Supraventricular Tachycardia (SVT): Sudden Fast Heartbeat Explained
Supraventricular tachycardia, or SVT, is when the heart suddenly beats much faster than normal. This article explains symptoms, triggers, tests and treatment options.
Scientist and Chief Medical OfficerDr. Ambed Mishra, PharmD, PhDEducational information only, not medical advice. Always ask a qualified doctor about your own health. In an emergency call 112 (India) or 911 (US). Read the full disclaimer.
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A heartbeat that suddenly races for no clear reason can be alarming. One possible cause is supraventricular tachycardia, or SVT. The NHS says it is not usually serious, but some people may need treatment. This article explains what the NHS says about it.
What is SVT?
SVT happens when the electrical system that controls the heart's rhythm is not working properly. A normal resting heart rate is 60 to 100 beats per minute, the NHS explains. During SVT, the rate suddenly rises above 100 beats per minute, either at rest or during exercise.
Symptoms and how it feels
The NHS says episodes usually last a few minutes but can sometimes last several hours. They may happen several times a day or only once a year. SVT can occur at any age and often starts in children and young adults, but many people have their first symptoms between 25 and 40.
Some people have no other symptoms apart from the fast heartbeat. Others may have:
- Chest pain or discomfort
- Weakness
- Breathlessness
- Light-headedness or dizziness
- Tiredness
MedlinePlus lists paroxysmal SVT among the rhythm problems that a Holter monitor can detect.
What can trigger it?
It can help to notice what was happening around the time of an episode, such as having had a lot of caffeine or alcohol. Writing this down gives your doctor useful clues. The NHS says triggers can include caffeine, alcohol or drugs, but often there is no obvious trigger. That means you may not be able to predict an episode, and it is not necessarily something you did wrong.
How is it checked?
The NHS advises seeing a doctor if fast heartbeats keep happening. A test such as an electrocardiogram (ECG) may be used to find out what is going on. Because episodes can come and go, catching one on a recording can be hard. MedlinePlus explains that a Holter monitor records the heart's rhythm continuously for 24 to 48 hours as you go about normal activities, and you keep a diary of symptoms to match to the recording. Your doctor decides which test is suitable.
Treatment options
The NHS says that if episodes are brief and do not cause problems, treatment may not be needed. Options the NHS describes include:
- Lifestyle changes: cutting down on caffeine or alcohol, and stopping or cutting back on smoking, which can reduce episodes.
- Simple techniques: a doctor may suggest techniques to help stop an episode. These should be learned from a doctor rather than tried without guidance.
- Hospital treatment: for long or frequent episodes, this may include medicines given as tablets or through a vein, cardioversion (a small electric shock to restore a normal rhythm) or catheter ablation, where thin tubes are placed in the heart and heat or freezing is used to correct the electrical fault.
Which option is right depends on how often episodes happen, how long they last and how they affect you. Your doctor makes that decision with you.
When to see a doctor
See a doctor if fast heartbeats keep happening, even if they stop on their own. Many people feel worried or anxious during an episode, and a doctor can explain what is happening and what to do next time. Tell them how often episodes happen and how long they last.
Call emergency services if you have been diagnosed with SVT and an episode lasts longer than usual, or if you have a fast heartbeat with shortness of breath, chest pain or feeling faint. The NHS says not to drive yourself to hospital and to follow the advice of the emergency call handler.
In an emergency, call your local emergency number (112 in India, 911 in the United States).
Common questions
Is SVT serious?
The NHS says it is not usually serious, but some people may need treatment.
How fast is the heartbeat in SVT?
The NHS says the rate suddenly rises above 100 beats per minute. A normal resting rate is 60 to 100.
What triggers SVT?
The NHS says triggers can include caffeine, alcohol or drugs, but often there is no obvious trigger.
How is SVT treated?
The NHS says treatment may not be needed for brief episodes. Others may need lifestyle changes, medicines, cardioversion or catheter ablation, as decided by a doctor.
Important: please read
- Educational information only. This article is general health education. It is not medical advice, diagnosis or treatment. Reading it does not create a doctor–patient relationship with MyDoctor or with anyone else.
- Ask a qualified doctor. Always talk to a qualified, registered doctor about your own health. In India, that means a doctor registered with the National Medical Commission (NMC) or a State Medical Council. In the United States, a licensed physician. Elsewhere, a doctor licensed where you live.
- Never ignore or delay professional advice because of something you read here. Do not start, stop or change any medicine or treatment without your doctor.
- Emergencies: call 112 in India, 911 in the United States, or your local emergency number. Do not wait for an online answer.
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- About the sources. This article summarises, in our own words, information from the public health bodies named under Sources. Health knowledge changes, and this summary may not reflect the latest research or your personal situation.
- Liability. To the extent permitted by law, MyDoctor (MODERNUS HEALTH TECHNOLOGIES PRIVATE LIMITED) accepts no liability for any decision made on the basis of this content.
Sources
- NHS. Supraventricular tachycardia (SVT) - NHS www.nhs.uk
- NIH MedlinePlus. Holter monitor (24 h) - MedlinePlus medlineplus.gov
- NHS. Electrocardiogram (ECG) - NHS www.nhs.uk
Dr. Ambed Mishra, PharmD, PhD
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Dr. Ambed Mishra is a clinical (patient care) scientist, author and former professor. He is Group CEO and Chief Medical Officer of MODERN US HEALTH (MODERN US GROUP), Austin, Texas, the group behind MyDoctor, and a senior consultant who teaches and trains MD/DO physicians, PharmD and PhD professionals, nurses and other healthcare professionals in patient care in the United States and India.
More about Dr. Ambed Mishra
- More than ten years of full-time leadership in United States healthcare, building patient care services that improve medication adherence and bring doctors, pharmacists and nurses together around each patient.
- Leads the MD and engineering teams behind MyDoctor: clinic and hospital management software, electronic health records and telehealth for hospitals and physician groups in the United States and India.
- Former Assistant Professor and Clinical Preceptor at Rajiv Gandhi University of Health Sciences, Bangalore, and senior researcher with hospitals, universities and patient care groups in India and the United States.
- More than 30 published research and review articles and case reports, and more than 15 international conference presentations in India, Australia, Canada, the United States, Spain and other countries.
- Chief Medical Officer and Global Program Head of a nonprofit mission that helps cover hospital and doctor visit bills for patients in need in India, Nepal, the United States and other countries.
The author's office answers questions about articles, research, speaking and collaboration. It cannot give personal medical advice.