In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Two patients had inadequate resting images , one DSE was terminated because of inferior hypokinesis , another DSE was terminated because of a rate - related atrial conduction deficit , and 1 patient did not reach the target heart rate .
### Output Text:
Two patients had inadequate resting images , one DSE was terminated because of inferior hypokinesis , another DSE was terminated because of a rate - related atrial conduction deficit , and 1 patient did not reach the target heart rate . 