What role does a sensor play in synchronized cardioversion?

In synchronized cardioversion, the role of the sensor is critical as it aligns the electrical shock with the patient's heart rhythm. Specifically, the sensor detects the QRS complex, which is the part of the ECG that represents the depolarization of the ventricles and occurs during a heartbeat. By timing the delivery of the shock to coincide with the QRS complex, the device maximizes the chances of successful conversion of an abnormal heart rhythm, such as atrial fibrillation or ventricular tachycardia, while minimizing the risk of inducing ventricular fibrillation.

This precise timing is crucial; if the shock were delivered during the refractory period of the cardiac cycle, particularly during the T wave, it could disrupt the heart's rhythm and lead to more dangerous arrhythmias. Therefore, the sensor's ability to synchronize the shock with the QRS complex is key to achieving effective and safe cardioversion.