Supraventricular Tachycardia (SVT) Overview and Treatment
Supraventricular Tachycardia is the umbrella term for an unusually fast heartbeat involving the right or left atrium. The atrium is the area “supra” or above the ventricles. These problem areas include individual “spots” in the atria, such as with atrial tachycardia, the pulmonary veins (as with atrial fibrillation), and the AV node (that directs electrical signals from the right atrium to the ventricles). Specifically, SVT can include:
Atrial Fibrillation (AFib or AF) – a condition where the electrical signals of the heart begin in the wrong place such as the pulmonary veins. This results in triggering of complete electrical disarray and almost random static like electrical activity in the atria. The disarray causes the muscle to quiver or fibrillate rather than squeeze in a coordinated fashion. The random electrical activity in the atria at between 300-600 quivers per minute can result in erratic beating of the ventricles. This may cause the heart to beat sometimes too fast, and sometimes too slow.
Atrial Flutter (AF) – a condition similar to AFib above, however, the fast heartbeat is regular, squeezing almost exactly 5 times per second. This is because the electrical activity wraps around the right upper chamber (atrium) in a very specific short circuit every 0.22 seconds. The ventricles always beat in some fraction of this rate, usually 75 or 150 beats per minute. Often the ventricles and thus the pulse are very regular in atrial flutter rather than the erratic pulse seen in Afib.
Wolff-Parkinson-White (WPW) Syndrome – a congenital condition where electrical impulses bypass the AV node. This condition is evident on an ECG, a simple office test. It may be associated with sporadic rapid heart rates that suddenly start and stop and is also associated with a risk of sudden death. It is among the easiest problems that we can actually cure with a catheter ablation.
Atrioventricular Nodal Reentry Tachycardia (AVNRT) – occurs when there is an additional electrical impulse pathway in or around the AV Node. With the exception of WPW (see above) the AV node is the only way the upper chambers can communicate to the lower chambers when to contract. AVNRT consists of several types and the rapid heart rate it causes can also be easily cured with a catheter ablation to disconnect or interrupt the electrical short circuit.
Atrial Tachycardia – a condition where the electrical impulse in the heart begins in the atria but somewhere other than the SA node. This can result in periods or rapid heart beats lasting from seconds to hours or more.
Treatment for SVT
Many EPs treat all of the above conditions with an advanced, effective and minimally invasive technique known as catheter ablation (CA) – destruction of improperly functioning heart tissue using the heat from highly concentrated radiofrequency waves. By using advanced techniques and 3-D, heart-mapping software, we can accurately and effectively locate and ablate the areas causing the tachycardia.