The heart uses electrical currents to tell the heart cells when to contract so that they contract in a coordinated fashion. When this orderly flow of electricity is disrupted by a short circuit, abnormal heart rhythms result. Most people with SVT notice a rapid pulsation from the heart beating quickly in the chest. Other symptoms may include: dizziness, fainting, chest tightness or chest pain, difficulty breathing and tiredness. Some patients feel the need to pass water during an attack of SVT or soon afterwards.
SVT is rarely fatal. If SVT causes dizziness or fainting it can be dangerous, particularly if a patient is in a situation where losing consciousness could be dangerous such as up a ladder or driving.
In most cases SVT simply occurs randomly and can not be predicted. In some patients attacks are brought on by exercise, emotion or stimulants such as caffeine or cold tablets. The time between attacks of SVT varies amongst patients. Some patients have attacks several times per day whereas others have an attack only every few years.
In general attacks tend to occur more frequently as the patient gets older. SVT does not usually cure itself. However, sometimes the attacks occur very frequently and at other times less frequently. However, the tendency is for attacks to occur more frequently as the patient gets older. If attacks do not cause severe symptoms, are short lived and not very frequent, no treatment may be required.
However, if attacks are starting to interfere with the activities of daily life treatment should be considered. The two main types of treatment are medication and catheter ablation see below.
It is important not to panic if you have an attack of SVT. If possible sit down and try to relax. Taking deep breaths and holding them may stop the attack of SVT. Fainting syncope. To "catch" an episode, your doctor may give you an ECG monitor to wear at home that will record your heart rhythm over time.
These include:. Holter monitor : a portable ECG you wear continuously for one to seven days to record your heart rhythms over time. Event monitor : a portable ECG you wear for one or two months, which records only when triggered by an abnormal heart rhythm or when you manually activate it. Implantable monitor : a tiny event monitor inserted under your skin, worn for several years to record events that only seldom take place. This test not only diagnoses the condition but also identifies the precise cause.
A diagnostic EP study is always done before catheter ablation , usually as part of the same procedure. With the patient under light sedation, several narrow, flexible wires are threaded through a vein to your heart. Fine wires inside the catheter can help pinpoint any areas outside the sinus node that produce electrical signals, then remove them using catheter ablation.
Valsalva maneuver : In many patients, the tachycardia episode can be stopped by bearing down or rubbing the carotid artery.
Medications : Different types of medications are available, which vary in frequency, side effects, risks and efficacy. Because PSVT does not resolve on its own, medications would be taken for a lifetime.
Catheter ablation : This outpatient procedure is used to treat or cure many types of heart arrhythmia, including PSVT. Catheter ablation is a mature technique known to be safe and effective. Symptoms most often start and stop suddenly. They can last for a few minutes or several hours. Symptoms may include:. A physical exam during a PSVT episode will show a rapid heart rate.
It may also show forceful pulses in the neck. The heart rate may be over , and even more than beats per minute bpm. In children, the heart rate tends to be very high. There may be signs of poor blood circulation such as lightheadedness.
Between episodes of PSVT, the heart rate is normal 60 to bpm. An electrophysiology study EPS may be needed for an accurate diagnosis and to find the best treatment. For longer periods of time, another tape of the rhythm recording device may be used. PSVT that occurs only once in a while may not need treatment if you don't have symptoms or other heart problems.
Long-term treatment for people who have repeat episodes of PSVT, or who also have heart disease, may include:. PSVT is generally not life threatening. If other heart disorders are present, it can lead to congestive heart failure or angina. Disturbances of rate and rhythm of the heart.
In: Kliegman RM, St. Nelson Textbook of Pediatrics. Philadelphia, PA: Elsevier; chap Supraventricular arrhythmias. PMID: pubmed.
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