Categories of Arrhythmias (2023)

Arrhythmias are generally divided into two categories: ventricular and supraventricular.

En español

Ventricular arrhythmias occur in the lower chambers of the heart, called the ventricles. Supraventricular arrhythmias occur in the area above the ventricles, usually in the upper chambers of the heart, called the atria. The irregular beats can either be too slow (bradycardia) or too fast (tachycardia).


Bradycardia is a very slow heart rate of less than 60 beats per minute. It happens when the electrical impulse that signals the heart to contract is not formed in your heart’s natural pacemaker, the sinoatrial node (SA node), or is not sent to the heart’s lower chambers (the ventricles) through the proper channels.

Bradycardia most often affects elderly people, but it may affect even the very young. It may be caused by one of two sources: The central nervous system does not signal that the heart needs to pump more, or the SA node may be damaged. This damage might be related to heart disease, aging, inherited or congenital defects, or it might be caused by certain medicines—including those used to control arrhythmias and high blood pressure.


Tachycardia is a very fast heart rate of more than 100 beats per minute. The many forms of tachycardia depend on where the fast heart rate begins. If it begins in the ventricles, it is called ventricular tachycardia. If it begins above the ventricles, it is called supraventricular tachycardia.

Ventricular Tachycardia

Ventricular tachycardia is a condition in which the SA node no longer controls the beating of the ventricles. Instead, other areas along the lower electrical pathway take over the pacemaking role. Since the new signal does not move through your heart muscle along the regular route, the heart muscle does not beat normally. Your heartbeat quickens, and you feel as if your heart is “skipping beats.” This rhythm may cause severe shortness of breath, dizziness, or fainting (syncope).

Ventricular Fibrillation

The most serious arrhythmia is ventricular fibrillation, which is an uncontrolled, irregular beat. Instead of one misplaced beat from the ventricles, you may have several impulses that begin at the same time from different locations—all telling the heart to beat. The result is a much faster, chaotic heartbeat that sometimes reaches 300 beats a minute. This chaotic heartbeat means very little blood is pumped from the heart to the brain and body and can result in fainting. Medical attention is needed right away. If cardiopulmonary resuscitation (CPR) can be started, or if electrical energy is used to “shock” the heart back to a normal rhythm, thenthe heart may not be too damaged. About 220,000 deaths from heart attacks each year are thought to be caused by ventricular fibrillation. People who have heart disease or a history of heart attack have the highest risk of ventricular fibrillation.

(Video) Cardiac Arrhythmias

Premature Ventricular Contractions

A less serious type of ventricular arrhythmia is a premature ventricular contraction (PVC). As the name suggests, the condition happens when the ventricles contract too soon, out of sequence with the normal heartbeat. PVCs (sometimes called PVB for premature ventricular beat) generally are not a cause for alarm and often do not need treatment. But if you have heart disease or a history of ventricular tachycardia, PVCs can cause a more serious arrhythmia. Although most PVCs happen quickly and without warning, they can also happen in response to caffeine, which is found in coffee, tea, sodas, and chocolate. Some kinds of over-the-counter cough and cold medicines may also cause PVCs.

Supraventricular Arrhythmias

Supraventricular arrhythmias begin in the areas above the heart’s lower chambers, such asthe upper chambers (the atria) or the atrial conduction pathways. Generally, supraventricular or “atrial arrhythmias” are not as serious as ventricular arrhythmias. Sometimes, they do not even require treatment. Like PVCs, atrial arrhythmias can happen in response to a number of things, including tobacco, alcohol, caffeine, and cough and cold medicines. The disorder also may result from rheumatic heart disease or an overactive thyroid gland (hyperthyroidism). Supraventricular arrhythmias can cause shortness of breath, heart palpitations, chest tightness, and a very fast pulse.

SupraventricularTachycardia (SVT) or Paroxysmal Supraventricular Tachycardia (PSVT)

Supraventricular tachycardia (SVT) is a rapid, regular heart rate where the heart beats anywhere from 150-250 times per minute in the atria. Another name for SVT is paroxysmal supraventricular tachycardia (PSVT). The word “paroxysmal” means occasionally or from time to time.

