Noninvasive Assessment of Right Ventricle Function and Pulmonary Artery Pressure Using Transthoracic Echocardiography in Women With Pre-Eclampsia: An Exploratory Study

Abstract

Background and objective Pre-eclampsia (PEC) is associated with the release of anti-angiogenic factors that are incriminated in raising systemic and pulmonary vascular resistance (PVR). Compared to the left heart and systemic circulation, much less attention has been paid to the right heart and pulmonary circulation in patients with PEC. We used transthoracic echocardiography (TTE) to estimate pulmonary artery (PA) pressure and right ventricular (RV) function in women with PEC. Materials and methods We conducted a case-control study at a tertiary care academic center. Ten early PEC (<34-week gestation) and nine late PEC (≥34-week gestation) patients with 11 early and 10 late gestational age-matched controls were enrolled. Two-dimensional TTE was performed on all patients. The estimated mean PA pressure (eMPAP) was calculated based on PA acceleration time (PAAT). PVR was estimated from eMPAP and RV cardiac output (RV CO). RV myocardial performance index (RV MPI), tricuspid annular plane systolic excursion (TAPSE), tissue tricuspid annular displacement (TTAD), and lateral tricuspid annular tissue peak systolic velocity (S') were measured. Results Compared to early controls, in early PEC, the eMPAP and estimated PVR (ePVR) were elevated, PAAT was reduced, RV MPI was increased, TTAD was reduced, and TAPSE and TV S' were unchanged. Compared to late controls, in late PEC, the eMPAP and ePVR were elevated, PAAT was reduced, and RV MPI was increased, while TAPSE, TTAD, and TV S' were unchanged. Conclusions In a sample of women with PEC, early PEC was found to be associated with increased eMPAP and ePVR and subclinical decrement of RV function as assessed by TTE. TTE may be a useful noninvasive screening tool for early detection of pulmonary hypertension and RV dysfunction in PEC. An adequately powered longitudinal study is needed to determine the implications of these findings on long-term outcomes.

Keywords: echo cardiogram; multifactorial pulmonary hypertension; pre-eclampsia.

Figure 1. Elevated estimated pulmonary artery pressure and pulmonary vascular resistance in pre-eclamptic women and controls

Flow characteristics in the RVOT were examined using TTE as described in Materials and Methods. Data shown are scatter plots of individual measurements overlaid with Mean ±SD, 95% CI of (A) eMPAP. The reference range is indicated by dashed lines. (B) RVOT Doppler waveform PAAT; inversely correlated with PA pressure and pulmonary vascular resistance. A 100-ms cutoff (reference value) is indicated with a dashed line. PAAT of <100 ms detects PAH with a sensitivity of 0.84 and specificity of 0.9. (C) PVR estimated as PVR = (eMPAP)/RV CO. (D) RV MPI. eMPAP, ePVR, and RV MPI increased and PAAT decreased in early PEC as compared to early and in late PEC vs. late controls Statistics by ANOVA with Bonferroni’s post-hoc analysis PVR: pulmonary vascular resistance: eMPAP: estimated mean pulmonary arterial pressure; RVOT: right ventricular outflow tract; PAAT: pulmonary artery acceleration time; PAH: pulmonary arterial hypertension; RV: right ventricle; MPI: myocardial performance index; PA: pulmonary artery; PEC: pre-eclampsia; ANOVA: analysis of variance; RV CO: right ventricular cardiac output

Figure 2. Tissue tricuspid annular displacement (TTAD) in pre-eclamptic women and controls

TTAD was assessed at three user-defined points in the RV-focused view as follows: at the point of insertion of the lateral (TTAD L), and septal (TTAD S) leaflets, and at the midpoint (TTAD MP) of the tricuspid valve to the tricuspid annulus and the RV apex. Data shown are individual data points and mean ±SD for each group for TTAD L (A), TTAD MP (B), TTAD S (C), and TTAD MP % (D). In TTAD MP, TTAD S, and TTAD MP %, early PEC was significantly decreased as compared to early controls. Statistics by Kruskal-Wallis; exact p-values are shown PEC: pre-eclampsia; RV: right ventricle; SD: standard deviation

Figure 3. Bland-Altman plot to illustrate inter-observer differences in assessing pulmonary artery acceleration time

The plot was generated by analyzing all measurements of PAAT performed by the first and second observers. Dashed lines indicate 95% limits of agreement PAAT: pulmonary artery acceleration time

Figure 4. Correlation between mean arterial pressure (MAP) and estimated mean pulmonary artery pressure (eMPAP)

MAP and eMPAP were determined as described in Materials and Methods and then plotted as shown. Data shown are as follows: (A) correlation of eMPAP and MAP in all control subjects, and (B) correlation of eMPAP and MAP in all PEC subjects. Linear regression is depicted in each graph by a solid line. The slopes were not significantly different from 0 in either plot by linear regression MAP: mean arterial pressure; eMPAP: estimated mean pulmonary arterial pressure; PEC: pre-eclampsia