-Point — The junction point where the QRS complex ends and the ST segment begins.
  • PR Interval — The time from the onset of atrial depolarization (P wave) to the onset of ventricular depolarization
  • QT Interval — The time from the start of the QRS complex to the end of the T wave, representing total ventricular
  • ST Segment — The interval between ventricular depolarization and repolarization. Elevation or depression can indi
  • P Wave — The first wave of the cardiac cycle, representing atrial depolarization.
  • T Wave — The wave following the QRS complex, representing ventricular repolarization.
  • U Wave — U Wave is an ECG-associated pattern often discussed in relation to metabolic, medication, or repolar
  • Electrode — A small adhesive patch placed on the patient's skin that detects the heart's electrical activity and
  • Lead — A specific electrical "view" of the heart's activity, like looking at a building from different angl
  • 12-Lead ECG — A 12-lead ECG is a multi-view recording used to evaluate electrical activity from different cardiac
  • Cardiac Axis — The average direction of the wave of depolarization through the ventricles.