General synonyms:
* Nervously
* Worriedly
* Uneasily
* Apprehensively
* Fearfully
* Restlessly
* Impatiently
More specific synonyms:
* With trepidation: If the anxiety is accompanied by fear or dread.
* With anticipation: If the anxiety is mixed with excitement or hope.
* With a heavy heart: If the anxiety is accompanied by sadness or a sense of foreboding.
* With a sinking feeling: If the anxiety is accompanied by a feeling of dread or hopelessness.
The best synonym will depend on the specific context and the intended meaning.