Ventricular tachycardia

 

Ventricular tachycardia by Pharmacytimess

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Ventricular tachycardia

Overview

Ventricular tachycardia is a heart rhythm problem (arrhythmia) caused by irregular electrical signals in the lower chambers of the heart (ventricles). This condition may also be called V-tach or VT.

A healthy heart typically beats about 60 to 100 times a minute at rest. In ventricular tachycardia, the heart beats faster, usually 100 or more beats a minute.

Sometimes the rapid heartbeat prevents the heart chambers from properly filling with blood. As a result, the heart may not be able to pump enough blood to the body. If this happens, you may feel short of breath or lightheaded, or you may lose consciousness.

Ventricular tachycardia episodes may be brief and last only a couple of seconds without causing harm. But episodes lasting more than a few seconds (sustained V-tach) can be life-threatening. Sometimes ventricular tachycardia can cause the heart to stop (sudden cardiac arrest).

Treatment for ventricular tachycardia may include medication, a shock to the heart (cardioversion), catheter procedures or surgery to slow the fast heart rate and reset the heart rhythm.

Symptoms

When the heart beats too fast, it may not pump enough blood to the rest of the body. So the organs and tissues may not get enough oxygen. Signs and symptoms that occur during an episode of ventricular tachycardia are due to a lack of oxygen and may include:

·         Chest pain (angina)

·         Dizziness

·         Pounding heartbeat (palpitations)

·         Lightheadedness

·         Shortness of breath

Ventricular tachycardia may go away on its own within 30 seconds (nonsustained V-tach) or last more than 30 seconds (sustained V-tach or VT). Brief episodes may not cause any symptoms. But sustained VT can cause serious problems, including:

·         Fainting

·         Loss of consciousness

·         Cardiac arrest (sudden death)

When to see a doctor

Many different things can cause ventricular tachycardia. It's important to get a prompt, accurate diagnosis and appropriate care. See your health care provider if you or your child has any problems with the heartbeat. In some cases, urgent or emergency care is needed.

Call 1122 or your local emergency number if anyone has these symptoms:

·         Chest pain that lasts more than a few minutes

·         Difficulty breathing

·         Fainting

Causes

Ventricular tachycardia is caused by faulty heart signaling that triggers a fast heart rate in the lower heart chambers (ventricles). The fast heart rate doesn't allow the ventricles to fill and squeeze (contract) to pump enough blood to the body.

Many things can cause or contribute to problems with heart signaling and lead to ventricular tachycardia. These include:

·         Prior heart attack or other heart condition that caused scarring of heart tissue (structural heart disease)

·         Poor blood flow to the heart muscle due to coronary artery disease

·         Congenital heart diseases, including long QT syndrome

·         Imbalance of substances in the blood called electrolytes — such as potassium, sodium, calcium and magnesium

·         Medication side effects

·         Use of stimulants such as cocaine or methamphetamine

Sometimes, the exact cause of ventricular tachycardia can't be determined (idiopathic ventricular tachycardia).

How does the heart beat?

To better understand the cause of ventricular tachycardia, it may be helpful to know how the heart typically works.

The heart is made of four chambers — two upper chambers (atria) and two lower chambers (ventricles).

The heart's rhythm is controlled by a natural pacemaker (the sinus node) in the right upper chamber (atrium). The sinus node sends electrical signals that typically start each heartbeat. These electrical signals move across the atria, causing the heart muscles to squeeze (contract) and pump blood into the ventricles.

Next, the signals arrive at a cluster of cells called the AV node, where they slow down. This slight delay allows the ventricles to fill with blood. When the electrical signals reach the ventricles, the chambers contract and pump blood to the lungs or to the rest of the body.

In a typical heart, this heart signaling process usually goes smoothly, resulting in a resting heart rate of 60 to 100 beats a minute.

In ventricular tachycardia, faulty electrical signaling in the heart's lower chambers causes the heart rate to increase to 100 or more beats a minute.

Risk factors

Any condition that puts a strain on the heart or damages heart tissue can increase the risk of ventricular tachycardia. Lifestyle changes or proper medical treatment for the following conditions and events may lower the risk:

·         Heart disease

·         Medication side effects

·         Severe electrolyte imbalances

·         Use of stimulant drugs such as cocaine or methamphetamine

A family history of tachycardia or other heart rhythm disorders makes a person more likely to develop ventricular tachycardia.

Complications

Complications of ventricular tachycardia depend on:

·         How fast the heart is beating

·         How long the rapid heart rate lasts

·         Whether there are other heart conditions

Possible complications of ventricular tachycardia include:

·         Frequent fainting spells or unconsciousness

·         Heart failure

·         Sudden death caused by cardiac arrest

Ventricular fibrillation

A dangerous condition related to ventricular tachycardia is ventricular fibrillation (V-fib). In V-fib, the lower heart chambers contract in a very rapid and uncoordinated manner.

This irregular rhythm happens most often in people with heart disease or a prior heart attack. It may also occur in those with electrolyte imbalances (such as high or low potassium levels).

