What is an arrhythmia?
An arrhythmia is an abnormal heart rhythm. Arrhythmias can cause your heart to pump less effectively. Sometimes arrhythmias also are called dysrhythmias. Arrhythmias can cause problems with contractions of the heart chambers by:
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not allowing the ventricles (lower chambers) to fill with an adequate amount of blood because the electrical signal is causing the heart to pump too fast.
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not allowing a sufficient amount of blood to be pumped out to the body because the electrical signal is causing the heart to pump too slowly or too irregularly.
In any of these situations, the body may not receive enough blood because the heart cannot pump out adequate amounts with each beat.
What are the symptoms of an arrhythmia?
It’s important to know that the symptoms of arrhythmias may resemble other conditions and some may even go unnoticed. Other arrhythmia’s may cause symptoms that range from a mild flutter to even fainting. Some symptoms of arrhythmias include, but are not limited to:
What causes arrhythmia to occur?
Arrhythmias may be caused by many different factors, including:
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Electrolyte imbalances in your blood (such as sodium or potassium)
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Changes in your heart muscle
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Advanced age
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Congenital (present from birth)
To better understand arrhythmias, is it helpful to understand the heart's electrical conduction system.
The heart is, in the simplest terms, a pump made up of muscle tissue. The heart's pumping action is regulated by an electrical conduction system that coordinates the contraction of the various chambers of the heart.
How does the heart beat?
An electrical stimulus is generated by the sinus node (also called the SA node), which is a small mass of specialized tissue located in the right atrium (right upper chamber) of the heart. The sinus node generates an electrical stimulus regularly (60-100 times per minute under normal conditions). This electrical stimulus travels down through the conduction pathways (similar to the way electricity flows through power lines from the power plant to your house) and causes the heart's lower chambers to contract and pump out blood. The right and left atria (the two upper chambers of the heart) are stimulated first and contract a short period of time before the right and left ventricles (the two lower chambers of the heart).
The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node), where impulses are slowed down for a very short period, then continue down the conduction pathway to provide electrical stimulation to the right and left ventricles.
Normally at rest, as the electrical impulse moves through the heart, the heart contracts about 60 to 140 times a minute, depending on a person's age. Each contraction pushes blood through the heart.
Any dysfunction in the heart's electrical conduction system can make the heartbeat too fast, too slow, or at an uneven rate — causing an arrhythmia.
Are there different types of arrhythmias?
Arrhythmias are classified into two main categories: arrhythmias that begin in the atria and arrhythmias that begin in the ventricles. Let’s take a closer look at these two categories:
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Supraventricular arrhythmias begin in the atria or the upper chambers of the heart.
Atrial fibrillation - You may have heard this condition referred to as “A-fib”. A-fib is a very common heart rhythm disorder. More than 2 million Americans are affected with atrial fibrillation. Individuals with A-fib have a heartbeat that is irregular and/or too fast. Although it is not life threatening, A-fib can lead to other problems, such as fatigue, congestive heart failure or stroke. It’s important to know that the risk of stroke is 5 times greater for those who have A-fib. Learn more about a new, robotic treatment option to treat A-fib at Missouri Baptist.
Atrial flutter (AF) – Similar to A-fib, atrial flutter is characterized by a rapid heartbeat. However, unlike A-fib, this condition is caused by a single electrical wave that circulates very rapidly in the atrium, which leads to a very fast, steady heartbeat.
Sick Sinus Syndrome (SSS) – This is a condition in which the sinus node, your heart’s natural electrical pacemaker, is not working properly. With Sick Sinus Syndrome, the heart may send out electrical signals either too slowly or too fast. There may be alternation between too-fast and too-slow rates. This condition may cause symptoms if the rate becomes too slow or too fast for the body to tolerate.
Sinus tachycardia – Sinus tachycardia is a normal increase in heart rate that happens with fever, excitement and exercise. This condition rarely requires treatment.
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Ventricular arrhythmias begin in the ventricles, or lower chambers of the heart.
Ventricular tachycardia (VT) - A life-threatening condition in which an electrical signal is sent from the ventricles at a very fast but often regular rate. If the heart rate is sustained at a high rate for more than 30 seconds, symptoms such as weakness, fatigue, dizziness, fainting, or palpitations may be experienced. A person in VT may require an electric shock or medications to convert the rhythm back to normal sinus rhythm.
Ventricular fibrillation (VF) - A condition in which many electrical signals are sent from the ventricles at a very fast and erratic rate. As a result, the ventricles are unable to fill with blood and pump. This rhythm is life-threatening because there is no pulse and complete loss of consciousness. A person in VF requires prompt defibrillation to restore the normal rhythm and function of the heart. It will result in sudden cardiac death if not treated within seconds.
Long QT Syndrome – This condition is an electric system disorder in which the heart cells take longer than normal to recover electrically after each heartbeat. Individuals with this condition may be at high risk of ventricular fibrillation.
For more information or a physician referral, call (314) 996-LIFE or toll-free, (800) 392-0936. We’ll put you in touch with a cardiac or vascular specialist who can give you the information and guidance you need. We can even make an appointment for you while you’re on the phone.