Time-resolved 3-dimensional magnetic resonance phase contrast imaging (4D Flow MRI) analysis of hemodynamics in valve-sparing aortic root repair with an anatomically shaped sinus prosthesis

Abstract

ObjectiveThe anatomically shaped sinus prosthesis (Uni-Graft W SINUS; Braun, Melsungen, Germany) used in valve-sparing aortic root replacement promises physiological hemodynamics believed to grant physiologic valve function. Using time-resolved 3-dimensional magnetic resonance phase contrast imaging (4D Flow MRI), we analyzed sinus vortex formation and transvalvular pressure gradients in patients with sinus prosthesis compared with age-matched and young healthy volunteers. MethodsTwelve patients with sinus prosthesis (55 ± 15 years), 12 age-matched and 6 young healthy volunteers (55 ± 6 years, 25 ± 3 years, respectively) were examined at 3T with a 4D flow magnetic resonance imaging sequence. Sinus vortices visualized by streamlines and time-resolved particle paths were graded on a 4-point Likert scale. Time resolved pressure differences of the left ventricular outflow tract and the ascending aorta to a reference point in the aortic bulb as well as the transvalvular pressure gradient were evaluated. Results4D flow visualizations revealed a propensity of the sinus prosthesis toward intermediate (50%) and large (28%) vortices compared with age-matched volunteers with small (61%) and intermediate (36%) vortices. Vortices in sinus prostheses had a similar configuration compared with those in volunteers. The peak transvalvular pressure gradient did not vary significantly between patients and age-matched volunteers (4.0 ± 0.9 mm Hg, 3.8 ± 0.7 mm Hg, P = .373), its temporal evolution resembled that of volunteers with a prolonged positive phase in patients. ConclusionsHemodynamics closely relating to those of volunteers were confirmed in sinus prostheses, believed to grant physiological valve function. Minor differences are presumably attributed to graft compliance and temporal resolution of the acquisition. Nevertheless, long-term deterioration of valve function as it was described for straight grafts could potentially be decelerated using sinus prostheses.