Reducing the risk of leaflet thrombosis in transcatheter aortic valve-in-valve implantation by BASILICA: a computational simulation study

Subclinical leaflet thrombosis of bioprosthetic aortic valves after transcatheter valve replacement (TAVR) and surgical aortic valve replacement (SAVR) has been found with CT imaging. The objective of this study was to report the prevalence of subclinical leaflet thrombosis in surgical and transcatheter aortic valves and the effect of novel oral anticoagulants (NOACs) on the subclinical leaflet thrombosis and subsequent valve haemodynamics and clinical outcomes on the basis of two registries of patients who had CT imaging done after TAVR or SAVR.

Background: Coronary artery obstruction is a rare but fatal complication of transcatheter aortic valve replacement (TAVR). Objectives: We developed a novel technique called BASILICA ( B ioprosthetic or native A ortic S callop I ntentional L aceration to prevent C oronary A rtery obstruction). Methods: We lacerated pericardial leaflets in vitro using catheter electrosurgery, and tested leaflet splaying after benchtop TAVR. The procedure was tested in swine. BASILICA was then offered to patients at high risk of coronary obstruction from TAVR and ineligible for surgical aortic valve replacement. BASILICA used marketed devices. Catheters directed an electrified guidewire to traverse and lacerate the aortic leaflet down the centreline. TAVR was performed as usual. Results: TAVR splayed lacerated bovine pericardial leaflets. BASILICA was successful in pigs, both to left and right cusps. Necropsy revealed full length lacerations with no collateral thermal injury. Seven patients underwent BASILICA on a compassionate basis. Six had failed bioprosthetic valves, both stented and stent-less. Two had severe aortic stenosis, including one patient with native disease, three had severe aortic regurgitation, and two had mixed aortic valve disease. One patient required laceration of both left and right coronary cusps. There was no hemodynamic compromise in any patient following BASILICA. All patients had successful TAVR, with no coronary obstruction, stroke, or any major complications. All patients survived to 30 days. Conclusions: BASILICA may durably prevent coronary obstruction from TAVR. The procedure was successful across a range of presentations, and requires further evaluation in a prospective trial. Its role in treatment of degenerated TAVR devices remains untested. Bioprosthetic or native Aortic Scallop Intentional Laceration to prevent Iatrogenic Coronary Artery obstruction (BASILICA) is a technique to prevent coronary artery obstruction complicating transcatheter aortic valve replacement (TAVR). BASILICA uses catheter electrosurgery to split aortic valve leaflets lengthwise immediately prior to TAVR. We describe the technique on the benchtop and in animals. We also report the first-in-human application in seven patients, including both aortic stenosis and regurgitation, in both bioprosthetic and native aortic valves. All patients had high predicted risk of coronary artery obstruction. All patients had successful BASILICA and TAVR, with no coronary obstruction, stroke or 30-day mortality.

In this paper, we present a spatio-temporal mathematical model for simulating the formation and growth of a thrombus. Blood is treated as a multi-constituent mixture comprised of a linear fluid phase and a thrombus (solid) phase. The transport and reactions of 10 chemical and biological species are incorporated using a system of coupled convection-reaction-diffusion (CRD) equations to represent three processes in thrombus formation: initiation, propagation and stabilization. Computational fluid dynamic (CFD) simulations using the libraries of OpenFOAM were performed for two illustrative benchmark problems: in vivo thrombus growth in an injured blood vessel and in vitro thrombus deposition in micro-channels (1.5 mm × 1.6 mm × 0.1 mm) with small crevices (125 μm × 75 μm and 125 μm × 137 μm). For both problems, the simulated thrombus deposition agreed very well with experimental observations, both spatially and temporally. Based on the success with these two benchmark problems, which have very different flow conditions and biological environments, we believe that the current model will provide useful insight into the genesis of thrombosis in blood-wetted devices, and provide a tool for the design of less thrombogenic devices.