Arrhythmias
Supraventricular tachycardia SVT
Supraventricular tachycardia, usually shortened to SVT, is a fast heart rhythm that starts above the ventricles, in the upper part of the heart. Symptoms vary widely from one person to another, so some people are very aware of an episode while others barely notice one. Short bouts of SVT can be common, and can usually be treated very easily.
What supraventricular tachycardia is
An SVT is a fast heart rhythm that originates above the ventricles, but not always in the same way as an atrial tachycardia. Tachycardia simply means a heart rate that is faster than normal, and in adults a resting heart rate above 100 beats per minute is generally considered tachycardia. The word supraventricular describes where the rhythm begins, which is in the upper part of the heart rather than in the main pumping chambers.
Your heart relies on a precise electrical system to control each heartbeat. Arrhythmias are heart rhythm or conduction issues whereby the electrical conduction of the heart is affected, and these rhythms can take many different forms, affecting both the upper and lower chambers of the heart. The upper chambers, the atria, primarily receive blood into the heart before it is pumped by the lower chambers, the ventricles, to either the lungs or the rest of the body.
Atrial arrhythmias can cause a wide range of symptoms including shortness of breath, palpitations and dizziness. Treatment options for SVT are personalised to the patient and the symptoms they experience, which is why two people with the same label on their record may be managed quite differently.
The forms of SVT most often seen
Atrial tachycardia is a form of SVT that occurs when an electrical signal emerges from another section of the atria and causes a rapid repeating beat, which means that the atria beat very fast. Atrial tachycardias can be worrying if they continue for a long period, because the rapid signals may be transmitted to the ventricles, so the heart would beat too fast and blood would not be pumped around the body effectively.
Another form of SVT which is commonly seen is a condition known as Wolff-Parkinson-White syndrome, where electrical conduction in the atria does not follow the normal pathway and uses an extra electrical connection to conduct impulses. A short circuit then forms, which triggers a rapid heart rhythm or tachycardia. This condition might be congenital, meaning it is present from birth, but most symptoms are not present until later on in life.
Sometimes patients may just have a WPW pattern on their ECG but do not suffer from WPW syndrome, which means they do not have irregular heart rhythms. That distinction matters a great deal, because it changes what, if anything, needs treating.
Symptoms you may notice
Symptoms for SVTs vary widely from one person to another. Some people are very aware of an episode, while others describe only occasional fluttering and the rhythm is picked up on a recording instead.
The sensations most often described are these.
Palpitations on their own are common and are frequently harmless. Stress or anxiety, caffeine, poor sleep, dehydration and alcohol can all increase adrenaline levels or affect the heart's electrical activity, leading to temporary changes in rhythm. What matters is the pattern of symptoms, how they feel and when they occur, which is why recurring episodes are worth having assessed rather than guessed at.
- Palpitations, which people describe as a racing, pounding or fluttering heartbeat
- Shortness of breath
- Dizziness or light-headedness
- A sense that the heartbeat is unusually fast
How SVT is diagnosed
The diagnosis of heart rhythm issues is usually done through an ECG, or a Holter monitor, which is a prolonged ECG recording, to get an understanding of the heart rhythm. The assessment usually begins with a detailed history of your symptoms, because when episodes happen and how they feel is often the most useful information available.
The practical difficulty with SVT is that an episode may not occur during a short clinic visit. This is where longer monitoring becomes particularly valuable, and where wearable technology and remote monitoring tools are increasingly helping to detect irregular rhythms earlier.
Investigations that may be arranged include the following.
Regular ECGs will be conducted to ensure that treatments are successful and effective, so monitoring does not stop once a diagnosis has been made.
- A 12 lead ECG to record the electrical activity of the heart
- An ECG monitor worn at home, over 24 to 48 hours or longer, to capture intermittent symptoms
- An echocardiogram to assess the structure of the heart
How SVT is treated
Short bouts of SVTs or atrial tachycardias can be common, and can usually be treated very easily. Treatment options are personalised to the patient and the symptoms they experience, taking account of how often episodes happen and how much they affect you.
Vagal manoeuvres such as coughing or an ice pack on the face can stimulate the vagus nerve, and this often relaxes and resolves the atrial tachycardia. These should only be used if Dr Jogiya has assessed you and shown you how, because they suit some patients and some rhythms better than others, and they are never a substitute for emergency help.
