Supraventricular Tachycardia (SVT) is an abnormally fast heart rhythm originating in the heart’s upper chambers. While an SVT episode can be alarming, these events are often not life-threatening.
Understanding Supraventricular Tachycardia (SVT)
Supraventricular tachycardia occurs when the heart beats rapidly, often over 100 beats per minute at rest, due to faulty electrical signals in the upper chambers, known as the atria. During an episode, the heart can beat 150 to 220 times a minute. This rapid beating reduces the time for the heart’s chambers to properly fill with blood, affecting the amount pumped to the body.
Individuals experiencing SVT often report a sudden onset of a racing or pounding heart, known as palpitations. Other common symptoms include shortness of breath, dizziness, lightheadedness, and chest discomfort. Some may also feel tired, weak, or experience a pounding sensation in their neck. Episodes can last from a few seconds to several hours, and the heart rate typically returns to normal on its own or with intervention.
Vagal Maneuvers to Interrupt an SVT Episode
Vagal maneuvers are simple physical actions that can help slow or stop an SVT episode by stimulating the vagus nerve, which controls heart rate. While these techniques can be effective, they are not always successful and should be attempted only if advised by a healthcare professional.
One common technique is the Valsalva maneuver, which involves bearing down as if having a bowel movement. To perform this, sit or lie down, take a deep breath, close your mouth and nose, and then push that breath out against the closed airways for 15 to 20 seconds. A modified Valsalva maneuver, involving lying flat and raising the legs to a 45-degree angle immediately after straining, has shown higher success rates.
Forceful coughing can also stimulate the vagus nerve and may help interrupt an SVT episode. The cough needs to be strong and sustained, as a single, weak cough is unlikely to be effective. Another method involves the diving reflex, where you immerse your face in ice-cold water for about 10 seconds. Placing an ice pack or a washcloth soaked in ice water on the face can achieve a similar effect. Inducing a gag reflex, by touching the back of the throat with a finger, can also stimulate the vagus nerve.
When to Seek Emergency Medical Attention
While SVT is generally not life-threatening, certain symptoms warrant immediate emergency medical care. Seek medical attention if an SVT episode lasts longer than 20 to 30 minutes despite attempts at vagal maneuvers. Persistent rapid heartbeats that do not return to normal after a few minutes also require professional evaluation.
Severe symptoms accompanying an SVT episode necessitate emergency care. These include fainting or nearly fainting, severe chest pain, extreme shortness of breath, or confusion. If it is the first time experiencing SVT symptoms, or if there is a known underlying heart condition, seek immediate medical consultation. Call emergency services if you experience a fast heartbeat with shortness of breath, chest pain, or feeling faint.
Diagnosis and Long-Term Management of SVT
Diagnosis of SVT typically begins with a physical examination and review of symptoms and medical history. An electrocardiogram (ECG or EKG) is a primary diagnostic tool, checking the heart’s electrical activity. Since SVT episodes can be intermittent, a Holter monitor, a portable ECG device worn for one to two days, may record heart activity during daily routines. Other tests, such as an echocardiogram or an electrophysiological (EP) study, may identify the specific type and origin of the SVT.
Long-term management of SVT often involves a combination of approaches. Medications like beta-blockers and calcium channel blockers help control heart rate or reset the heart rhythm. For some individuals, catheter ablation offers a potential curative procedure. This involves threading thin tubes through a blood vessel to the heart to create small scars that block the abnormal electrical signals causing the SVT.
Lifestyle adjustments are important in managing SVT and reducing episode frequency. Avoiding known triggers such as excessive caffeine, alcohol, and nicotine benefits. Managing stress through relaxation techniques, getting adequate sleep, and engaging in moderate, regular physical activity supports heart health and reduces SVT episodes. A cardiologist provides a personalized treatment plan based on individual circumstances.