Supraventricular tachycardia or PVST happens when electrical signals in the heart’s upper chambers fire abnormally, which interferes with electrical signals coming from the SA node (the heart’s natural pacemaker). The beats in the atria then speed up the heart rate.

This type of arrhythmia is more common in infants and young people. It is also more likely to occur in women, anxious young people, and people who are extremely tired (fatigued). People who drink a lot of coffee or alcohol or who are heavy smokers also have a greater risk.

Atrial fibrillation is a fast, irregular rhythm where single muscle fibers in your heart twitch or contract. It is a main cause of stroke, especially among elderly people. Atrial fibrillation may cause blood to pool in the heart’s upper chambers. The pooled blood can lead to the formation of clumps of blood called blood clots. A stroke can occur if a blood clot travels from the heart and blocks a smaller artery in the brain (a cerebral artery).

For this reason, many patients with atrial fibrillation need antiplatelet therapy. These medicines can prevent blood clots from forming and causing a stroke.

Wolff-Parkinson-White Syndrome

Wolff-Parkinson-White (WPW) syndrome is a group of abnormalities caused by extra muscle pathways between the atria and the ventricles. The pathways cause the electrical signals to arrive at the ventricles too soon, and the signals are sent back to the atria. The result is a very fast heart rate. People with this syndrome may feel dizzy, have chest palpitations, or have episodes of fainting.People with WPW may also be more likely to have episodes of paroxysmal supraventricular tachycardia (PSVT).

Atrial Flutter

Atrial flutter happens when the atria beat very fast, causing the ventricles to beat inefficiently as well.

Premature Supraventricular Contractions

Also called “premature atrial contractions” (PACs), they happen when the atria contract too soon, causing the heart to beat out of sequence.

Postural orthostatic tachycardia syndrome (POTS)

Normally, when a person stands up, the body makes any needed changes to compensate for the gravitational stress of a change in body position. To keep oxygen-rich blood flowing to your brain and upper body, your heart rate increases and the blood vessels in the lower part of your body tighten. In some people, this does not happen, affecting their ability to stand or remain standing. This is called orthostatic intolerance. POTS is one kind of orthostatic intolerance.

(Video) Arrhythmias | Types, Pathophysiology, Diagnosis, Treatment

In patients with POTS, the blood vessels in the lower body do not tighten during standing. Because of gravity, more blood than normal moves toward the lower body. The heart will try to make up for this by beating faster. If the faster heart rate does not help, blood can accumulate in the lower body, meaning less oxygen-rich blood can reach the brain. This can lead to fatigue, lightheadedness, headaches, blurry vision, and fainting.

Heart Block

Heart block takes place when the SA node sends its electrical signal properly, but the signal is not sent through the atrioventricular (AV) node or lower electrical pathways as quickly as it should be. The condition is most often caused by aging or by the swelling or scarring of the heart that sometimes results from coronary artery disease. It can also be caused by cardiac amyloidosis, which is a condition where proteindeposits (called amyloid deposits) take the place of normal heart muscle. There are several types of heart block, and they are named by their degree of severity.

  • First-degree heart block means that impulses are moving through the AV node too slowly.
  • Second-degree heart block means that impulses are traveling through the heart’s atria but are delayed in the AV node. Because of this delay, the ventricles do not beat at the right moment.
  • Third-degree heart block means that no impulses are reaching the ventricles. To make up for this, the ventricles use their own “backup” pacemaker with its slower rate. Because a gap in time is likely to occur between the impulse from the atria and the impulse from the“backup” pacemaker in the ventricles, a person may faint. This is known as a Stokes-Adams attack. Third-degree heart block is very serious and can lead to heart failure or death.


