Is Valium Drop Harmful For Person With Mitral Valve Prolapse?

I am going to an oral surgeon to have a tooth extracted. This is not a wisdom tooth. I want to have the valium drip during the extraction, but the doctor says I have to have my primary care physician sign a form saying it is okay to do this. I have mild mitral valve prolapse, which is the reason the oral surgeon wants this done. Why is this necessary?