context: Vagal maneuvers are ways to treat a fast heart rate of more than 100 beats per minute that starts in the upper chambers of your heart, the atria. Doctors call this type of heartbeat supraventricular tachycardia, or SVT. SVThappens when electrical signals in your heart's atria get out of sync. This interferes with signals from the sinoatrial ( SA) node, your heart's natural pacemaker. Early beats in the atria speed up your heart rate. How do vagal maneuvers work? Simply put, they affect the vagus nerve, a long nerve that runs from your brain to your belly. It sends signals to the atrioventricular node, a cluster of cells at the bottom of your heart's upper right chamber that helps control your heartbeat. Think of it as an electrical relay station. It takes signals from the sinoatrial node and slows them down before passing them along to the lower chambers. The result: A slower heart rate. These simple steps can slow your heart down right away. Valsalva maneuver. Hold your nose, close your mouth, and try to blow the air out. This creates pressure in your chest that may activate the vagus nerve. Sitting or squatting may help. Try it for 10 seconds. Cough. You need to cough hard to generate pressure in your chest and stimulate the vagus nerve. Children with tachycardia may not be able to cough hard enough to get a response from the vagus nerve. Gag. You can try it with a finger. You doctor might use a tongue depressor. Hold your knees against your chest: Do it for a minute. This may work best for babies and children. Cold water treatment. You might hear this called the diving reflex. You may need to put a plastic bag of ice on your face for 15 seconds. Or you can immerse your face in icy cold water for several seconds. It might also work to step into a cold shower or a cold bath. Carotid sinus massage: Only a doctor should perform this one: Lie down and stick out your chin. The doctor will put pressure on your carotid sinus, a bundle of nerves surrounding the carotid artery in your neck just below your jaw. You'll be monitored during the procedure. While vagal maneuvers may seem easy, they do have risks. And they aren't safe for everyone. You should only do them if your doctor has explained when and how. Carotid massage can cause a stroke, especially if you're older or you've had a stroke in the last 3 months. It may also be riskier for children. That's why it's best left to your doctor. The Valsalva maneuver can put an unhealthy strain on your heart. It can also raise your blood pressure. If you have coronary heart disease, a congenital heart defect, or other heart conditions, your doctor may advise you not to do it. If you sometimes have episodes of tachycardia, talk with your doctor about all your treatment options. When your doctor teaches you how to do a vagal maneuver, ask how long you should do it before stopping. You should also know when to stop and call 911. For many people who have tachycardia, waiting 30 minutes may be enough. Often, a fast heart rate will ease on its own. But if your doctor suggests you learn one or more vagal maneuvers to slow your heart down, you may be able to cut short the unsettling feeling that comes with a racing heart.