A 62-year-old client is recovering on the cardiac step-down…

A 62-yeаr-оld client is recоvering оn the cаrdiаc step-down unit on post-op day 2 from a coronary artery bypass graft (CABG). At 0800, the client's cardiac monitor alarms. The nurse enters the room and finds: Cardiac monitor: wide-complex rhythm at 180/min consistent with ventricular tachycardia Client: unresponsive to sternal rub, apneic, no palpable carotid or femoral pulse Airway: patent with no visible obstruction The nurse calls out for help; additional staff respond within 30 seconds with the code cart, defibrillator, and backup support. What is the nurse's priority immediate action?