Supraventricular Tachycardia

What Is Supraventricular Tachycardia?

Also called paroxysmal supraventricular tachycardia, supraventricular tachycardia (SVT) is a very rapid heartbeat that involves the heart’s upper chambers. The range for a normal resting heartbeat is about 60 to 100 times a minute in adults. During SVT, the heart beats approximately 150 to 220 times a minute.

Supraventricular Tachycardia Symptoms

SVT doesn’t always cause noticeable symptoms. When symptoms do occur, they usually don’t last long. Symptoms can include:

• Chest pain
• Fatigue
• Lightheadedness
• Sweating
• Dizziness
• Passing out
• Palpitations (fluttering in your chest)
• Feeling short of breath (dyspnea)

Supraventricular Tachycardia Causes

SVT can be caused by:

• Certain medical conditions, including lung disease, thyroid disease, heart failure, Wolff-Parkinson-White syndrome and congenital heart issues (present at birth).
• Certain medications, including those that treat asthma, allergies and colds.
• Heart surgery: Scar tissue left behind from heart surgery can change how electrical signals pass through the heart.
• Dehydration
• Lack of sleep
• Exercise
• Stress
• Anxiety
• Caffeine and alcohol
• Smoking and other tobacco use
• Illegal stimulant drugs such as cocaine and methamphetamine
• Pregnancy

Supraventricular Tachycardia Diagnosis

To diagnose SVT, your doctor may order certain tests, including:

• Electrocardiogram (ECG or EKG): A diagnostic tool that records your heart’s electrical activity on a graph. An ECG can detect fast, slow or otherwise abnormal heart rhythms.
• Echocardiogram (or echo): Uses sound waves to create a moving picture of the heart. In addition to showing the structure of the heart and its valves, this test can reveal areas of poor blood flow in the heart.
• Cardiac event recorder: Typically worn for about 30 days, this device records heart activity only at certain times for a few minutes at a time. You push a button when you feel symptoms. In addition, some event recorders automatically record when they detect an irregular heartbeat.
• Implantable loop recorder: An implantable cardiac device that continuously monitors heart rate and rhythm during daily activities. A cardiologist implants the device in the chest through a simple outpatient procedure. The device can record the heart for three to six years.
• Blood tests: A blood sample is taken to check for other causes of a fast heartbeat, including thyroid disease.
• Exercise stress test: Exercise can trigger or worsen SVT. An exercise stress test is conducted on a treadmill or stationary bike to measure heart and lung function during physical activity using an ECG.
• Tilt table test: This test may be done to see if a fast heartbeat will cause you to faint. While you lie flat on a table, your heart rate, heart rhythm and blood pressure are monitored. Under careful supervision, the table is then tilted to a standing position. A member of your care team observes how your heart and nervous system respond to the change in position.
• Electrophysiological (EP) study: During this test, your doctor guides one or more flexible tubes (catheters) through a blood vessel, usually in the groin, to various areas in the heart. Sensors on the tips of the tubes record the heart’s electrical signals. This test can show where faulty heart signals begin in the heart to cause fast and irregular heartbeats.

Supraventricular Tachycardia Treatment

Your SVT may not require treatment. However, if your SVT happens often or lasts for a long period of time, your healthcare provider may suggest treatment. Treatments for SVT include:

• Carotid sinus massage: During carotid sinus massage, a healthcare professional gently presses on a specific area of your neck near the carotid artery, causing your body to release chemicals that slow the heart rate. Carotid massage should only be performed by an experienced healthcare professional.
• Vagal maneuvers: Certain measures such as coughing, the Valsalva maneuver (a breathing technique that increases pressure in the chest) and putting an ice pack on the face can slow down the heart rate by affecting the vagus nerve, which helps control the heartbeat.
• Medications: Certain medications can be used to treat SVT by slowing the heartbeat, including adenosine, atropine, beta blockers, calcium channel blockers, digoxin and potassium channel blockers.
• Cardioversion: In this procedure, quick, low-energy shocks are delivered to the chest with paddles or patches to restore a regular heart rhythm. Cardioversion is generally used when emergency care is required or when vagal maneuvers and medicines are not helpful.
• Catheter ablation: This procedure uses radiofrequency energy (heating) or cryoablation (freezing) to create tiny scars in the heart’s upper chambers to block the faulty electrical signals that cause the abnormal heart rhythm.
• Implantable cardiac devices: Rarely, a small device called a pacemaker is needed to treat SVT. Implanted under the skin near the collarbone through a minor surgery, a pacemaker releases electrical impulses to stimulate the heart to maintain a regular heartbeat. Wires connect the device to the heart. Another implantable cardiac device called an implantable cardioverter defibrillator (ICD) delivers a shock to the heart when it needs it to restore a regular heart rhythm.