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Bradycardia: Difference between revisions
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Like AV-nodal conduction disorders (see below) multiple subtypes can be distinguished: | Like AV-nodal conduction disorders (see below) multiple subtypes can be distinguished: | ||
* Second degree Type I (Wenkebach) SA exit block: the P-P interval progressively shortens prior to the pause | * <b>Second degree Type I:</b> (Wenkebach) SA exit block: the P-P interval progressively shortens prior to the pause | ||
* Second degree Type II SA exit block: the pause equals approximately 2-4 times the preceding PP interval | * <b>Second degree Type II SA exit block:</b> the pause equals approximately 2-4 times the preceding PP interval | ||
* Third degree SA exit block: absence of P waves (can only be diagnosed with an sinus node electrode, during electrophysiological evaluation) | * <b>Third degree SA exit block:</b> absence of P waves (can only be diagnosed with an sinus node electrode, during electrophysiological evaluation) | ||
===Sinus Arrest=== | ===Sinus Arrest=== | ||
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===Second Degree AV Block=== | ===Second Degree AV Block=== | ||
The second degree AV block can be divided in two separate entities depending on the clinical characteristics of the conduction disorder. If conduction to the ventricle is conducted in a 2:1 fashion; that is if after every second P-wave there is no conduction to the ventricle, it is not possible to distinguish between the two types and a severe kind of conduction block should be assumed. If two sequential P-wave are not followed by a QRS-complex the term malignant block is used, as this could lead to or be an indication of a total block. | The second degree AV block can be divided in two separate entities depending on the clinical characteristics of the conduction disorder. If conduction to the ventricle is conducted in a 2:1 fashion; that is if after every second P-wave there is no conduction to the ventricle, it is not possible to distinguish between the two types and a severe kind of conduction block should be assumed. If two sequential P-wave are not followed by a QRS-complex the term malignant block is used, as this could lead to or be an indication of a total block. | ||
* <b>Mobitz I (Wenkebach)</b>: The Mobitz type I block is characterized by a progressively increased P-Q interval until atrial activation is blocked in the AV-node. Thereafter conduction is restored and this cycle repeats itself. A common finding in the Mobitz I block is that the first prolongation of the PR interval is associated with the largest increase in interval. After this first prolongation of the interval, the interval gradually increases. Usually Mobitz type II block is located at the atrioventricular node and rarely deteriorates to a more severe conduction block. | |||
The Mobitz type I block is characterized by a progressively increased P-Q interval until atrial activation is blocked in the AV-node. Thereafter conduction is restored and this cycle repeats itself. A common finding in the Mobitz I block is that the first prolongation of the PR interval is associated with the largest increase in interval. After this first prolongation of the interval, the interval gradually increases. Usually Mobitz type II block is located at the atrioventricular node and rarely deteriorates to a more severe conduction block. | * <b>Mobitz II</b>: | ||
When atrial activation is blocked, without progressively increasing P-Q interval a Mobitz Type II AV block is present. This sudden failure of AV conduction is an omen of severe conduction disease in usually infra-Hision part of the atrioventricular conduction system. | When atrial activation is blocked, without progressively increasing P-Q interval a Mobitz Type II AV block is present. This sudden failure of AV conduction is an omen of severe conduction disease in usually infra-Hision part of the atrioventricular conduction system. | ||
===Third Degree AV Block=== | ===Third Degree AV Block=== | ||