Introduction: Transcatheter aortic valve replacement (TAVR) leaflet thrombosis has been increasingly reported with raised clinical awareness. Based on published literature occurrence rates appear lower in CoreValve than SAPIEN 3 transcatheter heart valves (THVs). Clinically, the thrombus is primarily observed in the neo sinus - the space between the native and transcatheter aortic valve leaflets.
Methods: A novel quantitative dye flow visualization technique was used to measure the washout in the neo-sinus region of two commercial THVs. 29 mm CoreValve and 26 mm SAPIEN 3 THVs were nominally deployed (IFU defined) within a mock-native valve with an internal diameter of 26 mm. A dye bolus was injected directly into the neo-sinus of each THV at the beginning of diastole and the next 20 cardiac cycles were recorded en face at 30 fps using a GoPro HERO4 color camera attached to a Karl Storz 88630 SF borescope. Each washout experiment was performed 15 times. The dye intensity of each video frame was analyzed in MATLAB R2016a. The experiments were performed on a validated left heart simulator at three cardiac outputs (2.5, 5.0, and 6.5 L/min) with a pressure of 120/80 mmHg and rate of 70 bpm. Exponential decay rate constants (b) were determined through curve fitting the average washout data.
Results: At 5.0 L/min, the CoreValve neo-sinus washed out in a substantially shorter time than the SAPIEN 3 neo-sinus (4.27 ± 0.34 vs. 9.56 ± 0.42 cardiac cycles; p < 0.01). Similar trends were seen at 2.5 and 6.5 L/min. Washout times decreased with cardiac output in both THVs (p < 0.01).
Conclusions: In this in vitro study, SAPIEN 3 THVs showed longer neo-sinus washout times than CoreValve THVs. In addition, washout times were inversely related to cardiac output in both valves. These mechanisms may provide mechanistic insight into the role of neo-sinus flow in TAVR thrombosis.