AV Nodal Reentry (AVNRT)
AV Nodal Reentrant Tachycardia or AVNRT is the second most common supraventricular tachycardia or SVT, after Atrial Fibrillation (Afib) meaning that it causes a fast heart rhythm above the ventricles. In a normal heart, the electrical impulse that starts the heartbeat begins in the SA node and travels through the AV Node and into the ventricles – creating a coordinated, regular heartbeat. The AV node is the only pathway by which the electrical signal can transition from the upper to the lower chambers. However, AVNRT occurs when the electrical signal essentially loops around the AV node and short circuits, causing an irregular and fast heartbeat. Every time the signal creates follows the loop, an additional heartbeat is triggered, and the heart can race up to 250 beats per minute
AVNRT typically affects people in their 30s or 40s and rarely affects children or adolescents. This arrhythmia also affects women more than men. Typically, it does not cause long-term structural damage to the heart, however some patients may experience worsened heart failure or even heart attack due to underlying cardiovascular problems.
AVNRT is considered a paroxysmal or occasional arrhythmia, meaning that it is sporadic and temporary. Some episodes may last a few seconds up to a few hours or days. The severity of the episode can vary dramatically as well. Some patients may have very little discomfort while for others it may be debilitating.
Symptoms of AVNRT
Many patients will experience symptoms like other SVT’s including fast heartbeat or palpitations dizziness or lightheadedness, inability to exercise as before, weakness and fatigue chest pain or discomfort, and more.
Treatment for AVNRT
There are several treatments for AVNRT, depending on the severity of symptoms and how often it occurs. Your electrophysiologist may also suggest performing certain vagal nerve stimulation maneuvers including the Valsalva maneuver to help terminate an episode. Certain oral medications including beta blockers and calcium channel blockers can be used to terminate AVNRT episodes as well. However, much like in the treatment of other cardiac arrhythmias, medication and lifestyle changes may not be effective or may come with problematic side effects. If this is the case, a curative catheter ablation or cryoablation may be an option for qualifying patients. The success rate of an ablation for AVNRT is very high – in the 90% range. Risks of complications are generally low and if a second ablation procedure is required, these are often very successful as well.
The first step is to speak to a qualified electrophysiologist to understand your treatment options for AVNRT. After a complete work up, we can suggest a stepwise approach toward its treatment, starting with non-invasive lifestyle and medication management, eventually leading to safe and effective procedural solutions, when necessary.