What are arrhythmias?
The content of this page is for basic information only. If you have any concerns about your own heart rate you should seek advice from your GP.
The term arrhythmia refers to problems that affect the electrical system of the heart muscle, producing abnormal heart rhythms. They can cause the heart to pump less effectively.
Some arrhythmias are so brief (for example, a temporary pause or premature beat) that the overall heart rate or rhythm isn't greatly affected. But if arrhythmias last for some time, they may cause the heart rate to be too slow or too fast or the heart rhythm to be erratic.
The heart is a muscle that works like a pump and divided into four chambers. The top two are the atria, and the lower two are the ventricles. Normally the heartbeat starts in the right atrium when a special group of cells sends an electrical signal. (These cells are called the sinoatrial or SA node, the sinus node or the heart's "pacemaker.") This signal spreads throughout the atria and to the atrioventricular (A-V) node. The A-V node connects to a group of fibers in the ventricles that conduct the electrical signal. The impulse travels down these specialized fibers (the His-Purkinje system) to all parts of the ventricles. The electrical signal must follow this exact route for the heart to pump properly.
Under some conditions almost all heart tissue can start a heartbeat. In other words, another part of the heart can become the pacemaker. An arrhythmia occurs...
- when the heart's natural pacemaker develops an abnormal rate or rhythm.
- when the normal conduction pathway is interrupted.
- when another part of the heart takes over as pacemaker.
What is a normal heart rate or pulse?
The term tachycardia refers to a heart rate of more than 100 beats per minute. Bradycardia describes a rate of less than 60 beats per minute.
I suffer from tachycardia however I have included a brief description of bradycardia purely for your information.
What are the symptoms and treatments for a slow heartbeat?
A heart rate of less than 60 beats per minute is called bradycardia. Physically active people often have a resting heart rate slower than 60 beats per minute. For them, this isn't abnormally slow. Bradycardia doesn't usually require treatment unless there are prolonged or repeated symptoms such as fatigue, dizziness, lightheadedness, fainting or near-fainting spells. These symptoms are usually due to insufficient blood flow to the brain. Elderly people are more prone to problems with a slow heart rate. These symptoms can be treated and, in certain cases, can be corrected by implanting an electronic pacemaker under the skin to speed up the heart rhythm, when the heart rate becomes too slow.
What symptoms and types of tachycardia?
Rapid heart beating, called tachycardia or tachyarrhythmia, can produce palpitations, rapid heart action, chest pain, dizziness, lightheadedness, fainting or near fainting if the heart beats too fast to circulate blood effectively. Heartbeats may be either regular or irregular in rhythm.
Palpitations
Most palpitations are quite harmless although they can be quite unpleasant or even alarming. Everyone experiences them at some time and they have many causes including fear, anger, exercise, fever, stomach upsets or drinking alcohol and do not have cause for concern.
However, some palpitations are caused by disease or an underlying heart rhythm disorder. These palpitations may be particularly unpleasant as the heartbeat may be very fast, very slow or very irregular. Bouts of palpitations may last for seconds, minutes or even hours. Some people have very rare attacks; others have attacks every day. Many attacks occur suddenly and unexpectedly but a few may be provoked by specific circumstances such as anxiety or exercise. Palpitations that cause symptoms such as sweating, faintness, chest pain or dizziness usually indicate that there is an upset in heart rhythm that needs further investigation.
Types
There are many different types of heart rhythm disorders however for the purposes of this website I have only identified the classifications by the areas of origin. For further information click here.
Atrial tachycardia
Atrial tachycardia is an electrical circuit originating in the upper or atrial chambers. This electrical circuit or focus takes over and generates rapid impulses across the atrial chambers. These impulses are transmitted to the ventricular chambers resulting in a rapid rate. These arrhythmias may originate from a variety of places across the atria. They may exist as an isolated problem or be related to an ongoing structural problem within the heart. Rapid heart beating can be controlled with medications or by identifying and destroying the focus of rhythm disturbances.
Ventricular tachycardia
When rapid heart beating starts in the ventricles — called ventricular tachycardia — it can interfere with the heart's ability to pump enough blood to the brain and other vital organs. This dangerous arrhythmia can change without warning into the most serious heart rhythm disturbance — ventricular fibrillation. In this, the lower chambers quiver and the heart can't pump any blood. Ventricular tachycardia may become an emergency situation and requires emergency treatment, electrical defibrillation or cardioversion (electric shock), or intravenous anti-arrhythmic medications. Ventricular fibrillation is very serious. Collapse and sudden cardiac death will follow in minutes unless medical help is provided immediately.
Next page: Arrhythmia Facts