An arrhythmia (also referred to as dysrhythmia) is an abnormal rhythm of the heart, which can cause the heart to pump less effectively.
Arrhythmias can cause problems with contractions of the heart chambers by:
In any of these situations, the body may not receive enough blood because the heart cannot pump out an adequate amount with each beat as a result of the arrhythmia's effects on the heart rate.
The effects on the body are often the same, however, whether the heartbeat is too fast, too slow, or too irregular. Some symptoms of arrhythmias include, but are not limited to:
The symptoms of arrhythmias may resemble other conditions. Consult your physician for a diagnosis.
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.
An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or 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 via the bundle of His into the ventricles. The bundle of His divides into right and left pathways 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 of the ventricles represents one heartbeat. The atria contract a fraction of a second before the ventricles so their blood empties into the ventricles before the ventricles contract.
Any dysfunction in the heart's electrical conduction system can make the heartbeat too fast, too slow, or at an uneven rate, thus, causing an arrhythmia.
The electrical activity of the heart is measured by an electrocardiogram (ECG or EKG). By placing electrodes at specific locations on the body (chest, arms, and legs), a graphic representation, or tracing, of the electrical activity can be obtained. Changes in an ECG from the normal tracing can indicate arrhythmias, as well as other heart-related conditions.
Almost everyone knows what a basic ECG tracing looks like. But what does it mean?
When your physician studies your ECG, he/she looks at the size and length of each part of the ECG. Variations in size and length of the different parts of the tracing may be significant. The tracing for each lead of a 12-lead ECG will look different, but will have the same basic components as described above. Each lead of the 12-lead is "looking" at a specific part of the heart, so variations in a lead may indicate a problem with the part of the heart associated with the lead.
An atrial arrhythmia is an arrhythmia caused by abnormal function of the sinus node or the atrioventricular node, or by the development of another atrial pacemaker within the atrium that takes over the function of the sinus node.
A ventricular arrhythmia is an arrhythmia caused by an abnormal electrical focus within the ventricles, resulting in abnormal conduction of electrical signals within the ventricles. The sinus node and atrioventricular node may function normally.
Arrhythmias can also be classified as slow (bradyarrhythmia) or fast (tachyarrhythmia). "Brady-" means slow, while "tachy-" means fast.
Listed below are some of the more common arrhythmias:
The symptoms of various arrhythmias may resemble other medical conditions. Consult your physician for a diagnosis.
There are several different types of procedures that may be used to diagnose arrhythmias. Some of these procedures include the following:
Arrhythmias may be present but cause few, if any, problems. In this case, the physician may elect not to treat the arrhythmia. However, when the arrhythmia causes symptoms, there are several different options for treatment. The physician will choose an arrhythmia treatment based on the type of arrhythmia, the severity of symptoms being experienced, and the presence of other conditions (diabetes, kidney failure, heart failure, etc.) which can affect the course of the treatment.
Some treatments for arrhythmias include:
© 2015 Main Line Health
Copyright 2015 Main Line Health
Printed from: www.mainlinehealth.org/oth/Page.asp?PageID=OTH005465