Can ventricular tachycardia self-terminate after 30 seconds?

[Nandorph]

NSVT is defined as an episode of v-tach lasting less than 30 seconds.  Why 30?  I read a post on here where some guy said he went into a v-tach episode that lasted 37 or 38 seconds during a stress test.  He also said that he remained conscious the whole time through the episode.  That got me wondering whether he knew what he was actually talking about.  Could it have been PSVT and not VT?  The fact that he remained conscious the entire time is one thing, but my bigger question is about the duration of NSVT.  Why is it defined as lasting under 30 seconds?  Is it impossible for VT to terminate on its own after 30 seconds?  Or is it just exceedingly rare?  

[2210485]

30 seconds has more to do with impact on other systems of the body.. lack of adequate blood flow and possible underlying causes than anything.. VT can terminate on its own at any time.

After 30 seconds however you might start to really feel like crap and your doctor may start to get worried about the possibility of a more serious underlying cause of the VT that has yet to be discovered.