Why is your heart racing?
You’re sitting in your favorite chair one lazy afternoon when all of sudden it feels like your heart is beating funny. You also feel slightly lightheaded and short of breath. When you check your pulse, you notice that it’s very fast. What’s causing this? Is it an emergency? How is it treated?
Definition
Tachycardia is when your heart beats at a faster than normal rate, which would be over 100 times a minute. When exercising, this isn’t always an abnormality. If it occurs while you’re resting, it’s most likely the result of something interrupting the normal electrical impulses of your heart. Your heart is divided into four chambers with two atria on top and two ventricles on the bottom. Your blood enters your heart via the right atrium and goes into the right ventricle before being sent to your lungs where it gets rid of carbon dioxide and picks up oxygen before coming back to your heart in the left atria and passing to the left ventricle before being pumped to the rest of your body. The trigger that initiates this action is the electrical current that originates in the sinus node, which sits in the tissue of your right atrium. This is your heart’s natural pacemaker. After the electrical impulse starts in the sinus node, it travels across both atria, which results in them contracting and pushing your blood into your ventricles. The electrical impulse then reaches the atrioventricular (AV) node, which is situated right near the middle of your heart. The contraction of your ventricles starts, but the signal reaches the bundle of His, which slows the signal down just enough that the ventricles have time to finish filling with blood before the signal moves to the nerve fibers that come from the bundle of His (half going down to the right ventricle and the other half going to the left), which completes the transmission of the signal and finishes the contraction of the ventricles.
There are several different types of tachycardia, which are classified by their origin and cause. Atrial fibrillation (AFib) is when your atria are receiving chaotic, irregular electrical signals and this triggers them to have rapid, uncoordinated and weak contractions. This is the most common type of tachycardia and usually related to a structural abnormality related to an underlying condition. Atrial flutter (AFlutter) is similar to AFib in that it originates in the atria, but the rate is regular. It’s caused by irregular circuitry within the atria and results in weak atrial contractions. Often, people who experience AFlutter also have episodes of AFib. Supraventricular tachycardia (SVT) is when the signal for the fast heart rate comes from somewhere above the ventricles and causes them to beat fast. This is the result of an abnormal circuitry creating overlapping signals (often present at birth). Ventricular tachycardia (VTach) is when the rapid heart rate signal comes from the ventricles. The rate is usually so fast that the ventricles don’t have time to fill with enough blood or contract efficiently enough to get the blood to your body. Sometimes, episodes are brief, lasting only a few seconds. Other times, the episodes last longer than a few seconds, this can quickly become life-threatening. Ventricular fibrillation (VFib) is when the electrical signal is rapid and chaotic (similar to AFib, but originating in the ventricles). It causes the ventricles to quiver and not pump blood at all. This is fatal unless the heart is shocked back into a normal rhythm within a few minutes of onset. This usually occurs during/after a heart attack, the result of an underlying heart disease or from a serious trauma.
There are many things that can cause a disruption of your heart’s electrical system, such as abnormal electrical pathways (usually present at birth), damage to the heart tissue, aging, anemia, sleep apnea, exercise, sudden stress, smoking, fever, high/low blood pressure, drinking too much alcohol/caffeine, medication side effects, imbalance of electrolytes and overactive thyroid. However, sometimes the cause can’t be determined. Symptoms are similar for all the types and include shortness of breath, lightheadedness, rapid heart rate, palpitations, chest pain and fainting. The complications associated with tachycardia vary in severity and depend on the type, your heart rate, the duration of the episode and if you have any other heart conditions. These complications can include blood clots that cause a stroke or heart attack, heart failure (your heart can’t pump enough blood around your body), frequent fainting or sudden death. This is why if you have any symptoms of tachycardia you should be seen by a doctor. If you faint, feel short of breath or have chest pain that lasts longer than a few minutes, call 911.
Treatment
In order to treat tachycardia, you need to know the type. This is usually determined by an electrocardiogram (EKG). Your doctor might do other testing as well to get more information about your heart. The goal of treatment is to slow your heart to a normal rate, prevent future episodes from occurring and minimize complications. Sometimes, your heart will correct itself. Otherwise, you can try a simple technique called a Vagal maneuver. Your vagus nerve helps to regulate your heart rate, so by stimulating it, it can help to decrease the rate. Ways to do this include coughing, bearing down as if you’re having a bowel movement or putting an ice pack on your face. If this doesn’t work, you might need an injection of medication, called an anti-arrhythmic. This can only be done at a hospital and the medication that is given depends on the type of tachycardia. If your heart responds to the medication, your doctor will likely prescribe the pill form for you to take to prevent future episodes. If neither of these works or your heart is in a lethal arrhythmia, then you’ll probably need to undergo cardioversion. This is when a shock is delivered to your heart to help it regain a normal rhythm. The current is usually delivered via paddles, patches or automated external defibrillator (AED) that are attached to your chest. In emergent situations, even if you’re awake, the doctor will deliver the shock. However, the amount of electrical current used is less than that of someone who is unresponsive.
Once you’re stable and the type of tachycardia is identified, then your doctor will discuss options to help prevent it from recurring. One of these is taking the anti-arrhythmic pills, as long as the injectable form corrected your arrhythmia initially. Another option that is used when there is an extra electrical pathway is cardiac ablation. This uses either extreme cold or radiofrequency to destroy the extra pathway so it can’t send electrical signals. Pacemakers can tell when your heart beats abnormally and send an electrical signal to help it resume normal function. This is different from an implantable cardioverter, which monitors your heart and sends a shock at a precisely calibrated amount to restore your heart to a normal rhythm. Open heart surgery is the last resort. Typically, this is done in conjunction with other procedures, such as heart valve replacement or artery repair. One surgical procedure done to correct tachycardia is a maze procedure, which is used to destroy an extra electrical pathway by making small incisions in that area of the heart tissue. This creates scar tissue and that doesn’t conduct electricity.
There are a few other things to consider when treating tachycardia. One is preventing blood clots since your risk of developing them is increased. To prevent these, your doctor will most likely prescribe medication that decreases your blood’s natural ability to clot. Another important thing to treat is any underlying problems that could contribute to tachycardia episodes. Your doctor will likely recommend an exercise routine to help you reach/maintain a healthy weight because this decreases your chances of having high blood pressure or sleep apnea, both of which increase your chances of having a tachycardic episode. Make sure you ask your doctor how to take your pulse, what your normal heart rate should be, what (if any) vagal maneuvers you should do and how to do them, when to call them and when to seek emergency care.
Prevention
The best way to prevent tachycardia is to decrease your risk for developing heart disease. To do this, you should exercise regularly and eat a healthy diet that is low in fat and salt and high in fruits, vegetables and whole grains. This will help you to maintain a healthy weight, keep your blood pressure under control and reduce your chances of having high cholesterol. Also, make sure you stop/never start smoking and don’t use recreational drugs. In addition, limit the amount of alcohol and caffeine you ingest. It’s key to find ways to reduce and manage your stress. Another consideration is to be careful when using over-the-counter medications because some cough and cold medicines include stimulants that could trigger tachycardia. Getting regular checkups is also key.
Tachycardia is a very serious medical condition that sometimes needs emergent treatment. Don’t hesitate to seek help if you have any symptoms. By being prepared and acting quickly, you’ll decrease your risk of any negative complications. If you have any questions or concerns about tachycardia, please speak with your doctor. If you would like more information, please visit the American Heart Association’s Tachycardia page at https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/tachycardia–fast-heart-rate