Supraventricular Tachycardia is a condition that causes sudden rapid racing of the heart. It results in symptoms such as palpitations, weakness, lightheadedness, and shortness of breath… sometimes even fainting spells. Some people have infrequent episodes – once or twice a year – and do not need to be on medications every day for this, but can use special maneuvers to get the heart to beat normally again. A recently published study suggested there is a better way to get the tachycardia to stop, so if you suffer from rapid heartbeats, you might benefit from reading this article.
What is Tachycardia
Tachycardia simply means a rapid heartbeat. Many things can cause the heart to beat rapidly. Sometimes the normal electrical system is simply “revved up” by adrenaline that is released by exercise, anxiety, highly emotional states, anemia, or even fever, so that the pulse rate runs fast, generally above 100 beats per minute. This condition is known as “Sinus Tachycardia,” since each normal heartbeat is generated by a structure called the Sinus Node. The electrical signals generated by the sinus node pass down the top chambers (atria) to the electrical connection between the top and bottom chambers. This connection is called the AV (atrioventricular) Node. The AV node allows the top and bottom chambers to work together and maintains efficient pumping of the blood.
What is Supraventricular Tachycardia?
Supraventricular Tachycardia (SVT) is an abnormal rhythm that occurs because of a “short circuit” somewhere in the heart’s electrical system. SVT results in sudden racing of the heart at rates often above 140 or 150 beats per minute. Often, the tachycardia will suddenly stop after a few minutes or hours, but some patients have to go to the emergency room to receive intravenous medications to get the heart back to beating normally again. This is not the same as atrial flutter or atrial fibrillation, where the atrial rates are much faster – usually above 240 beats per minute. There are many different kinds of SVT, but most of them involve the AV node somehow. The AV node is part of the short circuit. In that case, if you can get the AV node to transiently slow down, the tachycardia will often stop or “break.”
Vagal Maneuvers to Stop Tachycardia
The AV node is very sensitive to signals from the autonomic nervous system, which is the part of your brain that controls heart rate and blood pressure (among other things). The signals that cause the AV node to “hit the brakes” are carried along a nerve that arises from the brain and controls virtually every organ – this is the Vagus Nerve. “Vagal maneuvers” are physical things that a patient can do to get the vagus nerve to fire, thus slowing the AV node in order to get a tachycardia to stop. Vagal maneuvers can be learned and then performed at home. Some vagal maneuvers include coughing, rubbing one side of the neck, holding the breath and splashing ice-cold water on the face. One of the more effective vagal maneuvers is called the “Valsalva Maneuver.”
The Valsalva maneuver is performed by holding your breath and bearing down like you are trying to move your bowels. It can work about 20% of the time to stop SVT. A recent study demonstrated a modification to the Valsalva that increases the effectiveness to about 45%. If you hold your breath and push down for 15 seconds (while sitting up at about a 45 degree angle) and then immediately lie down and raise your legs about 45 degrees, the rapid flow of blood from your legs into your heart seems to activate the vagus nerve more effectively, essentially doubling the chance of success in stopping the arrhythmia. This can be done more than once and is more likely to work if you catch the SVT in the first minute or so.
Although vagal maneuvers can be used to successfully stop certain kinds of tachycardia, if you are having recurrent episodes, you owe it to yourself to speak to a heart rhythm specialist. The short circuits that cause SVT are potentially curable with a catheter ablation procedure, which is generally very successful and is associated with very low risk. You may be asked to try to grab a picture of the tachycardia on a monitor of some sort, but there are several ECG recording devices that you can now purchase, including the new Apple Watch, that will allow you to record your own electrocardiogram and show it to your doctor. Seeing a picture of the arrhythmia is invaluable to diagnose the type of arrhythmia and make the most appropriate recommendation.
If you experience sudden rapid heartbeats, you can try this modified Valsalva maneuver and see if it makes you feel better. Ultimately, recurrent tachycardia should be investigated by your doctor since it is likely to keep happening unless you determine the nature of the problem and correct it.