Everything You Should Know About Tachycardia

What do these three scenarios have in common: Running up the stairs; standing in front of your crush fumbling over what to say; narrowly escaping a head-on collision during your commute. Give up? All of these situations get your heart racing a mile a minute—and there’s a word for that. It’s what cardiologists call tachycardia.

“Tachycardia means an elevated heart rate or faster heart rate than what’s normal,” says Aeshita Dwivedi, M.D., a cardiologist at Lenox Hill Hospital in New York City. “It can be a normal response to increased demands of your body, such as when you’re exercising or under stress or anxious.”

The normal rhythm of your heart is controlled by the sinus, or sinoatrial, node, found in the top right corner of your heart. The sinus node is your heart’s pacemaker, sending electrical signals that tell your heart to contract, or beat, in time to your body’s demands. When you’re just chilling out, your sinus node keeps your heart beating anywhere from around 60 to 100 times each minute. Get moving, and your heart rate goes up—this is known as sinus tachycardia: Your heart is beating faster, but the rhythm is regular. Again, that’s normal. But sometimes, things go awry.

“Any fast heart rate that originates from anything but the sinus node is characterized as tachyarrhythmia,” says Dr. Dwivedi. An arrhythmia is an abnormal heartbeat, so a tachyarrhythmia is an abnormally fast heartbeat. There are many different types of tachyarrhythmias. Some of them are harmless and require no treatment, while others are life-threatening.

Tachyarrhythmias can take time to diagnose. If your doctor suspects you have one, you will undergo an electrocardiogram (ECG or EKG), a painless, non-invasive test that records your heart’s rhythm and helps to pinpoint abnormalities.

If your tachyarrhythmia is not active in your doctor’s office, you likely will be given a monitor to wear, such as a Holter monitor. These devices record your heart’s rhythm over a period of 24 hours to two weeks. Your doctor will examine the recordings for signs of a problem. If your arrhythmia happens very infrequently, you might be advised to have a tiny monitor implanted just under the skin of your chest. Such monitors, called loop recorders, can track your heart for a few years.

There are three common or concerning kinds of tachyarrhythmias:

• supraventricular tachycardia (SVT)

• atrial fibrillation (aFib)

• ventricular tachycardia (VT)

Maybe you’ve heard them mentioned on Grey’s Anatomy or other medical dramas, but here’s a breakdown of what they actually mean.

Supraventricular Tachycardia (SVT)

Supraventricular tachycardia (SVT) is an irregular, erratic, or fast heartbeat in your heart’s upper chambers, called the atria. It’s called “supraventricular” specifically because it’s happening above the heart’s lower chambers, known as ventricles (you have four chambers in total). “SVT is the most likely arrhythmia to occur in people with normal hearts and no other medical problems,” says Eric Buch, M.D., an electrophysiologist at UCLA’s Cardiac Arrhythmia Center in Los Angeles.

Causes of SVT

SVT is typically caused by an extra connection between the heart’s upper and lower chambers, says Dr. Buch. In a normal heart, the upper and lower chambers are connected by the atrioventricular (AV) node, which coordinates the beating of the chambers. Fewer than one in 100 people are born with an extra connection outside the AV node, according to Dr. Buch. That extra connection can cause fast, irregular heartbeats.

Symptoms of SVT

The signs of SVT can come on suddenly, Dr. Buch says. “You’ll be feeling well one minute and then it’s like a light switch is turned on.” These symptoms include:

• Dizziness

• Feeling short of breath

• Lightheadedness

• Sensation of your heart racing

When you’re struck by these symptoms, try to remain calm. “It’s not dangerous but can be uncomfortable,” Dr. Buch says.

SVT treatment

Treatment aims to reduce symptoms, and the right method for you will depend on how often it happens and how bothersome your symptoms are.

• Avoid triggering situations. Some people with SVT find it only happens when they’re dehydrated or stressed, for instance says Dr. Buch. Avoiding those situations may be enough to prevent episodes.

• Vagal maneuvers. Certain forms of breathing, like the Valsalva manuever, can help slow your heart rate.

• Explore medications. Beta blockers and calcium channel blockers, for example, can slow your heart rate and possibly prevent future episodes of SVT.

• Consider cardiac ablation. In this procedure, a thin tube called a catheter is threaded through a vein to your heart. Your doctor will locate the extra connection that’s causing your SVT and apply hot or cold energy to it with the catheter to disable the connection.

Atrial Fibrillation

Atrial fibrillation—or aFib for short—is an irregular, usually rapid, heart rhythm. Technically a type of SVT, aFib is a worrisome tachyarrhythmia because it increases the risk of a stroke, in which the blood supply to parts of the brain gets cut off. Strokes are a leading cause of long-term serious disability as well as a leading cause of death, according to the Centers for Disease Control and Prevention (CDC).

