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: Iatrogenically induced intractable atrioventricular reentrant tachycardia after verapamil and catheter ablation in a patient with Wolff - Parkinson - White syndrome and idiopathic dilated cardiomyopathy .
### Output Text:
Iatrogenically induced intractable atrioventricular reentrant tachycardia after <span class="chemical">verapamil</span> and catheter ablation in a patient with Wolff - Parkinson - White syndrome and idiopathic dilated cardiomyopathy . 