<prompt> Which of the following calcium channel blocker would be useful in the treatment of supra-ventricular tachycardia by suppressing AV node conduction ?AmlodipineNimodipineVerapamilNifedipine  <response>: Ans. is c i.e., Verapamil o Amongst calcium channel blockers, verapamil has the most prominent cardiac electrophysiological action.o CCBs primarily act on SA node and AV node slow channel - Ca2 channel action potential - automaticity in SA node and decreased conduction in AV node. 