Realistic Vascular Replicator for TAVR Procedures

Abstract

Transcatheter aortic valve replacement (TAVR) is an over-the-wire procedure for treatment of severe aortic stenosis (AS). TAVR valves are conventionally tested using simplified left heart simulators (LHS). While those provide baseline performance reliably, their aortic root geometries are far from the anatomical in situ configuration, often overestimating the valves' performance. We report on a novel benchtop patient-specific arterial replicator designed for testing TAVR and training interventional cardiologists in the procedure. The Replicator is an accurate model of the human upper body vasculature for training physicians in percutaneous interventions. It comprises of fully-automated Windkessel mechanism to recreate physiological flow conditions. Calcified aortic valve models were fabricated and incorporated into the Replicator, then tested for performing TAVR procedure by an experienced cardiologist using the Inovare valve. EOA, pressures, and angiograms were monitored pre- and post-TAVR. A St. Jude mechanical valve was tested as a reference that is less affected by the AS anatomy. Results in the Replicator of both valves were compared to the performance in a commercial ISO-compliant LHS. The AS anatomy in the Replicator resulted in a significant decrease of the TAVR valve performance relative to the simplified LHS, with EOA and transvalvular pressures comparable to clinical data. Minor change was seen in the mechanical valve performance. The Replicator showed to be an effective platform for TAVR testing. Unlike a simplified geometric anatomy LHS, it conservatively provides clinically-relevant outcomes and complement it. The Replicator can be most valuable for testing new valves under challenging patient anatomies, physicians training, and procedural planning.

Novel Polymeric Valve for Transcatheter Aortic Valve Replacement Applications: In Vitro Hemodynamic Study

“…This is necessary for predicting more realistically the performance of the valve by taking into account the anatomical variability of CAVD patients, as well as the effect of the diseased native valve leaflets with embedded calcifications, which are essentially absent in the ISO-compliant PDs. 30 Endoscopic video from the Replicator is available (Online Video 2). Figure 5 depicts the valves deployed in the patient-specific CAVD valve model before it was mounted inside the matching aorta in the Replicator system for testing.…”

“…5a), and importantly may also affect the leaflet kinematics of the under-expanded valve. 30 The differences in performance per valve when comparing the Vivitro to the Replicator are as follows: the SAVR valve had the least drop in terms of EOA and transvalvular pressure drop, with average decline of 0.22 cm 2 and 7.92 mmHg, respectively. These values in the Replicator are consistent with previously reported clinical measurements, 16,29 and demonstrate again the importance of testing prosthetic heart valves in challenging anatomical replica as complementary to baseline hydrodynamic testing.…”

“…While ISO-compliant pulse duplicators (PD) provide baseline hydrodynamic performance of prosthetic valves, it tends to overestimate TAVR valve performance due to the simplified anatomical modeling of the aortic annulus and aorta, 30 and has been shown to have a significant effect on turbulence as well as on the sinus flow. 13,14 We therefore complemented the hydrodynamic assessment by testing the valves under more realistic deployed TAVR conditions in a patient-specific anatomical model of an AS patient with an advanced stage CAVD, using the Replicator pulse duplicator system (Vascular Simulations LLC, Stony Brook, NY, USA).…”

“…13,14 We therefore complemented the hydrodynamic assessment by testing the valves under more realistic deployed TAVR conditions in a patient-specific anatomical model of an AS patient with an advanced stage CAVD, using the Replicator pulse duplicator system (Vascular Simulations LLC, Stony Brook, NY, USA). 30 Importantly, the setup and testing conditions performed in this section were also compliant with ISO guidelines. CT scans of the patient were provided anonymously by Stony Brook University Hospital after obtaining approval from the institutional review board.…”

“…3D printing and molding of the aortic arch model was performed as previously described. 30 Several calcified aortic valve replicas were manufactured. Each of the test valves was then deployed in them: the 20-mm Polynova valves ( n = 3) with the nitinol stent were deployed manually, while the 20-mm Inovare valves ( n = 2) were balloon inflated to 3.5 atm according to the manufacturer guidelines.…”