Sino-Atrial Block

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