Medication is a good way to manage the condition, with beta-blockers or calcium channel blockers proving effective at controlling it. Where Wolff-Parkinson-White syndrome is involved, treatment options are based on individual cases and can again range from vagal manoeuvres to medication and, if necessary, a cardioversion or an EP (electrophysiology) study to look at the electrical pathways in more detail.
Any medication, procedure or monitoring plan is discussed with you first, and reviewed as your symptoms change. Nothing on this page is a substitute for a personal assessment.
When to seek help
It is always reasonable to seek advice if you are unsure about your symptoms. Certain features make palpitations more likely to need further assessment.
A common pattern is that patients ignore these symptoms initially, particularly if the episodes settle on their own. Recurring episodes should always be evaluated, because early assessment provides reassurance when the cause is benign and allows timely treatment when it is not.
Call 999 immediately if you have chest pain, if you or someone with you collapses or loses consciousness, or if you become severely breathless. Do not wait to see whether the episode settles.
If your palpitations are frequent or worsening, if they come with dizziness or breathlessness, or if an episode feels different from anything you have experienced before, you can arrange a consultation with Dr Jogiya to discuss the most appropriate assessment for your heart rhythm.
- Palpitations that occur alongside dizziness or fainting
- Palpitations associated with chest discomfort
- Episodes that happen during physical exertion
- Episodes that last for prolonged periods
- Palpitations in someone with known heart disease
Where the figures on this page come from
Every figure above is quoted from one of these. This page is general information, not individual medical advice.
More in arrhythmias
Related conditions he treats.
- Atrial fibrillationAtrial fibrillation, commonly known as AF, is a condition where the atria, or upper chambers of the heart, fire chaotic electrical impulses. This leads the muscle to quiver, or fibrillate, instead of beat, so the heartbeat becomes irregular and is often faster than normal. It is one of the most common heart rhythm issues and around 1.7 million people in the UK have been diagnosed with it.
- Atrial flutterAtrial flutter is a heart rhythm problem that affects the upper chambers of the heart, known as the atria. Instead of beating at a normal pace, the atria beat rapidly, but in a regular and organised pattern rather than a chaotic one. Because the chambers do not have enough time to fill properly, blood is not pumped efficiently from the top chambers to the bottom chambers, which is what leads to shortness of breath.
- Atrial tachycardiaAtrial tachycardia is a fast heart rhythm that starts in the atria, the two upper chambers of the heart. An electrical signal emerges from another section of the atria and causes a rapid repeating beat, which means the atria beat very fast. It is one form of supraventricular tachycardia, or SVT, and short bouts of it can be common.
- Bundle branch blockBundle branch block describes a block in the part of the heart's conduction system known as the bundle branches. These branches carry the electrical impulse from the AV node down to each ventricle, and when one of them is blocked the signal reaches one side of the heart before the other, so the two ventricles no longer contract in step. It is a pattern picked up on an ECG, and mostly it is something monitored rather than actively treated.
- First degree heart blockFirst degree heart block is common, and it can affect anyone at any age. It describes a delay in the electrical signal as it travels from the upper chambers of the heart to the lower chambers, rather than a true blockage. Every signal still gets through, which is why many people notice nothing at all and why the condition is usually diagnosed when testing is being done for something else.
- Second degree heart blockSecond degree heart block is a fault in the heart's electrical wiring, not a blockage in an artery. Some of the electrical signals travelling from the upper chambers of the heart fail to reach the lower chambers, so a heartbeat is occasionally missed. There are two types, known as Mobitz I and Mobitz II, and they are treated very differently.
- Sick sinus syndromeSick sinus syndrome, also called sinus node disease, is a condition where the sinus node, the small area of tissue that acts as the heart's own natural pacemaker, is not functioning properly. Sometimes the node will send an impulse as it should, and sometimes it may not fire an impulse at all, or the impulses may be out of sync. Some patients notice symptoms such as palpitations and shortness of breath, and because the node is unreliable rather than permanently stopped, those symptoms often come and go.
- Tachy brady syndromeTachy brady syndrome is a heart rhythm problem in which the heart rate increases and then decreases spontaneously, without any external influence. Instead of settling at a pace that matches what you are doing, the heart swings between periods of a slow rate and sudden bursts of a fast one. It is closely linked to sinus node disease, and it occurs mostly alongside atrial fibrillation.