Ventricular fibrillation may cause sudden cardiac arrest and lead to death if not treated immediately.

Prevention

The best ways to prevent tachycardia are to maintain a healthy heart and prevent heart disease. If you already have heart disease, monitor it and follow your treatment plan. Be sure you understand your treatment plan, and take all medications as prescribed.

Take the following steps to keep the heart healthy:

·         Eat a balanced, nutritious diet. A diet low in saturated and trans fats and rich in fruits, vegetables and whole grains helps keep the heart healthy.

·         Exercise and maintain a healthy weight. Being overweight increases the risk of developing heart disease. As a general goal, aim for at least 30 minutes of moderate exercise every day.

·         Control blood pressure and cholesterol levels. Make lifestyle changes and take medications as prescribed to manage high blood pressure (hypertension) or high cholesterol.

·         Control stress. Avoid unnecessary stress and learn strategies to manage and reduce stress.

·         Don't use illegal drugs. Don't use stimulants, such as cocaine. If you need help stopping drug use or misuse, talk to your health care provider about an appropriate program for you.

·         Go to scheduled health checkups. Have regular physical exams and report any new signs or symptoms to your health care provider.

·         Limit alcohol. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men. Some people may need to avoid alcohol entirely. Ask your health care provider how much alcohol, if any, is safe for you.

·         Limit caffeine. If you drink caffeinated beverages, do so in moderation (no more than 1 to 2 beverages daily).

·         Stop smoking. If you smoke and can't quit on your own, talk to your health care provider about strategies or programs to help you break a smoking habit.

·         Use over-the-counter medications with caution. Some cold and cough medications contain stimulants that may increase the heart rate. Always tell your health care provider about the medications you take, including those bought without a prescription.

Diagnosis

To diagnose ventricular tachycardia, the health care provider will usually do a physical exam and ask questions about your symptoms, habits and medical history. Sometimes, ventricular tachycardia is a medical emergency that requires urgent diagnosis and treatment.

Tests

If you have signs or symptoms of tachycardia, tests can be done to evaluate the heart and help confirm the diagnosis. Tests can also help determine if another health problem is contributing to ventricular tachycardia.

Electrocardiogram (ECG or EKG)

An electrocardiogram is the most common tool used to diagnose tachycardia. This painless test detects and records the heart's electrical activity using small sensors (electrodes) attached to the chest and arms.

An ECG records the timing and strength of electrical signals as they travel through the heart. A health care provider can look for patterns among the signals to determine the type of tachycardia and how problems in the heart may be causing a fast heart rate.

Your health care provider may also ask you to use a portable ECG device at home to obtain more information about your heart rate. These devices include:

·         Holter monitor. This portable ECG device can be worn for a day or more to record the heart's activity during daily activities. It may be recommended if a traditional ECG doesn't give your care provider enough information about your heart's condition. Some personal devices, such as smartwatches, offer portable ECG monitoring. Ask your health care provider if this is an option for you.

·         Event monitor. This portable ECG device is intended to be worn for up to 30 days or until you have an irregular heart rhythm (arrhythmia) or symptoms. You typically press a button when symptoms occur. However, some monitors automatically sense arrhythmias and then start recording.

·         Implantable loop recorder. This implantable device has no wires and can sit underneath the skin for up to three years to continuously monitor the heart rhythm.

Heart (cardiac) imaging

If you have an irregular heartbeat (arrhythmia), your health care provider may recommend cardiac imaging tests to evaluate the structure of your heart. Cardiac imaging tests used to diagnose ventricular tachycardia include:

·         Chest X-ray. A chest X-ray can show the condition of the heart and lungs. A chest X-ray can help diagnose an enlarged heart.

·         Echocardiogram. An echocardiogram uses sounds waves to create a picture of the heart in motion. It can identify areas of poor blood flow and heart valve problems.

·         Magnetic resonance imaging (MRI). A cardiac MRI provides still or moving pictures of how blood flows through the heart.

·         Computerized tomography (CT). A heart (cardiac) CT scan combines several X-ray images to provide a more detailed cross-sectional view of the heart.

·         Coronary angiogram. A coronary angiogram is done to check for blockages in the heart's arteries. It uses a contrast dye and special X-rays to show the inside of the coronary arteries.

Stress test

Some types of tachycardia are triggered or worsened by exercise. During a stress test, the heart's activity is typically monitored while you're riding on a stationary bicycle or walking on a treadmill. Other heart tests may be done with a stress test. If you have difficulty exercising, a drug may be given to stimulate the heart in a way that's similar to exercise.

Electrophysiological (EP) test and cardiac mapping

This test, also called an EP study, may be done to confirm a diagnosis of ventricular tachycardia and to determine the precise location of the irregular heartbeat (arrhythmia).

During an EP study, a health care provider inserts thin, flexible tubes (catheters) tipped with sensors (electrodes) into a blood vessel, usually in the groin, and guides them to various areas in the heart. Once in place, the electrodes can precisely map the spread of electrical signals during each heartbeat.

