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MCQ on antiarrhythmic agents: Page-3

Which of the following drugs exhibit interaction with adenosine
(P) Theophylline (Q) Dipyridamole (R) Diltiazem (S) Lidocaine

(A) Q,R

(B) P,S

(C) P,Q

(D) R,S

Adenosine acts on A1 receptors which are coupled with opening of potassium channels resulting in decrease in the rate of contraction of the heart. It also decreases AV conduction. Hence adenosine is a drug of choice in supraventricular tachycardia.

Which of the following drug belongs to the class IV antiarrhythmic agents?

(A) Encainide

(B) Verapamil

(C) Sotalol

(D) Propranolol

Verapamil is class IV, propranolol in class II, Sotalol is class III and encainide is class Ic.

Which of the following drug is used to estimate hepatic blood flow

(A) Phenytoin

(B) Lidocaine

(C) Amiodarone

(D) Diltiazem

Lidocaine has high extraction by liver and used to estimate hepatic blood flow.

All of the following mechanisms are responsible for arrhythmias, except

(A) Ectopic pacemaker activity

(B) Re-entry

(C) Delayed after depolarization

(D) Heart failure

It is the heart block but not heart failure. Heart block because of a decreased conduction at AV node may lead to ventricular arrhythmias.

The anticonvulsant that has antiarrhythmic action is

(A) Lidocaine

(B) Procainamide

(C) Disopyramide

(D) Phenytoin

Phenytoin is both class Ib antiarrhythmic agent as well as anticonvulsant. Nowadays its use is mainly confined to convulsions.