ARRHYTHMIAS
Cardiac arrhythmia refers to a group of conditions in which the cardiac muscle contracts irregularly. It may be faster or slower than normal. Arrhythmias arise from problems with the electrical conduction system of the heart. Another term "cardiac dysrhythmia" is considered more suitable to describe the disorder as arrhythmia means "no rhythm". Even though the term cardiac dysrhythmia is more suitable, it is used less frequently. Arrhythmia can occur in the atria / auricles or the ventricles. Ventricular arrhythmias are much more dangerous than atrial arrhythmias. This is because ventricular arrhythmias are more likely to alter the heart's ability to pump blood to all parts of the body.

Sometimes arrhythmias can be life threatening as they can cause cardiac arrest. Some people have long lasting minor arrhythmias that are not dangerous. A temporary arrhythmia can be the result of intake of alcohol or caffeine or due to lack of sleep. The tendency to develop arrhythmias increases after damage to the heart muscle. Damage to the heart muscle may occur due to a heart attack or some infection or due to a congenital heart defect. Congenital defects are defects in the body parts that are acquired from birth. Sinus arrhythmia is the mild acceleration followed by slowing of the normal rhythm that occurs with breathing. The sino-atrial node (SA node) controls the rate at which the heart beats.

If the heart rate is faster than 100 beats per minute, it is considered as Tachycardia. When the body is physically exerted, the sinus node increases its rate of electrical activity to accelerate the heart rate. This is done to supply more amounts of oxygen and nutrients to the tissues. The normal fast rate that results is termed as Sinus Tachycardia. It can be dangerous if the ventricles of the heart experience tachycardia for long periods of time. Persons with tachycardia experience a pounding sensation of the heart in the chest region. These sensations are referred to as palpitations. Tachycardia may at times lead to lowering of blood pressure. Dizziness or fainting may result from lowering of blood pressure from tachycardia. At times tachycardia can be so fast that the heart cannot function. This leads to sudden death. Causes of tachycardia include stress, ingestion of substances like caffeine or alcohol and hyperthyroidism. Any substance that increases the amount of adrenaline in the blood or the effects of adrenaline on the heart can cause tachycardia and palpitations.

A slow rhythm is termed as Bradycardia. Bradycardia is usually not life threatening but may cause evident symptoms. Implantation of a permanent pacemaker is a solution to bradycardia if the symptoms are evident.

A serious variety of arrhythmias is fibrillation. Fibrillation occurs when the heart muscle starts a quivering motion instead of a normal healthy pumping rhythm. Atrial fibrillation is the chaotic, quivering motion of the atria. Atrial fibrillation is not typically a medical emergency. Ventricular fibrillation occurs in the ventricles and is imminently life threatening. If left untreated, ventricular fibrillation can lead to death within minutes. When a heart goes into ventricular fibrillation, effective pumping of blood to all parts of the body is hampered. Ventricular fibrillation is considered as a form of cardiac arrest and a person suffering from it will not survive unless cardiopulmonary resuscitation and defibrillation are provided immediately.

Cardiac dysrhythmias are often detected by auscultation of the heart beat with a stethoscope or feeling for peripheral pulse. These cannot give indication of specific dysrhythmias but only give a general indication. Specific dysrhythmias are detected using an electrocardiogram. A Holter monitor is an ECG recorded over a 24 hour period to detect dysrhythmias.