Heart block is a disease or inherited condition that causes a fault within the
heart's natural pacemaker due to some kind of obstruction (or "block") in the
electrical conduction system of the
heart. Despite the severe-sounding name, heart block may often cause no symptoms at all in some cases, or occasional missed heartbeats in other cases (which can cause lightheadedness,
syncope (fainting), and
palpitations), or may require an
artificial pacemaker to be implanted, depending upon exactly where in the heart conduction is being impaired and how significantly it is affected.