A 45-year-old man is noted to have dilated cardiomyopathy with atrial fibrillation and a rapid ventricular rate. An agent is used to control the ventricular rate, but the cardiac contractility is also affected, wof agents was most likely used
Verapamil
Digoxin
Nifedipine
Amiodarone
Verapamil Of the many Ca2+ channel blockers, verapamil has the most prominent cardiac electrophysiological action. It blocks L type Ca2+ channels and delays their recovery. mech of action:- The basic action of verapamil is to depress Ca2+ mediated depolarization. This suppresses automaticity and reentry dependent on slow channel response. Phase-4 depolarization in SA node is reduced resulting in bradycardia. The most consistent action of verapamil is prolongation of A-V nodal ERP. As a result A-V conduction is markedly slowed (P-R interval increases) and reentry involving A-V node is terminated. Verapamil has negative inotropic action due to interference with Ca2+ mediated excitation-contraction coupling in myocardium. Ref:- kd tripathi; pg num:-535
Cardiovascular system