Atrioventricular block (AVB) is a cardiac arrhythmia in which there is an alteration in the transmission of electrical impulses between the heart chambers, the atria and the ventricles. Second-degree AVB involves a discontinuous interruption of conduction between the atria and the ventricles.
There are two types: type I (Mobitz I or Wenckebach) and type II (Mobitz II).
In second-degree Mobitz II AVB, there is an intermittent block in the electrical impulse generated in the atria, which is not transmitted to the ventricles.
It is caused by congenital diseases, heart muscle infections (myocarditis) and heart surgery.
Symptoms include dizziness, shortness of breath on exertion and an irregular heart rate. In more severe cases, it can lead to loss of consciousness and even sudden cardiac arrest.
The diagnosis is based on a clinical history and physical examination. It is confirmed by an electrocardiogram, which shows the blockage of electrical conduction.
In symptomatic cases, the patient needs to be stabilised with drugs that speed up the heart rate. If the symptoms are severe or the arrhythmia is causing organ failure, a temporary pacemaker should be fitted until a permanent one can be implanted.
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