What are the types of heart block?
First-degree heart block (also called first-degree AV block). The electrical impulses are slowed as they pass through the conduction system, but all of them successfully reach the ventricles. First-degree heart block rarely causes any symptoms or problems, and well-trained athletes may have this. Medications can contribute to the condition. No treatment is generally necessary for first degree heart block.
Type I second-degree heart block (also known as Mobitz Type I second-degree AV block or Wenckebach AV block). In this condition, the electrical impulses are delayed further and further with each heartbeat until a beat is skipped entirely. The condition generally is not as serious as type II second-degree heart block, but it sometimes causes dizziness and/or other symptoms. Normal people may sometimes have this when they are sleeping.
Type II second-degree heart block (Mobitz Type II second-degree AV block) is also a condition in which some of the electrical impulses are unable to reach the ventricles. This condition is less common than Type I, but is generally more serious. In some cases, a pacemaker is implanted to treat the abnormally slow heartbeat that may result from this condition.
Third-degree heart block (also known as complete heart block or complete AV block) is when none of the electrical impulses can 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 functional or ventricular escape beats. Ventricular escape beats, natural backup signals, usually are very slow, however, and cannot generate the signals needed to maintain full functioning of the heart muscle.
Bundle Branch Block is when electrical impulses are slowed or blocked as they travel through specialized conducting tissue in the ventricles.
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