Mechanism of digitalis in atrial fibrillation:: (A) Decrease in contractility, (B) Na+ K+ ATP ase pump inhibition, (C) Increase refractoriness of AV node, (D) Bradycardia
Answer is C. Ans. C. Increase refractoriness of AV nodeDigoxin is inotropic agent used in heart failure. It has positive inotropic effect and negative chronotropic effect. Inotropic effect is due to blockade of Na+K+ATPase pump. Chronotropic effect is due to vagomimetic effect which increase the refractoriness of AV node. This mechanism is utilized in atrial flutter and fibrillation. Answer is C