As a medical professional with expertise in cardiology, I can provide you with an accurate explanation of the terms you've asked about. Unsynchronized cardioversion and defibrillation are related but distinct procedures used to treat abnormal heart rhythms. Both are life-saving measures, but they are applied in different contexts and with different techniques. Unsynchronized cardioversion is a controlled electrical shock delivered to the heart to restore a normal heart rhythm. This procedure is typically used when the patient is experiencing atrial fibrillation or atrial flutter, which are less life-threatening conditions. Unsynchronized cardioversion does not coordinate the shock with the heart's electrical activity, hence the term "unsynchronized." It is used when the heart's rhythm is regular but abnormal. Defibrillation, on the other hand, is an emergency procedure that delivers a high-energy shock to the heart to correct life-threatening conditions like ventricular fibrillation or pulseless ventricular tachycardia. Defibrillation is always performed unsynchronized because these rhythms are chaotic and do not have a regular pattern that can be synchronized with. In summary, while both unsynchronized cardioversion and defibrillation involve the delivery of an electrical shock to the heart, they are used for different types of heart rhythms and have different urgency levels in their application. read more >>

This means that the shock may fall randomly anywhere within the cardiac cycle (QRS complex). Unsynchronized cardioversion (defibrillation) is used when there is no coordinated intrinsic electrical activity in the heart (pulseless VT/VF) or the defibrillator fails to synchronize in an unstable patient.read more >>