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, 09:50, 2 July 2010
===1. SA Block===
*The delay (sinus block) or failure (sinus arrest) of the sinoatrial node to conduct impulses.
*SA Block=when an impulse does not leave the SA node
*SA Arrest=momentary failure in the SA node to start an impulse causes a pause in the normal cardiac cycle
====Causes====
Sick sinus syndrome, electrolyte imbalances, atrial diseases, hypothyroidism etc.
'''ECG Appearance:''' Absence of P-QRS-T complexes for a brief period of time
-Sinus block=no P-QRS-T complexes for twice the R-R interval
-Sinus arrest=no P-QRS-T complexes for greater than two R-R intervals
====Treatment====
Treat the underlying causes; atropine etc., surgical implantation of a pacemaker
[[Category:Impulse Conduction Abnormalities]][[Category:To_Do_-_Cardiovascular]]