OP 34 Systolic notch in severe preeclampsie – A Doppler marker of maternal hemodynamic dysfunction?

Introduction A systolic notch in the uterine artery (UtA) is an ominous sign in severe preeclampsia (PE) and is scarcely referenced in the literature (Thaler, 1992; Polat, 2015). Timing and hemodynamic conditions for its appearance remain unclear. Objectives As PW velocity (PWV) is times faster than blood flow velocity, signs of PW reflection should be present in the blood flow velocity waveform (FVW), but is not easily visible. In PE maternal condition is impaired by cardiac dysfunction (Melchiorre, 2011) and arterial PW reflection is increased (Khalil, 2014). We speculate that a systolic notch coincides with the earlier arrival of a stronger reflected PW. Patients and methods The entire transit time of an outgoing and reflected PW is given by the time to inflection, T-infl, in the pressure waveform (Phan 2016). Half of this time corresponds to the 1-way travel time T from the aortic valve to the prodominant sites of reflection (Curtis 2007) and approximately to the UtA: T  = (T-infl)/2  = t(AoV-UtA). UtA Doppler was performed in patients with PE. When a systolic notch was present, the time to inflection was assessed. A rough estimate of PWV was calculated dividing the 1-way travel distance D by the 1-way travel time T : PWV  = D/T. The 1-way travel distance D  = d(AoV-UtA), corresponds approximately to the sum of the lengths of aorta, common and internal iliac artery. Vessel lengths were taken from the literature and yield D  = 56 cm (Matthys, 2007, Sherwin, 2003). Results In 6 singleton pregnancies with severe PE we found a systolic notch. Mean gestational age at the time of Doppler sampling was 29 ± 3wks and delivery by cesarean section was indicated within 1 week in all patients. Mean time to inflection, T-infl (±SD) was 123 ± 9 ms. Thus mean 1-way travel time T is 61 ms and mean maternal PWV =  D / T  = 560 mm/61 ms = 9.16 m/s. Conclusion The observed timing of the systolic notch in severe PE is considerably shorter than PW travel time in normal pregancy (Macedo 2008) and inicates the arrival of the reflected PW at the site of Doppler sampling. In addition, PWV was found to be abnormally increased, in accordance with reported PWV in PE (Khalil 2014, Katsipi 2014). Thus a systolic notch may be explained by increased PW reflection and may indicate maternal hemodynamic dysfunction.