Sinoatrial arrest pathophysiology: Difference between revisions

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Latest revision as of 14:03, 2 September 2013

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Sinoatrial arrest (also known as sinus arrest or sinus pause) is a medical condition wherein the sinoatrial node of the heart transiently ceases to generate the electrical impulses that normally stimulate the myocardial tissues to contract and thus the heart to beat. It is defined as lasting from 2.0 seconds to several minutes.

Pathophysiology

In sinoatrial arrest, the SA node is not generating electrical complexes due to impairment of automaticity. In patients with sinus arrest, the pause is more frequently associated with either an atrial or an AV junctional escape rhythm. If associated with sick sinus syndrome, lower pacemakers are impaired as well, therefore it can present as a complete absence of electrical activity on EKG.

References

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 ==Overview==
-In this disorder, the [[sinoatrial node]] is generating electrical complexes, but the electrical activity fails to conduct in the [[atrium]]. Sinoatrial automaticity is preserved, and the [[P wave]]s are generated at a regular rate in a regular pattern which are a multiple of the basic sinus cycle.  In patients with sinus exit block, the block is more frequently associated with either an atrial or an AV junctional escape rhythm.
+Sinoatrial arrest (also known as sinus arrest or sinus pause) is a medical condition wherein the sinoatrial node of the heart transiently ceases to generate the electrical impulses that normally stimulate the myocardial tissues to contract and thus the heart to beat. It is defined as lasting from 2.0 seconds to several minutes.
 ==Pathophysiology==
-===First Degree SA Exit Block===
+In sinoatrial arrest, the SA node is not generating electrical complexes due to impairment of automaticity.  In patients with sinus arrest, the pause is more frequently associated with either an atrial or an AV junctional escape rhythm. If associated with sick sinus syndrome, lower pacemakers are impaired as well, therefore it can present as a complete absence of electrical activity on EKG.
-There is a conduction delay (a slowing of conduction not a block or completion cessation in electrical conduction) in the impulse traveling from the [[sinus node]] to the [[atrium]] and there are no discernible changes on the surface [[EKG]].
-===Second Degree SA Exit Block===
-This condition refers to intermittent conduction block (not a delay or slowing of conduction but a completion cessation of conduction) between the sinus node and the atrium.
-====Type I (Wenckebach Phenomenon) Sinoatrial Exit Block====
-This is an example of group beating. The P-P cycle (time between two [[P wave]]s) is progressively shortened until there is a pause. This pause is less than twice the shortest P-P interval.  The cycle is then repeated. The pause is due to the dropped P wave and measures less than twice the P-P cycle. It is similar to the behavior of the RR intervals in type I [[second-degree AV block]].
-====Type II Second Degree Sinoatrial Exit Block====
-There is an unexpected drop of the P wave. Following this drop, there is a pause in the sinus cycle which is a multiple of the basic sinus cycle. Blocked atrial premature beats sometimes mimic second-degree sinoatrial block.
-====Third Degree Sinoatrial Exit Block====
-This SA block cannot be distinguished from sinus arrest when the sinus node ceases to fire. Under such circumstances, subsidiary pacemakers in the AV junction or ventricles may take over.
 ==References==

Sinoatrial arrest pathophysiology: Difference between revisions

Latest revision as of 14:03, 2 September 2013

Overview

Pathophysiology

References

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