First-degree heart block
The electrical impulses are slowed as they pass through the conduction system, but they all successfully reach the ventricles. First-degree heart block rarely causes symptoms or problems. Well-trained athletes may have first-degree heart block. Some medications can also cause this condition. No treatment is generally needed for first-degree heart block.
Second-degree heart block (Type I)
The electrical impulses are delayed further and further with each subsequent heartbeat until a beat fails to reach to the ventricles entirely. This type of block can is usually normal and is seen at rest and during sleep. It rarely causes symptoms of feeling light headed or dizzy.
Second-degree heart block (Type II)
With this condition, some of the electrical impulses from the atria are unable to reach the ventricles. This condition is less common than Type I, and is more serious. Usually, your doctor will recommend a pacemaker to treat type II second degree heart block, as it frequently progresses to third degree heart block.
Third-degree heart block
Third-degree heart block, also called complete heart block, occurs when none of the electrical impulses from the atria reach the ventricles. When the ventricles (lower chambers) do not receive electrical impulses from the atria (upper chambers), they may generate some impulses on their own, called junctional or ventricular escape beats. Ventricular escape beats, the heart's naturally occurring backups, are usually very slow. Patients frequently feel fatigue, lightheaded, and notice decreased stamina. Patients are usually treated by implanting a permanent pacemaker.
Bundle Branch Block
With this condition, the electrical impulses are slowed or blocked as they travel through the specialized conducting tissue in one of the two ventricles. This type of block is detected on the electrocardiogram or ECG and does not usually cause any symptoms.
