In the treatment of severe bradycardia, all of the following can be the best modality of treatment except:

Answer is D (Diltiazem) Diltiazem is used in the treatment of tachvarhythmias and not in the treatment of bradvarrhEthmias. Diltiazem is a class IV antiarrhythmogenic drug, used in atrial fibrillation/flutter and supraventricular tachycardias (tachycardias) to slow the ventricular rate, by decreasing conduction velocity and increasing refractoriness in the AV nodal tissue. Atropine, lsoproterenol and pacemakers are all useful in the management of bradycardia. Atropine and isoproterenol are useful in increasing hea rate and decreasing symptoms in patients with sinus bradycardia or AV block localized to AV node.' - Harrison 16th/1339 Long term therapy of brady arrhythmias is best accomplished by pacemakers.