I'd read the BBC account, not the linked one
Having looked at it now, It doesn't seem to answer that point. The difficulties with an IV line to deliver the current 3 preferred drugs are discussed at length. Using a single heroin overdose instead would not require a line.
It wouldn't work with someone with fugitive veins to the extent that one could not be found at all, but in general single injection is easier than placing a line.
But as I said first, and reiterate now. I think the death penalty is wrong, and the US's inability to find an acceptable, humane method just adds an extra level of wrong.