Prognostic implications of pulmonary wave reflection and reservoir pressure in patients with pulmonary hypertension

Background: Right ventricular (RV) coupling to the pulmonary circulation influences the response of the RV to the increased afterload caused by pulmonary hypertension (PH), which ultimately determines prognosis. A methodology that accounts for pulsatile flow is required when assessing ventriculo-arterial coupling. We applied wave intensity analysis (WIA) methods to assess the compliance of the main pulmonary artery (PA) in patients with or without PH and compared this to PA distensibility, RV function and clinical outcomes.Methods: High-fidelity blood pressure and Doppler flow velocity tracings were obtained simultaneously during cardiac catheterisation for suspected PH. RV volumes, main PA distensibility and ventriculo-arterial coupling (E-max/E-a) were analysed using cardiovascular magnetic resonance.Results: The study included 17 PH patients and 6 controls. Wave speed, reservoir and excess pressure were higher in PH patients compared to controls (p < 0.01 for all). Waveforms relating to RV ejection, microvascular wave reflection and late systolic proximal deceleration were higher in PH patients compared to controls (p < 0.01 for all) and related to echocardiographic findings, including PA Doppler notching and shortened acceleration time. Wave speed, reservoir pressure and excess pressure were strongly correlated to main PA distensibility, RV function and E-max/E-a. A higher total pressure integral was associated with an increased risk of death (all-cause mortality).Conclusion: The reservoir-excess pressure model, in combination with conventional clinical imaging, provides valuable information on the pathophysiology of PH that standard haemodynamic parameters do not. Future studies should further investigate the prognostic implications of WIA in PH, and its potential role in clinical practice.