Sinus Arrest
cautionSinus Arrest
The SA node transiently fails to generate an impulse, producing a pause with no P wave or QRS. Unlike SA exit block, the pause duration is not a multiple of the underlying P-P interval because the SA node itself did not fire.
- Pauses with no P wave or QRS
- Pause NOT a multiple of baseline PP interval
- Regular rhythm between pauses
- Escape beat may terminate long pauses
SA node transiently fails to fire — no impulse generated
The SA node itself fails to depolarize and generate an electrical impulse. This differs from SA exit block (where the node fires but the impulse cannot exit). Because the SA node didn't fire, the timing resets unpredictably, so the pause is not a mathematical multiple of the baseline cycle length.
- Regular sinus rhythm interrupted by pauses lacking P waves and QRS complexes.
- The pause is not an exact multiple of the baseline P-P interval.
- A junctional or ventricular escape beat may terminate prolonged pauses.
May be benign or indicate sick sinus syndrome — depends on symptoms
Primary Treatment
Identify and treat underlying cause (vagal stimulation, medications, ischemia).
Additional Options
Symptomatic patients with recurrent pauses require pacemaker implantation.
Long-term Management
Asymptomatic brief pauses may only need observation.