![]() It is important to diagnose AV-blocks precisely because unnecessary pacemaker placement in patients with pseudo-AV blocks can worsen symptoms and create complications. However, one important consideration when diagnosing AV blocks from ECGs is the possibility of pseudo- AV blocks which are due to concealed junctional extrasystoles. An ECG is used to differentiate between the different types of AV blocks. There are three types, or degrees, of AV block: (1) first-degree, (2) second-degree, and (3) third-degree, with third-degree being the most severe. Other blocks are pathologic, or abnormal, and have several causes, including ischemia, infarction, fibrosis, and drugs. Some AV blocks are benign, or normal, in certain people, such as in athletes or children. The heart rate produced by the ventricles is much slower than that produced by the SA node. When the signal is completely blocked, the ventricles produce their own electrical signal to control the heart rate. ![]() In an AV block, this electrical signal is either delayed or completely blocked. ![]() The signal travels from the SA node to the ventricles through the atrioventricular node (AV node). Normally, the sinoatrial node (SA node) produces an electrical signal to control the heart rate. Representative electrocardiogram recordings of the different degrees of heart blockĪtrioventricular block ( AV block) is a type of heart block that occurs when the electrical signal traveling from the atria, or the upper chambers of the heart, to ventricles, or the lower chambers of the heart, is impaired.
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