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: Diltiazem ( 30 micrograms / kg / min ) also prevented the decrease in percentage segmental shortening from 34 + / - 14 % to 63 + / - 18 % of the control value ( P < . 05 ) and ST - segment elevation from 4 . 7 + / - 0 . 7 mV to 2 . 1 + / - 0 . 7 mV ( P < . 01 ) at 3 min after ISO infusion with stenosis .
### Output Text:
<span class="chemical">Diltiazem</span> ( 30 micrograms / kg / min ) also prevented the decrease in percentage segmental shortening from 34 + / - 14 % to 63 + / - 18 % of the control value ( P < . 05 ) and ST - segment elevation from 4 . 7 + / - 0 . 7 mV to 2 . 1 + / - 0 . 7 mV ( P < . 01 ) at 3 min after <span class="chemical">ISO</span> infusion with stenosis . 