Pressure-Regulated Deployment of Balloon Expandable Transcatheter Aortic Valves: A Novel Approach to Valve Expansion

Abstract

Annular rupture is a devastating complication of transcatheter aortic valve implantation. The risk of rupture increases with prosthesis oversizing and subannular calcification. Conversely, under expanding valves to reduce risk of rupture increases the likelihood of paravalvular regurgitation, which is associated with poor long-term outcomes. Current deployment techniques are volume regulated and estimate prosthesis cross sectional area, based upon the volume to which a deployment balloon is filled. However, arterial wall tension is determined by both inflation pressure and balloon diameter, as demonstrated by Laplace's Law where: Hoop stress = Pressure × Diameter. Therefore, avoiding high pressures during valve deployment should reduce wall tension and risk of rupture. This study evaluated the safety and feasibility of deploying balloon-expandable transcatheter heart valves in a pressure-regulated manner. Valves were deployed between 4–5 atm, which resulted in residual volumes within the deployment syringe. Ninety-nine patients were included: 52 received valves deployed at 4 atm. Of these, 44% required postdilatation balloon aortic valvuloplasty (BAV), a surrogate marker for significant paravalvular regurgitation. In contrast, 41 patients received valves deployed between 4.5–5 atm and 24% required postdilatation BAV. This suggests that deployment at ≥4.5 atm significantly reduces paravalvular regurgitation after the initial deployment (p = 0.047). This cohort included 30 patients who received valves that would have been oversized by >20% if deployed at nominal volume, and 18 patients with moderate-severe subannular calcification. No patient experienced annular rupture. Thus, using pressure-limited technique it was demonstrated that safe deployment is possible, even in patients who are at high risk of annular rupture.