This sends out electrical impulses through the atrial muscle to another clump of cells called the atrioventricular AV node, found between the atria and ventricles. The impulse then continues through the AV node down fibres that conduct the impulse into the muscle of the ventricles.
The AV node determines the rate of contraction of the ventricles. The pulse felt at the wrist is due to the contraction of the ventricles. If your GP suspects that you have supraventricular tachycardia SVT , they may ask you to have an electrocardiogram and refer you to a heart specialist.
An electrocardiogram ECG is a test that records the rhythm and electrical activity of your heart. Small stickers electrodes are stuck to your arms, legs and chest, and connected via wires to an ECG machine. Every time your heart beats, it produces tiny electrical signals. An ECG machine traces these signals onto paper. Your heart rate during SVT may be as high as beats per minute, but is usually between and ECGs are usually done in hospital or in your GP's surgery. It takes about five minutes and is painless.
The diagnosis of SVT can then be confirmed and other conditions ruled out. However, it may be difficult to capture an attack. So your doctor may ask you to wear a small, portable electrocardiogram monitor that will record your heart rate either continuously over 24 hours, or when you switch it on at the start of an attack. Further tests may be done once episodes of SVT are confirmed. These aim to determine the exact location within the heart that is triggering the episodes of SVT.
For example, you may be asked to take part in a electrophysiology study done under sedation, in which doctors pass electrodes soft flexible wires up through a vein in your leg to your heart. These electrodes measure the electrical signals in your heart and enable doctors to determine where the abnormal signals are coming from.
In many cases, the symptoms of supraventricular tachycardia SVT stop quickly and no treatment is needed. If treatment is needed, you will have to go to hospital. If symptoms last for a long time or are severe, a medicine — usually adenosine — can be injected into your vein, which blocks the abnormal electrical impulses in your heart. When adenosine is not recommended — for example, if you have asthma — an injection of verapamil can be given instead.
Electric shock treatment called cardioversion is occasionally used to stop an episode of SVT. A machine called a defibrillator applies an electrical current to your chest. This is usually done under general anaesthetic you are put to sleep. Catheter ablation is an extremely effective procedure that produces small scars in your heart that block the electrical signal travelling around the abnormal electrical circuit.
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Tachycardia July 1, Research health conditions Check your symptoms Prepare for a doctor's visit or test Find the best treatments and procedures for you Explore options for better nutrition and exercise Learn more about the many benefits and features of joining Harvard Health Online ». Sign Me Up. Print This Page Click to Print. Free Healthbeat Signup Get the latest in health news delivered to your inbox! By correlating all of this information, and looking at the symptoms your daughter experiences at the moment that a tachycardia episode is occurring, a physician can confirm what type of tachycardia your daughter has, reassure you about whether it is dangerous or not, and recommend the best options for treatment.
But if the episodes happen fairly often, last a long time, or cause a lot of anxiety, then treatment may be beneficial and reassuring. Depending on the type of tachycardia, treatment options might include antiarrhythmic medications or a procedure called catheter ablation, which permanently eliminates the tissue that was causing the short-circuit in the electrical pathway.
For many arrhythmias, catheter ablation is first-line therapy, correcting the problem and allowing people to avoid daily medications and their potential side effects. Another opinion is always worthwhile if there is concern about the initial evaluation, or if procedures are recommended that you have questions about or are uncomfortable with. In addition, the conditions that cause the life-threatening types of tachycardias are often treatable.
Ask an Expert: Is Tachycardia dangerous? Find out: What is tachycardia? SVT is also called paroxysmal supraventricular tachycardia. A normal heart rate is 60 to beats per minute. A heart rate of more than beats per minute is called a tachycardia tak-ih-KAHR-dee-uh. During an episode of SVT , your heart beats about to times per minute, but it can occasionally beat faster or slower. Most people with supraventricular tachycardia live healthy lives without restrictions or treatment.
For others, lifestyle changes, medication and heart procedures may be needed to control or eliminate the rapid heartbeats and related symptoms.
The main symptom of supraventricular tachycardia SVT is a very fast heartbeat beats a minute or more that may last for a few minutes to a few days. The fast heartbeat may come and go suddenly, with stretches of normal heart rates in between. Some people with SVT have no signs or symptoms at all. In infants and very young children, signs and symptoms may be difficult to identify. They include sweating, poor feeding, pale skin and a rapid pulse.
If your infant or young child has any of these symptoms, ask your child's doctor about SVT screening. Supraventricular tachycardia is generally not life-threatening unless you have heart damage or other heart problems.
However, in extreme cases, an episode of SVT may cause unconsciousness or cardiac arrest. Call your doctor if you have an episode of a very fast heartbeat for the first time, and if the abnormal heartbeat lasts longer than a few seconds. Some signs and symptoms may be related to a serious health condition.
Call or your local emergency number if you have an episode of SVT that lasts for more than a few minutes, or if you have an episode with any of the following symptoms:. SVT occurs when the electrical signals that coordinate your heartbeats don't work properly. For some people, a supraventricular tachycardia episode is related to an obvious trigger, such as exercise, stress or lack of sleep. Some people may not have a noticeable trigger. In a typical heart rhythm, a tiny cluster of cells at the sinus node sends out an electrical signal.
The signal then travels through the atria to the atrioventricular AV node and into the ventricles, causing them to contract and pump blood. Supraventricular tachycardia is an abnormally fast heartbeat. It occurs when faulty electrical connections in the heart set off a series of early beats in the upper chambers of the heart atria.
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