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Supraventricular tachycardia, or SVT, causes unexpected and often short-lived heart palpitations. The good news is they are rarely a health threat and most of the time they stop on their own after a few seconds or minutes. However, more serious cases of SVT may require medications or surgery to get the heart back on the beat. Read on to learn more about the symptoms and treatments for SVT.
What is SVT?
Supraventricular tachycardia occurs when the heart occasionally beats too fast for no identifiable reason. A glitch in nerve signals rather than a problem with heart muscles causes the heart to beat too fast (tachycardia).
The heart is divided into four chambers. The two upper chambers, the atria, fill with the blood returning from the body (right atrium) or the lungs (left atrium). A heartbeat begins when the atria contract and push blood into the bottom two chambers—the ventricles. After the ventricles fill with blood, they contract and push blood out to the lungs (right ventricle) or the rest of the body (left ventricle).
Each beat is controlled by a circuit of nerves that begins with a nerve bundle called the sinoatrial node at the top of the right atrium. Sometimes referred to as the heart’s “pacemaker,” this nerve bundle first sends out electrical impulses that cause the two upper chambers to contract. The nerve signal terminates at another node, the atrioventricular node (AV node), a kind of crossing gate to the lower chambers. This node pauses the signal for a tiny fraction of a second as the upper chambers push blood into the lower chambers. The AV node then passes the nerve signal to the ventricles, causing them to contract. This well-timed one-two beat is the basic rhythm of the heart and can easily be heard through a stethoscope.
Supraventricular tachycardia happens when nerve conduction go wrong and the signal to initiate a heartbeat doesn’t come from the SA node as it should. Instead, it comes from the atria or the AV node, the crossing gate from the upper to the lower chambers. This can happen in three ways:
- Atrioventricular nodal reentrant tachycardia (AVNRT), also called paroxysmal supraventricular tachycardia (PSVT), happens when you have two channels through the AV node so that the nerve signal not only passes through the AV node to the lower chambers but simultaneously circles around the AV node back to the atria, causing the upper chambers to contract a second time. Round and round the signal can go, making the upper chambers beat very quickly with a rapid and regular ventricular responseAVNRT is the most common form of SVT among adults, particularly in women and older adults.
- Atrioventricular reciprocating tachycardia (AVRT) happens when the nerve signal passes to the ventricles through the AV node but also an extra electrical connection exists that bridges the atrium and ventricle which can conduct electricity - known as an accessory pathway. The heart can get caught up in a looping circuit where electricity either goes down the AV node and returns back to the atrium through the accessory pathway, or the reverse happens with the signal traveling down the accessory pathway and returns through the AV node. Again, one heartbeat can produce two or more additional heartbeats as the electrical signal cycles back on itself. This is the most common form of SVT found in infants and children.
- Atrial tachycardia occurs when a part of the atria starts firing off stray nerve signals to the AV node, producing extra heartbeats. Unlike AVNRT and AVRT, this type of SVT does not involve reentry through the AV node or ventricle.
SVT should not be confused with atrial fibrillation or atrial flutter. Technically, both are types of supraventricular tachycardias. SVT is characterized by a fast but regular heartbeat. In atrial flutter the atria beat fast and regularly but more often than the ventricles - you may have multiple atrial beats to each ventricular beat. In atrial fibrillation the atria beat fast but irregularly. Heart specialists consider atrial fibrillation and atrial flutter distinct and separate conditions. Most people with SVT have structurally normal hearts, and the condition is usually not a health threat.
A person with atrial fibrillation often has structural problems with their heart and patients are at increased risk for blood clots, stroke, heart failure, or heart attack. However, the symptoms of SVT and atrial fibrillation can be very similar, so intermittent bouts of racing heartbeats should be looked at by a medical professional, just in case.
About 570,000 people in the United States live with supraventricular tachycardia not counting atrial fibrillation. Most people successfully manage their symptoms with either physical maneuvers or prescription drugs.
How is SVT diagnosed?
Supraventricular tachycardia is diagnosed from the patient’s symptoms and an electrocardiogram (ECG), a device that measures the heart’s electrical activity. The most common symptoms of supraventricular tachycardia include:
- Rapid heart rate
- Palpitations
- Chest discomfort
- Lightheadedness
- Feeling faint
- Shortness of breath
Symptoms can be mild to severe. Some patients, however, experience no symptoms at all. However, unless the patient sees a healthcare provider while experiencing symptoms, the condition may not be identifiable on an office visit or ECG. For this reason, the patient’s history of symptoms is vital at arriving at an accurate diagnosis. During a medical history, be prepared to answer questions such as:
- What are your symptoms?