During an episode of aFib, your atria fibrillate, or quiver, at about 400 beats per minute, says Dr. Dwivedi. When that happens, there’s decreased blood flow in your heart. Blood that can’t flow starts to pool in the left atrium. This allows clots to form.

“If the clot just sits in the heart, it’s not that dangerous,” says Dr. Dwivedi. “The problem is the clot can break off and go to other parts of your body. If it goes to the brain, that causes a stroke.” This can be dangerous or deadly.

Causes of AFib

Atrial fibrillation often develops in people who already have some form of heart disease. High blood pressure, for example, makes your heart work harder than it should. Over time, this can interfere with your heart’s electrical system, leading to aFib. Heart attacks, heart failure, and heart valve diseases also increase your risk of aFib.

Other risk factors include:

• Diabetes

• Obesity

• Older age

• Sleep apnea

Symptoms of AFib

The symptoms of atrial fibrillation include:

• Chest pain

• Dizziness and lightheadedness that can lead to fainting

• Heart palpitations

• Shortness of breath

Treatments for AFib

Fortunately, there are several effective treatments for atrial fibrillation. Which one you try depends on the severity of your symptoms and your overall health. These are the options your doctor will discuss with you:

• Beta blockers and calcium channel blockers are frequently prescribed for aFib to control your heart rate. “They don’t prevent aFib from happening but they will slow your heart down,” says Dr. Buch.

• Blood thinners may also be used to prevent strokes.

• Anti-arrhythmic drugs. Your doctor might prescribe anti-arrhythmic drugs, but these can have significant side effects, including more dangerous arrhythmias, and they require monitoring in the hospital and/or regular checkups.

• Pulmonary vein isolation, a type of ablation, also may be used to isolate the areas of the heart where aFib is triggered (usually the pulmonary veins). This is done with a catheter, which uses energy to create tiny scars that block the abnormal signals that trigger episodes of aFib. Unlike with SVT, this procedure does not cure aFib, says Dr. Buch.

“More and more people are opting for catheter ablation to treat their aFib rather than anti-arrhythmic drugs because this procedure has become more routine, safe, and effective,” says Dr. Buch.

Ventricular Tachycardia (VT)

VT, a.k.a. V-tach, is another heart rhythm issue caused by irregular electrical signals firing in the lower chambers of your heart (the ventricles). Of the three major tachyarrhythmias, VT can be the most dangerous because the abnormal heartbeat caused by VT can prevent your heart from pumping blood. If it lasts more than 30 seconds or so, it can lead to sudden cardiac arrest, in which your heart stops beating—which can be fatal. “When the bottom chambers of the heart, the ventricles, are initiating your heartbeat, that is extremely dangerous,” says Dr. Dwivedi. “It is life threatening.”

Most of the time though, VT episodes are brief and not cause for concern. Called a non-sustained VT, they don’t always cause symptoms. In fact, you may not even know you had one. “It’s like a muscle twitch in your heart,” says Dr. Buch. “It rarely requires treatment.”

Causes of VT

Brief, benign VT incidents can be brought on by factors that make your heart irritable, Dr. Buch explains. Common culprits include:

• Dehydration

• High levels of stress

• Lack of sleep

The deadly form of VT, called sustained VT, occurs most often as a result of structural problems in the heart. These problems can be caused by conditions like:

• Blockages in the heart due to coronary artery disease, and hypertrophic cardiomyopathy, which causes the heart muscle to thicken.

• Heart attack

• Heart failure

All of these conditions can disrupt the normal electrical signaling that controls your heart’s rhythm.

Symptoms of VT

While usually brief and not a cause for concern, VT episodes can be frightening. If it lasts for any duration of time, it can become serious, so you’ll want to know the red flags to watch for. The symptoms of VT in order of usual progression include:

• Racing heartbeat

• Dizziness

• Lightheadedness

• Fainting

• Cardiac arrest

Treatments for VT

There are a number of ways to treat VT. If you are at high risk of VT or have had a sustained VT in the past, your cardiologist likely will recommend an implantable cardioverter-defibrillator (ICD). These devices monitor your heart constantly. If you go into VT, it will shock your heart to restore a normal rhythm.

Catheter ablation may also be an option. Your doctor threads a thin tube called a catheter through a vein to your heart. There, your doctor uses the catheter to make scars using hot or cold energy. These scars block the abnormal signals that trigger VT.

And finally, antiarrhythmic medications, such as those used for aFib, can help treat VT, as can beta blockers and calcium channel blockers.

Whatever form of tachycardia you may have, the very good news is that treatment exists. The most important thing is that you have your racing heart checked out by a cardiologist who can evaluate the type and severity of tachycardia you’re dealing with. Left untreated, your condition could be dangerous; properly managed, you’ll likely return to your regularly scheduled routine in no time.