What are the 3 types of arrhythmias? ›

AV nodal re-entrant tachycardia (AVNRT): A fast heart rhythm caused by the presence of more than one pathway through the atrioventricular (AV) node. Atrial tachycardia: A rapid heart rhythm that starts in the atria. Atrial fibrillation: A very common irregular heart rhythm.

How are arrhythmias categorized? ›

Arrhythmia is broadly categorized into bradyarrhythmias and tachyarrhythmia based on the heart rate. They are further divided according to the origin, means of transmission, and syndromes associated with it.

What are the 5 lethal arrhythmias? ›

In this course, you will study ventricular arrhythmias and lethal rhythms. You will learn about Premature Ventricular Contractions, Ventricular Tachycardia, Ventricular Fibrillation, Pulseless Electrical Activity, Agonal Rhythms, and Asystole.

What are the two broad categories of arrhythmias? ›

The main types of arrhythmia are: atrial fibrillation (AF) – this is the most common type, where the heart beats irregularly and faster than normal. supraventricular tachycardia – episodes of abnormally fast heart rate at rest.

What are the six arrhythmias? ›

There are a number of different types of arrhythmias, including atrial fibrillation (AFib), atrial flutter, ventricular tachycardia, paroxysmal supraventricular tachycardia (PSVT), and more.

What are 3 ways arrhythmias may be diagnosed? ›

Tests to diagnose heart arrhythmias may include:
  • Electrocardiogram (ECG or EKG). During an ECG , sensors (electrodes) that can detect the electrical activity of the heart are attached to the chest and sometimes to the arms or legs. ...
  • Holter monitor. ...
  • Event recorder. ...
  • Echocardiogram. ...
  • Implantable loop recorder.
30 Apr 2022

What is the most common type of heart arrhythmia? ›

Atrial fibrillation, often called AFib or AF, is the most common type of treated heart arrhythmia. An arrhythmia is when the heart beats too slowly, too fast, or in an irregular way.

Which type of arrhythmia is the most serious? ›

The most serious arrhythmia is ventricular fibrillation, which is an uncontrolled, irregular beat.

What is classification in ECG? ›

The ECG classification algorithm was based on 19 classes. Features were extracted from the averaged QRS and from the intervals between the detected points. The 12-lead ECG deep learning model found its reference mainly to ECG diagnosis in the automatic classification of cardiac arrhythmias.

What is a Class 3 or Class 4 cardiac condition? ›

Class III - Marked limitation in activity due to symptoms, even during less-than-ordinary activity, e.g. walking short distances (20–100 m). Comfortable only at rest. Class IV - Severe limitations. Experiences symptoms even while at rest.

What are the 3 non shockable rhythms? ›

The two shockable rhythms are ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) while the non–shockable rhythms include sinus rhythm (SR), supraventricular tachycardia (SVT), premature ventricualr contraction (PVC), atrial fibrilation (AF) and so on.

What arrhythmia causes most cardiac arrests? ›

Ventricular fibrillation is a type of arrhythmia and is the most common cause of cardiac arrest. Ventricular fibrillation is a rapid heartbeat in the heart's ventricle, which causes the heart to tremble instead of normally pumping blood.

What are the 2 types of ventricular fibrillation? ›

Fast (type I) VF is associated with a steep APD restitution, a flat CT1 restitution, and wandering wavelets. Slow (type II) VF is associated with a flat APD restitution, a steep CT1 restitution, and spatiotemporal periodicity.

What's the difference between arrhythmia and AFib? ›

Atrial Fibrillation, also called AFib, is the most common form of arrhythmia and occurs more frequently as we age. It happens when the upper chambers quiver rather than beating regularly and effectively. People with AFib often experience palpitations, fatigue, chest discomfort or shortness of breath.

What is the most common arrhythmia in heart failure? ›

Atrial fibrillation (AF) is one of the most common arrhythmias. AF and congestive heart failure (CHF) are frequent co-morbidity in the geriatric population. The probability that AF precedes CHF or vice versa is similar. They can deteriorate each other and make the therapy more difficult.

