Supraventricular Tachycardia

Supraventricular Tachycardia Overview

Supraventricular tachycardia is one type of heart rhythm disorder.

  • Tachycardias are rhythm disorders in which the heart beats faster than normal. 
  • Supraventricular means "above the ventricles," in other words, originating from the atria, the upper chambers of the heart. 
  • Supraventricular tachycardia, then, is a rapid heartbeat originating in the atria. 
  • These are sometimes referred to as atrial tachycardias. However, the atrioventricular (AV) node may be involved directly or indirectly, so AV nodal tachycardias are also included in this category.

The heart consists of 4 chambers: 2 upper chambers called atria and 2 lower chambers called ventricles.

  • The atria receive blood from blood vessels and contract to push blood into the ventricles. 
  • The ventricles then contract to push the blood out of the heart into the blood vessels of your lungs and the rest of your body. 
  • The heart usually beats 60-90 times a minute. A heart rate faster than 100 beats per minute is considered tachycardia.

Specialized heart cells coordinate the contractions by means of electrical signals.

  • These specialized cells consist of the sinoatrial (SA) or sinus node in the right atrium and the AV node and the bundle of His in the wall between the right and left ventricles. 
  • The SA node, the natural pacemaker of the heart, starts the electrical signals and transmits them to the AV node. 
  • The AV node then activates the bundle of His and its branches, resulting in contraction of the ventricles. 
  • The atria and ventricles contract in quick sequence. Each sequence is 1 heartbeat.

Nerve impulses and the level of hormones in your blood influence the rate of heart contraction. A problem in any of these areas can cause abnormal heart rhythm (arrhythmia or dysrhythmia).

In supraventricular tachycardia, the heart rate is sped up by an abnormal electrical impulse starting in the atria.

  • The heart beats so fast that the heart muscle cannot relax between contractions. 
  • When the chambers don't relax, they cannot contract strongly or fill with enough blood to satisfy the body's needs. 
  • Because of the ineffective contractions of the heart, the brain does not receive enough blood and oxygen. You can become light-headed, dizzy, or feel likefainting (syncope).

Supraventricular tachycardia can be found in healthy young children, in adolescents, and in people with underlying heart disease. Most people who experience it live a normal life without restrictions.

Supraventricular tachycardia often occurs in episodes with stretches of normal rhythm in between. This is usually referred to as paroxysmal supraventricular tachycardia (often abbreviated PSVT). Supraventricular tachycardia also may be chronic (ongoing, long term).

 

Supraventricular Tachycardia Causes

Paroxysmal, or sporadic, supraventricular tachycardia usually occurs without other symptoms. However, it may be associated with a number of medical conditions, such as the following:

Supraventricular tachycardia may also be a side effect of medications such as digitalis, asthma medications, or cold remedies.

In some cases, the cause of supraventricular tachycardia is unknown.

 

Supraventricular Tachycardia Symptoms

Paroxysmal supraventricular tachycardia (PSVT) can cause a number of symptoms, depending on your overall health and how fast your heart is beating. People with heart damage or other coexisting medical problems experience a greater degree of discomfort and complications than those who are healthy. Some people have no symptoms at all.

Symptoms can come on suddenly and may go away by themselves. They can last a few minutes or as long as 1-2 days. The rapid beating of the heart during PSVT can make your heart a less effective pump so that your body organs do not receive enough blood to work normally. The following symptoms are typical with a rapid pulse of 140-250 beats per minute:

 

When to Seek Medical Care

Supraventricular tachycardia is generally not life threatening unless you have other heart disorders. Call your health care provider if any of the following conditions occur:

  • The episode of rapid heartbeat or palpitations is your first, and the symptoms last longer than a few seconds to a minute or two. 
  • You have had previous episodes of supraventricular tachycardia, and the current episode does not go away with vagal maneuvers (coughing, deep breathing, or muscle tensing).

The following conditions warrant a visit to the nearest hospital emergency department. Do not drive yourself to the hospital. Call 911 for emergency help.

  • You have rapid heartbeat and feel dizzy or faint. 
  • You have rapid heartbeat with chest pain. 
  • You feel short of breath with rapid heartbeat.

 

Exams and Tests

Your health care provider, whether your primary care provider or an emergency department physician, will ask you questions about your symptoms, medical and surgical history, lifestyle, and medications. Your physical examination will focus on your heart and other organs, such as your lungs, that might explain your symptoms.

