Symptoms of second- and third-degree heart block include fatigue, fainting, dizziness, lightheadedness and shortness of breath. A person suffering from first-degree heart block may not have symptoms, according to the National Heart, Lung and Blood Institute.
Heart block is a condition in which the electrical signal that causes the heart to contract is slowed or disrupted, states the National Heart, Lung and Blood Institute. It is a type of arrhythmia that some patients are born with and some develop as they age. The disease is broken into three degrees of severity, with the first being the least severe and the third being the most severe, and it can prove fatal if not treated in time.