A systolic shoulder in uterina artery Doppler waveforms – a sign of cardiovascular dysfunction with increased pulse wave reflection and biochemical markers in severe Preeclampsia

Introduction:

In severe preeclampsia (PE) a systolic shoulder may appear in uterina artery (UtA) Doppler waveforms. Severe PE is characterized by cardiovascular dysfunction, with increased vascular tone and resistance, thus increasing pulse wave (PW) reflection. We assume that this may induce systolic UtA shoulder (UtA-S).

Patients and methods:

The concept of PW propagation and reflection is well established. Reflected waves (RW) seem to originate from the pelvic region and will be re-reflected at cardiac level to propagate downstream again (re-RW). Superposition of re-RW may exert an accelerative impulse to lower body flow and UtA.

According to this hemodynamic model the appearance of a UtA-S indicates the arrival of re-RW at this Doppler recording site. Then the timing Δt of the UtA-S should correspond to the delay of the re-RW (2-way travel time = 2 ×τ), travelling back (τ) and forth (τ) along the systemic arterial tree, known as Tr (reflection travel time, Fig.).

To test this model we performed UtA-Doppler in severe PE and assessed sFlt/PlGF-ratio. When UtA-S was present, we compared observed Δt with published Tr data in severe PE, assesed by applanation tonometry.

Results:

We identified 10 patients with severe PE, where finally a UtA-S appeared, showing adequate Doppler quality for Δt evaluation, and delivery ≤34wks was required.

GA was 29 ± 3wks (mean ± SD), sFlt/PlGF-Ratio = 772 [405 – 1139], and Doppler estimated UtA-S timing Δt = 133 [126 – 140]ms [mean, 95% CI]. Thus we obtained good agreement between observed Δt with published Tr data in severe PE: 136 ms (Kaihura 2009) and 133 ms (Avni 2010).

Fig. 1

Conclusions:

We could identify a hemodynamic model, which may explain the appearance of a UtA-S as a result of increased pulse wave reflection in severe PE. Higher reflective conditions in accordance with considerably increased sFlt/PlGF-ratio may indicate maternal cardiovascular dysfunction.