Why is your heart racing?
You no sooner get to work in the morning, and your boss is yelling that you need to turn in the monthly report in an hour because he must talk about it on a conference call. You completely forgot that it was due today, and your stress level immediately skyrockets, and your heart starts to race. In fact, your heart feels like it’s going to beat out of your chest. Is this dangerous? Does it require treatment? What can you do to make it stop?
Definition
Supraventricular tachycardia (SVT) is when your heart beats abnormally fast or erratically. Whenever your heart beats abnormally, it’s called an arrhythmia. To understand what’s happening during an SVT episode, we need to take a quick look at how your heart normally functions. Your heart has four chambers — two upper chambers (atria) and two lower chambers (ventricles). The sinus (SA) node is your heart’s natural pacemaker, and it’s situated in the right upper chamber (atrium). It sends out electrical signals that start each heartbeat. The signal moves across the atria, causing them to contract and pump blood into the ventricles. While this is happening, the signal arrives at the atrioventricular (AV) node, which slows it down enough to allow the ventricles to finish filling with blood. The signal finally gets to the muscles of the ventricles resulting in them contracting pumping blood to the lungs or the rest of the body. Usually, this process goes smoothly, resulting in an average resting heart rate of 60 – 100 beats a minute (bpm). SVT occurs when defective electrical connections in the heart set off a series of early beats in the atria. This causes the heart rate to become so fast so quickly that the heart doesn’t have enough time to fill with blood before the chambers contract. When a person has an episode of SVT, their heart rate is between 150 – 220 bpm.
There are several different types of SVT, such as sinus tachycardia, sinus nodal reentrant tachycardia (SNRT), inappropriate sinus tachycardia (IST), multifocal atrial tachycardia (MAT), junctional ectopic tachycardia (JET), and nonparoxysmal junctional tachycardia (NPJT). However, the three main types are atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and atrial tachycardia. AVNRT is the most common type in males and females of any age but occurs more often in young women. AVRT is the second-most-common type and is most often diagnosed in younger people. Atrial tachycardia is commonly diagnosed in people with heart disease and doesn’t involve the AV node.
Some people have things that trigger episodes of SVT, while others don’t. Some things that can cause SVT are heart disease, heart failure, other heart conditions (ex. Wolff-Parkinson-White syndrome), chronic lung disease, consuming too much caffeine, drinking too much alcohol, drug use (especially stimulants like cocaine and methamphetamines), pregnancy, smoking, thyroid disease, and certain medications (ex. asthma medications and over-the-counter cold and allergy drugs). Similarly, some people don’t have any symptoms, but others do. Symptoms can include very fast (rapid) heartbeat, palpitations (fluttering or pounding in your chest), pounding sensation in the neck, weakness or feeling very tired (fatigue), chest pain, shortness of breath, lightheadedness, dizziness, sweating, and fainting. Symptoms may come and go and can last a few minutes to a few days. Infants or young children may experience sweating, poor feeding, pale skin, and rapid pulse. If you have frequent episodes of SVT that aren’t treated, over time, your heart becomes weaker, leading to heart failure.
Treatment
When it comes to treating SVT, most people don’t require any medical intervention. However, if you have long or frequent episodes, your doctor may recommend one of the following techniques. The first is something that you can do at home, called the vagal maneuver. To do it, you can try holding your breath and straining as you would during a bowel movement, dunking your face in ice water, or coughing. All of these moves affect the nervous system that controls your heartbeat (vagus nerves), often causing your heart rate to slow. The next method is a carotid sinus massage, during which a doctor applies gentle pressure on the neck where the carotid artery splits into two branches. This causes the body to release chemicals that slow the heart rate. It’s vital to note that you should not do this on your own. If neither of these stops an SVT episode, your doctor may use cardioversion. It can be done using medications or a shock delivered to your heart through paddles or patches on your chest. The current from the shock affects the electrical signals in your heart and can restore a normal rhythm.
If you have frequent episodes of SVT, your doctor may prescribe medication that can control your heart rate or restore a normal heart rhythm. It’s critical to take the medication exactly as directed by your doctor to reduce the chances of complications. If the medicines aren’t effective, your doctor will suggest catheter ablation. For this, the doctor inserts a thin, flexible tube (catheter) through your veins or arteries, usually in the groin, and advances it to the correct location in your heart. Sensors on the tip of the catheter use either heat or cold energy to create tiny scars in the tissue to block abnormal electrical signals, which should restore a normal heartbeat. In rare cases, the doctor might recommend a pacemaker, which is a small, implantable device used to stimulate your heart to beat at a normal rate. The device is placed under the skin near the collarbone, and a wire connects the device to your heart.
Prevention
A critical step to preventing SVT is knowing what triggers the episodes and avoiding them. Consider keeping a diary to help identify your triggers. It’s a good idea to track your heart rate, symptoms, and activity at the time of an SVT episode. Another essential element is to make healthy lifestyle changes. This can include eating a heart-healthy diet, increasing your physical activity, avoiding smoking, maintaining a healthy weight, limiting or avoiding alcohol, reducing stress, getting plenty of rest, avoiding illegal drug use, and not consuming large amounts of caffeine. Also, use over-the-counter medications with caution since some cold and cough medicines contain stimulants that may trigger a rapid heartbeat.
SVT can be scary to experience, but you can have a normal life with the proper treatment and management of the condition. If you have any questions or concerns about SVT, please speak with your doctor. If you would like more information, please visit Cleveland Clinic’s SVT page at https://my.clevelandclinic.org/health/diseases/22152-svt-supraventricular-tachycardia