What Is A Heart Arrhythmia

What Is A Heart Arrhythmia? Heart arrhythmia is defined as an abnormally patterned series of heart beats which tend to be either very slow (bradyarrhythmia) or too fast (tachyarrhythmia) and produced by electrical impulses travelling in the heart through a faulty electrical circuitry.

  • Heart Arrhythmia is usually caused by underlying heart disorders.
  • Palpitations associated with arrhythmias are occasionally felt by some people, but often, weakness and fainting are the only symptoms felt.
  • Electrocardiography (ECG) can diagnose arrhythmia
  • Treatment focuses on restoring the normal rhythm of the heart and preventing recurrence.

Heart is a strong, muscular pump that works round the clock and non-stop throughout the entire lifespan of a person. This four- chambered organ pumps out blood to the entire body, by a series of contractions with a definite pattern and a regular rhythm.

Contraction of the heart is an electrically controlled process with a series of well orchestrated events, starting with an electric pulse originating in the upper right chamber of the heart, at a point called the sinoatrial node. Heart rate is determined by the frequency at which this electric pulse is discharged, which in turn is controlled by specific hormones and the impulses from nerves.

Autonomic nervous system, consisting of a sympathetic division and a parasympathetic division, automatically regulates the heart rate. While the sympathetic system acts through a group of nerves called sympathetic plexus to increase the heart rate, the parasympathetic division acting through the vagus nerve has the opposite action; that of decreasing heart rate.

The rate at which the heart beats can be affected by hormones delivered into the bloodstream by the sympathetic nervous system. These hormones include the Thyroid hormone produced by the thyroid gland, epinephrine (adrenaline) produced by the adrenal gland, and norepinephrine (noradrenaline). All these hormones cause the heart to beat faster.

The usual heart rate for an adult when idle varies between 60 bpm to 100 bpm (beats per minute).The heart rate is sometimes lower in healthy, younger adults.

Exercise and other strenuous physical activity cause the number of beats per minute to increase. Emotions which activate the sympathetic nervous system, such as anger, love or pain also increase the heart rate by secreting sympathetic hormones like adrenaline.

When the heart rate is considerably low it is called bradycardia and when it is high, it is called tachycardia. Both are abnormal heart rhythms or arrhythmias. When the beat is irregular or when the electric impulse follows a faulty circuit across the heart; then again, they are arrhythmias.

Normal Electrical Pathway

The sinoatrial node in the right atrium, which can be called the pacemaker of the heart, is the starting point of the electrical activity. The electrical impulse that starts in the sinoatrial node travels across the right atrium and then the left atrium, making them contract, pushing the blood into the ventricles. When the electrical impulse is picked up by the atrioventricular node, it is delayed there, to allow time for the complete contraction of the atria and the maximum filling up of the ventricles.

From the atrioventricular node, after a brief delay, the current passes into the Bundle of His. This bundle of fibers branches out into left and right bundles and pass into respective ventricles and spread out, causing the ventricles to contract, and pump blood out of the heart.

Causes of heart arrhythmia

Disorders of the heart such as coronary artery disease, valve defects and heart failure are the major causes of heart arrhythmias, especially coronary artery disease that affects the blood supply to the muscular walls of the heart. Sometimes arrhythmia has its roots in certain congenital abnormality in the anatomy of the heart. Certain medications, including several of those used in the treatment of heart disorders, are also known to cause arrhythmias. Excessive levels of thyroid hormone may increase heart rate resulting in tachyarrhythmia while low levels of the same hormone may result in bradyarrhythmia. An ageing heart is also more prone to arrhythmias due to possible deterioration in the electrical transmission system of the heart.

Symptoms of heart arrhythmia

Awareness of heartbeats or the feeling of the heart thumbing inside the chest is called palpitations. Irregular heart rhythm (arrhythmias), especially an abnormally fast heart beat (tachyarrhythmia) is the usual reason for this feeling of awareness; but it can vary from person to person. Everybody feels a racing heart in very stressful situations, but a few people feel their normal heartbeats too, as do most people when they are lying on the left side (or right side, if they have situs inversus or reversed body symmetry).

Arrhythmia can often be quite harmless even when their symptoms are severe. On the other hand, extremely dangerous arrhythmias can be asymptomatic too. Seriousness of an arrhythmia cannot be gauged by the symptoms exhibited. In other words, the heart disorders that cause the arrhythmia are of greater importance than the symptoms arrhythmia precipitates, however severe they are.

Arrhythmias interfering with the pumping action of the heart produce various symptoms such as shortness of breath, fatigue, a dizzy and light-headed feeling or even fainting. Fainting (syncope) is due to lowering of blood pressure resulting from the inability of the heart to pump out adequate quantity of blood. Such arrhythmia, if prolonged, can be fatal. Arrhythmias can worsen the symptoms of the heart disorder that is causing it, such as shortness of breath and chest pain and such situations call for immediate attention.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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