Development of Novel Sutureless Balloon Expandable Fetal Heart Valve Device Using Absorbable Polycaprolactone Leaflets.

Congenital heart disease (CHD) accounts for nearly one-third of all congenital defects, and patients often require repeated heart valve replacements throughout their lives, due to failed surgical repairs and lack of durability of bioprosthetic valve implants. This objective of this study is to develop and in vitro test a fetal transcatheter pulmonary valve replacement (FTPVR) using sutureless techniques to attach leaflets, as an option to correct congenital defects such as pulmonary atresia with intact ventricular septum (PA/IVS), in utero. A balloon expandable design was analyzed using computational simulations to identify areas of failure. Five manufactured valves were assembled using the unique sutureless approach and tested in the fetal right heart simulator (FRHS) to evaluate hemodynamic characteristics. Computational simulations showed that the commissural loads on the leaflet material were significantly reduced by changing the attachment techniques. Hemodynamic analysis showed an effective orifice area of 0.08 cm2, a mean transvalvular pressure gradient of 7.52 mmHg, and a regurgitation fraction of 8.42%, calculated over 100 consecutive cardiac cycles. In conclusion, the FTPVR exhibited good hemodynamic characteristics, and studies with biodegradable stent materials are underway.

The role of flow stasis in transcatheter aortic valve leaflet thrombosis.

OBJECTIVE: With the recent expanded indication for transcatheter aortic valve replacement to low-risk surgical patients, thrombus formation in the neosinus is of particular interest due to concerns of reduced leaflet motion and long-term transcatheter heart valve durability. Although flow stasis likely plays a role, a direct connection between neosinus flow stasis and thrombus severity is yet to be established. METHODS: Patients (n = 23) were selected to minimize potential confounding factors related to thrombus formation. Patient-specific 3-dimensional reconstructed in vitro models were created to replicate in vivo anatomy and valve deployment using the patient-specific cardiac output and idealized coronary flows. Dye was injected into each neosinus to quantify washout time as a measure of flow stasis. RESULTS: Flow stasis (washout time) showed a significant, positive correlation with thrombus volume in the neosinus (rho = 0.621, P < .0001). Neither thrombus volume nor washout time was significantly different in the left, right, and noncoronary neosinuses (P ≥ .54). CONCLUSIONS: This is the first patient-specific study correlating flow stasis with thrombus volume in the neosinus post-transcatheter aortic valve replacement across multiple valve types and sizes. Neosinus-specific factors create hemodynamic and thrombotic variability within individual patients. Measurement of neosinus flow stasis may guide strategies to improve outcomes in transcatheter aortic valve replacement.

Influence of Patient-Specific Characteristics on Transcatheter Heart Valve Neo-Sinus Flow: An In Silico Study.

Thrombosis in post-transcatheter aortic valve replacement (TAVR) patients has been correlated with flow stasis in the neo-sinus. This study investigated the effect of the post-TAVR geometry on flow stasis. Computed tomography angiography of 155 patients who underwent TAVR using a SAPIEN 3 were used to identify patients with and without thrombosis, and quantify thrombus volumes. Six patients with 23-mm SAPIEN 3 valves were then selected from the cohort and used to create patient-specific post-TAVR computational fluid dynamic models. Regions of flow stasis (%Volstasis, velocities below 0.05 m/s) were identified. The results showed that all post-TAVR anatomical measurements were significantly different in patients with and without thrombus, but only sinus diameter had a linear correlation with thrombus volume (r = 0.471, p = 0.008). A linear correlation was observed between %Volstasis and thrombus volume (r = 0.821, p = 0.007). The combination of anatomy and valve deployment created a unique geometry in each patient, which when combined with patient-specific cardiac output, resulted in distinct flow patterns. While parametric studies have shown individual anatomical or deployment metrics may relate to flow stasis, the combined effects of these metrics potentially contributes to the biomechanical environment promoting thrombosis, therefore hemodynamic studies of TAVR should account for these patient-specific factors.