Nonuniformly Distributed Flow Patterns After Melody® Implantation: Implications For Focal Elevated Pulmonary Wall Shear Rates And Right Ventricular Function

Research Article
Soha Romeih, Rob J. Van Der Geest, Arno AW Roest, Anje M Spijkerboer1., Mark G Hazekamp, Barbara JM Mulder, Nico A Blom, and Maarten Groenink
4D pulmonary flow, Melody® valve, Contegra® conduit

Background: Turbulent flow patterns distal to Melody® valves are frequently observed by standard performed MRI. These turbulent flow patterns may have an impact on RV afterload conditions and RV function. The aim of this study was to compare pulmonary flow patterns between patients who underwent Melody® and Contegra® implantation and the impact of these flow patterns on pulmonary wall shear rates and right ventricular morphology and function. Patients and Methods: Fifteen patients after Melody® valve implantation (17.2 ± 2.0 years), 15 patients after Contegra® implantation (15.8 ± 1.7 years), and 15 healthy volunteers, as a control group, (16.5 ± 1.5 years) were included. All subjects underwent a comprehensive cardiac MRI protocol, assessing RV morphology, function, pulmonary flow and vortices. From 3D flow analysis pulmonary flow eccentricity and pulmonary wall shear rate (WSR) were calculated. Results: Patients in the Melody® group showed reduced RVEF as compared to controls, eccentric pulmonary flow (deviation angle from the midline 31 ± 10º) with vortex formation (vortex size 73 ± 18 %), and a significant asymmetric elevated WSR at focal regions of the conduit. In contrast, those after surgical Contegra® implantation showed a laminar pulmonary flow with no visible vortex and had symmetric, although elevated WSR in all conduit regions and an RV function comparable to controls. Conclusion: Unfavorable pulmonary flow patterns with vortex formation distal from the Melody® valve lead to abnormal hemodynamic conditions that may influence RV function and might be a predisposing factor for pulmonary aneurysm formation.