Stent placement complication

My husband recently went in for a stent placement for a 98% blockage in the right coronary artery.  Just after the stent was placed the artery disected and he then had to have emergency bypass surgery.  Can you tell me about the complication and why it happens?

[Flycaster305]

I had three stents placed for a 90% blockage in the RCA, it was a difficult procedure, I was told; the operative procedure report said I have 'torcherous' (twisted) artery.  About a month afterwards, I had angina, SOB, the usual symptoms of a blockage, but it was found I had a dissected artery also.  My leakage was corrected by a really long stent, and I've been fine since then, it's been 1 1/2 years.  In my case, I was told that the harmonic vibration between the two stents caused the problem.  

I think that is a plausible answer, but also wonder if the artery was weakened by the procedure.  I don't worry about it, though, the first procedure probably kept me from another heart attack and the second procedure worked.  We have no guarantees.  

I hope your husband is doing well, keep us informed.