What are the basic heart rhythms? ›

The QRS complex corresponds to the depolarization of the left and right ventricles. It generally corresponds to the contraction of the ventricles. The T wave corresponds to a repolarization of the ventricles. A sinus rhythm is regular with normal P, Q-R-S, T deflections and intervals.

What is the main cause of arrhythmia? ›

The most common type of arrhythmia is atrial fibrillation, which causes an irregular and fast heart beat. Many factors can affect your heart's rhythm, such as having had a heart attack, smoking, congenital heart defects, and stress. Some substances or medicines may also cause arrhythmias.

What is the difference between heart palpitations and arrhythmia? ›

An arrhythmia is an abnormal heart rhythm, where the heart beats irregularly, too fast or too slowly. A palpitation is a short-lived feeling of your heart racing, fluttering, thumping or pounding in your chest. An occasional palpitation that does not affect your general health is not usually something to worry about.

What is the most common type of arrhythmia in older adults? ›

Atrial fibrillation is the most common sustained arrhythmia, increases with age, and presents with a wide spectrum of symptoms and severity. Paroxysmal, persistent, and permanent forms require very individualized approaches to management.

Which arrhythmia is caused by stress? ›

Stress can contribute to heart rhythm disorders (arrhythmias) such as atrial fibrillation. Some studies suggest that stress and mental health issues may cause your atrial fibrillation symptoms to worsen. High levels of stress may also be linked to other health problems.

What are two life threatening arrhythmias? ›

Arrhythmias that start in the ventricle include ventricular tachycardia and ventricular fibrillation. These are serious, often life-threatening arrhythmias since the ventricles do most of the pumping.

What are the 4 classes of antiarrhythmic drugs? ›

Antiarrhythmic drug classes:
  • Class I - Sodium-channel blockers.
  • Class II - Beta-blockers.
  • Class III - Potassium-channel blockers.
  • Class IV - Calcium-channel blockers.
  • Miscellaneous - adenosine. - electrolyte supplement (magnesium and potassium salts) - digitalis compounds (cardiac glycosides)

What is class 3 antiarrhythmic? ›

Class III antiarrhythmic drugs act by blocking repolarising currents and thereby prolong the effective refractory period of the myocardium. This is believed to facilitate termination of re-entry tachyarrhythmias. This class of drugs is developed for treatment of both supraventricular and ventricular arrhythmias.

What are Class 4 antiarrhythmics used for? ›

WHAT ARE CLASS IV ANTIDYSRHYTHMICS AND HOW DO THEY WORK? Antidysrhythmics, also known as antiarrhythmics, are drugs used to prevent abnormal cardiac rhythms such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation.

What are the 7 steps to interpret an ECG? ›

  • Step 1: Rate.
  • Step 2: Rhythm.
  • Step 3: Axis.
  • Step 4: Intervals.
  • Step 5: P wave.
  • Step 6: QRS complex.
  • Step 7: ST segment-T wave.
  • Step 8: Overall interpretation.
20 Apr 2022

What are the 6 leads of ECG? ›

The information from the limb electrodes is combined to produce the six limb leads (I, II, III, aVR, aVL, and aVF), which view the heart in the vertical plane. The information from these 12 leads is combined to form a standard electrocardiogram.

What are classification codes? ›

Classification codes are a type of categorization for patents which are used to classify the contents of a patent in a uniform manner. There are various different types of classification codes that are used which are used for different kind of patents and in some cases are jurisdiction-specific.

What are the 3 primary cardiac conditions? ›

The most common and serious types of CVD include coronary heart disease, stroke and heart failure.

What are the 3 cardiac conditions? ›

angina – chest pain caused by restricted blood flow to the heart muscle. heart attacks – where the blood flow to the heart muscle is suddenly blocked. heart failure – where the heart is unable to pump blood around the body properly.

