I have Junctional Tachycardia. The doctors told me that it's not life threatening, but it will effect my quality of life. It's extremely rare and difficult to treat. Ablation did not/will not work for mine because it's on the AV node. They will try medications, but even those may not work 100%. My EP said that the Atrial and Ventricle chambers pump simultaneously during an episode. I don't know if that's standard with JT or if it was how mine was...I think it's standard though. I don't really have much information other than that.
See:
http://www.medhelp.org/posts/Heart-Rhythm/junctional-tachardia/show/1825077
Perhaps the two of you can share whatever you learn.
Hope your doctors are able to provide whatever you need to effect a cure.