Tilt table test

A tilt table test may be done to better understand how tachycardia contributes to fainting. Heart rate and blood pressure are monitored while lying flat on a table. Then, under careful supervision, the table is tilted to a position that mimics standing. The health care provider watches how the heart and the nervous system that controls it respond to the changes in position.

Treatment

Ventricular fibrillation that lasts longer than 30 seconds (sustained VT) often requires urgent medical treatment, as this condition may sometimes lead to sudden cardiac death.

The goals of ventricular tachycardia treatment are to slow a rapid heartbeat when it occurs and to prevent future episodes of a fast heart rate. Treatment may include medications or procedures to control or reset the heart rhythm.

If another medical condition is causing tachycardia, treating the underlying problem may reduce or prevent episodes of a fast heartbeat.

Medications

If you have ventricular tachycardia, you may be given medications called anti-arrhythmics by mouth or IV to slow the fast heart rate. Other heart medications, such as calcium channel blockers and beta blockers, may be prescribed with anti-arrhythmic drugs.

Cardioversion

This medical procedure is generally used when emergency care is needed for a rapid heart rate, such as that seen with sustained ventricular tachycardia. Cardioversion sends electric shocks to the heart through sensors (electrodes) placed on the chest. The shock affects the heart's electrical signals and restores a regular heartbeat. It's also possible to do cardioversion with medications.

A shock can also be delivered to the heart using an automated external defibrillator (AED).

Surgery or other procedures

A catheter procedure or heart surgery may be needed to help prevent or manage episodes of ventricular tachycardia.

·         Catheter ablation. In this procedure, a health care provider threads one or more thin, flexible tubes (catheters) through an artery, usually in the groin, and guides them to the heart. Sensors (electrodes) on the tip of the catheter use heat or cold energy to create tiny scars in the heart to block irregular electrical signals and restore the heart rhythm. Catheter ablation is often done when an extra signaling pathway is responsible for the fast heart rate.

·         Implantable cardioverter-defibrillator (ICD). Your health care provider may recommend this device if you're at high risk of developing ventricular tachycardia or ventricular fibrillation. An ICD is a pager-sized device implanted under the skin near the collarbone. It continuously monitors the heartbeat and delivers precisely calibrated electrical shocks when an irregular rhythm (arrhythmia) is detected. The shocks help restore a regular heart rhythm.

·         Pacemaker. This small device is surgically implanted under the skin in the chest area. When the pacemaker detects an irregular heartbeat, it sends an electrical pulse that helps correct the heart's rhythm.

·         Maze procedure. In this procedure, a surgeon makes tiny incisions in the upper half of the heart (atria) to create a pattern (or maze) of scar tissue. The heart's signals can't pass through scar tissue. So the maze can block stray electrical heart signals that cause some types of tachycardia.

·         Open-heart surgery. Sometimes open-heart surgery may be needed to destroy an extra electrical pathway causing tachycardia. Surgery is usually done only when other treatment options don't work or when surgery is needed to treat another heart disorder.

Coping and support

If you have a plan in place to manage an episode of a fast heartbeat, you may feel calmer and more in control when one occurs. Talk to your care provider about:

·         How to take your pulse and what pulse rate is best for you

·         When to call your doctor

·         When to seek emergency care

Preparing for your appointment

Whether you first see your family health care provider or get emergency care, you'll likely be referred to a doctor trained in heart conditions (cardiologist) for a complete evaluation.

If possible, bring along a family member or friend who can provide support and help you remember any new information. Because there may be a lot to discuss, it may be helpful to prepare a list of questions ahead of time.

Your list should include:

·         Symptoms that you've had, including any that may seem unrelated to your heart

·         Key personal information, including any major stresses or recent life changes

·         Medications that you take, including vitamins or supplements

·         Questions to ask your health care provider

List your questions from most important to least important in case time runs out. Basic questions include:

·         What is likely causing my fast heart rate?

·         What kinds of tests do I need?

·         What's the most appropriate treatment?

·         What risks does my heart condition create?

·         How will we monitor my heart?

·         How often will I need follow-up appointments?

·         How will other conditions I have or medications I take affect my heart condition?

·         Do I need to restrict my activities?

·         Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

Don't hesitate to ask additional questions that you may have.

What to expect from your doctor

Your health care provider is likely to ask you several questions. Being ready to answer them may save time to go over any information you want to spend more time on. Your health care provider may ask:

·         When did you first begin having symptoms?

·         How often do you have episodes of a fast heartbeat?

·         How long do the episodes of a fast heartbeat last?

·         Does anything, such as exercise, stress or caffeine, seem to trigger or worsen episodes?

·         Does anyone in your family have heart disease or a history of irregular heartbeats (arrhythmias)?

·         Has anyone in your family had sudden cardiac death or died suddenly?

·         Do you smoke?

·         How much alcohol or caffeine do you use?

·         Do you use illegal drugs?

·         Do you have high blood pressure, high cholesterol, or other heart or blood vessel conditions?

·         What medications do you take for these conditions, and do you take them as prescribed?