Atrioventricular (AV) block is a cardiac arrhythmia in which the conduction of electrical impulses between the different chambers of the heart, the atria and the ventricles, is altered. In second-degree AV block, one or more atrial impulses do not reach the ventricles (not all p-waves are followed by a QRS on the electrocardiogram).
There are two types: type I (Mobitz I or Wenckebach) and type II (Mobitz II).
In Mobitz I or Wenckebach second-degree AV block, there is a prolongation of the PR interval (the time it takes for the electrical impulse to travel from the atria to the ventricles becomes progressively longer) until one beat is blocked and cannot travel to the ventricles.
It can occur in normal individuals and athletes without underlying heart disease. Possible causes include: congenital disease, ischaemic cardiopathy (heart attacks), medication and previous heart surgery.
Most patients are asymptomatic. When symptoms occur, they are: fatigue, dizziness, loss of consciousness, chest pain and shortness of breath.
The diagnosis is based on the patient's medical history and a physical examination. An electrocardiogram and chest X-ray are usually done to complete the examination.
Treatment is given to correct the cause and treat the symptoms.
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