You MUST pair any intermediate bond holdings with PST or a direct short position in similar-duration Treasuries. The explosive expansion of the money supply and the risk of a hyperinflationary recovery are too great to take on that kind of duration without a hedge. But BIV holds a lot of Treasuries and Agencies, so you're better off with corporate-only bond funds that will reduce the cost of your hedge. Not to mention the fact that Treasuries are in a bubble of epic proportions.
For Safety, Two Income Securities [View article]