They are going to remove and replace the implanted defibrillator. Has to be done every 6 to 7 years. Hopefully they will not need to replace the leads (that is unpleasant and more dangerous). Usually they try to get away with pulling the device out and unscrewing the leads that connect it to the heart and attaching them to the new device before putting it back in.
Local anaesthetic job ~ more uncomfortable and unpleasant than anything ~ although they do turn up the tap on the drip fed valium to put me out in order to deliver shocks to test the damned thing before closing the wound.
It will, of course, take weeks to heal properly because of the blood thinning drugs I take and I shall have many sleepless nights because every time I move it will hurt.