This op was to not only to check the valves and remove any imperfections so that they do actually close properly but also to install some different hardware.....
An automated implantable cardioverter defibrillator (AICD)
To quote from Wikipedia
"The ICD is the first-line treatment and prophylactic therapy for patients at risk for sudden cardiac death due to ventricular fibrillation and ventricular tachycardia."
