A former 29+3 weeks GA preterm shows the following ECG tracing during Holter recording on the 17th day of life:
Lead 3 clearly shows artifacts. On leads 1 & 2 you can appreciate a 2.8 second sinus pause. Basic heart rate 125 bpm (cycle lengths 480ms). There is slight decrease in cycle lengths of the beats preceding the pause (480ms --> 890ms). Most commonly such episodes appear with elevated vagal tone of preterm infants. Sometimes they might be associated with gastroesophageal regurgitation or other vagal stimuli.
In general these brief episodes resolve within seconds and do not affect hemodynamics. The infant remains asymptomatic. We have seen such pauses up tp >5seconds, which seems rather long considering average basic heart rates of 160 bpm in preterm and term born neonates. However, all of these cases have resolved spontaneously as the infants grew.