What defines synchronized cardioversion?

Synchronized cardioversion is a procedure used primarily to restore normal heart rhythm in patients experiencing certain types of tachycardias, such as atrial fibrillation or atrial flutter. The key aspect of synchronized cardioversion is that it must be carefully timed or 'synchronized' with the R wave of the patient's ECG. This synchronization is crucial because delivering an electrical shock during the vulnerable period of the cardiac cycle (such as during the T wave) can induce ventricular fibrillation, which is a life-threatening arrhythmia. Therefore, proper synchronization minimizes the risk of adverse effects and enhances the chances of successful conversion back to a normal rhythm.

In this context, the other options do not accurately define synchronized cardioversion: it is not indicated for patients in cardiac arrest, as immediate defibrillation rather than synchronized cardioversion is the appropriate treatment; it can be a non-invasive or invasive procedure, depending on the context; and continuous ECG monitoring is essential during the procedure to ensure accurate synchronization and assess the patient's cardiac rhythm.