On pediatric ICU you encounter the following tracing in a child that underwent Glenn anastomosis today:
The patient has a temporary pacemaker in place (AAI, notice the pacing spikes preceding the P waves in the tracing). Upon cessation of pacing (second row) the patient exhibits slow junctional escape rhythm (40 bpm). No sinus rhythm present.
This is not common, but may occur right after Glenn anastomosis. The superior vena cave is transferred from the right atrium to the right pulmonary artery. The sinus node tissue typically sits at the SVC/RA junction. Thus sinus node dysfunction may occur but frequently remains temporary.
The latter was the case in our patient. Sinus node function recovered within 24 hours after surgery. No further pacing was needed.
Glenn anastomosis; from https://apps.childrenshospital.org/MML/index.cfm?CAT=media&MEDIA_ID=1836