How do I make the item descriptions show up when using Wordpress and Authorize.net?

I am wondering how I get the description of the items to show up in my email receipts from Authorize.net? They are always blank and I have to go through wordpress to see what the payment was for. Is there a way to set a description for the items that shows up in my authorize.net receipts?How do I make the item descriptions show up when using Wordpress and Authorize.net?
You can set a description by passing a value for the x_description field.