Pacemakers, defibrillator

A pacemaker helps the heart keep a steady beat. If the device finds a slow heartbeat, it sends electrical signals to correct the beat. A dual chamber pacemaker checks, or paces, the heart signals in the right upper and lower heart chambers. A biventricular pacemaker paces both lower heart chambers. An implantable cardioverter-defibrillator (ICD) continuously checks for irregular heartbeats. If it finds one, it sends a brief shock to reset the heart rhythm.