Simple method to distinguish the type of fetal premature contraction using arterial Doppler time interval measurements.

Aim: The purpose of this study was to establish a simple method to distinguish premature ventricular contractions (PVC) from premature atrial contractions (PAC) using a fetal Doppler ultrasound arterial pulse waveform to measure time intervals between sinus node restarting.

Methods: We retrospectively identified 14 fetuses with premature contraction (8 with PAC, 6 with PVC). We measured two distinct parts of time intervals using an arterial pulsed-wave Doppler: the two consecutive waveforms just before the premature contraction (2-V interval) and two consecutive waveforms including the premature contraction (XV interval) to measure time intervals between sinus node restarting. We then evaluated the time difference between the 2-V and XV intervals in PVC compared to PAC.

Results: For PVC, the difference between the 2-V interval and the XV interval was significantly shorter than that for PAC. A cut-off point of 33 ms, where a difference ≤33 ms was clearly shown to be associated with a PVC and a difference more than 33 ms signified a PAC was demonstrated.

Conclusion: The 2-V and XV interval measurements, used to measure time intervals between sinus node restarting, could easily distinguish PVC from PAC in utero. Therefore, this study could potentially be a feasible and effective method for obstetricians or sonographers to employ usefully.