Paroxysmal Supraventricular Tachycardia (PSVT)

The short circuit is caused by one of three conditions and will have a different location and behavior depending on the cause.

The short circuit is caused by one of three conditions and will have a different location and behavior depending on the cause.

Atrioventricular Nodal Re-entrant Tachycardia (AVNRT)

Atrioventricular nodal re-entrant tachycardia (AVNRT) is the most common cause of PSVT. It occurs when a small extra pathway exists in or near the AV node — the "gate" that sends electricity from the upper chambers (atria) to the lower chambers (ventricles). An electrical impulse that enters this pathway will circle rapidly, causing a sudden (paroxysmal), fast heartbeat in both the atria and the ventricles. AVNRT is not a life-threatening arrhythmia, but it can cause symptoms such as lightheadedness or fainting.

Wolff-Parkinson-White Syndrome (WPW)

Wolff-Parkinson-White syndrome occurs when an extra muscle fiber connects the upper and lower chambers of the heart. In normal hearts, the only connection between the upper and lower chambers is the AV node — the electrical signal passes from the atria, through the AV node, and ends in the ventricles. The presence of this extra path can encourage a "short circuit" arrhythmia known as an atrioventricular reciprocating tachycardia (AVRT). The symptoms of AVRT vary widely from mild heart racing to syncope. Due to an increased risk of sudden cardiac death, people with Wolfe-Parkinson White syndrome are advised to have curative catheter ablation.

Wolff-Parkinson-White syndrome is congenital, developing in utero. Although present from birth, the tachycardias (rapid heartbeats) that result from the abnormal electrical connection often take years or decades before they become a problem.

Atrial Tachycardia

Atrial tachycardia is responsible for about 5 percent of PSVTs. It occurs when an electrical impulse fires rapidly from a site outside the sinus node and circles the atria, often due to a short circuit.

Certain things can trigger the causes of PSVT, like:

• Thyroid disease
• Heart disease
• Lung disease
• Pregnancy
• Drug use such as cocaine  
• Prescription medication like asthma drugs and over-the-counter cold and allergy drugs
• Smoking
• Alcohol
• Caffeine

Over time, untreated and frequent episodes of supraventricular tachycardia may weaken the heart and lead to heart failure, particularly if the patient has other coexisting medical conditions.

In extreme cases, an episode of supraventricular tachycardia may cause unconsciousness or cardiac arrest.

it also can lead to death.

Most people with SVT do not require medical treatment. However, if a person experience frequent episodes, then the doctor may recommend or try:

• Carotid sinus massage

The doctor may try this type of massage that involves applying gentle pressure on the neck, where the carotid artery splits into two branches — to release certain chemicals that slow the heart rate. 

• Vagal maneuvers

In order to stop an episode of SVT using particular maneuvers that include holding the breath and straining, dunking your face in ice water, or coughing may be helpful.

These maneuvers affect the nervous system that controls the heartbeat (vagus nerves), often causing the heart rate to slow.

• Cardioversion

If vagal maneuvers is not helpful enough, the doctor may use cardioversion, which can be conducted as a procedure or by using medications.

In the procedure, a shock is delivered to patient’s  heart through paddles or patches on his’her chest. The current affects the electrical impulses in the heart and can restore a normal rhythm.

• Medications

The doctor may prescribe medication to control the heart rate or restore a normal heart rhythm. It's very important to take any anti-arrhythmic medication exactly as directed by the doctor in order to minimize complications.

• Catheter ablation

In this procedure, the doctor threads one or more catheters through patient’s blood vessels to the heart. Electrodes at the catheter tips can use heat, extreme cold or radiofrequency energy to destroy a small spot of heart tissue and create an electrical block along the pathway that's causing the arrhythmia.

• Pacemaker

In rare instances, treatment for SVT may involve use of a small, implantable device called a pacemaker to emit electrical impulses that stimulate your heart to beat at a normal rate. The pacemaker is placed under the skin near the collarbone in a minor surgical procedure. An insulated wire extends from the device to the heart, where it's permanently anchored.

PSVT is generally not life threatening. If other heart disorders are present, it can lead to congestive heart failure or angina.

A person can try the following techniques to interrupt a fast heartbeat during an episode of PSVT:

• Coughing while sitting with the upper body bent forward
• Splashing ice water on face during an episode of PSVT
• Avoid smoking, caffeine, alcohol, and illicit drugs in routine
• Eating a heart-healthy diet
• Increasing physical activity
• Getting plenty of rest

Some types of complementary therapies may be helpful to reduce stress, such as:

• Yoga
• Meditation
• Relaxation techniques

Some studies have shown that acupuncture may help reduce irregular heart rates in certain arrhythmias, but further research is needed.

The role of omega-3 fatty acids, a nutrient found mostly in fish, in the prevention and treatment of arrhythmias isn't yet clear. But it appears as though this substance may be helpful in preventing and treating some arrhythmias.

To diagnose SVT, the doctor will review your symptoms and patient’s medical history and conduct a physical examination. Doctor may test for — conditions that may trigger the SVT, such as heart disease or a problem with patient’s thyroid gland. The doctor may also perform heart-monitoring tests specific to arrhythmia. These may include:

• Electrocardiogram (ECG)

During an ECG, sensors (electrodes) that can detect the electrical activity of patient’s heart are attached to your chest and sometimes to your limbs. An ECG measures the timing and duration of each electrical phase in patient’s heartbeat.

• Holter monitor

This portable ECG device can be worn for a day or more to record patient’s heart's activity as he/she go about his/her routine.

• Event monitor

For sporadic episodes of SVT, patient keep this portable ECG device available, attaching it to patient’s body and pressing a button when he/she has symptoms. This lets the doctor check patient’s heart rhythm at the time of their symptoms.

• Echocardiogram

In this noninvasive test, a hand-held device (transducer) placed on patient’s chest uses sound waves to produce images of his/her heart's size, structure and motion.

• Implantable loop recorder

This device detects abnormal heart rhythms and is implanted under the skin in the chest area.If the doctor doesn't find an arrhythmia during those tests, he/she may try to trigger arrhythmia with other tests, which may include:

• Stress test

For some people, SVT is triggered or worsened by stress or exercise. During a stress test, patient will be asked to exercise on a treadmill or stationary bicycle while his/her heart activity is monitored. If doctors are evaluating to determine if coronary artery disease may be causing the arrhythmia, and if he/she has difficulty exercising, then the doctor may use a drug to stimulate the heart in a way that's similar to exercise.

• Tilt table test

The doctor may recommend this test if the patient had fainting spells. The heart rate and blood pressure are monitored as the patient lie flat on a table. The table is then tilted as if he/she was standing up. The doctor observes how the heart and the nervous system that controls it respond to the change in angle.

• Electrophysiological testing and mapping

In this test, doctors thread thin tubes (catheters) tipped with electrodes through patient’s blood vessels to a variety of spots within heart. Once in place, the electrodes can map the spread of electrical impulses through the heart.

• In addition, the cardiologist can use the electrodes to stimulate patient’s heart to beat at rates that may halt- an arrhythmia. This allows the doctor to see the location of the arrhythmia and what may be causing it.