Microsoft Visio can by default exports its diagrams and drawings to several formats, including the SVG and other common graphics format, or even some CAD formats like DWG, which means that vdx to svg conversion should be doable.
If you do not have access to Visio, the easiest way would be to get your hands on some of the available converters like the VDXtoSVG tool, which you can download for free.