Impact of pulmonary endarterectomy on pulmonary arterial wave propagation and reservoir function

High wave speed and large wave reflection in the pulmonary artery have previously been reported in patients with chronic thromboembolic pulmonary hypertension (CTEPH). We assessed the impact of pulmonary endarterectomy (PEA) on pulmonary arterial wave propagation and reservoir function in patients with CTEPH. Right heart catheterization was performed using a combined pressure and Doppler flow sensor-tipped guidewire to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery in eight patients with CTEPH before and 3 mo after PEA. Wave intensity and reservoir-excess pressure analyses were then performed. Following PEA, mean pulmonary arterial pressure (PAPm; similar to 49 vs. similar to 32 mmHg), pulmonary vascular resistance (PVR; similar to 11.1 vs. similar to 5.1 Wood units), and wave speed (similar to 16.5 vs. similar to 8.1 m/s), i.e., local arterial stiffness, markedly decreased. The changes in the intensity of the reflected arterial wave and wave reflection index (pre: similar to 28%; post: similar to 22%) were small, and patients post-PEA with and without residual pulmonary hypertension (i.e., PAPm similar to 25 mmHg) had similar wave reflection index (similar to 20 vs. similar to 23%). The reservoir and excess pressure decreased post-PEA, and the changes were associated with improved right ventricular afterload, function, and size. In conclusion, although PVR and arterial stiffness decreased substantially following PEA, large wave reflection persisted, even in patients without residual pulmonary hypertension, indicating lack of improvement in vascular impedance mismatch. This may continue to affect the optimal ventriculoarterial interaction, and further studies are warranted to determine whether this contributes to persistent symptoms in some patients. NEW & NOTEWORTHY We performed wave intensity analysis in the pulmonary artery in patients with chronic thromboembolic pulmonary hypertension before and 3 mo after pulmonary endarterectomy. Despite substantial reduction in pulmonary arterial pressures, vascular resistance, and arterial stiffness, large pulmonary arterial wave reflection persisted 3 mo postsurgery, even in patients without residual pulmonary hypertension, suggestive of lack of improvement in vascular impedance mismatch.