You may need other tests to confirm the diagnosis of supraventricular tachycardia and to assist your health care provider in tailoring the most appropriate treatment.

  • Electrocardiogram (ECG): The ECG is a painless, quick, noninvasive test that detects the electrical activity of your heart. Through 12 electrodes, or leads, attached to your chest, arms, and legs, tracings or waves represent the electrical activity of your heart from different points of view. This allows detection of a number of different kinds of problems in the heart. The ECG can help identify supraventricular tachycardia and in some cases its cause. Further tests or therapy may depend on the findings of the ECG. 
  • Ambulatory ECG: By the time you reach a medical facility, the symptoms will sometimes have stopped and the ECG will be normal. This is frustrating because an accurate diagnosis depends on capturing the rapid heartbeat on ECG. Ambulatory monitoring solves this problem by monitoring your heart over a period of time, usually 1-2 days. The ambulatory ECG is more likely to document any abnormal heart rhythms that you experience. You wear the monitor device, called a Holter monitor, while you go about your daily activities. You also keep a diary while you are wearing the device. If your health care provider finds any abnormalities on the ECG recording, these will be compared with what you were doing and feeling at the time. 
  • Echocardiogram (ECHO): This is a noninvasive ultrasound examination of your heart. A small handheld device is passed over your chest. It transmits pictures of your heart walls and valves to a television screen. It also measures how well your left ventricle is pumping. The echo is used to screen for any problems in your heart structure, valves, or muscles. 
  • Stress test: The stress test is an ECG done both at rest and while the heart is under stress, usually exercise on a treadmill or exercise bicycle. If you cannot exercise, you will be given a drug that will temporarily "stress" your heart. This test helps in the diagnosis of coronary heart disease, that is, blockage of your coronary arteries by fatty plaques (atherosclerosis). Coronary heart disease prevents your heart from getting enough blood, and this can cause abnormal heart rhythms. 
  • Cardiac catheterization and coronary angiography: If your stress test result is abnormal or if you have chest pain, shortness of breath, or loss of consciousness, you may undergo cardiac catheterization under local anesthesia to assess disease in your heart and heart valves. Angiography is a type of imaging study that uses a dye in the arteries to highlight blockages and damage. 
  • Electrophysiologic study: You may need this test if you have rapid heartbeat but your body does not tolerate treatment, or if your heart has created new electrical pathways that contribute to your abnormal rhythm. This test involves placement of several pacemaker electrodes into your heart chambers to record electrical activity. The electrodes are placed via a catheter that is threaded through the veins to the heart, under local anesthesia in the cardiac catheterization lab.

Lab tests

  • Blood tests may be performed to rule out thyroid disease and evidence of heart muscle damage (heart attack). 
  • Urine tests and additional blood tests may be performed to rule out abnormal levels of drugs that can cause rapid heartbeat.

 

Supraventricular Tachycardia Treatment

Treatment for supraventricular tachycardia focuses on decreasing your heart rate and breaking up the electrical circuits made by the abnormal conducting pathways. Treatment can be divided into 2 broad categories: halting the acute episode and preventing any new ones. One of the most important considerations in treating an acute episode of supraventricular tachycardia is how severely your heart function has been affected.

 

Self-Care at Home

In most people, supraventricular arrhythmias are not dangerous. Mild arrhythmias, such as isolated premature beats, may require no treatment. A few people, however, may have arrhythmias that become dangerous and require immediate, perhaps prolonged, treatment.

In most cases, you might attempt the following simple maneuvers, called vagal maneuvers, to assist your body in slowing your heart rate.

  • Hold your breath for a few seconds 
  • Dip your face in cold water 
  • Cough 
  • Tense your stomach muscles as if you are bearing down to have a bowel movement

If these maneuvers do not work, lie down and relax. Take some slow, deep breaths. Often, your heart will slow by itself.

If the symptoms continue, get immediate transport to a hospital. If you have frequent episodes of rapid heartbeat, you should be evaluated by a medical professional.

