One of the most common arrhythmias is a sinus arrhythmia. It involves cyclic changes in the heart rate during breathing. It is very common in children and often found in young adults. Patients with sinus arrhythmia do not experience any cardiovascular symptoms.

Premature Atrial Contractions (PACs) are amongst the most common forms of arrhythmias.  It is due to the premature discharge of an electrical impulse in the atrium, causing a premature contraction. 

Therefore, it is named “premature atrial contraction,” or PAC.  A PAC is premature, because the it occurs earlier than the next regular beat should have occurred.

Problems with the heart’s electrical system, called arrhythmias, can make it hard for the heart to pump blood efficiently.

Introduction

Atrial fibrillation (AF) is an irregular and often rapid heart rate that commonly causes poor blood flow to your body. Although AF itself usually isn’t life-threatening, it is a serious medical condition. 

Inappropriate sinus tachycardia (IST) is a condition in which the resting heart rate is abnormally high (greater than 100 beats per minute), and increases rapidly with minimal exertion, accompanied by symptoms of palpitations, fatigue, and exercise intolerance.

Palpitations are feelings that your heart is skipping a beat, fluttering, or beating irregularly, too hard or too fast. Some will be diagnosed by your doctor as Premature Ventricular Contractions (PVCs). PVCs are an arrhythmia and relatively common. Some people are very sensitive and feel every abnormal heart beat; others are blissfully unaware of them.

In this condition, the normal heartbeat passing from the hearts upper to lower chambers is interrupted. This result in a condition called a “heart block.” When a heart block occurs the heart rate usually slows considerably. This can result in inadequate blood flow to the brain and fainting.Take a look at this animation of your heart’s electrical system for a better understanding of what happens normally:

Take a look at this animation of your heart’s electrical system for a better understanding :

POTS is a condition in which a change from supine to an upright position causes an abnormally large increase in heart rate, called tachycardia.

Ventricular tachycardia (VT) is a rapid heartbeat that starts in the ventricles of your heart, with a pulse rate of more than 100 beats per minute and at least three irregular heartbeats in a row.

Long QT syndrome (LQTS) is a disorder of the heart’s electrical activity. It may cause you to develop a sudden, uncontrollable, and dangerous heart rhythm called an arrhythmia in response to exercise or stress.

Arrhythmias also can develop for no known reason in people who have LQTS. Not everyone who has LQTS develops dangerous heart rhythms. However, if one does occur, it may be fatal.

Ventricular fibrillation (VF) is an uncontrolled twitching or quivering of the muscle fibers of the lower chambers of your heart. During ventricular fibrillation, blood is no longer pumped out of your heart.