Response by Sharma et al to Letter Regarding Article, “The Fluid Mechanics of Transcatheter Heart Valve Leaflet Thrombosis in the Neosinus”
Authors: Rahul Sharma, Prem A. Midha, Vasilis Babaliaros, Raj R. Makkar, Ajit P. Yoganathan
Journal: Circulation (2018)

In Response:Tang and colleagues raise 3 pertinent issues related to our study 1 and its related findings.First, they seek clarification regarding the prevalence of observed leaflet thrombosis across the different inflation parameters quoted in a prior study 2 arising from a similar data pool.In addition, they question the potential suggestion that nominal inflation should be avoided given the presence of thrombus in valves expanded <100%.Although the data from this study originated from the same registry as the previously quoted study by Kazuno et al, 2 there is no way to determine which, if any, of the 39 patients in that study overlap with the 72 cases in our study, as all data were deidentified.This study is a purely mechanistic assessment of leaflet thrombosis in the context of the neosinus and in no way is designed to make any clinical recommendations.The findings, although somewhat counterintuitive to our initial predictions, remain interesting observations that are merely hypothesis generating and that require further exploration in future studies.Second, Tang et al mention a number of anatomic factors that affect flow and therefore thrombosis in the aortic root.Furthermore, they identify changes that may occur after transcatheter aortic valve replacement as a result of native leaflet position and valve orientation.Although perhaps not explored in detail, the background of the study states that the native anatomy of the patient, the geometry of the deployed transcatheter valve and the relative location of the transcatheter heart valve deployment create a unique geometry which may alter flow stasis; in variable hemodynamic states, this may impact thrombosis.We certainly agree with Tang and colleagues that leaflet thrombosis is truly a multifactorial process, with variable interactions between native aortic root anatomy, leaflet tissue, flow states, the valve, and the changes that result after deployment of the valve.Indeed, the impact of transcatheter aortic valve replacement valve orientation on flow states is the subject of current research by our group.Third, the authors of the letter suggest that analysis of a potential relationship between the presence or absence of thrombus and implant depth across both devices would be helpful.We performed this analysis, similar to the analysis performed regarding expansion depicted in Figure 6.However, this analytic approach and the resulting figure did not clearly illustrate our findings.It was therefore not included and we decided to instead perform separate analysis based on valve type and unadjusted implant depth then a combined analysis based on adjusted implant depth for comparative ease.In any case, the finding was that there was no significant difference in thrombus based on implant depth (no thrombus, -3.1±2.7 mm versus thrombus, -1.4±5.6 mm, P=0.13).We thank the authors of the letter for their insightful inquiries, and we re-emphasize that our study was an initial attempt at identifying variables associated with low