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: The ventricular arrhythmias responded to intravenous administration of lidocaine and to direct current electric shock ; ventricular pacing was required in some instances and intravenous administration of propranolol combined with ventricular pacing in one .
### Output Text:
The ventricular arrhythmias responded to intravenous administration of <span class="chemical">lidocaine</span> and to direct current electric shock ; ventricular pacing was required in some instances and intravenous administration of <span class="chemical">propranolol</span> combined with ventricular pacing in one . 