Dear PikaPika,
The presence of the extra pathway, also known as an accessory pathway, allows for SVT to occur, as electricity goes down the normal electrical connection (through the A-V node) and back up through the accessory pathway. Wolff-Parkinson-White syndrome, or WPW, is associated with a certain kind of accessory pathway that allows forward electrical conduction from the atria to the ventricles, with evidence of this seen on the electrocardiogram. Thus, it is certainly able to cause SVT. It is associated with greater risk than typical SVT (sometimes also referred to as a "concealed pathway"), as any atrial tachyarrhythmias (fast heart rhythms originating in the atria, such as atrial flutter or fibrillation) can potentially go down this pathway into the ventricles and cause the ventricles to beat so fast as to be incompatible with life. This causes sudden cardiac death.
Is that all SVT associated with extra electrical pathway? Would "Extra electrical pathway" also same as "accessory pathway" and "wpw"? If not, what are the differences? Thanks.
Dear Umar Khan,
Supraventricular tachycarda (SVT) occurs when there is an extra electrical pathway that connects the top and the bottom of the heart, so that electricity goes down the normal pathway, then comes back up the extra pathway quickly. It causes a fast abnormal heartrate, called a dysrhythmia; SVT is just one of many kinds of dysrhythmias. Although I am not evaluating her myself, so I can’t tell you everything about her prognosis for sure, there are a few things that I can say. We need to think about her initial management, evaluation, and subsequent management. If she does go into SVT, you can do what are called “vagal maneuvers”, which your cardiologist can show you how to do. These can sometimes break an episode of SVT. One of these is having her blow really hard into a straw whose end is squeezed tightly. There are others that are similar. Typically, a few hours of SVT is not dangerous to her as long as her heart is structurally normal—it is a nuisance, though, and can be somewhat scary.
As part of the evaluation, the cardiologist will likely perform an echocardiogram to evaluate for certain structural defects that can be associated with SVT, such as Ebstein’s anomaly of the tricuspid valve. A Holter monitor will demonstrate how frequently she is having SVT. Next, after evaluating this information, she can be put on medications to prevent her from going into this arrhythmia. Since the likelihood of spontaneous resolution of SVT is quite low at this point, subsequent management needs to be considered. As part of this, you may eventually want to consider an electrophysiology study with radiofrequency ablation. This is an elective procedure performed with several catheters to electrically map the heart. During this, the extra pathway is found. Then, a special ablation catheter can burn the pathway and make it go away. This is routinely done when the children are around 8-12 years of age. That said, there are several approaches to this. As mentioned previously, since SVT with a structurally normal heart is typically a nuisance and is not life-threatening, it can be treated and either prevented with lifelong medications to prevent its occurrence, or ablated and completely eliminated.