Converting .pdf documents directly to .vsd format.
Converting Adobe Portable Documents directly to Microsoft Visio Drawings (.pdf to .vsd conversion) seems very unlikely, even though several online conversion tools claim they are capable of such a conversion. The actual quality of such supposed conversions is highly questionable, at best.
You could try to create vector graphics from a diagram (.vmf / .emf / .svg), and import it to MS Visio. Such conversion will obviously not be perfect, and you will be left with loss of data.
In a word, direct pdf to vsd conversion is not possible.
So don't expect any so-called pdf to vsd converter or pdf to vsd free online conversion tool available.
A vector based diagramming software from Microsoft