Do you shock PEA or asystole? ›

Pulseless electrical activity (PEA) and asystole are related cardiac rhythms in that they are both life-threatening and unshockable cardiac rhythms. Asystole is a flat-line ECG (Figure 27).
Rules for PEA and Asystole.
PEA RegularityAny rhythm including a flat line (asystole).
QRSPossible QRS complex or none detectable.
3 more rows

Is V-tach always pulseless? ›

Is ventricular tachycardia always pulseless? Ventricular tachycardia is not always pulseless. In ventricular tachycardia, the heart rate usually exceeds 100 beats per minute. A normal resting heart rate is 60 to 100 beats per minute.

What rhythms do you shock in ACLS? ›

There are two shockable rhythms and two non-shockable rhythms. The two shockable rhythms are: Ventricular Fibrillation, or VFib. Pulseless ventricular tachycardia, or V-tach.

What two rhythms can you defibrillate? ›

There are two AED shockable rhythms in an electrical-related cardiac arrest: Ventricular fibrillation. Pulseless ventricular tachycardia.

What are the only two rhythms an AED can shock? ›

The computer analyzes the heart rhythm and advises the operator whether a shock is needed. AEDs advise a shock only to ventricular fibrillation and fast ventricular tachycardia. The electric current is delivered through the victim's chest wall through adhesive electrode pads.

Why do we not shock asystole? ›

The Advanced Life Support guidelines do not recommend defibrillation in asystole. They consider shocks to confer no benefit, and go further claiming that they can cause cardiac damage; something not really founder in the evidence.

What rhythm causes sudden cardiac death? ›

The most common heart rhythm at the time of cardiac arrest is an arrhythmia in a lower chamber of your heart (ventricle). Rapid, erratic electrical impulses cause your ventricles to quiver uselessly instead of pumping blood (ventricle fibrillation).

What is the most common type of arrhythmia? ›

Atrial fibrillation, often called AFib or AF, is the most common type of treated heart arrhythmia. An arrhythmia is when the heart beats too slowly, too fast, or in an irregular way.

What is the most fatal arrhythmia? ›

The most common life-threatening arrhythmia is ventricular fibrillation. This is an erratic, disorganized firing of impulses from your heart's ventricles (lower chambers). When this happens, your heart is unable to pump blood. Without treatment, you can die within minutes.

What is the most common arrhythmia in elderly? ›

Atrial fibrillation (AF) is the most frequent arrhythmia with increasing incidence in concordance with aging, reaching up to 10% prevalence in the population over 75 years [1].

What is the difference between arrhythmia and irregular heartbeat? ›

A heart arrhythmia (uh-RITH-me-uh) is an irregular heartbeat. Heart rhythm problems (heart arrhythmias) occur when the electrical signals that coordinate the heart's beats don't work properly. The faulty signaling causes the heart to beat too fast (tachycardia), too slow (bradycardia) or irregularly.

Is arrhythmia a death sentence? ›

The AHA notes that an episode of AFib rarely causes death. However, these episodes can contribute to you experiencing other complications, such as stroke and heart failure, that can lead to death. In short, it's possible for AFib to affect your lifespan. It represents a dysfunction in the heart that must be addressed.

What arrhythmias require a pacemaker? ›

Pacemaker for arrhythmias

The most common reason people get a pacemaker is their heart beats too slowly (called bradycardia), or it pauses, causing fainting spells or other symptoms. In some cases, the pacemaker may also be used to prevent or treat a heartbeat that is too fast (tachycardia) or irregular.

Which heart rhythm can cause death? ›

Without immediate treatment, ventricular fibrillation can cause death within minutes. The condition's rapid, erratic heartbeats cause the heart to abruptly stop pumping blood to the body.

What is the best test for arrhythmia? ›

Electrocardiogram (EKG): This test uses a monitor with electrodes attached to your body to measure your heart's electrical activity for a short time. A standard EKG is best for detecting persistent arrhythmias.

What drugs are used to control irregular heartbeats? ›

Flecainide, sotalol (also a beta blocker) and amiodarone are also commonly prescribed for arrhythmias. They have the ability to terminate an arrhythmia and are usually given to prevent the abnormal rhythm from occurring or reduce its frequency or duration.


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