Atrioventricular nodal reentry tachycardia (AVNRT)

Overview 

Atrioventricular nodal reentry tachycardia (AVNRT) the most common type of supraventricular tachycardia (SVT) is caused by a reentrant circuit, which is an extra pathway in the AV node that causes a patient’s heart to beat prematurely. The disease causes episodes of an abnormally rapid heartbeat at a rate of more than 100 beats per minute. Although any person can develop this disease, it is mostly found in young women.

Symptoms of AVNRT

AVNRT may cause sudden episodes of fast heartbeats and resolve in a short period of time.

AVNRT may cause some common signs, including:

• Lightheadness
• Dizziness
• Rapid heartbeat (140 to 280 beats per minute).
• Heart pounding
• Urinary frequency
• Breathing difficulties

As a rare case, AVNRT may be severe and cause serious symptoms and complications such as:

• Tightness in the chest
• Confusion
• Fainting or passing out
• Low blood pressure
• Shock

Causes of AVNRT

There are four chambers in the heart, two upper chambers called the atria and two lower chambers called the ventricles. Our sinus node in the upper right chamber, or the atrium, acts as a natural pacemaker which controls how the heart beats by sending electrical signals, which causes the heart muscles start to contract to pump blood into the ventricles. The heart signals will then continue to go the AV node, where they slow down to allow blood to fill the ventricles which will pump blood to the lungs as well as other organs in the body.

For a normal person, this process with run smoothly with a heart rate of 60-100 beats per minute, but those with AVNRT will suffer from a faster rate, which the heart cannot fill blood in the chambers fast enough, leading to a quickly rising heartbeat causing patients to suffer from vertigo or wooziness as the brain cannot receive enough blood and oxygen.

AVNRT is a most common type of SVT

AVNRT causes the heart to contract too early, which is a defect called premature contraction. This defect may cause the heart’s electrical impulse to enter and circle around a small pathway near the AV node. This is a condition called a reentrant circuit which may quickly cause fast heartbeats that are persistent.

Despite the lack of supporting research, some doctors believe genetics play a role in developing AVNRT as some patients with this disease have a family history of AVNRT.

Risk factors

Supraventricular tachycardia (SVT) can be found in anyone but most frequently found in pregnant women, as well as being the most common type of arrhythmia among newborns and kids.

AVNRT and SVT can be triggered by the following:

• Age: People who are middle-aged face a higher risk of developing SVT.
• Cardiac conditions: those with coronary artery disease, a history of heart surgery, narrow heart arteries, heart attack, injured heart valves, cardiac scars, and heart muscle disease.
• Congenital heart disease: as it can disrupt how the heart beats.
• Thyroid disease: includes both hyperthyroidism and hypothyroidism.
• Diabetes: which is untreated puts you at risk of developing cardiac complications including hypertension.
• Obstructive sleep apnea: causes irregular breathing while you are sleeping, which raises the risk of SVT.
• Use of drugs: like nicotine, amphetamines and cocaine.