Final answer:
Cardioversion most significantly differs from defibrillation in that it is synchronized with the patient's R wave to restore a regular but abnormal heart rhythm, whereas defibrillation is an unsynchronized shock delivered in response to life-threatening arrhythmias such as ventricular fibrillation or pulseless ventricular tachycardia.
Step-by-step explanation:
The differentiation between cardioversion and defibrillation primarily lies in their indications and synchronization with heart rhythm. The statement that most accurately differentiates cardioversion from defibrillation is A) Cardioversion is timed to be synchronous with the patient's R wave. Cardioversion is a procedure that is used to restore a normal heart rhythm when the patient has a regular, but rapid or abnormal rhythm, like atrial fibrillation or atrial flutter. It is synchronized with the R wave on the ECG, to prevent the shock from occurring during the vulnerable period of the heart's rhythm, which could otherwise induce ventricular fibrillation.
In contrast, defibrillation is an unsynchronized delivery of a high-energy shock and is used in cases of cardiac arrest where there is no discernible rhythm, or there is ventricular fibrillation or pulseless ventricular tachycardia. Automated external defibrillators (AED) are used for defibrillation and can be found in many public areas, often used in emergency situations even before the arrival of healthcare professionals.