Echo with contrast?

[Susan M(PA)]

My ab/ct is clear of lung mets, second time since diagnosis of BC with lung mets
in March 2002! It's been clear since June following Navelbine Jan-June with Herceptin.

I had a 50% (borderline) Muga in October, taking a break on Herceptin.
I dropped from a 63% to 50% in ten months, so oncologist said see a cardiologist. He didn't seem concerned but ordered echo WITHOUT contrast.
Now the nurse calls late today and doc wants an echo WITH contrast.
Doc is gone for the day.

So what's going on?
Should I be concerned?
Or should they always order echo WITH contrast?

Happy New Year to All!

Susan M(PA)