Atrioventricular nodal reentry tachycardia (AVNRT)
Make an Appointment
Talk to DoctorOverview
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.
Diagnosis
AVNRT can be diagnosed by the following:
- Blood tests: for thyroid disease, cardiac disorders and other health concerns that raise the risk of developing irregular heartbeats.
- Electrocardiogram (ECG):used to look at the functioning of cardiac electrical signals including the timing and duration of the heartbeat.
- Holter monitor: helps the doctor record the activities of the heart with this portable ECG device while you are doing your normal activities.
- Echocardiogram: which creates images of your heart and shows its size, structure and movement with sound waves.
AVNRT can also be diagnosed by deliberately triggering an episode of the disease. The following tests are used to trigger the symptoms:
- Stress test: A patient is required to run on a treadmill or stationary bicycle while having the cardiac activity recorded and analyzed.
- Electrophysiological study and cardiac mapping: help the doctor with the location of the arrhythmia occurrence.
Treatment
Most people with AVNRT don’t need treatment. Those with frequent or prolonged episodes of AVNRT or those that have symptoms continuously recurring might be recommended any of the following treatment approaches:
- Vagal maneuvers: a process that requires you to hold your breath and strain, dunk your face in ice water, or cough to stop the episode of AVNRT.
- Cardioversion: This option is recommended for patients who do not respond well to vagal maneuvers. In this process, you will either be prescribed medications or receive a shock to the heart sent from paddles or patches on your chest. Your doctor uses the shocking process to restore a normal heart rhythm.
- Medications: which are mostly prescribed to those with frequent episodes of AVNRT to put the heart rate under control or make the heart rhythm normal.
- Catheter ablation: One or more catheters are delivered into the blood vessels before being guided to the heart. The surgeons will then use sensors at the tip of the catheter to create scars on the heart’s lining to block the irregular signals that are causing the heart to beat faster. In order to close the scars radiofrequency which is heat energy or extreme cold energy called cryoablation is used.
