The glossary contains terms frequently encountered during a discussion of heart rhythms and treatment options — it is not intended to be an all inclusive listing. If you would like additional or more detailed information, a good resource for general medical terminology is Wikipedia.
Where terms are described elsewhere in this website, clicking on the term in the glossary will bring you to a more complete discussion.
Ablation – Also called radiofrequency ablation. This is a nonsurgical procedure used to correct certain types of rapid heart rhythms. This procedure can be used to treat SVTs and atrial fibrillation. A catheter is guided into the heart and is used to determine what localized tissue (also called an accessory pathway) in the heart is causing the rapid rate. Then a painless radiofrequency stimulus is applied to the tissue, destroying the tissue and stopping the inappropriate rapid rates. Success rate is usually 90+ percent.
Accessory Pathway – An abnormal area of conductive tissue between the atria and the ventricles which can sometimes lead to inappropriate rapid rates, such as SVTs. Patients with WPW will have accessory pathways.
Angioplasty – A noninvasive procedure used to evaluate and sometimes correct problems with circulation in the hearts arteries.
Arrhythmia – A term used to describe an abnormal heart rhythm
Asystole – The absence of cardiac electrical activity. These can sometimes be of short duration, but the underlying cause must be addressed. If not corrected, this rhythm is life threatening or ending.
Atria/Atrium – Atrium is singular, atria is plural. The atria, right and left, are the upper chambers of the heart. The SA node, which is the natural pacemaker of the heart is in the right atrium.
Atrial Ectopic Rhythm – Heart rhythm in which the impulse triggering the atria is moving around the atria and not coming from the SA node. This is a relatively benign rhythm.
Atrial Flutter – Heart rhythm in which the atria are contracting rapidly, but regularly at rates of 150-400 beats per minute. If controlled, the ventricles will beat at 70-100 beats per minute.
Atrial Fibrillation – Heart rhythm very similar to atrial flutter, but the atrial rate is faster and is totally irregular. If controlled, the ventricles will beat at 70-100 beats per minute.
Auto Trigger Monitors – This means that they will automatically record a patient’s heart rhythm if certain rhythms are detected. They can be set to trigger on rhythms that are too slow or too fast or if atrial fibrillation is detected.
AV Node – The atrioventricular node, connects the atria and the ventricles and delays the impulse from the atria to the ventricles to allow the ventricles to fill with blood.
Bundle Branches – Part of the electrical conduction system of the heart connecting the atria and the ventricles. There are two primary branches, the left and right and subdivisions of the left bundle.
Bundle Branch Block – One of the forms of heart block which causes a delay in the signals from the atria to the ventricles.
Cardioversion – This is a procedure which is used, generally under sedation, to shock your heart back into a normal rhythm if other procedures have been unsuccessful. This is often used with patients in rapid atrial fibrillation or flutter.
Complete Heart Block – Complete heart block exists when the AV node does not allow impulses to conduct from the atria to the ventricles.
Electocardiogram (EKG or ECG) – A recording of the electrical activity of the heart. EKGs can be one lead or view (which is what event monitors typically are) up to twelve leads.
Echocardiogram – A noninvasive test used to look at and make an image of your heart.
Electrophysiology – The study of the electrical system of the heart. An Electrophysiologist is a cardiologist who specializes in electrophysiology.
Event Monitor – A cardiac event monitor, also referred to as looping or 30 day monitor is a heart monitor prescribed for patients whose symptoms occur only occasionally and are worn up to 30 days. These monitors can be patient activated or can be autotrigger monitors. These monitors temporarily save short segments of a patient’s rhythm. When the patient feels abnormalities they want to record, the monitor will still have the segment saved temporarily, so when the patient presses the Record button, it will be saved permanently until it is transmitted to the Service Center.
First Degree Block – This is a rhythm which occurs when the AV node causes a longer than normal delay when transmitting an impulse from the atria to the ventricles.
Heart Block – There are a number of types of Heart Block (as opposed to blockages in the heart when arteries are clogged). There are first degree AV blocks, second degree blocks, complete or third degree blocks and bundle branch blocks. All of these are rhythms in which the normal conduction system of the heart is varied in some manner. These range from very minor to very severe, depending on the rhythm.
Heart Rate – This the number of times per minute your heart beats. It is referred to as heart rate or pulse. The normal heart rate range for adults is 50-100 beats per minute.
Holter Monitor – A Holter monitor is a device which a patient wears for 24-48 hours which records every heart beat for further analysis.
ICD – An implantable cardiac defibrillator is an implantable device used with patients who have recurrent ventricular tachycardia. The device continuously monitors the patient’s rhythm and when the offending rhythm is detected, the device delivers a small shock to the heart to convert the rhythm back to normal.
Idioventricular Rhythm – An idioventricular rhythm is a rhythm that originates in the ventricles when the ventricles are not stimulated to beat through the normal conduction system. These rates are usually very slow, 20-30 beats per minute. (The second rhythm under third or complete heart block is an idioventricular rhythm.)
Ischemia – The lack of blood flow to the heart muscle itself. This can be the source of chest discomfort or pain. This sometimes will require angioplasty or an ablation to correct the condition.
Junctional Rhythm – This is a rhythm which occurs when the AV node takes over as the heart’s primary pacemaker site in the heart either because the SA node has failed or the AV node is going faster and over takes the SA node.
Long QT Syndrome – Long QT syndrome is a rhythm in which the QT interval, which is the amount of time it takes for the ventricles to contract and then relax, is longer than normal. The normal range, at 60 beats per minute is .30* – .46 seconds. The underlying cause of the long QT must be evaluated to determine treatment.
