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. 2019 Feb 1;20(2):209-217.
doi: 10.1093/ehjci/jey069.

Proximal pulmonary vascular stiffness as a prognostic factor in children with pulmonary arterial hypertension

Richard M Friesen  1   2 , Michal Schäfer  1   3 , D Dunbar Ivy  1 , Steven H Abman  4 , Kurt Stenmark  5 , Lorna P Browne  6 , Alex J Barker  7 , Kendall S Hunter  1   3 , Uyen Truong  1
Affiliations

Proximal pulmonary vascular stiffness as a prognostic factor in children with pulmonary arterial hypertension

Richard M Friesen et al. Eur Heart J Cardiovasc Imaging. .

Abstract

Aims: Main pulmonary artery (MPA) stiffness and abnormal flow haemodynamics in pulmonary arterial hypertension (PAH) are strongly associated with elevated right ventricular (RV) afterload and associated with disease severity and poor clinical outcomes in adults with PAH. However, the long-term effects of MPA stiffness on RV function in children with PAH remain poorly understood. This study is the first comprehensive evaluation of MPA stiffness in children with PAH, delineating the mechanistic relationship between flow haemodynamics and MPA stiffness as well as the prognostic ability of these measures regarding clinical outcomes.

Methods and results: Fifty-six children diagnosed with PAH underwent baseline cardiac magnetic resonance (CMR) acquisition and were compared with 23 control subjects. MPA stiffness and wall shear stress (WSS) were evaluated using phase contrast CMR and were evaluated for prognostic potential along with standard RV volumetric and functional indices. Pulse wave velocity (PWV) was significantly increased (2.8 m/s vs. 1.4 m/s, P < 0.0001) and relative area change (RAC) was decreased (25% vs. 37%, P < 0.0001) in the PAH group, correlating with metrics of RV performance. Decreased WSS was associated with a decrease in RAC over time (r = 0.679, P < 0.001). For each unit increase in PWV, there was approximately a 3.2-fold increase in having a moderate clinical event.

Conclusion: MPA stiffness assessed by non-invasive CMR was increased in children with PAH and correlated with RV performance, suggesting that MPA stiffness is a major contribution to RV dysfunction. PWV is predictive of moderate clinical outcomes, and may be a useful prognostic marker of disease activity in children with PAH.

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Figures

Figure 1
Figure 1
(A) Magnetic resonance angiography reconstructed MPA with superimposed plane of phase-contrast CMR was applied to ensure the universally applied location for flow and stiffness analysis. (B) Exemplary phase-contrast image with the segmentation line derived from corresponding magnitude image. (C) Magnitude image with location specific labelled point of WSS analysis. (D) Created flow and area waveforms with highlighted region of the PWV analysis at the early ejection phase.
Figure 2
Figure 2
(A) Representative control flow haemodynamic waveform with corresponding PWV analysis depicted by linear fit between the flow and area data points during systolic upstroke. (B) Representative PAH case depicts typical characteristics of MPA stiffness, including presence of downstroke notch and backward post-systolic flow.
Figure 3
Figure 3
(A) Intergroup analysis between different WHO-FC categories did not reveal any variability between considered groups. (B) Similarly no intergroup variability existed among different PAH categories. P-values are derived Kruskal–Wallis analysis.
Figure 4
Figure 4
Regional WSSmax distribution comparison between controls (blue dashed line) and PAH group (red line). The WSSmax was significantly lowered along the entire aspect of the MPA lumen except at the inferior portion of the vessel.
Figure 5
Figure 5
(A) Random slope analysis depicting the trend between PWV and WSSmax failed to reveal significant relationship between two metrics. (B) Contrary, same analysis between the RAC and WSSmax revealed significant positive trend.
Figure 6
Figure 6
The Kaplan–Meier curve for the PWV measured at the MPA predicting moderate clinical outcomes.
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References

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