WASHINGTON - Vice President Dick Cheney got good news Friday during his annual heart checkup, with a pacemaker detecting no irregular heartbeat, his office said. Cheney has had four heart attacks, and a pacemaker was placed in his chest in June 2001. The checkup determined that the pacemaker, called an implantable cardioverter defibrillator, was working fine and never had to be activated. The device is designed to activate automatically if needed to regulate the patient's heartbeat. Cheney underwent the routine exam at George Washington University Medical Center. It included a physical exam, an electrocardiogram, an echocardiogram and a stress test....