Supraventricular tachycardia (SVT), also called paroxysmal supraventricular tachycardia, is defined as an abnormally fast heartbeat. It's a broad term that includes many forms of heart rhythm problems (heart arrhythmias) that originate above the ventricles (supraventricular) in the atria or AV node.
A normal heart rate is 60 to 100 beats per minute. A heart rate of more than 100 beats per minute is called a tachycardia (tak-ih-KAHR-dee-uh). This occurs when the electrical impulses that coordinate your heartbeats don't work properly. It may feel like a fluttering or racing heart.
Most people with rare episodes of supraventricular tachycardia live healthy lives without restrictions or interventions. For others, treatment and lifestyle changes can often control or eliminate rapid heartbeats.
Supraventricular tachycardia care at Mayo Clinic
Source: http://www.mayoclinic.com
Supraventricular tachycardia may come and go suddenly, with stretches of normal heart rates in between. Symptoms may last anywhere from a few minutes to a few days, and some people have no symptoms at all.
Supraventricular tachycardia becomes a problem when it occurs frequently and is ongoing, particularly if you have heart damage or other coexisting medical problems.
Signs and symptoms of supraventricular tachycardia may include:
In infants and very young children, signs and symptoms may be difficult to identify. Sweating, poor feeding, pale skin and infants with a pulse rate greater than 200 beats per minute may have supraventricular tachycardia.
Supraventricular tachycardia is generally not life-threatening unless you have other heart disorders, but you should talk to your doctor if you are experiencing bothersome symptoms.
Some signs and symptoms, such as shortness of breath, weakness, dizziness, lightheadedness and fainting or near fainting, may be related to a serious health condition.
Seek urgent medical care if you suddenly or frequently experience any of these signs and symptoms at a time when you wouldn't expect to feel them.
In extreme cases, an episode of SVT may cause you to pass out.
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For some people, a supraventricular tachycardia episode is related to an obvious trigger, such as psychological stress, lack of sleep or physical activity. For others, there may be no noticeable trigger. Things that may lead to, or cause, an episode include:
Your heart is made up of four chambers â two upper chambers (atria) and two lower chambers (ventricles). The rhythm of your heart is normally controlled by a natural pacemaker (the sinus node) located in the right atrium. The sinus node produces electrical impulses that normally start each heartbeat.
From the sinus node, electrical impulses travel across the atria, causing the atria muscles to contract and pump blood into the ventricles.
The electrical impulses then arrive at a cluster of cells called the atrioventricular node (AV node) â usually the only pathway for signals to travel from the atria to the ventricles.
The AV node slows down the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood either to the lungs or to the rest of the body.
In a healthy heart, this process usually goes smoothly, resulting in a normal resting heart rate of 60 to 100 beats a minute.
Supraventricular tachycardia occurs when faulty electrical connections in the heart or abnormal areas of electrical activity trigger and sustain an abnormal rhythm. When this happens, the heart rate accelerates too quickly and doesn't allow enough time for the heart to fill before it contracts again. These ineffective contractions of the heart may cause you to feel light-headed or dizzy because the brain isn't receiving enough blood and oxygen.
There are three major types of supraventricular tachycardia:
Other types of supraventricular tachycardia include:
Source: http://www.mayoclinic.com
To diagnose supraventricular tachycardia, your doctor will review your symptoms and your medical history and conduct a physical examination. Your doctor may ask about â or test for â conditions that may trigger your SVT, such as heart disease or a problem with your thyroid gland. Your doctor may also perform heart-monitoring tests specific to arrhythmia. These may include:
If your doctor doesn't find an arrhythmia during those tests, he or she may try to trigger your arrhythmia with other tests, which may include:
Electrophysiological testing and mapping. In this test, doctors thread thin tubes (catheters) tipped with electrodes through your blood vessels to a variety of spots within your heart. Once in place, the electrodes can map the spread of electrical impulses through your heart.
In addition, your cardiologist can use the electrodes to stimulate your heart to beat at rates that may trigger â or halt â an arrhythmia. This allows your doctor to see the location of the arrhythmia and what may be causing it.
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Over time, untreated and frequent episodes of supraventricular tachycardia may weaken the heart and lead to heart failure, particularly if you have other coexisting medical conditions.
In extreme cases, an episode of supraventricular tachycardia may cause unconsciousness or cardiac arrest.
Source: http://www.mayoclinic.com
To prevent an episode of supraventricular tachycardia, it's important to know what triggers the episodes to occur and try to avoid them. You might want to try:
For most people with supraventricular tachycardia, moderate amounts of caffeine do not trigger an episode. Large amounts of caffeine should be avoided, however.
Consider keeping a diary to help identify your triggers. Track your heart rate, symptoms and activity at the time of an SVT episode.
Source: http://www.mayoclinic.com
Research is ongoing regarding the effectiveness of several forms of complementary and alternative medical therapies for supraventricular tachycardia.
Some types of complementary and alternative therapies may be helpful to reduce stress, such as:
Some studies have shown that acupuncture may help reduce irregular heart rates in certain arrhythmias, but further research is needed.
The role of omega-3 fatty acids, a nutrient found mostly in fish, in the prevention and treatment of arrhythmias isn't yet clear. But it appears as though this substance may be helpful in preventing and treating some arrhythmias.
Source: http://www.mayoclinic.com
Your doctor may suggest that, in addition to other treatments, you make lifestyle changes that will keep your heart as healthy as possible.
These lifestyle changes may include:
Source: http://www.mayoclinic.com
Supraventricular tachycardia is the most common type of arrhythmia in infants and children. It also tends to occur twice as often in women, particularly pregnant women, though it may occur in either sex.
Other factors that may increase your risk of supraventricular tachycardia include:
Source: http://www.mayoclinic.com
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