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A patient has periodic episodes of paroxysmal supraventricular tachycardia. Which of the following would be most suitable for outpatient prophylaxis?
Ans. D Verapamil
a. Verapamil, a non dihydropyridine ca channel blocker (ccb), depresses both the s-a node and the a-v node and would be effective for prophylaxis of paroxysmal atrial or supraventricular tachycardia. Nifedipine, the prototypic dihydropyridine ccb, has little effect on svt.
b. If we chose a fast-/immediate-acting dosage form of nifedipine, we would probably trigger substantial reflex cardiac stimulation.
c. The increased sympathetic tone to the heart could worsen the psvt. (and, although nitroglycerin is mainly a venodilator, it too could trigger reflex cardiac activation and worsen matters.)
d. Lidocaine and adenosine are parenteral drugs with short half-lives and, thus, are not suitable for prophylactic therapy.