This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Digoxin is useful in - \nSelect and explain. \nA. Atrial fibrillation in thyrotoxicosis, B. Complete hea-block with CHF, C. Ventricular tachycardia, D. Myocarditis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Complete hea-block with CHF Digitalis has depressant action on AV node -4 it delayes the conduction through AV node by increased ERP. If paial block is present, digitals may conve it into complete block. But, if complete block is already present, digitalis cannot worsen the condition (as conduction is blocked to maximum block, i.e., complete hea block). So, in this condition digitalis can be used for hea failure. About other options In thyrotoxicosis and myocarditis there is reduced responsiveness and patient becomes more prone for digitalis induced arrhythmias. Digitalis is contraindicated in ventricular tachycardia as ventricular fibrillation may be precipitated.", 'role': 'assistant'}]