Severe Supraventricular Tachycardias

Severe Supraventricular Tachycardias: Overview and Treatment

Supraventricular tachycardia (SVT), also called paroxysmal supraventricular tachycardia (PSVT), is a serious heart condition that causes the heart to beat rapidly. It can cause symptoms such as a rapid heart rate, chest pain, shortness of breath, lightheadedness, or dizziness. Severe supraventricular tachycardias occur when the condition is severe, and the heart rate is very rapidly beyond a normal rate. Severe SVTs require urgent medical intervention to correct the heartbeat and restore normal breathing and blood flow. In this article, we will discuss what severe SVTs are, how they are diagnosed, and the treatments available.

What are Severe Supraventricular Tachycardias?

Severe SVTs are a type of arrhythmia, or heart rhythm abnormality, in which the heart rate increases to a dangerously high rate. The normal resting heart rate for adults is between 60 and 100 beats per minute (bpm). During a severe SVT, the heart rate can exceed 150 bpm and can even reach as high as 250 bpm. Severe SVTs can last from several seconds to several minutes and can be associated with the onset of chest pain, shortness of breath, lightheadedness, or dizziness.

Causes & Risk Factors

Severe SVTs can be caused by a variety of factors, including congenital heart defects, heart disease, injury or trauma to the heart, certain heart medications, an overactive thyroid, smoking, excessive alcohol consumption, or caffeine intake.

In addition, certain risk factors increase the chance of having a severe SVT, such as age (over 65), gender (men are more likely to experience SVTs than women), and family history of arrhythmias, especially if they occur at a younger age.

Diagnosis & Treatment

Diagnosis of severe SVTs is done through diagnostic tests such as electrocardiography (ECG), Holter monitoring, and echocardiography (echo). Treatment for severe SVTs depends on the cause and the severity of the condition. Treatment options range from medications to vagal maneuvers to catheter ablation, and even surgery in some cases.


  • Beta blockers: these medications slow the heart rate by blocking the effects of adrenaline. These medications are usually used in mild SVTs but are also sometimes used in more severe cases. Common beta blockers include metoprolol, carvedilol, and propranolol.
  • Calcium channel blockers: these medications relax the muscles of the heart, allowing blood to flow freely throughout the body. Common calcium channel blockers include verapamil and diltiazem.
  • Antiarrhythmics: these medications help the heart to beat in a regular rhythm and are usually used in severe cases. Common antiarrhythmics include amiodarone, sotalol, and procainamide.

Vagal Maneuvers:

  • Valsalva maneuver: This method involves bearing down as if you were trying to force air out of your lungs. It can help slow the heart rate in the short-term.
  • Carotid sinus massage: This method involves massaging the carotid artery, which is located in the neck, in order to slow the heart rate.
  • Diving reflex: This method involves immersing the face in cold water to slow the heart rate. This is not recommended in cases of severe SVT.

Catheter Ablation:

Catheter ablation is a minimally invasive procedure used to destroy abnormal parts of the heart that are causing the rapid heart rate. It is usually done by inserting catheters, or thin flexible tubes, into the blood vessels and delivering an electrical current to destroy the area. This procedure is highly effective in correcting the abnormal heart rhythm and restoring normal rhythm.


Severe SVTs require urgent medical attention. Diagnosis and treatment is usually done by a cardiac specialist, though depending on the severity of the case, it may require a more invasive procedure or cardiac surgery. With the right diagnosis and treatment, SVTs can usually be managed in a relatively safe and effective manner.