Sino-Atrial Block

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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