Supraventricular Tachycardia – Symptoms and Causes
Supraventricular tachycardia (SVT) is when the upper parts of the heart beat too quickly. A normal heart beats 60-100 times per minute, but with SVT, the heart races at 150-220 beats per minute.
The main types of SVT include:
Atrioventricular Nodal Reentrant Tachycardia (AVNRT): This is the most common form of SVT.
Atrioventricular Reciprocating Tachycardia (AVRT): This is the second most common type and appears more often in younger people.
Atrial Tachycardia: This type usually affects people with existing heart disease and does not involve the AV node.
Several less common types of SVT exist:
| Type | Description |
|---|---|
| Sinus nodal reentrant tachycardia (SNRT) | Involves the heart’s natural pacemaker |
| Inappropriate sinus tachycardia (IST) | Heart beats too fast, even at rest |
| Multifocal atrial tachycardia (MAT) | Multiple spots in the atria trigger fast beats |
| Junctional ectopic tachycardia (JET) | Fast rhythm from the junction area |
| Nonparoxysmal junctional tachycardia (NPJT) | Gradual onset fast rhythm |
Many people with SVT don’t need treatment. When needed, treatment might include special movements, medications, procedures, or devices to control heart rhythm.
Signs of SVT
SVT causes a very fast heart rate that can start and stop suddenly. The heart beats 100 or more times per minute, often between 150 to 220 beats per minute. This rapid heartbeat may last from minutes to days.
Common symptoms include:
- Fluttering or pounding feelings in the chest (palpitations)
- Strong pounding sensation in the neck
- Chest pain
- Fainting or near-fainting episodes
- Dizziness or lightheadedness
- Shortness of breath
- Sweating
- Weakness or extreme tiredness
Some people with SVT don’t notice any symptoms at all.
For babies and very young children, SVT symptoms may not be obvious. Watch for:
- Unusual sweating
- Poor feeding
- Changes in skin color
- Rapid pulse
When to Get Medical Help
While SVT isn’t usually life-threatening without existing heart problems, severe cases can lead to sudden cardiac arrest in rare situations.
Contact your doctor if you:
- Experience a very fast heartbeat for the first time
- Have an irregular heartbeat that lasts longer than a few seconds
Seek emergency care (call 911) if you have a rapid heartbeat that lasts more than a few minutes, especially when combined with:
- Chest pain
- Dizziness
- Trouble breathing
- Weakness
These symptoms could indicate a serious condition that needs immediate medical attention.
Causes
The heart relies on electrical signals to create a steady rhythm. In a healthy heart, these signals start in the sinus node, a group of special cells in the upper right chamber.
This natural pacemaker sends electrical impulses that travel across the upper chambers (atria).
When these signals reach another cell group called the AV node, they typically slow down before continuing to the lower chambers (ventricles). This careful timing ensures the heart fills with blood properly before pumping it out to the body.
A normal resting heart beats about 60 to 100 times per minute. This controlled rhythm keeps blood flowing smoothly through your body.
Supraventricular tachycardia (SVT) disrupts this process. The electrical signals start too early in the upper chambers, causing the heart to beat much faster than normal—often 150 to 220 beats per minute.
At these high speeds, the heart doesn’t have enough time to fill properly with blood between beats. This can lead to symptoms like:
- Dizziness
- Lightheadedness
- Shortness of breath
- Chest discomfort
The heart has four main chambers working together:
| Upper Chambers | Lower Chambers |
|---|---|
| Right atrium | Right ventricle |
| Left atrium | Left ventricle |
When SVT occurs, this carefully balanced system becomes disrupted by faulty electrical signaling, creating a racing heartbeat that affects how efficiently your heart can pump blood.
Risk Factors
Several health conditions may raise your chances of developing supraventricular tachycardia (SVT). SVT occurs more frequently in women, especially during pregnancy, and is the most common heart rhythm disorder in infants and children.
Medical conditions that increase SVT risk include:
- Heart problems (coronary artery disease, valve disease, heart failure)
- Congenital heart defects
- Previous heart surgery
- Obstructive sleep apnea
- Thyroid disease
- Uncontrolled diabetes
Certain medications, particularly those for asthma, allergies, and colds, may trigger SVT episodes.
Lifestyle factors also play a role in SVT risk:
| Risk Factor | Details |
|---|---|
| Emotional stress | Can trigger episodes |
| Caffeine | Excessive consumption increases risk |
| Alcohol | More than 14 drinks weekly (men) or 7 drinks weekly (women) |
| Nicotine | Smoking and other forms of nicotine use |
| Stimulants | Drugs like cocaine and methamphetamine |
Managing these risk factors can help reduce the likelihood of experiencing SVT episodes.
Complications
If the heart beats too fast, it might not pump enough blood to the body. This can prevent organs and tissues from getting the oxygen they need.
People who have frequent SVT attacks without treatment may face weakened heart muscles over time. This can lead to heart failure, particularly in those with other health conditions.
In some cases, a severe SVT episode can cause:
- Fainting
- Sudden cardiac arrest (when the heart suddenly stops working)
These serious complications highlight why proper treatment and management of SVT are important for long-term heart health.
Prevention
You can take steps to prevent supraventricular tachycardia (SVT) episodes. These strategies can help manage your heart health and reduce triggers.
- Follow a heart-healthy lifestyle. Eat nutritious foods, avoid smoking, exercise regularly, and find ways to manage stress. These habits support overall heart function.
- Limit caffeine intake. While moderate amounts don’t trigger SVT for most people, large quantities might cause problems. Be mindful of coffee, tea, energy drinks, and chocolate consumption.
- Track your symptoms in a notebook. Write down when fast heartbeats occur, what you were doing, and how you felt. This record helps identify personal triggers.
- Be careful with medications. Some over-the-counter products contain stimulants that can trigger SVT episodes. Always read labels and ask your healthcare provider about potential interactions with your current medications.
