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AV Conduction: Difference between revisions
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[[Image:AV_block_sequence.png|thumb|Sequence of AV block from incomplete to complete]] | [[Image:AV_block_sequence.png|thumb|Sequence of AV block from incomplete to complete]] | ||
Conduction disturbances can occur at the level of the sinoatrial (SA) node, the atrioventricular (AV) node and the bundle branch system. | Conduction disturbances can occur at the level of the sinoatrial (SA) node, the atrioventricular (AV) node and the bundle branch system. | ||
In atrioventricular block the conduction between atria and ventricles is disturbed, leading to an increased [[Conduction#PQ interval|PQ interval]] or to | In atrioventricular block the conduction between atria and ventricles is disturbed, leading to an increased [[Conduction#PQ interval|PQ interval]] or to P waves that are not followed by QRS complexes: atrial activity that is not followed by ventricular activity. Three degrees of block can be distinguished. | ||
[[Image:PR_interval_buildup.svg|300px|thumb|right|The PR duration depends on the conduction velocity in the atria, AV node, His bundle, bundle branches and Purkinje fibers.]] | [[Image:PR_interval_buildup.svg|300px|thumb|right|The PR duration depends on the conduction velocity in the atria, AV node, His bundle, bundle branches and Purkinje fibers.]] | ||
==First degree AV block== | ==First degree AV block== | ||
[[Image:Rhythm_1stAVblock.png|thumb| 1st degree AV block. Although the PQ interval is prolonged all | [[Image:Rhythm_1stAVblock.png|thumb| 1st degree AV block. Although the PQ interval is prolonged, all P waves are followed by QRS complexes: there is no dropout of complexes]] | ||
In first degree AV block there is a prolongation of PQ duration (PQ time > 0.20 sec). Still every | In first degree AV block there is a prolongation of PQ duration (PQ time > 0.20 sec). Still every P wave is being followed by a QRS complex. | ||
First degree AV block is present in 16% of >90-year olds <cite>kelley</cite> and is mostly caused by a degeneration of the conduction system. First degree AV block is relatively harmless. | First degree AV block is present in 16% of >90-year olds <cite>kelley</cite> and is mostly caused by a degeneration of the conduction system. First degree AV block is relatively harmless. | ||
{{clr}} | {{clr}} | ||