Normal Sinus Rhythm (NSR) – This is the term used to describe a heart rhythm which originates in the SA node and is in the normal rate range of 50-100 beats per minute.
PACs – Premature atrial contractions are beats which occur early, coming from the upper chambers of the heart, the atria. One of the most common abnormal rhythms, these are often described as palpitations, skipped beats or irregular beats.
Pacemaker – This can refer to cells in the heart acting as a backup pacemaker to the SA node or an implantable device used to act as a backup pacemaker to the heart’s SA node. The most common indications for pacemaker implantation are second or third degree heart block or a block due to a surgical procedure.
Palpitations – A term frequently used to describe irregular heart beats or heart rhythms.
P Wave – The P wave is the impulse which appears on an EKG which is the result of the atria contracting.
PAT – A paroxysmal atrial tachycardia is the sudden onset of a rapid rate originating in the atria but not in the SA node.
PR Interval – The PR interval is the amount of time which elapses from the beginning of the atrial contraction (seen as a P wave) to the beginning of the ventricular contraction (seen as a QRS complex or R wave). This delay allows time for the ventricles to fill. The normal interval is .12-.20 seconds. This interval can be shorter in children, in the presence of Long-Ganong-Levine syndrome or in WPW syndrome. It is prolonged in first degree AV block and can also be in second degree AV block.
PSVT – A paroxysmal supraventricular tachycardia is the sudden onset of a rapid rate originating above the ventricles. It can originate from the area of the AV node or in the atria. PSVT is a more general term than PAT and includes PAT as a subset.
PVCs – Premature ventricular contractions are beats which occur early, coming from the lower chambers of the heart, the ventricles. One of the most common abnormal rhythms, these are often described as palpitations, skipped beats or irregular beats.
QRS Complex – The QRS complex, also known as the R wave is the impulse which appears on an EKG which is the result of the ventricles contracting. In most heart rhythms, a wide QRS complex generally suggests the presence of a bundle branch block.
QT Interval – The QT interval is the amount of time which elapses from the beginning of the QRS complex or R wave and the end of the T wave. This is the amount of time it takes for the ventricles to contract and then relax.
R Wave – Another name for QRS complex.
SA Node or Sinus Node – This is the natural pacemaker of the heart which resides in the right atrium. Under normal circumstances, it emits an impulse at the rate of 50-100 beats per minute.
Second Degree Heart Block – Either of two related heart rhythms which cause impulses originating in the atrium to be occasionally blocked from reaching the ventricles. This rhythm can be an indication for the implantation of a pacemaker.
Sinus Arrhythmia – A term frequently used to describe a normal heart rhythm in which the heart rate varies by more than 10 beats in a minute. We prefer the term sinus dysrhythmia since this rhythm is generally normal and the term arrhythmia suggests the presence of an abnormal rhythm.
Sinus Bradycardia – Sinus bradycardia is term used to describe a rhythm which is formed in the normal manner, but which is slower than normal. EquiMed uses a cutoff of 50 beats per minute. Normal rhythms which are slower than 50 beats per minute are sinus bradycardia.
Sinus Dysrhythmia – This rhythm can be a normal rhythm, but rather than having a steady rate, the rate varies by more than 10 beats per minute. These rhythms can be broadly split into respiratory and non respiratory origins. Many people use the term sinus arrhythmia to describe this rhythm.
Sinus Pause – Sinus pause is a rhythm in which the SA node fails to generate an impulse, or in related sinus block, generates an impulse which is blocked from stimulating the atria.
Sinus Tachycardia – Sinus tachycardia is the term used to describe a rhythm which is formed in the normal manner, but which is faster than normal. Normal rhythms which are faster than 100 beats per minute are sinus tachycardia. This rhythm can be a normal response to exercise, stress, anxiety, caffeine, alcohol or a number of other factors.
ST Segment – This is the segment of the EKG extending from the end of the QRS complex to the beginning of the T wave. It is normally isoelectric (flat) but can be elevated or depressed which can suggest the presence of ischemia or lack of blood flow to the heart muscle itself.
ST Changes – Changes in the ST Segment can suggest ischemia as described above.
SVT – A supraventricular tachycardia is a rapid rate originating above the ventricles, typically the area of the AV node or in the atria. SVT is a more general term than PSVT and is used when the onset of the rhythm is not seen.
T Wave – The T wave is the impulse which appears on an EKG which results from the ventricles relaxing or repolarizing. It is generally upright but can be inverted in the presence of ischemia or from a prior myocardial infarction (MI or heart attack).
Tilt Table Test – This is a term used to describe a test used to elicit heart rhythms which can cause lightheadedness or dizziness.
Ventricles – The ventricles, left and right, are the lower chambers of the heart and are the main pumping chambers, sending blood to the lungs and the rest of the body.
Ventricular Fibrillation – Ventricular fibrillation is a rhythm in which the ventricles are not contracting in any meaningful way and no blood is being pumped through the body. It is an ominous rhythm which is life ending if not corrected immediately.
Ventricular Standstill – Ventricular standstill is the absence of any ventricular activity, a rhythm which is life ending if not corrected immediately.
Ventricular Tachycardia – Ventricular tachycardia is a rapid rate originating in the ventricles which is dangerous and requires immediate correction.
Wolff-Parkinson-White Syndrome – Wolff-Parkinson-White (WPW for short) is a syndrome in which pre-excitation of the ventricles can occur due to impulses traveling through an accessory pathway in the heart from the atria to the ventricles.