is it possible to refinance a heloc without refinancing your first mortgage?

I have a good rate with my first mortage at 4.25 fixed for 15 years. I also have a heloc that is adjustible and is at about 8.5 percent right. I would like to refinance the heloc without loosing the rates on the 1st. Is there such a thing? http://bit.ly/kvOjcZ