Effect of reduced cardiac output on blood stasis on transcatheter aortic valve leaflets: implications for valve thrombosis

Abstract

There is an increasing awareness of leaflet thrombosis following transcatheter aortic valve implantation (TAVI) and valve-in-valve (ViV) procedures. Nevertheless, the predisposing factors affecting transcatheter aortic valve (TAV) thrombosis have remained unclear. This study aimed to quantify the effects of reduced cardiac output (CO) on blood stasis on the TAV leaflets as a permissive factor for valve thrombosis. An idealised computational model representing a TAV was developed in a patient-specific geometry. Three-dimensional flow fields were obtained via a fluid-solid interaction modelling approach at different COs: 5.0, 3.5, 2.0 L/min. Blood residence time (BRT) was subsequently calculated on the leaflets. An association between reduced CO and increased blood stasis on the TAV leaflets was observed. At the end of diastole, larger areas of high BRT (>1.2 s) were observed at the leaflet's fixed edge at low COs. Such areas were calculated to be 2, 8, and 11% of the total surface area of leaflets at CO=5.0, 3.5, and 2.0 L/min, respectively, indicating a ~sixfold increase of BRT on the leaflets from the highest to the lowest CO. This study indicates an association between reduced CO and increased blood stasis on the TAV leaflets which can be regarded as a precursor of valve thrombosis.