As a result of these multiple directly mediated and vagally mediated effects of digitalis, the drug is capable of causing a variety of tachy- and brady-dysrhythmias. The tachycardias are manifestations of the directly mediated effects of the drug and include ectopic atrial, AV junctional and ventricular tachycardia, and atrial and ventricular fibrillation. The bradycardias include sinus bradycardia and the sino-atrial and atrio-ventricular blocks. These are manifestations of the vagally mediated effects of the drug.