The following lifestyle choices may help control your condition:

  • Learn how to count your pulse. Then make sure your pulse is regular. Ask your health care provider or nurse to teach you how to count your pulse. It should be between 50-100 per minute and regular. 
  • Check with your health care provider before taking any over-the-counter cough, cold, or pain medicines. 
  • Exercise regularly. Exercise makes your heart stronger and more efficient and lowers your overall blood pressure and heart rate. 
  • Learn to relax to control stress. Some relaxation techniques include muscle relaxation, deep breathing, meditation, and biofeedback
  • Control other illnesses by complying with your doctor's recommendations. 
  • Quit smoking. 
  • Reduce caffeine intake. 
  • Avoid illicit drug use. Most stimulate your heart. 
  • Control your weight. Obesity makes your heart work much harder. 
  • Work toward a diet low in fat, cholesterol, and salt. 
  • Cut back on excessive alcohol use.

 

Medical Treatment

If you have low blood pressure, chest pain, or a failing heart with tachycardia, your condition is considered unstable. In such cases, you may be in serious danger and need immediate treatment. You may need an electrical shock(cardioversion) to convert your heart to normal rhythm. If your condition is stable, a number of options are available to end the abnormal rhythm:

  • Vagal maneuvers: Coughing, holding your breath, immersing the face in cold water, and tensing your muscles as if having a bowel movement are called vagal maneuvers because they increase the tone of the vagus nerve on your heart. Increased vagal tone stimulates release of substances that decrease your heart rate, which can break the abnormal electrical circuit. 
  • Carotid massage: Carotid massage involves gently pressing and rubbing your carotid sinus, located in your neck just under the angle of your jaw. Carotid massage can release chemicals to slow your heart rate. This step is generally limited to young, healthy people because older people are at risk of stroke. You will be connected to a heart monitor because the decrease in heart rate can be dramatic. 
  • Medications: You may be given adenosine (Adenocard), a short-acting medication that decreases your heart rate. This medication is given by IV to act quickly. Adenosine has some temporary side effects, including facial flushing, chest pain, shortness of breath, nausea, and dizziness. If a single dose does not stop supraventricular tachycardia, then your doctor may give higher doses. Adenosine successfully stops paroxysmal supraventricular tachycardia (PSVT) in more than 90% of cases. 
  • If adenosine is unsuccessful, other medications can be used, such as calcium channel blockers, digoxin (Lanoxin), or beta-blockers.

Your health care provider will devise treatment that meets the specific cause of your supraventricular tachycardia.

  • Pacemaker: A pacemaker is an electronic device that takes over the role of the SA node as pacemaker of the heart. It is often implanted inside the heart by a cardiologist in the cardiac cath lab, not by a surgeon in the typical operating room. 
  • In special cases, the source of your arrhythmia or abnormal electrical pathways can be interrupted by chemicals, ablated by high frequency energy through a catheter (such as in the Wolff Parkinson White syndrome), or by a surgeon.

 

Next Steps

Follow-up

Your health care provider may want to monitor your progress, depending on the severity of your symptoms and the source of your supraventricular tachycardia. He or she may choose to monitor you for a few weeks or months for the following reasons:

  • To assess the frequency of the recurrence of arrhythmias and heart rate 
  • To adjust or change medications based on clinical, repeat ECG, or Holter evaluations 
  • To plan further therapy if your condition worsens

 

Prevention

 

  • Reduce stress in your life. 
  • Exercise regularly and maintain a healthy lifestyle. 
  • Eliminate caffeine and other stimulants and alcohol. 
  • Comply with medications and medical advice. 
  • Learn more about your problem.

 

Outlook

Most people with episodes of paroxysmal supraventricular tachycardia live a healthy life without restrictions.

  • If you take medications, you may or may not experience some side effects. Discuss those potential side effects with your health provider. 
  • In rare cases, if you have a continuous fast heart rate that goes untreated, your heart muscle can weaken and lead to heart failure. 
  • If your doctor finds a specific cause related to an underlying heart or systematic condition, your recovery may depend on your prognosis for that underlying condition.

 

Multimedia

Media file 1: A 12-lead electrocardiogram from a patient with supraventricular tachycardia (heart rate = 148 beats per minute).
Click to view original file
Media type: Rhythm Strip

 

Synonyms and Keywords

supraventricular tachycardia, arrhythmia, atrial tachycardia, atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia, paroxysmal supraventricular tachycardia, PSVT, rapid heartbeat, tachyarrhythmias, Wolff-Parkinson-White syndromeWPW syndrome, vagal maneuvers, stress, anxiety, dizziness, fainting, chest pain, palpitations

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