The 2 main mechanisms for SVT's are eitheir automaticity from an ectopic focus (a rebel group of cells that decide when they want to fire) or a re-entrant circuit ( a short circuit around the electrical relay station of the heart, so that in a circular motion, the spark sends impulses down to the heart to contract). Unclear which type you have but going with the odds and the medications you have been on, it is likely an AVNRT or AVRT (AV nodal re-entrant tachycardia
). The main treatment is either to make that relay station more "sluggish" (with either verapamil
or other medications) so that if the short circuit bursts, then the relay station does not conduct the impulses further dowm. Options for treatment include medications on a regular basis (you don't know when the arrhytmia will return) or having an electrophysiology study; if it is one of these short cicuits I am describing, it can be burned with good success rates.
Hope this helps,
Mayo Clinic Rochester