SA-exit-blok: verschil tussen versies

{{Chapter|Sinus node rhythms and arrhythmias}}

[[Image:sa_exit_blok.jpg|thumb|Sino-atrial exit block (more precisely: type II second degree SA exit block)]]

[[Image:sa_exit_blok2.png|thumb|Sino-atrial exit block]]

[[Image:sa_exit_blok3.jpg|thumb|Sino-atrial exit block]]

During sino-atrial exit block, the depolarizations that occur in the sinus node cannot leave the node towards the atria. They are blocked. On the ECG this is expressed as a pause. SA exit block can be destinguished from [[sinusarrest]] because the pause in SA exit block is a multiple of the P-P interval that preceded the pause.

Three subtypes can be destinguished:<cite>Braunwald</cite>

*Type I second degree (Wenkebach) SA exit block: the P-P interval progressively shortens prior to the pause

*Type II second degree SA exit block: 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)