Final answer:
Amiodarone (Cordarone) is used to convert new-onset atrial fibrillation, acting as a potassium channel blocker that affects the repolarization phase of the cardiac action potential. It is useful in controlling heart rhythm when patients do not respond to other medications. The Correct Answer is Option. B.
Step-by-step explanation:
The drug that may be used to convert new-onset atrial fibrillation is amiodarone (Cordarone). Amiodarone is a potassium channel blocker which acts on the potassium channels during the action potential of the heart's electrical cycle. This drug impedes the movement of K+ through voltage-gated K+ channels, specifically affecting the repolarization phase, and is also known for its ability to slow certain types of irregular heartbeat, particularly atrial fibrillation.
While digitalis, dopamine, and ß-blockers like metoprolol and propranolol have positive inotropic effects or other influences on the sympathetic system, amiodarone stands out as a preferred option for the acute management of new-onset atrial fibrillation. It is used commonly when the patient's heart rhythm needs to be controlled, and they are not responsive to other medications like ACE inhibitors and diuretics.