- Do symptoms come on gradually or all at once?
- What triggers symptoms?
- How long do symptoms last?
- Do symptoms occur when you are active or sitting around?
- How old were you when you first had symptoms?
- How often do you have symptoms?
An ECG will provide an accurate diagnosis, but usually during an actual attack in an emergency room or urgent care. In the event of a normal ECG, other diagnostic options include:
Wearing a Holter monitor, essentially a portable ECG to measure and record your heart's activity for 24 hours.
- Taking a stress test while attached to an ECG to see if an attack can be provoked by physical activity on a treadmill.
- Wearing an event monitor that, with a push of a button, allows you to record what is happening when you feel symptoms such as chest pain, dizziness, or palpitations. Electrodes are placed on your chest and are connected by wire leads to the recording device. You generally will wear an event monitor for one month.
A physical examination will help identify signs of other heart problems. Blood tests are usually required, but imaging tests are only used if the doctor suspects there may be other problems with the heart.
SVT treatment options
The treatment of supraventricular tachycardia focuses either on treating symptoms or preventing attacks.
An attack of rapid heartbeats is typically treated with physical maneuvers or a self-administered, as needed “pill-in-the-pocket” approach to restore a slower heartbeat. For emergency and unstable situations, an adenosine injection or electrical cardioversion will rapidly restore a normal heartbeat. For patients with more frequent attacks, daily medications can reduce the incidence of attacks. In certain cases, surgery can restore normal electrical activity to the heart in most patients.
Vagal maneuvers
The vagus nerve slows down the two central nerve nodes in the heart. When the vagus nerve is stimulated, then, the heart rate decreases. It goes to work whenever blood pressure rises in the aorta, the main artery leaving the heart. Vagal maneuvers are physical movements that rapidly increase blood pressure in the aorta to decrease heart rate, and are very effective at stopping SVT attacks in stable patients:
- The Valsalva maneuver Tightly close your mouth, pinch your nose shut, and try to breathe out as hard as you can for 10 to 15 seconds. The Valsalva maneuver is always the first-line treatment for an attack of SVT.
- Cold water Apply ice water to the face for about five seconds. This will restore a normal heart rate in 90% or more of patients with SVT.
Medications
Medications are used to restore a normal heartbeat or to prevent symptoms in patients with SVT. There are two major types of SVT medications. Rate control medications return the heart to a normal pace. Rhythm control medications (arrhythmic drugs) restore an organized heartbeat. Either will be used depending on the type and severity of the patient’s condition.
Cardioversion
In emergencies, unstable patients will undergo electrical cardioversion to rapidly restore a normal heartbeat. Unlike defibrillation—a well-recognized procedure from movies and TV—normalizing an SVT rapid heartbeat requires a low-level shock that is precisely timed to one particular part of the heart’s electrical cycle.
Surgery
Some cases are candidates for surgical treatment, particularly SVT patients with Wolff-Parkinson-White syndrome for whom medications should not be used long-term as they can predispose the patient to the serious and life-threatening complication of ventricular defibrillation. People with this condition are born with an alternate electrical pathway from the upper chambers of the heart to the lower chambers, causing the lower chamber to beat too early, a condition called ventricular preexcitation. Patients with this syndrome frequently have SVT symptoms, as well. However, all types of SVT can be treated with surgery. A catheter (or radiofrequency) ablation destroys the atrial tissues generating or recycling erratic electric signals. A cardiac surgeon feeds a long, flexible tube into a vein until it reaches the upper chambers of the heart. Once there, the surgeon finds tissue in the atria causing or passing on stray electrical signals and uses electrically-generated heat to selectively destroy aberrant nerves. Catheter ablation is 95% successful at preventing SVT attacks.
SVT medications
Medications are used to rapidly restore a normal heartbeat or prevent symptoms. Emergency situations involve a high dose of intravenous medications to rapidly restore a normal heartbeat in an unstable patient. Patients with infrequent but prolonged SVT episodes may be put on a “pill-in-the-pocket,” a self-administered oral medication taken by mouth whenever symptoms occur. Patients with frequent symptoms might be prescribed similar medications that are taken daily to prevent symptoms.
Emergency treatments
In medical emergencies, a doctor will administer a dose of adenosine to rapidly restore a normal heart rate. When taken as an injection, adenosine slows down the AV node, the primary cause of SVT symptoms. If intravenous adenosine does not work, the next step will be intravenous calcium-channel blockers (diltiazem or verapamil), beta-blockers (esmolol or metoprolol), or antiarrhythmic medications (procainamide or amiodarone). All of these drugs slow down the AV node.
Rate control medications
Rate control medications slow the heart down. They can be taken as a “pill-in-the-pocket” to restore a normal heartbeat or taken daily to prevent symptoms. Rate-control medications work by interfering with the chemical processes responsible for nerve conduction in the heart.
- Beta-blockers such as metoprolol slow down nerve signals in the heart’s electrical circuitry by blocking adrenaline (epinephrine). In particular, they slow down the AV node, the part of the heart’s circuit that recycles stray electrical signals that cause the heart to race. They are commonly prescribed to prevent SVT symptoms.
- Certain types of calcium-channel blockers, called non-dihydropyridine calcium-channel blockers (verapamil and diltiazem), specifically slow down nerve signals in the AV node. Like beta-blockers, they are prescribed to prevent SVT symptoms but are also commonly used to alleviate symptoms.
Rhythm control medications
Rhythm control medications, or antiarrhythmic drugs, not only slow down nerves in the heart, they prevent stray electrical signals from recycling through the heart. Drugs such as flecainide, amiodarone, dofetilide, and sotalol are rhythm control medications prescribed by a cardiologist as a “pill-in-the-pocket” to slow a racing heart or in lower doses to ward off symptoms.
What is the best medication for SVT?
The mechanism and symptoms of supraventricular tachycardia can vary widely between patients, so there is no “best” medication for SVT. The management of supraventricular tachycardia will depend on the type of SVT, the symptoms, and the patient’s overall medical situation and tolerance for side effects.
| Best medications for SVT | ||||
|---|---|---|---|---|
| Drug Name | Drug Class | Administration Route | Standard Dosage | Common Side Effects |
| Adenocard (adenosine) | Antiarrhythmic | Intravenous injection | Short term, only. 6 mg as a rapid IV push, may repeat with 12 mg if needed. | Facial flushing, shortness of breath, nausea |
| Cardizem (diltiazem) | Calcium-channel blocker | Oral or injection | Short term: 15 to 20 mg slow IV push, repeat with 20 to 25 mg in 15 minutes if needed. Prevention: 240 to 360mg orally per day. | Swelling, headache, nausea |
| Calan (verapamil) | Calcium-channel blocker | Oral or injection | Short term: 2.5 to 5 mg slow IV push, repeat with 5 to 10 mg every 15 to 30 minutes (maximum dose of 30 mg). Prevention: 240 to 480mg orally per day. | Constipation, dizziness, nausea |
| Lopressor (metoprolol tartrate) | Beta-blocker | Oral or injection | Short term: 5 mg slow IV push, repeat every 5 minutes as needed. Prevention: 25 to 100mg orally twice daily. | Dizziness, slow heart rate, accidental injury |
| Pacerone (amiodarone) | Antiarrhythmic | Oral or injection | Short term: 150 mg IV infusion over 10 minutes; may repeat if SVT recurs. Prevention: 200 to 400 mg orally daily. | Abnormal heart rhythm, fast heartbeat, thyroid problems |
| Betapace (sotalol) | Antiarrhythmic | Oral or injection | Short term: 100 mg slow IV push. Prevention: Dose will be individualized (average dose 160 to 320 mg orally in two divided doses). | Dizziness, fatigue, slow heart rate |
Many of the standard dosages above are from the U.S. Food and Drug Administration (FDA). Dosage is determined by your doctor based on your medical condition, response to treatment, age, and weight. Other possible side effects exist. This is not a complete list.
What are the common side effects of SVT medication?
Different classes of medications have different side effects. However, this is not a complete list, and you should consult with a healthcare professional for possible side effects and drug interactions based on your specific situation.
Adenosine lasts only for a short time in the body, so side effects don’t last long. Adenosine widens blood vessels and lowers blood pressure, so the most common side effects are lightheadedness, flushing, and fainting. Other side effects include shortness of breath, nausea, nervousness, tingling, numbness, and psychological effects. The most serious but rare side effects are heart block, arrhythmia, respiratory problems, and heart attack.
Most rate-controlling medications cause few side effects. They are primarily used to lower blood pressure, so their most common side effects are related to lower blood pressure such as lightheadedness, dizziness, feeling tired, and cold fingers and toes.
Rhythm control medications also reduce blood pressure, so dizziness, lightheadedness, and fatigue are common side effects. Side effects of antiarrhythmic drugs, however, can be serious and hard to manage. Serious side effects include lung or liver damage, irregular or rapid heartbeats, and heart failure.
What is the best home remedy for SVT?
In most people, lifestyle changes and home remedies are enough to manage and prevent supraventricular tachycardia. However, if symptoms persist or breathing becomes difficult, immediate medical help is needed.
Avoid triggers
SVT can happen suddenly with no discernible cause. However, many episodes of SVT are triggered by caffeine, chocolate, alcohol, smoking, medications, stress, lack of sleep, or physical activity. It helps to keep a symptom diary. Whenever you have an attack, note down the time, duration, and what you were doing, drinking, or eating before the attack. This will help you identify triggers so you can take positive steps to ward off attacks.
Eat a balanced and nutritious diet
There is no magic diet for supraventricular tachycardia. It’s enough to say that many minerals and vitamins are necessary for nerves and muscles to function properly. In particular, potassium, magnesium, calcium, and even sodium play an outsized role in nerve conduction and muscle contraction. Too little or too much of these minerals will cause problems. Eat a healthy diet sufficient in nutrients and minerals without overdoing it.
Use vagal maneuvers
When your heart starts racing, you can slow it down by stimulating the vagus nerve. This nerve tells the heart to slow down whenever blood pressure rises in the aorta, the main “exit” corridor from the heart to the rest of the body. The Valsalva maneuver is often successful at reducing a fast heartbeat: pinch your nose, close your mouth, and either attempt to breathe out hard or bear down like you’re going to the bathroom. Coughing, gagging, curling the knees up to the face, and putting your face in ice-cold water also stimulate the vagus nerve.
Frequently asked questions about SVT
What triggers an SVT episode?
While many episodes of SVT occur without any identifiable reason, SVT can be triggered in many people by caffeine, smoking, stress, physical activity, medications, or alcohol.
What is the drug of choice for supraventricular tachycardia?
The symptoms of SVT can vary widely both in their frequency and severity. Many people with SVT do not need drugs. When drugs are necessary, doctors will use heart rate medications to slow down the heart or heart rhythm medications to both slow down the heart and block stray electrical signals that are causing the heart to beat fast.
What happens if SVT goes untreated?
In most patients, untreated SVT may not be a medical problem if episodes are infrequent, brief, and easily controlled by vagal maneuvers. If SVT episodes are frequent, long-lasting, or uncontrolled, there is a risk the heart will reform, eventually leading to heart failure. A severe episode can lead to oxygen deprivation and even heart attack. If SVT symptoms include changes in mental status, chest pain, low blood pressure, or shock, seek immediate medical help.
What foods to avoid if you have SVT?
Both caffeine—found in tea, coffee, and soda—and theophylline—found in chocolate—increase nerve activity in the heart, so they are the most common triggers for SVT. Drinking excessive amounts of alcohol is also strongly linked to SVT episodes, a condition nicknamed “holiday heart syndrome.”
How serious is SVT?
If SVT episodes are infrequent and short-lived, patients can live with the condition safely without drugs or surgery. Surgical or medical management may be necessary if episodes are frequent, long-lasting, or decrease the patient’s quality of life. However, a severe or uncontrolled SVT episode is a medical emergency.
How do you stop SVT attacks?
In most people, the heart rate can be brought under control with vagal maneuvers. These are physical exercises that stimulate the body’s involuntary nervous system to slow down the heart. These include the Valsalva maneuver, curling the knees to the face, coughing, gagging, or applying ice water to the face for a few seconds.
Can SVT cause sudden death?
A severe SVT attack can cause sudden death, but this happens only very rarely. Most patients at risk of severe SVT attacks will be treated appropriately to minimize the risk.
Can you die from SVT?
A severe and uncontrolled attack of SVT can cause oxygen deprivation and even a heart attack. If an SVT episode involves altered mental status, unconsciousness, low blood pressure, or shock, a trip to the emergency department is required.
Can SVT go away on its own?
SVT episodes go away on their own, but the underlying condition does not.
Can SVT make you tired?
Feeling tired is a symptom of SVT, but the symptoms people experience vary.
Can losing weight help SVT?
SVT is caused by a problem with the electrical circuits in the heart. While weight loss is always a good idea, it will not fix the nerve glitch that causes SVT symptoms. That being said, many SVT episodes are triggered by exertion. Excess weight or a sedentary lifestyle can make many daily activities more strenuous than they should be. In that context, losing weight and exercise can help reduce SVT episodes.
Is SVT hereditary?
SVT is a problem with the heart’s electrical circuitry. The problem may be hereditary in some people, but for others, the cause is usually a mystery.
Related resources for SVT
- Supraventricular tachycardia CardioSmart: American College of Cardiology.
- Supraventricular tachycardia Circulation. 2002 Dec 17;106(25):e206-e208.
- Supraventricular Tachycardia Stanford Health Care.
- Supraventricular Tachycardia StatPearls.
- Supraventricular tachycardia: information from your family doctor American Family Physician